Merge pull request #10609 from facebook/revert-10606-7.6.1

Revert "Patch 7.6.1"

.circleci/config.yml

@@ -3,11 +3,6 @@ version: 2.1
 orbs:
   win: circleci/windows@2.4.0
 
-aliases:
-  - &notify-on-main-failure
-    fail_only: true
-    only_for_branches: main
-
 commands:
   install-cmake-on-macos:
     steps:
@@ -61,35 +56,21 @@ commands:
       - store_artifacts: # store LOG for debugging if there's any
           path: LOG
       - run: # on fail, compress Test Logs for diagnosing the issue
-         name: Compress Test Logs
-         command: tar -cvzf t.tar.gz t
-         when: on_fail
+          name: Compress Test Logs
+          command: tar -cvzf t.tar.gz t
+          when: on_fail
       - store_artifacts: # on fail, store Test Logs for diagnosing the issue
           path: t.tar.gz
           destination: test_logs
           when: on_fail
-
-  install-clang-10:
-    steps:
-      - run:
-          name: Install Clang 10
+      - run: # store core dumps if there's any
           command: |
-            wget -O - https://apt.llvm.org/llvm-snapshot.gpg.key | sudo apt-key add -
-            echo "deb http://apt.llvm.org/focal/ llvm-toolchain-focal-10 main" | sudo tee -a /etc/apt/sources.list
-            echo "deb-src http://apt.llvm.org/focal/ llvm-toolchain-focal-10 main" | sudo tee -a /etc/apt/sources.list
-            echo "APT::Acquire::Retries \"10\";" | sudo tee -a /etc/apt/apt.conf.d/80-retries # llvm.org unreliable
-            sudo apt-get update -y && sudo apt-get install -y clang-10
-
-  install-clang-13:
-    steps:
-      - run:
-          name: Install Clang 13
-          command: |
-            echo "deb http://apt.llvm.org/focal/ llvm-toolchain-focal-13 main" | sudo tee -a /etc/apt/sources.list
-            echo "deb-src http://apt.llvm.org/focal/ llvm-toolchain-focal-13 main" | sudo tee -a /etc/apt/sources.list
-            echo "APT::Acquire::Retries \"10\";" | sudo tee -a /etc/apt/apt.conf.d/80-retries # llvm.org unreliable
-            wget -O - https://apt.llvm.org/llvm-snapshot.gpg.key|sudo apt-key add -
-            sudo apt-get update -y && sudo apt-get install -y clang-13
+            mkdir -p /tmp/core_dumps
+            cp core.* /tmp/core_dumps
+          when: on_fail
+      - store_artifacts:
+          path: /tmp/core_dumps
+          when: on_fail
 
   install-gflags:
     steps:
@@ -98,33 +79,6 @@ commands:
           command: |
             sudo apt-get update -y && sudo apt-get install -y libgflags-dev
 
-  install-benchmark:
-    steps:
-      - run:
-          name: Install ninja build
-          command: sudo apt-get update -y && sudo apt-get install -y ninja-build
-      - run:
-          name: Install benchmark
-          command: |
-            git clone --depth 1 --branch v1.6.1 https://github.com/google/benchmark.git ~/benchmark
-            cd ~/benchmark && mkdir build && cd build
-            cmake .. -GNinja -DCMAKE_BUILD_TYPE=Release -DBENCHMARK_ENABLE_GTEST_TESTS=0
-            ninja && sudo ninja install
-
-  install-valgrind:
-    steps:
-      - run:
-          name: Install valgrind
-          command: sudo apt-get update -y && sudo apt-get install -y valgrind
-
-  upgrade-cmake:
-    steps:
-      - run:
-          name: Upgrade cmake
-          command: |
-            sudo apt remove --purge cmake
-            sudo snap install cmake --classic
-
   install-gflags-on-macos:
     steps:
       - run:
@@ -132,48 +86,8 @@ commands:
           command: |
             HOMEBREW_NO_AUTO_UPDATE=1 brew install gflags
 
-  install-gtest-parallel:
-    steps:
-      - run:
-          name: Install gtest-parallel
-          command: |
-            git clone --single-branch --branch master --depth 1 https://github.com/google/gtest-parallel.git ~/gtest-parallel
-            echo 'export PATH=$HOME/gtest-parallel:$PATH' >> $BASH_ENV
-
-  install-compression-libs:
-    steps:
-      - run:
-          name: Install compression libs
-          command: |
-            sudo apt-get update -y && sudo apt-get install -y libsnappy-dev zlib1g-dev libbz2-dev liblz4-dev libzstd-dev
-
-  install-streaming-compress-libs:
-    steps:
-      - run:
-          name: Install streaming compression libs
-          command: |
-            sudo apt-get update -y && sudo apt-get install -y libzstd-dev
-
-  install-libprotobuf-mutator:
-    steps:
-      - run:
-          name: Install libprotobuf-mutator libs
-          command: |
-            git clone -b v1.0 git@github.com:google/libprotobuf-mutator.git ~/libprotobuf-mutator
-            cd ~/libprotobuf-mutator && git checkout ffd86a32874e5c08a143019aad1aaf0907294c9f && mkdir build && cd build
-            cmake .. -GNinja -DCMAKE_C_COMPILER=clang-13 -DCMAKE_CXX_COMPILER=clang++-13 -DCMAKE_BUILD_TYPE=Release -DLIB_PROTO_MUTATOR_DOWNLOAD_PROTOBUF=ON
-            ninja && sudo ninja install
-      - run:
-          name: Setup environment variables
-          command: |
-            echo "export PKG_CONFIG_PATH=/usr/local/OFF/:~/libprotobuf-mutator/build/external.protobuf/lib/pkgconfig/" >> $BASH_ENV
-            echo "export PROTOC_BIN=~/libprotobuf-mutator/build/external.protobuf/bin/protoc" >> $BASH_ENV
   setup-folly:
     steps:
-      - run:
-          name: Install folly dependencies
-          command: |
-            sudo apt-get install libgoogle-glog-dev
       - run:
           name: Checkout folly sources
           command: |
@@ -190,14 +104,17 @@ commands:
   perform-benchmarks:
     steps:
       - run:
-          name: "Run basic benchmark, 5 min"
-          command: ./tools/benchmark.sh fillseq_enable_wal
+          name: "Test low-variance benchmarks"
+          command: ./tools/benchmark_ci.py --db_dir /tmp/rocksdb-benchmark-datadir --output_dir /tmp/benchmark-results --num_keys 10000000
           environment:
             LD_LIBRARY_PATH: /usr/local/lib
-            DB_DIR: /tmp/rocksdb-benchmark-datadir
-            WAL_DIR: /tmp/rocksdb-benchmark-waldir
-            OUTPUT_DIR: /tmp/benchmark-results
-            NUM_KEYS: 10000000
+            # How long to run parts of the test(s)
+            DURATION_RO: 450
+            DURATION_RW: 450
+            # The benchmark host has 32GB memory
+            # The folllowing values are tailored to work with that
+            # Note, tests may not exercise the targeted issues if the memory is increased on new test hosts.
+
 
   post-benchmarks:
     steps:
@@ -206,7 +123,11 @@ commands:
           destination: test_logs
       - run:
           name: Send benchmark report to visualisation
-          command: ./build_tools/benchmark_log_tool.py --tsvfile /tmp/benchmark-results/report.tsv --esdocument https://search-rocksdb-bench-k2izhptfeap2hjfxteolsgsynm.us-west-2.es.amazonaws.com/bench_test3/_doc
+          command: |
+            set +e
+            set +o pipefail
+            ./build_tools/benchmark_log_tool.py --tsvfile /tmp/benchmark-results/report.tsv --esdocument https://search-rocksdb-bench-k2izhptfeap2hjfxteolsgsynm.us-west-2.es.amazonaws.com/bench_test3_rix/_doc
+            true
 
 executors:
   windows-2xlarge:
@@ -214,6 +135,21 @@ executors:
       image: 'windows-server-2019-vs2019:stable'
       resource_class: windows.2xlarge
       shell: bash.exe
+  linux-docker:
+    docker:
+      # The image configuration is build_tools/ubuntu20_image/Dockerfile
+      # To update and build the image:
+      #  $ cd build_tools/ubuntu20_image
+      #  $ docker build -t zjay437/rocksdb:0.5 .
+      #  $ docker push zjay437/rocksdb:0.5
+      # `zjay437` is the account name for zjay@meta.com which readwrite token is shared internally. To login:
+      #  $ docker login --username zjay437
+      # Or please feel free to change it to your docker hub account for hosting the image, meta employee should already have the account and able to login with SSO.
+      # To avoid impacting the existing CI runs, please bump the version every time creating a new image
+      # to run the CI image environment locally:
+      #  $ docker run --cap-add=SYS_PTRACE --security-opt seccomp=unconfined -it zjay437/rocksdb:0.5 bash
+      # option `--cap-add=SYS_PTRACE --security-opt seccomp=unconfined` is used to enable gdb to attach an existing process
+      - image: zjay437/rocksdb:0.5
 
 jobs:
   build-macos:
@@ -265,172 +201,132 @@ jobs:
       - post-steps
 
   build-linux:
-    machine:
-      image: ubuntu-2004:202111-02
+    executor: linux-docker
     resource_class: 2xlarge
     steps:
       - pre-steps
-      - install-gflags
-      - install-streaming-compress-libs
       - run: make V=1 J=32 -j32 check
       - post-steps
 
   build-linux-encrypted_env-no_compression:
-    machine:
-      image: ubuntu-2004:202111-02
+    executor: linux-docker
     resource_class: 2xlarge
     steps:
       - pre-steps
-      - install-gflags
       - run: ENCRYPTED_ENV=1 ROCKSDB_DISABLE_SNAPPY=1 ROCKSDB_DISABLE_ZLIB=1 ROCKSDB_DISABLE_BZIP=1 ROCKSDB_DISABLE_LZ4=1 ROCKSDB_DISABLE_ZSTD=1 make V=1 J=32 -j32 check
       - run: |
           ./sst_dump --help | egrep -q 'Supported compression types: kNoCompression$' # Verify no compiled in compression
       - post-steps
 
   build-linux-shared_lib-alt_namespace-status_checked:
-    machine:
-      image: ubuntu-2004:202111-02
+    executor: linux-docker
     resource_class: 2xlarge
     steps:
       - pre-steps
-      - install-gflags
       - run: ASSERT_STATUS_CHECKED=1 TEST_UINT128_COMPAT=1 ROCKSDB_MODIFY_NPHASH=1 LIB_MODE=shared OPT="-DROCKSDB_NAMESPACE=alternative_rocksdb_ns" make V=1 -j32 check
       - post-steps
 
   build-linux-release:
-    machine:
-      image: ubuntu-2004:202111-02
+    executor: linux-docker
     resource_class: 2xlarge
     steps:
       - checkout # check out the code in the project directory
       - run: make V=1 -j32 release
-      - run: if ./db_stress --version; then false; else true; fi # ensure without gflags
-      - install-gflags
-      - run: make V=1 -j32 release
       - run: ./db_stress --version # ensure with gflags
+      - run: make clean
+      - run: apt-get remove -y libgflags-dev
+      - run: make V=1 -j32 release
+      - run: if ./db_stress --version; then false; else true; fi # ensure without gflags
       - post-steps
 
   build-linux-release-rtti:
-    machine:
-      image: ubuntu-2004:202111-02
+    executor: linux-docker
     resource_class: xlarge
     steps:
       - checkout # check out the code in the project directory
-      - run: make clean
-      - run: USE_RTTI=1 DEBUG_LEVEL=0 make V=1 -j16 static_lib tools db_bench
-      - run: if ./db_stress --version; then false; else true; fi # ensure without gflags
-      - run: sudo apt-get update -y && sudo apt-get install -y libgflags-dev
-      - run: make clean
       - run: USE_RTTI=1 DEBUG_LEVEL=0 make V=1 -j16 static_lib tools db_bench
       - run: ./db_stress --version # ensure with gflags
+      - run: make clean
+      - run: apt-get remove -y libgflags-dev
+      - run: USE_RTTI=1 DEBUG_LEVEL=0 make V=1 -j16 static_lib tools db_bench
+      - run: if ./db_stress --version; then false; else true; fi # ensure without gflags
 
   build-linux-lite:
-    machine:
-      image: ubuntu-2004:202111-02
+    executor: linux-docker
     resource_class: large
     steps:
       - pre-steps
-      - install-gflags
       - run: LITE=1 make V=1 J=8 -j8 check
       - post-steps
 
   build-linux-lite-release:
-    machine:
-      image: ubuntu-2004:202111-02
+    executor: linux-docker
     resource_class: large
     steps:
       - checkout # check out the code in the project directory
       - run: LITE=1 make V=1 -j8 release
-      - run: if ./db_stress --version; then false; else true; fi # ensure without gflags
-      - install-gflags
-      - run: LITE=1 make V=1 -j8 release
       - run: ./db_stress --version # ensure with gflags
+      - run: make clean
+      - run: apt-get remove -y libgflags-dev
+      - run: LITE=1 make V=1 -j8 release
+      - run: if ./db_stress --version; then false; else true; fi # ensure without gflags
       - post-steps
 
   build-linux-clang-no_test_run:
-    machine:
-      image: ubuntu-2004:202111-02
+    executor: linux-docker
     resource_class: xlarge
     steps:
       - checkout # check out the code in the project directory
-      - run: sudo apt-get update -y && sudo apt-get install -y clang libgflags-dev libtbb-dev
       - run: CC=clang CXX=clang++ USE_CLANG=1 PORTABLE=1 make V=1 -j16 all
       - post-steps
 
   build-linux-clang10-asan:
-    machine:
-      image: ubuntu-2004:202111-02
+    executor: linux-docker
     resource_class: 2xlarge
     steps:
       - pre-steps
-      - install-gflags
-      - install-clang-10
       - run: COMPILE_WITH_ASAN=1 CC=clang-10 CXX=clang++-10 ROCKSDB_DISABLE_ALIGNED_NEW=1 USE_CLANG=1 make V=1 -j32 check # aligned new doesn't work for reason we haven't figured out
       - post-steps
 
   build-linux-clang10-mini-tsan:
-    machine:
-      image: ubuntu-2004:202111-02
-    resource_class: 2xlarge
-    # find test list by `make list_all_tests`
-    parameters:
-      start_test:
-        default: ""
-        type: string
-      end_test:
-        default: ""
-        type: string
+    executor: linux-docker
+    resource_class: 2xlarge+
     steps:
       - pre-steps
-      - install-gflags
-      - install-clang-10
-      - install-gtest-parallel
-      - run:
-          name: "Build unit tests"
-          command: |
-            echo "env: $(env)"
-            ROCKSDBTESTS_START=<<parameters.start_test>> ROCKSDBTESTS_END=<<parameters.end_test>> ROCKSDBTESTS_SUBSET_TESTS_TO_FILE=/tmp/test_list COMPILE_WITH_TSAN=1 CC=clang-10 CXX=clang++-10 ROCKSDB_DISABLE_ALIGNED_NEW=1 USE_CLANG=1 make V=1 -j32 --output-sync=target build_subset_tests
-      - run:
-          name: "Run unit tests in parallel"
-          command: |
-            sed -i 's/[[:space:]]*$//; s/ / \.\//g; s/.*/.\/&/' /tmp/test_list
-            cat /tmp/test_list
-            gtest-parallel $(</tmp/test_list) --output_dir=/tmp | cat  # pipe to cat to continuously output status on circleci UI. Otherwise, no status will be printed while the job is running.
+      - run: COMPILE_WITH_TSAN=1 CC=clang-13 CXX=clang++-13 ROCKSDB_DISABLE_ALIGNED_NEW=1 USE_CLANG=1 make V=1 -j32 check
       - post-steps
 
   build-linux-clang10-ubsan:
-    machine:
-      image: ubuntu-2004:202111-02
+    executor: linux-docker
     resource_class: 2xlarge
     steps:
       - pre-steps
-      - install-gflags
-      - install-clang-10
       - run: COMPILE_WITH_UBSAN=1 OPT="-fsanitize-blacklist=.circleci/ubsan_suppression_list.txt" CC=clang-10 CXX=clang++-10 ROCKSDB_DISABLE_ALIGNED_NEW=1 USE_CLANG=1 make V=1 -j32 ubsan_check # aligned new doesn't work for reason we haven't figured out
       - post-steps
 
   build-linux-valgrind:
-    machine:
-      image: ubuntu-2004:202111-02
+    executor: linux-docker
     resource_class: 2xlarge
     steps:
       - pre-steps
-      - install-gflags
-      - install-valgrind
       - run: PORTABLE=1 make V=1 -j32 valgrind_test
       - post-steps
 
   build-linux-clang10-clang-analyze:
-    machine:
-      image: ubuntu-2004:202111-02
+    executor: linux-docker
     resource_class: 2xlarge
     steps:
       - pre-steps
-      - install-gflags
-      - install-clang-10
-      - run: sudo apt-get update -y && sudo apt-get install -y clang-tools-10
       - run: CC=clang-10 CXX=clang++-10 ROCKSDB_DISABLE_ALIGNED_NEW=1 CLANG_ANALYZER="/usr/bin/clang++-10" CLANG_SCAN_BUILD=scan-build-10 USE_CLANG=1 make V=1 -j32 analyze # aligned new doesn't work for reason we haven't figured out. For unknown, reason passing "clang++-10" as CLANG_ANALYZER doesn't work, and we need a full path.
       - post-steps
+      - run:
+          name: "compress test report"
+          command: tar -cvzf scan_build_report.tar.gz scan_build_report
+          when: on_fail
+      - store_artifacts:
+          path: scan_build_report.tar.gz
+          destination: scan_build_report
+          when: on_fail
 
   build-linux-runner:
     machine: true
@@ -445,26 +341,20 @@ jobs:
       - post-steps
 
   build-linux-cmake-with-folly:
-    machine:
-      image: ubuntu-2004:202111-02
+    executor: linux-docker
     resource_class: 2xlarge
     steps:
       - pre-steps
-      - install-gflags
-      - upgrade-cmake
       - setup-folly
       - run: (mkdir build && cd build && cmake -DUSE_FOLLY=1 -DWITH_GFLAGS=1 .. && make V=1 -j20 && ctest -j20)
       - post-steps
 
   build-linux-cmake-with-benchmark:
-    machine:
-      image: ubuntu-2004:202111-02
+    executor: linux-docker
     resource_class: 2xlarge
     steps:
       - pre-steps
-      - install-gflags
-      - install-benchmark
-      - run: (mkdir build && cd build && cmake -DWITH_GFLAGS=1 -DWITH_BENCHMARK=1 .. && make V=1 -j20 && ctest -j20)
+      - run: mkdir build && cd build && cmake -DWITH_GFLAGS=1 -DWITH_BENCHMARK=1 .. && make V=1 -j20 && ctest -j20
       - post-steps
 
   build-linux-unity-and-headers:
@@ -481,93 +371,95 @@ jobs:
       - post-steps
 
   build-linux-gcc-7-with-folly:
-    machine:
-      image: ubuntu-2004:202111-02
+    executor: linux-docker
     resource_class: 2xlarge
     steps:
       - pre-steps
-      - run: sudo add-apt-repository -y ppa:ubuntu-toolchain-r/test && sudo apt-get update -y && sudo apt-get install gcc-7 g++-7 libgflags-dev
       - setup-folly
       - run: USE_FOLLY=1 CC=gcc-7 CXX=g++-7 V=1 make -j32 check
       - post-steps
 
   build-linux-gcc-8-no_test_run:
-    machine:
-      image: ubuntu-2004:202111-02
-    resource_class: xlarge
+    executor: linux-docker
+    resource_class: 2xlarge
     steps:
       - pre-steps
-      - run: sudo add-apt-repository -y ppa:ubuntu-toolchain-r/test && sudo apt-get update -y && sudo apt-get install gcc-8 g++-8 libgflags-dev
-      - run: CC=gcc-8 CXX=g++-8 V=1 make -j16 all
+      - run: CC=gcc-8 CXX=g++-8 V=1 make -j32 all
       - post-steps
 
   build-linux-gcc-10-cxx20-no_test_run:
-    machine:
-      image: ubuntu-2004:202111-02
-    resource_class: xlarge
+    executor: linux-docker
+    resource_class: 2xlarge
     steps:
       - pre-steps
-      - run: sudo apt-get update -y && sudo apt-get install gcc-10 g++-10 libgflags-dev
-      - run: CC=gcc-10 CXX=g++-10 V=1 ROCKSDB_CXX_STANDARD=c++20 make -j16 all
+      - run: CC=gcc-10 CXX=g++-10 V=1 ROCKSDB_CXX_STANDARD=c++20 make -j32 all
       - post-steps
 
   build-linux-gcc-11-no_test_run:
-    machine:
-      image: ubuntu-2004:202111-02
-    resource_class: xlarge
+    executor: linux-docker
+    resource_class: 2xlarge
     steps:
       - pre-steps
-      - run: sudo add-apt-repository -y ppa:ubuntu-toolchain-r/test && sudo apt-get update -y && sudo apt-get install gcc-11 g++-11 libgflags-dev
-      - install-benchmark
-      - run: CC=gcc-11 CXX=g++-11 V=1 make -j16 all microbench
+      - run: CC=gcc-11 CXX=g++-11 V=1 make -j32 all microbench
       - post-steps
 
   build-linux-clang-13-no_test_run:
-    machine:
-      image: ubuntu-2004:202111-02
-    resource_class: xlarge
+    executor: linux-docker
+    resource_class: 2xlarge
     steps:
       - pre-steps
-      - install-clang-13
-      - install-benchmark
-      - run: CC=clang-13 CXX=clang++-13 USE_CLANG=1 make -j16 all microbench
+      - run: CC=clang-13 CXX=clang++-13 USE_CLANG=1 make -j32 all microbench
       - post-steps
 
   # Ensure ASAN+UBSAN with folly, and full testsuite with clang 13
   build-linux-clang-13-asan-ubsan-with-folly:
-    machine:
-      image: ubuntu-2004:202111-02
+    executor: linux-docker
     resource_class: 2xlarge
     steps:
       - pre-steps
-      - install-clang-13
-      - install-gflags
       - setup-folly
       - run: CC=clang-13 CXX=clang++-13 USE_CLANG=1 USE_FOLLY=1 COMPILE_WITH_UBSAN=1 COMPILE_WITH_ASAN=1 make -j32 check
       - post-steps
 
   # This job is only to make sure the microbench tests are able to run, the benchmark result is not meaningful as the CI host is changing.
   build-linux-run-microbench:
-    machine:
-      image: ubuntu-2004:202111-02
+    executor: linux-docker
     resource_class: 2xlarge
     steps:
       - pre-steps
-      - install-benchmark
       - run: DEBUG_LEVEL=0 make -j32 run_microbench
       - post-steps
 
   build-linux-mini-crashtest:
-    machine:
-      image: ubuntu-2004:202111-02
+    executor: linux-docker
     resource_class: large
     steps:
       - pre-steps
-      - install-gflags
-      - install-compression-libs
       - run: ulimit -S -n `ulimit -H -n` && make V=1 -j8 CRASH_TEST_EXT_ARGS=--duration=960 blackbox_crash_test_with_atomic_flush
       - post-steps
 
+  build-linux-crashtest-tiered-storage-bb:
+    executor: linux-docker
+    resource_class: 2xlarge
+    steps:
+      - pre-steps
+      - run:
+          name: "run crashtest"
+          command: ulimit -S -n `ulimit -H -n` && make V=1 -j32 CRASH_TEST_EXT_ARGS=--duration=10800 blackbox_crash_test_with_tiered_storage
+          no_output_timeout: 100m
+      - post-steps
+
+  build-linux-crashtest-tiered-storage-wb:
+    executor: linux-docker
+    resource_class: 2xlarge
+    steps:
+      - pre-steps
+      - run:
+          name: "run crashtest"
+          command: ulimit -S -n `ulimit -H -n` && make V=1 -j32 CRASH_TEST_EXT_ARGS=--duration=10800 whitebox_crash_test_with_tiered_storage
+          no_output_timeout: 100m
+      - post-steps
+
   build-windows:
     executor: windows-2xlarge
     parameters:
@@ -637,14 +529,10 @@ jobs:
             build_tools\run_ci_db_test.ps1 -SuiteRun db_basic_test,db_test,db_test2,db_merge_operand_test,bloom_test,c_test,coding_test,crc32c_test,dynamic_bloom_test,env_basic_test,env_test,hash_test,random_test -Concurrency 16
 
   build-linux-java:
-    machine:
-      image: ubuntu-2004:202111-02
+    executor: linux-docker
     resource_class: large
-    environment:
-      JAVA_HOME: /usr/lib/jvm/java-1.8.0-openjdk-amd64
     steps:
       - pre-steps
-      - install-gflags
       - run:
           name: "Set Java Environment"
           command: |
@@ -658,14 +546,10 @@ jobs:
       - post-steps
 
   build-linux-java-static:
-    machine:
-      image: ubuntu-2004:202111-02
+    executor: linux-docker
     resource_class: large
-    environment:
-      JAVA_HOME: /usr/lib/jvm/java-1.8.0-openjdk-amd64
     steps:
       - pre-steps
-      - install-gflags
       - run:
           name: "Set Java Environment"
           command: |
@@ -751,34 +635,25 @@ jobs:
       - post-steps
 
   build-examples:
-    machine:
-      image: ubuntu-2004:202111-02
+    executor: linux-docker
     resource_class: large
     steps:
       - pre-steps
-      - install-gflags
       - run:
           name: "Build examples"
           command: |
-            OPT=-DTRAVIS V=1 make -j4 static_lib && cd examples && make -j4
+            make V=1 -j4 static_lib && cd examples && make V=1 -j4
       - post-steps
 
   build-cmake-mingw:
-    machine:
-      image: ubuntu-2004:202111-02
+    executor: linux-docker
     resource_class: large
     steps:
       - pre-steps
-      - install-gflags
-      - run: sudo apt-get update -y && sudo apt-get install -y mingw-w64
-      - run: sudo update-alternatives --set x86_64-w64-mingw32-g++ /usr/bin/x86_64-w64-mingw32-g++-posix
+      - run: update-alternatives --set x86_64-w64-mingw32-g++ /usr/bin/x86_64-w64-mingw32-g++-posix
       - run:
           name: "Build cmake-mingw"
           command: |
-            sudo apt-get install snapd && sudo snap install cmake --beta --classic
-            export PATH=/snap/bin:$PATH
-            sudo apt-get install -y openjdk-8-jdk
-            export JAVA_HOME=/usr/lib/jvm/java-8-openjdk-amd64
             export PATH=$JAVA_HOME/bin:$PATH
             echo "JAVA_HOME=${JAVA_HOME}"
             which java && java -version
@@ -787,14 +662,12 @@ jobs:
       - post-steps
 
   build-linux-non-shm:
-    machine:
-      image: ubuntu-2004:202111-02
+    executor: linux-docker
     resource_class: 2xlarge
     environment:
       TEST_TMPDIR: /tmp/rocksdb_test_tmp
     steps:
       - pre-steps
-      - install-gflags
       - run: make V=1 -j32 check
       - post-steps
 
@@ -852,13 +725,10 @@ jobs:
       - post-steps
 
   build-format-compatible:
-    machine:
-      image: ubuntu-2004:202111-02
+    executor: linux-docker
     resource_class: 2xlarge
     steps:
       - pre-steps
-      - install-gflags
-      - install-compression-libs
       - run:
           name: "test"
           command: |
@@ -869,14 +739,10 @@ jobs:
       - post-steps
 
   build-fuzzers:
-    machine:
-      image: ubuntu-2004:202111-02
+    executor: linux-docker
     resource_class: large
     steps:
       - pre-steps
-      - install-clang-13
-      - run: sudo apt-get update -y && sudo apt-get install -y cmake ninja-build binutils liblzma-dev libz-dev pkg-config autoconf libtool
-      - install-libprotobuf-mutator
       - run:
           name: "Build rocksdb lib"
           command: CC=clang-13 CXX=clang++-13 USE_CLANG=1 make -j4 static_lib
@@ -907,12 +773,7 @@ workflows:
     jobs:
       - build-linux-clang10-asan
       - build-linux-clang10-ubsan
-      - build-linux-clang10-mini-tsan:
-          start_test: ""
-          end_test: "env_test"
-      - build-linux-clang10-mini-tsan:
-          start_test: "env_test"
-          end_test: ""
+      - build-linux-clang10-mini-tsan
       - build-linux-shared_lib-alt_namespace-status_checked
   jobs-linux-no-test-run:
     jobs:
@@ -964,6 +825,16 @@ workflows:
   build-fuzzers:
     jobs:
       - build-fuzzers
+  benchmark-linux:
+    triggers:
+      - schedule:
+          cron: "0 * * * *"
+          filters:
+            branches:
+              only:
+                - main
+    jobs:
+      - benchmark-linux
   nightly:
     triggers:
       - schedule:

.travis.yml

@@ -1,280 +0,0 @@
-dist: xenial
-language: cpp
-os:
-  - linux
-arch:
-  - arm64
-  - ppc64le
-  - s390x
-compiler:
-  - clang
-  - gcc
-cache:
-  - ccache
-
-addons:
-  apt:
-    update: true
-    sources:
-      - ubuntu-toolchain-r-test
-    packages:
-      - libgflags-dev
-      - libbz2-dev
-      - liblz4-dev
-      - libsnappy-dev
-      - liblzma-dev  # xv
-      - libzstd-dev
-      - zlib1g-dev
-
-env:
-  - TEST_GROUP=platform_dependent # 16-18 minutes
-  - TEST_GROUP=1 # 33-35 minutes
-  - TEST_GROUP=2 # 18-20 minutes
-  - TEST_GROUP=3 # 20-22 minutes
-  - TEST_GROUP=4 # 12-14 minutes
-  # Run java tests
-  - JOB_NAME=java_test # 4-11 minutes
-  # Build ROCKSDB_LITE
-  - JOB_NAME=lite_build # 3-4 minutes
-  # Build examples
-  - JOB_NAME=examples # 5-7 minutes
-  - JOB_NAME=cmake # 3-5 minutes
-  - JOB_NAME=cmake-gcc8 # 3-5 minutes
-  - JOB_NAME=cmake-gcc9 # 3-5 minutes
-  - JOB_NAME=cmake-gcc9-c++20 # 3-5 minutes
-  - JOB_NAME=cmake-mingw # 3 minutes
-
-matrix:
-  exclude:
-  - os : linux
-    arch: arm64
-    env: JOB_NAME=cmake-mingw
-  - os: linux
-    arch: ppc64le
-    env: JOB_NAME=cmake-mingw
-  - os: linux
-    arch: s390x
-    env: JOB_NAME=cmake-mingw
-  - os: linux
-    compiler: clang
-  - if: type = pull_request AND commit_message !~ /FULL_CI/
-    os: linux
-    arch: arm64
-    env: TEST_GROUP=platform_dependent
-  - if: type = pull_request AND commit_message !~ /FULL_CI/
-    os : linux
-    arch: arm64
-    env: TEST_GROUP=1
-  - if: type = pull_request AND commit_message !~ /FULL_CI/
-    os: linux
-    arch: ppc64le
-    env: TEST_GROUP=1
-  - if: type = pull_request AND commit_message !~ /FULL_CI/
-    os: linux
-    arch: s390x
-    env: TEST_GROUP=1
-  - if: type = pull_request AND commit_message !~ /FULL_CI/
-    os : linux
-    arch: arm64
-    env: TEST_GROUP=2
-  - if: type = pull_request AND commit_message !~ /FULL_CI/
-    os: linux
-    arch: ppc64le
-    env: TEST_GROUP=2
-  - if: type = pull_request AND commit_message !~ /FULL_CI/
-    os: linux
-    arch: s390x
-    env: TEST_GROUP=2
-  - if: type = pull_request AND commit_message !~ /FULL_CI/
-    os : linux
-    arch: arm64
-    env: TEST_GROUP=3
-  - if: type = pull_request AND commit_message !~ /FULL_CI/
-    os: linux
-    arch: ppc64le
-    env: TEST_GROUP=3
-  - if: type = pull_request AND commit_message !~ /FULL_CI/
-    os: linux
-    arch: s390x
-    env: TEST_GROUP=3
-  - if: type = pull_request AND commit_message !~ /FULL_CI/
-    os : linux
-    arch: arm64
-    env: TEST_GROUP=4
-  - if: type = pull_request AND commit_message !~ /FULL_CI/
-    os: linux
-    arch: ppc64le
-    env: TEST_GROUP=4
-  - if: type = pull_request AND commit_message !~ /FULL_CI/
-    os: linux
-    arch: s390x
-    env: TEST_GROUP=4
-  - if: type = pull_request AND commit_message !~ /FULL_CI/
-    os : linux
-    arch: arm64
-    env: JOB_NAME=cmake
-  - if: type = pull_request AND commit_message !~ /FULL_CI/ AND commit_message !~ /java/
-    os : linux
-    arch: arm64
-    env: JOB_NAME=java_test
-  - if: type = pull_request AND commit_message !~ /FULL_CI/ AND commit_message !~ /java/
-    os: linux
-    arch: ppc64le
-    env: JOB_NAME=java_test
-  - if: type = pull_request AND commit_message !~ /FULL_CI/ AND commit_message !~ /java/
-    os: linux
-    arch: s390x
-    env: JOB_NAME=java_test
-  - if: type = pull_request AND commit_message !~ /FULL_CI/
-    os : linux
-    arch: arm64
-    env: JOB_NAME=lite_build
-  - if: type = pull_request AND commit_message !~ /FULL_CI/
-    os: linux
-    arch: ppc64le
-    env: JOB_NAME=lite_build
-  - if: type = pull_request AND commit_message !~ /FULL_CI/
-    os: linux
-    arch: s390x
-    env: JOB_NAME=lite_build
-  - if: type = pull_request AND commit_message !~ /FULL_CI/
-    os : linux
-    arch: arm64
-    env: JOB_NAME=examples
-  - if: type = pull_request AND commit_message !~ /FULL_CI/
-    os: linux
-    arch: ppc64le
-    env: JOB_NAME=examples
-  - if: type = pull_request AND commit_message !~ /FULL_CI/
-    os: linux
-    arch: s390x
-    env: JOB_NAME=examples
-  - if: type = pull_request AND commit_message !~ /FULL_CI/
-    os : linux
-    arch: arm64
-    env: JOB_NAME=cmake-gcc8
-  - if: type = pull_request AND commit_message !~ /FULL_CI/
-    os: linux
-    arch: ppc64le
-    env: JOB_NAME=cmake-gcc8
-  - if: type = pull_request AND commit_message !~ /FULL_CI/
-    os: linux
-    arch: s390x
-    env: JOB_NAME=cmake-gcc8
-  - if: type = pull_request AND commit_message !~ /FULL_CI/
-    os : linux
-    arch: arm64
-    env: JOB_NAME=cmake-gcc9
-  - if: type = pull_request AND commit_message !~ /FULL_CI/
-    os: linux
-    arch: ppc64le
-    env: JOB_NAME=cmake-gcc9
-  - if: type = pull_request AND commit_message !~ /FULL_CI/
-    os: linux
-    arch: s390x
-    env: JOB_NAME=cmake-gcc9
-  - if: type = pull_request AND commit_message !~ /FULL_CI/
-    os : linux
-    arch: arm64
-    env: JOB_NAME=cmake-gcc9-c++20
-  - if: type = pull_request AND commit_message !~ /FULL_CI/
-    os: linux
-    arch: ppc64le
-    env: JOB_NAME=cmake-gcc9-c++20
-  - if: type = pull_request AND commit_message !~ /FULL_CI/
-    os: linux
-    arch: s390x
-    env: JOB_NAME=cmake-gcc9-c++20
-
-install:
-  -  CC=gcc-7 && CXX=g++-7
-  - if [ "${JOB_NAME}" == cmake-gcc8 ]; then
-      sudo apt-get install -y g++-8 || exit $?;
-      CC=gcc-8 && CXX=g++-8;
-    fi
-  - if [ "${JOB_NAME}" == cmake-gcc9 ] || [ "${JOB_NAME}" == cmake-gcc9-c++20 ]; then
-      sudo apt-get install -y g++-9 || exit $?;
-      CC=gcc-9 && CXX=g++-9;
-    fi
-  - if [ "${JOB_NAME}" == cmake-mingw ]; then
-      sudo apt-get install -y mingw-w64 || exit $?;
-    fi
-  - if [ "${CXX}" == "g++-7" ]; then
-      sudo apt-get install -y g++-7 || exit $?;
-    fi
-  - |
-    if [[ "${JOB_NAME}" == cmake* ]]; then
-      sudo apt-get remove -y cmake cmake-data
-      export CMAKE_DEB="cmake-3.14.5-Linux-$(uname -m).deb"
-      export CMAKE_DEB_URL="https://rocksdb-deps.s3-us-west-2.amazonaws.com/cmake/${CMAKE_DEB}"
-      curl --silent --fail --show-error --location --output "${CMAKE_DEB}" "${CMAKE_DEB_URL}" || exit $?
-      sudo dpkg -i "${CMAKE_DEB}" || exit $?
-      which cmake && cmake --version
-    fi
-  - |
-    if [[ "${JOB_NAME}" == java_test || "${JOB_NAME}" == cmake* ]]; then
-      # Ensure JDK 8
-      sudo apt-get install -y openjdk-8-jdk || exit $?
-      export PATH=/usr/lib/jvm/java-8-openjdk-$(dpkg --print-architecture)/bin:$PATH
-      export JAVA_HOME=/usr/lib/jvm/java-8-openjdk-$(dpkg --print-architecture)
-      echo "JAVA_HOME=${JAVA_HOME}"
-      which java && java -version
-      which javac && javac -version
-    fi
-
-before_script:
-  # Increase the maximum number of open file descriptors, since some tests use
-  # more FDs than the default limit.
-  - ulimit -n 8192
-
-script:
-  - date; ${CXX} --version
-  - if [ `command -v ccache` ]; then ccache -C; fi
-  - export MK_PARALLEL=4;
-    if [[ "$TRAVIS_CPU_ARCH" == s390x ]]; then
-      export MK_PARALLEL=1;
-    fi
-  - case $TEST_GROUP in
-    platform_dependent)
-      OPT=-DTRAVIS LIB_MODE=shared V=1 ROCKSDBTESTS_PLATFORM_DEPENDENT=only make -j$MK_PARALLEL all_but_some_tests check_some
-      ;;
-    1)
-      OPT=-DTRAVIS LIB_MODE=shared V=1 ROCKSDBTESTS_PLATFORM_DEPENDENT=exclude ROCKSDBTESTS_END=backup_engine_test make -j$MK_PARALLEL check_some
-      ;;
-    2)
-      OPT="-DTRAVIS -DROCKSDB_NAMESPACE=alternative_rocksdb_ns" LIB_MODE=shared V=1 make -j$MK_PARALLEL tools && OPT="-DTRAVIS -DROCKSDB_NAMESPACE=alternative_rocksdb_ns" LIB_MODE=shared V=1 ROCKSDBTESTS_PLATFORM_DEPENDENT=exclude ROCKSDBTESTS_START=backup_engine_test ROCKSDBTESTS_END=db_universal_compaction_test make -j$MK_PARALLEL check_some
-      ;;
-    3)
-      OPT=-DTRAVIS LIB_MODE=shared V=1 ROCKSDBTESTS_PLATFORM_DEPENDENT=exclude ROCKSDBTESTS_START=db_universal_compaction_test ROCKSDBTESTS_END=table_properties_collector_test make -j$MK_PARALLEL check_some
-      ;;
-    4)
-      OPT=-DTRAVIS LIB_MODE=shared V=1 ROCKSDBTESTS_PLATFORM_DEPENDENT=exclude ROCKSDBTESTS_START=table_properties_collector_test make -j$MK_PARALLEL check_some
-      ;;
-    esac
-  - case $JOB_NAME in
-    java_test)
-      OPT=-DTRAVIS LIB_MODE=shared V=1 make rocksdbjava jtest
-      ;;
-    lite_build)
-      OPT='-DTRAVIS -DROCKSDB_LITE' LIB_MODE=shared V=1 make -j$MK_PARALLEL all
-      ;;
-    examples)
-      OPT=-DTRAVIS LIB_MODE=shared V=1 make -j$MK_PARALLEL static_lib && cd examples && make -j$MK_PARALLEL
-      ;;
-    cmake-mingw)
-      sudo update-alternatives --set x86_64-w64-mingw32-g++ /usr/bin/x86_64-w64-mingw32-g++-posix;
-      mkdir build && cd build && cmake -DJNI=1 -DWITH_GFLAGS=OFF .. -DCMAKE_C_COMPILER=x86_64-w64-mingw32-gcc -DCMAKE_CXX_COMPILER=x86_64-w64-mingw32-g++ -DCMAKE_SYSTEM_NAME=Windows && make -j4 rocksdb rocksdbjni
-      ;;
-    cmake*)
-      case $JOB_NAME in
-        *-c++20)
-          OPT=-DCMAKE_CXX_STANDARD=20
-          ;;
-      esac
-
-      mkdir build && cd build && cmake -DCMAKE_BUILD_TYPE=Release -DWITH_TESTS=0 -DWITH_GFLAGS=0 -DWITH_BENCHMARK_TOOLS=0 -DWITH_TOOLS=0 -DWITH_CORE_TOOLS=1 .. && make -j$MK_PARALLEL && cd  .. && rm -rf build && mkdir build && cd build && cmake -DJNI=1 .. -DCMAKE_BUILD_TYPE=Release $OPT && make -j$MK_PARALLEL rocksdb rocksdbjni
-      ;;
-    esac
-notifications:
-    email:
-      - leveldb@fb.com

CMakeLists.txt

@@ -598,6 +598,7 @@ set(SOURCES
         cache/cache_entry_roles.cc
         cache/cache_key.cc
         cache/cache_reservation_manager.cc
+        cache/charged_cache.cc
         cache/clock_cache.cc
         cache/compressed_secondary_cache.cc
         cache/fast_lru_cache.cc
@@ -627,7 +628,11 @@ set(SOURCES
         db/compaction/compaction_picker_fifo.cc
         db/compaction/compaction_picker_level.cc
         db/compaction/compaction_picker_universal.cc
+        db/compaction/compaction_service_job.cc
+        db/compaction/compaction_state.cc
+        db/compaction/compaction_outputs.cc
         db/compaction/sst_partitioner.cc
+        db/compaction/subcompaction_state.cc
         db/convenience.cc
         db/db_filesnapshot.cc
         db/db_impl/compacted_db_impl.cc
@@ -666,6 +671,7 @@ set(SOURCES
         db/range_del_aggregator.cc
         db/range_tombstone_fragmenter.cc
         db/repair.cc
+        db/seqno_to_time_mapping.cc
         db/snapshot_impl.cc
         db/table_cache.cc
         db/table_properties_collector.cc
@@ -678,6 +684,7 @@ set(SOURCES
         db/wal_edit.cc
         db/wal_manager.cc
         db/wide/wide_column_serialization.cc
+        db/wide/wide_columns.cc
         db/write_batch.cc
         db/write_batch_base.cc
         db/write_controller.cc
@@ -1003,7 +1010,7 @@ set(ROCKSDB_PLUGIN_BUILTINS "")
 message(STATUS "ROCKSDB PLUGINS TO BUILD ${ROCKSDB_PLUGINS}")
 list(APPEND PLUGINS ${ROCKSDB_PLUGINS})
 foreach(PLUGIN IN LISTS PLUGINS)
-  set(PLUGIN_ROOT "${CMAKE_SOURCE_DIR}/plugin/${PLUGIN}/")
+  set(PLUGIN_ROOT "${CMAKE_CURRENT_SOURCE_DIR}/plugin/${PLUGIN}/")
   message("including rocksb plugin ${PLUGIN_ROOT}")
   set(PLUGINMKFILE "${PLUGIN_ROOT}${PLUGIN}.mk")
   if (NOT EXISTS ${PLUGINMKFILE})
@@ -1231,6 +1238,7 @@ if(WITH_TESTS)
         db/compaction/compaction_iterator_test.cc
         db/compaction/compaction_picker_test.cc
         db/compaction/compaction_service_test.cc
+        db/compaction/tiered_compaction_test.cc
         db/comparator_db_test.cc
         db/corruption_test.cc
         db/cuckoo_table_db_test.cc
@@ -1291,6 +1299,7 @@ if(WITH_TESTS)
         db/perf_context_test.cc
         db/periodic_work_scheduler_test.cc
         db/plain_table_db_test.cc
+        db/seqno_time_test.cc
         db/prefix_test.cc
         db/range_del_aggregator_test.cc
         db/range_tombstone_fragmenter_test.cc
@@ -1301,6 +1310,7 @@ if(WITH_TESTS)
         db/version_set_test.cc
         db/wal_manager_test.cc
         db/wal_edit_test.cc
+        db/wide/db_wide_basic_test.cc
         db/wide/wide_column_serialization_test.cc
         db/write_batch_test.cc
         db/write_callback_test.cc
@@ -1500,6 +1510,20 @@ if(WITH_BENCHMARK_TOOLS)
     ${ROCKSDB_LIB} ${GFLAGS_LIB})
 endif()
 
+option(WITH_TRACE_TOOLS "build with trace tools" ON)
+if(WITH_TRACE_TOOLS)
+  add_executable(block_cache_trace_analyzer_tool${ARTIFACT_SUFFIX}
+    tools/block_cache_analyzer/block_cache_trace_analyzer_tool.cc)
+  target_link_libraries(block_cache_trace_analyzer_tool${ARTIFACT_SUFFIX}
+    ${ROCKSDB_LIB} ${GFLAGS_LIB})
+
+  add_executable(trace_analyzer${ARTIFACT_SUFFIX}
+    tools/trace_analyzer.cc)
+  target_link_libraries(trace_analyzer${ARTIFACT_SUFFIX}
+    ${ROCKSDB_LIB} ${GFLAGS_LIB})
+
+endif()
+
 if(WITH_CORE_TOOLS OR WITH_TOOLS)
   add_subdirectory(tools)
   add_custom_target(core_tools

HISTORY.md

@@ -1,4 +1,91 @@
 # Rocksdb Change Log
+## 7.6.0 (08/19/2022)
+### New Features
+* Added `prepopulate_blob_cache` to ColumnFamilyOptions. If enabled, prepopulate warm/hot blobs which are already in memory into blob cache at the time of flush. On a flush, the blob that is in memory (in memtables) get flushed to the device. If using Direct IO, additional IO is incurred to read this blob back into memory again, which is avoided by enabling this option. This further helps if the workload exhibits high temporal locality, where most of the reads go to recently written data. This also helps in case of the remote file system since it involves network traffic and higher latencies.
+* Support using secondary cache with the blob cache. When creating a blob cache, the user can set a secondary blob cache by configuring `secondary_cache` in LRUCacheOptions.
+* Charge memory usage of blob cache when the backing cache of the blob cache and the block cache are different. If an operation reserving memory for blob cache exceeds the avaible space left in the block cache at some point (i.e, causing a cache full under `LRUCacheOptions::strict_capacity_limit` = true), creation will fail with `Status::MemoryLimit()`. To opt in this feature, enable charging `CacheEntryRole::kBlobCache` in `BlockBasedTableOptions::cache_usage_options`.
+* Improve subcompaction range partition so that it is likely to be more even. More evenly distribution of subcompaction will improve compaction throughput for some workloads. All input files' index blocks to sample some anchor key points from which we pick positions to partition the input range. This would introduce some CPU overhead in compaction preparation phase, if subcompaction is enabled, but it should be a small fraction of the CPU usage of the whole compaction process. This also brings a behavier change: subcompaction number is much more likely to maxed out than before.
+* Add CompactionPri::kRoundRobin, a compaction picking mode that cycles through all the files with a compact cursor in a round-robin manner. This feature is available since 7.5.
+* Provide support for subcompactions for user_defined_timestamp.
+* Added an option `memtable_protection_bytes_per_key` that turns on memtable per key-value checksum protection. Each memtable entry will be suffixed by a checksum that is computed during writes, and verified in reads/compaction. Detected corruption will be logged and with corruption status returned to user.
+* Added a blob-specific cache priority level - bottom level. Blobs are typically lower-value targets for caching than data blocks, since 1) with BlobDB, data blocks containing blob references conceptually form an index structure which has to be consulted before we can read the blob value, and 2) cached blobs represent only a single key-value, while cached data blocks generally contain multiple KVs. The user can specify the new option `low_pri_pool_ratio` in `LRUCacheOptions` to configure the ratio of capacity reserved for low priority cache entries (and therefore the remaining ratio is the space reserved for the bottom level), or configuring the new argument `low_pri_pool_ratio` in `NewLRUCache()` to achieve the same effect.
+
+### Public API changes
+* Removed Customizable support for RateLimiter and removed its CreateFromString() and Type() functions.
+* `CompactRangeOptions::exclusive_manual_compaction` is now false by default. This ensures RocksDB does not introduce artificial parallelism limitations by default.
+* Tiered Storage: change `bottommost_temperture` to `last_level_temperture`. The old option name is kept only for migration, please use the new option. The behavior is changed to apply temperature for the `last_level` SST files only.
+* Added a new experimental ReadOption flag called optimize_multiget_for_io, which when set attempts to reduce MultiGet latency by spawning coroutines for keys in multiple levels.
+
+### Bug Fixes
+* Fix a bug starting in 7.4.0 in which some fsync operations might be skipped in a DB after any DropColumnFamily on that DB, until it is re-opened. This can lead to data loss on power loss. (For custom FileSystem implementations, this could lead to `FSDirectory::Fsync` or `FSDirectory::Close` after the first `FSDirectory::Close`; Also, valgrind could report call to `close()` with `fd=-1`.)
+* Fix a bug where `GenericRateLimiter` could revert the bandwidth set dynamically using `SetBytesPerSecond()` when a user configures a structure enclosing it, e.g., using `GetOptionsFromString()` to configure an `Options` that references an existing `RateLimiter` object.
+* Fix race conditions in `GenericRateLimiter`.
+* Fix a bug in `FIFOCompactionPicker::PickTTLCompaction` where total_size calculating might cause underflow
+* Fix data race bug in hash linked list memtable. With this bug, read request might temporarily miss an old record in the memtable in a race condition to the hash bucket.
+* Fix a bug that `best_efforts_recovery` may fail to open the db with mmap read.
+* Fixed a bug where blobs read during compaction would pollute the cache.
+* Fixed a data race in LRUCache when used with a secondary_cache.
+* Fixed a bug where blobs read by iterators would be inserted into the cache even with the `fill_cache` read option set to false.
+* Fixed the segfault caused by `AllocateData()` in `CompressedSecondaryCache::SplitValueIntoChunks()` and `MergeChunksIntoValueTest`.
+* Fixed a bug in BlobDB where a mix of inlined and blob values could result in an incorrect value being passed to the compaction filter (see #10391).
+* Fixed a memory leak bug in stress tests caused by `FaultInjectionSecondaryCache`.
+
+### Behavior Change
+* Added checksum handshake during the copying of decompressed WAL fragment. This together with #9875, #10037, #10212, #10114 and #10319 provides end-to-end integrity protection for write batch during recovery.
+* To minimize the internal fragmentation caused by the variable size of the compressed blocks in `CompressedSecondaryCache`, the original block is split according to the jemalloc bin size in `Insert()` and then merged back in `Lookup()`.
+* PosixLogger is removed and by default EnvLogger will be used for info logging. The behavior of the two loggers should be very similar when using the default Posix Env.
+* Remove [min|max]_timestamp from VersionEdit for now since they are not tracked in MANIFEST anyway but consume two empty std::string (up to 64 bytes) for each file. Should they be added back in the future, we should store them more compactly.
+* Improve universal tiered storage compaction picker to avoid extra major compaction triggered by size amplification. If `preclude_last_level_data_seconds` is enabled, the size amplification is calculated within non last_level data only which skip the last level and use the penultimate level as the size base.
+* If an error is hit when writing to a file (append, sync, etc), RocksDB is more strict with not issuing more operations to it, except closing the file, with exceptions of some WAL file operations in error recovery path.
+* A `WriteBufferManager` constructed with `allow_stall == false` will no longer trigger write stall implicitly by thrashing until memtable count limit is reached. Instead, a column family can continue accumulating writes while that CF is flushing, which means memory may increase. Users who prefer stalling writes must now explicitly set `allow_stall == true`.
+* Add `CompressedSecondaryCache` into the stress tests.
+* Block cache keys have changed, which will cause any persistent caches to miss between versions.
+
+### Performance Improvements
+* Instead of constructing `FragmentedRangeTombstoneList` during every read operation, it is now constructed once and stored in immutable memtables. This improves speed of querying range tombstones from immutable memtables.
+* When using iterators with the integrated BlobDB implementation, blob cache handles are now released immediately when the iterator's position changes.
+* MultiGet can now do more IO in parallel by reading data blocks from SST files in multiple levels, if the optimize_multiget_for_io ReadOption flag is set.
+
+## 7.5.0 (07/15/2022)
+### New Features
+* Mempurge option flag `experimental_mempurge_threshold` is now a ColumnFamilyOptions and can now be dynamically configured using `SetOptions()`.
+* Support backward iteration when `ReadOptions::iter_start_ts` is set.
+* Provide support for ReadOptions.async_io with direct_io to improve Seek latency by using async IO to parallelize child iterator seek and doing asynchronous prefetching on sequential scans.
+* Added support for blob caching in order to cache frequently used blobs for BlobDB.
+  * User can configure the new ColumnFamilyOptions `blob_cache` to enable/disable blob caching.
+  * Either sharing the backend cache with the block cache or using a completely separate cache is supported.
+  * A new abstraction interface called `BlobSource` for blob read logic gives all users access to blobs, whether they are in the blob cache, secondary cache, or (remote) storage. Blobs can be potentially read both while handling user reads (`Get`, `MultiGet`, or iterator) and during compaction (while dealing with compaction filters, Merges, or garbage collection) but eventually all blob reads go through `Version::GetBlob` or, for MultiGet, `Version::MultiGetBlob` (and then get dispatched to the interface -- `BlobSource`).
+* Add experimental tiered compaction feature `AdvancedColumnFamilyOptions::preclude_last_level_data_seconds`, which makes sure the new data inserted within preclude_last_level_data_seconds won't be placed on cold tier (the feature is not complete).
+
+### Public API changes
+* Add metadata related structs and functions in C API, including
+  * `rocksdb_get_column_family_metadata()` and `rocksdb_get_column_family_metadata_cf()` to obtain `rocksdb_column_family_metadata_t`.
+  * `rocksdb_column_family_metadata_t` and its get functions & destroy function.
+  * `rocksdb_level_metadata_t` and its and its get functions & destroy function.
+  * `rocksdb_file_metadata_t` and its and get functions & destroy functions.
+* Add suggest_compact_range() and suggest_compact_range_cf() to C API.
+* When using block cache strict capacity limit (`LRUCache` with `strict_capacity_limit=true`), DB operations now fail with Status code `kAborted` subcode `kMemoryLimit` (`IsMemoryLimit()`) instead of `kIncomplete` (`IsIncomplete()`) when the capacity limit is reached, because Incomplete can mean other specific things for some operations. In more detail, `Cache::Insert()` now returns the updated Status code and this usually propagates through RocksDB to the user on failure.
+* NewClockCache calls temporarily return an LRUCache (with similar characteristics as the desired ClockCache). This is because ClockCache is being replaced by a new version (the old one had unknown bugs) but this is still under development.
+* Add two functions `int ReserveThreads(int threads_to_be_reserved)` and `int ReleaseThreads(threads_to_be_released)` into `Env` class. In the default implementation, both return 0. Newly added `xxxEnv` class that inherits `Env` should implement these two functions for thread reservation/releasing features.
+* Add `rocksdb_options_get_prepopulate_blob_cache` and `rocksdb_options_set_prepopulate_blob_cache` to C API.
+* Add `prepopulateBlobCache` and `setPrepopulateBlobCache` to Java API.
+
+### Bug Fixes
+* Fix a bug in which backup/checkpoint can include a WAL deleted by RocksDB.
+* Fix a bug where concurrent compactions might cause unnecessary further write stalling. In some cases, this might cause write rate to drop to minimum.
+* Fix a bug in Logger where if dbname and db_log_dir are on different filesystems, dbname creation would fail wrt to db_log_dir path returning an error and fails to open the DB.
+* Fix a CPU and memory efficiency issue introduce by https://github.com/facebook/rocksdb/pull/8336 which made InternalKeyComparator configurable as an unintended side effect.
+
+## Behavior Change
+* In leveled compaction with dynamic levelling, level multiplier is not anymore adjusted due to oversized L0. Instead, compaction score is adjusted by increasing size level target by adding incoming bytes from upper levels. This would deprioritize compactions from upper levels if more data from L0 is coming. This is to fix some unnecessary full stalling due to drastic change of level targets, while not wasting write bandwidth for compaction while writes are overloaded.
+* For track_and_verify_wals_in_manifest, revert to the original behavior before #10087: syncing of live WAL file is not tracked, and we track only the synced sizes of **closed** WALs. (PR #10330).
+* WAL compression now computes/verifies checksum during compression/decompression.
+
+### Performance Improvements
+* Rather than doing total sort against all files in a level, SortFileByOverlappingRatio() to only find the top 50 files based on score. This can improve write throughput for the use cases where data is loaded in increasing key order and there are a lot of files in one LSM-tree, where applying compaction results is the bottleneck.
+* In leveled compaction, L0->L1 trivial move will allow more than one file to be moved in one compaction. This would allow L0 files to be moved down faster when data is loaded in sequential order, making slowdown or stop condition harder to hit. Also seek L0->L1 trivial move when only some files qualify.
+* In leveled compaction, try to trivial move more than one files if possible, up to 4 files or max_compaction_bytes. This is to allow higher write throughput for some use cases where data is loaded in sequential order, where appying compaction results is the bottleneck.
+
 ## 7.4.0 (06/19/2022)
 ### Bug Fixes
 * Fixed a bug in calculating key-value integrity protection for users of in-place memtable updates. In particular, the affected users would be those who configure `protection_bytes_per_key > 0` on `WriteBatch` or `WriteOptions`, and configure `inplace_callback != nullptr`.
@@ -13,6 +100,7 @@
 * Avoid a crash if the IDENTITY file is accidentally truncated to empty. A new DB ID will be written and generated on Open.
 * Fixed a possible corruption for users of `manual_wal_flush` and/or `FlushWAL(true /* sync */)`, together with `track_and_verify_wals_in_manifest == true`. For those users, losing unsynced data (e.g., due to power loss) could make future DB opens fail with a `Status::Corruption` complaining about missing WAL data.
 * Fixed a bug in `WriteBatchInternal::Append()` where WAL termination point in write batch was not considered and the function appends an incorrect number of checksums.
+* Fixed a crash bug introduced in 7.3.0 affecting users of MultiGet with `kDataBlockBinaryAndHash`.
 
 ### Public API changes
 * Add new API GetUnixTime in Snapshot class which returns the unix time at which Snapshot is taken.
@@ -39,9 +127,14 @@
 * Add support for timestamped snapshots (#9879)
 * Provide support for AbortIO in posix to cancel submitted asynchronous requests using io_uring.
 * Add support for rate-limiting batched `MultiGet()` APIs
+* Added several new tickers, perf context statistics, and DB properties to BlobDB
+  * Added new DB properties "rocksdb.blob-cache-capacity", "rocksdb.blob-cache-usage", "rocksdb.blob-cache-pinned-usage" to show blob cache usage.
+  * Added new perf context statistics `blob_cache_hit_count`, `blob_read_count`, `blob_read_byte`, `blob_read_time`, `blob_checksum_time` and `blob_decompress_time`.
+  * Added new tickers `BLOB_DB_CACHE_MISS`, `BLOB_DB_CACHE_HIT`, `BLOB_DB_CACHE_ADD`, `BLOB_DB_CACHE_ADD_FAILURES`, `BLOB_DB_CACHE_BYTES_READ` and `BLOB_DB_CACHE_BYTES_WRITE`.
 
 ### Behavior changes
 * DB::Open(), DB::OpenAsSecondary() will fail if a Logger cannot be created (#9984)
+* DB::Write does not hold global `mutex_` if this db instance does not need to switch wal and mem-table (#7516).
 * Removed support for reading Bloom filters using obsolete block-based filter format. (Support for writing such filters was dropped in 7.0.) For good read performance on old DBs using these filters, a full compaction is required.
 * Per KV checksum in write batch is verified before a write batch is written to WAL to detect any corruption to the write batch (#10114).
 

Makefile

@@ -136,6 +136,7 @@ CXXFLAGS += $(PLATFORM_SHARED_CFLAGS) -DROCKSDB_DLL
 CFLAGS +=  $(PLATFORM_SHARED_CFLAGS) -DROCKSDB_DLL
 endif
 
+GIT_COMMAND ?= git
 ifeq ($(USE_COROUTINES), 1)
 	USE_FOLLY = 1
 	OPT += -DUSE_COROUTINES
@@ -1383,6 +1384,9 @@ db_blob_compaction_test: $(OBJ_DIR)/db/blob/db_blob_compaction_test.o $(TEST_LIB
 db_readonly_with_timestamp_test: $(OBJ_DIR)/db/db_readonly_with_timestamp_test.o $(TEST_LIBRARY) $(LIBRARY)
 	$(AM_LINK)
 
+db_wide_basic_test: $(OBJ_DIR)/db/wide/db_wide_basic_test.o $(TEST_LIBRARY) $(LIBRARY)
+	$(AM_LINK)
+
 db_with_timestamp_basic_test: $(OBJ_DIR)/db/db_with_timestamp_basic_test.o $(TEST_LIBRARY) $(LIBRARY)
 	$(AM_LINK)
 
@@ -1500,6 +1504,9 @@ db_table_properties_test: $(OBJ_DIR)/db/db_table_properties_test.o $(TEST_LIBRAR
 log_write_bench: $(OBJ_DIR)/util/log_write_bench.o $(TEST_LIBRARY) $(LIBRARY)
 	$(AM_LINK) $(PROFILING_FLAGS)
 
+seqno_time_test: $(OBJ_DIR)/db/seqno_time_test.o $(TEST_LIBRARY) $(LIBRARY)
+	$(AM_LINK)
+
 plain_table_db_test: $(OBJ_DIR)/db/plain_table_db_test.o $(TEST_LIBRARY) $(LIBRARY)
 	$(AM_LINK)
 
@@ -1779,6 +1786,9 @@ write_unprepared_transaction_test: $(OBJ_DIR)/utilities/transactions/write_unpre
 timestamped_snapshot_test: $(OBJ_DIR)/utilities/transactions/timestamped_snapshot_test.o $(TEST_LIBRARY) $(LIBRARY)
 	$(AM_LINK)
 
+tiered_compaction_test: $(OBJ_DIR)/db/compaction/tiered_compaction_test.o $(TEST_LIBRARY) $(LIBRARY)
+	$(AM_LINK)
+
 sst_dump: $(OBJ_DIR)/tools/sst_dump.o $(TOOLS_LIBRARY) $(LIBRARY)
 	$(AM_LINK)
 
@@ -2353,9 +2363,9 @@ commit_prereq:
 # integration.
 checkout_folly:
 	if [ -e third-party/folly ]; then \
-		cd third-party/folly && git fetch origin; \
+		cd third-party/folly && ${GIT_COMMAND} fetch origin; \
 	else \
-		cd third-party && git clone https://github.com/facebook/folly.git; \
+		cd third-party && ${GIT_COMMAND} clone https://github.com/facebook/folly.git; \
 	fi
 	@# Pin to a particular version for public CI, so that PR authors don't
 	@# need to worry about folly breaking our integration. Update periodically

README.md

@@ -1,7 +1,6 @@
 ## RocksDB: A Persistent Key-Value Store for Flash and RAM Storage
 
 [![CircleCI Status](https://circleci.com/gh/facebook/rocksdb.svg?style=svg)](https://circleci.com/gh/facebook/rocksdb)
-[![TravisCI Status](https://api.travis-ci.com/facebook/rocksdb.svg?branch=main)](https://travis-ci.com/github/facebook/rocksdb)
 [![Appveyor Build status](https://ci.appveyor.com/api/projects/status/fbgfu0so3afcno78/branch/main?svg=true)](https://ci.appveyor.com/project/Facebook/rocksdb/branch/main)
 [![PPC64le Build Status](http://140-211-168-68-openstack.osuosl.org:8080/buildStatus/icon?job=rocksdb&style=plastic)](http://140-211-168-68-openstack.osuosl.org:8080/job/rocksdb)
 

TARGETS

@@ -13,6 +13,7 @@ cpp_library_wrapper(name="rocksdb_lib", srcs=[
         "cache/cache_entry_roles.cc",
         "cache/cache_key.cc",
         "cache/cache_reservation_manager.cc",
+        "cache/charged_cache.cc",
         "cache/clock_cache.cc",
         "cache/compressed_secondary_cache.cc",
         "cache/fast_lru_cache.cc",
@@ -38,11 +39,15 @@ cpp_library_wrapper(name="rocksdb_lib", srcs=[
         "db/compaction/compaction.cc",
         "db/compaction/compaction_iterator.cc",
         "db/compaction/compaction_job.cc",
+        "db/compaction/compaction_outputs.cc",
         "db/compaction/compaction_picker.cc",
         "db/compaction/compaction_picker_fifo.cc",
         "db/compaction/compaction_picker_level.cc",
         "db/compaction/compaction_picker_universal.cc",
+        "db/compaction/compaction_service_job.cc",
+        "db/compaction/compaction_state.cc",
         "db/compaction/sst_partitioner.cc",
+        "db/compaction/subcompaction_state.cc",
         "db/convenience.cc",
         "db/db_filesnapshot.cc",
         "db/db_impl/compacted_db_impl.cc",
@@ -81,6 +86,7 @@ cpp_library_wrapper(name="rocksdb_lib", srcs=[
         "db/range_del_aggregator.cc",
         "db/range_tombstone_fragmenter.cc",
         "db/repair.cc",
+        "db/seqno_to_time_mapping.cc",
         "db/snapshot_impl.cc",
         "db/table_cache.cc",
         "db/table_properties_collector.cc",
@@ -93,6 +99,7 @@ cpp_library_wrapper(name="rocksdb_lib", srcs=[
         "db/wal_edit.cc",
         "db/wal_manager.cc",
         "db/wide/wide_column_serialization.cc",
+        "db/wide/wide_columns.cc",
         "db/write_batch.cc",
         "db/write_batch_base.cc",
         "db/write_controller.cc",
@@ -343,6 +350,7 @@ cpp_library_wrapper(name="rocksdb_whole_archive_lib", srcs=[
         "cache/cache_entry_roles.cc",
         "cache/cache_key.cc",
         "cache/cache_reservation_manager.cc",
+        "cache/charged_cache.cc",
         "cache/clock_cache.cc",
         "cache/compressed_secondary_cache.cc",
         "cache/fast_lru_cache.cc",
@@ -368,11 +376,15 @@ cpp_library_wrapper(name="rocksdb_whole_archive_lib", srcs=[
         "db/compaction/compaction.cc",
         "db/compaction/compaction_iterator.cc",
         "db/compaction/compaction_job.cc",
+        "db/compaction/compaction_outputs.cc",
         "db/compaction/compaction_picker.cc",
         "db/compaction/compaction_picker_fifo.cc",
         "db/compaction/compaction_picker_level.cc",
         "db/compaction/compaction_picker_universal.cc",
+        "db/compaction/compaction_service_job.cc",
+        "db/compaction/compaction_state.cc",
         "db/compaction/sst_partitioner.cc",
+        "db/compaction/subcompaction_state.cc",
         "db/convenience.cc",
         "db/db_filesnapshot.cc",
         "db/db_impl/compacted_db_impl.cc",
@@ -411,6 +423,7 @@ cpp_library_wrapper(name="rocksdb_whole_archive_lib", srcs=[
         "db/range_del_aggregator.cc",
         "db/range_tombstone_fragmenter.cc",
         "db/repair.cc",
+        "db/seqno_to_time_mapping.cc",
         "db/snapshot_impl.cc",
         "db/table_cache.cc",
         "db/table_properties_collector.cc",
@@ -423,6 +436,7 @@ cpp_library_wrapper(name="rocksdb_whole_archive_lib", srcs=[
         "db/wal_edit.cc",
         "db/wal_manager.cc",
         "db/wide/wide_column_serialization.cc",
+        "db/wide/wide_columns.cc",
         "db/write_batch.cc",
         "db/write_batch_base.cc",
         "db/write_controller.cc",
@@ -5240,6 +5254,12 @@ cpp_unittest_wrapper(name="db_wal_test",
             extra_compiler_flags=[])
 
 
+cpp_unittest_wrapper(name="db_wide_basic_test",
+            srcs=["db/wide/db_wide_basic_test.cc"],
+            deps=[":rocksdb_test_lib"],
+            extra_compiler_flags=[])
+
+
 cpp_unittest_wrapper(name="db_with_timestamp_basic_test",
             srcs=["db/db_with_timestamp_basic_test.cc"],
             deps=[":rocksdb_test_lib"],
@@ -5674,6 +5694,12 @@ cpp_unittest_wrapper(name="ribbon_test",
             extra_compiler_flags=[])
 
 
+cpp_unittest_wrapper(name="seqno_time_test",
+            srcs=["db/seqno_time_test.cc"],
+            deps=[":rocksdb_test_lib"],
+            extra_compiler_flags=[])
+
+
 cpp_unittest_wrapper(name="sim_cache_test",
             srcs=["utilities/simulator_cache/sim_cache_test.cc"],
             deps=[":rocksdb_test_lib"],
@@ -5758,6 +5784,12 @@ cpp_unittest_wrapper(name="thread_local_test",
             extra_compiler_flags=[])
 
 
+cpp_unittest_wrapper(name="tiered_compaction_test",
+            srcs=["db/compaction/tiered_compaction_test.cc"],
+            deps=[":rocksdb_test_lib"],
+            extra_compiler_flags=[])
+
+
 cpp_unittest_wrapper(name="timer_queue_test",
             srcs=["util/timer_queue_test.cc"],
             deps=[":rocksdb_test_lib"],

build_tools/benchmark_log_tool.py

@@ -30,45 +30,60 @@ class BenchmarkResultException(Exception):
 
 class BenchmarkUtils:
 
-    expected_keys = ['ops_sec', 'mb_sec', 'total_size_gb', 'level0_size_gb', 'sum_gb', 'write_amplification',
-                     'write_mbps', 'usec_op', 'percentile_50', 'percentile_75',
-                     'percentile_99', 'percentile_99.9', 'percentile_99.99', 'uptime',
-                     'stall_time', 'stall_percent', 'test_name', 'test_date', 'rocksdb_version',
-                     'job_id', 'timestamp']
-
-    metric_keys = ['ops_sec', 'mb_sec', 'total_size_gb', 'level0_size_gb', 'sum_gb', 'write_amplification',
-                   'write_mbps', 'usec_op', 'percentile_50', 'percentile_75',
-                   'percentile_99', 'percentile_99.9', 'percentile_99.99', 'uptime',
-                   'stall_time', 'stall_percent']
+    expected_keys = ['ops_sec', 'mb_sec',  'lsm_sz',  'blob_sz', 'c_wgb',   'w_amp',
+    'c_mbps',  'c_wsecs', 'c_csecs', 'b_rgb',   'b_wgb',   'usec_op',
+    'p50',     'p99',     'p99.9',   'p99.99', 'pmax',
+    'uptime',  'stall%', 'Nstall',  'u_cpu',   's_cpu',   'rss', 'test', 'date', 'version', 'job_id']
 
     def sanity_check(row):
-        if not 'test_name' in row:
+        if not 'test' in row:
+            logging.debug(f"not 'test' in row: {row}")
             return False
-        if row['test_name'] == '':
+        if row['test'] == '':
+            logging.debug(f"row['test'] == '': {row}")
             return False
-        if not 'test_date' in row:
+        if not 'date' in row:
+            logging.debug(f"not 'date' in row: {row}")
             return False
         if not 'ops_sec' in row:
+            logging.debug(f"not 'ops_sec' in row: {row}")
             return False
         try:
             v = int(row['ops_sec'])
         except (ValueError, TypeError):
+            logging.debug(f"int(row['ops_sec']): {row}")
+            return False
+        try:
+            (_, _) = parser.parse(row['date'], fuzzy_with_tokens=True)
+        except (parser.ParserError):
+            logging.error(f"parser.parse((row['date']): not a valid format for date in row: {row}")
             return False
         return True
 
     def conform_opensearch(row):
-        (dt, _) = parser.parse(row['test_date'], fuzzy_with_tokens=True)
+        (dt, _) = parser.parse(row['date'], fuzzy_with_tokens=True)
+        # create a test_date field, which was previously what was expected
+        # repair the date field, which has what can be a WRONG ISO FORMAT, (no leading 0 on single-digit day-of-month)
+        # e.g. 2022-07-1T00:14:55 should be 2022-07-01T00:14:55
         row['test_date'] = dt.isoformat()
+        row['date'] = dt.isoformat()
         return dict((key.replace('.', '_'), value)
                     for (key, value) in row.items())
 
 
 class ResultParser:
-    def __init__(self, field="(\w|[+-:.])+", intrafield="(\s)+", separator="\t"):
+    def __init__(self, field="(\w|[+-:.%])+", intrafield="(\s)+", separator="\t"):
         self.field = re.compile(field)
         self.intra = re.compile(intrafield)
         self.sep = re.compile(separator)
 
+    def ignore(self, l_in: str):
+        if len(l_in) == 0:
+            return True
+        if l_in[0:1] == '#':
+            return True
+        return False
+
     def line(self, l_in: str):
         '''Parse a line into items
         Being clever about separators
@@ -102,7 +117,7 @@ class ResultParser:
 
     def parse(self, lines):
         '''Parse something that iterates lines'''
-        rows = [self.line(line) for line in lines]
+        rows = [self.line(line) for line in lines if not self.ignore(line)]
         header = rows[0]
         width = len(header)
         records = [{k: v for (k, v) in itertools.zip_longest(
@@ -123,7 +138,7 @@ def load_report_from_tsv(filename: str):
 def push_report_to_opensearch(report, esdocument):
     sanitized = [BenchmarkUtils.conform_opensearch(row)
                  for row in report if BenchmarkUtils.sanity_check(row)]
-    logging.debug(f"upload {len(sanitized)} benchmarks to opensearch")
+    logging.debug(f"upload {len(sanitized)} sane of {len(report)} benchmarks to opensearch")
     for single_benchmark in sanitized:
         logging.debug(f"upload benchmark: {single_benchmark}")
         response = requests.post(
@@ -133,6 +148,13 @@ def push_report_to_opensearch(report, esdocument):
             f"Sent to OpenSearch, status: {response.status_code}, result: {response.text}")
         response.raise_for_status()
 
+def push_report_to_null(report):
+    
+    for row in report:
+        if BenchmarkUtils.sanity_check(row):
+            logging.debug(f"row {row}")
+            conformed = BenchmarkUtils.conform_opensearch(row)
+            logging.debug(f"conformed row {conformed}")
 
 def main():
     '''Tool for fetching, parsing and uploading benchmark results to OpenSearch / ElasticSearch
@@ -151,11 +173,15 @@ def main():
     parser.add_argument('--tsvfile', default='build_tools/circle_api_scraper_input.txt',
                         help='File from which to read tsv report')
     parser.add_argument('--esdocument', help='ElasticSearch/OpenSearch document URL to upload report into')
+    parser.add_argument('--upload', choices=['opensearch', 'none'], default='opensearch')
 
     args = parser.parse_args()
     logging.debug(f"Arguments: {args}")
     reports = load_report_from_tsv(args.tsvfile)
-    push_report_to_opensearch(reports, args.esdocument)
+    if (args.upload == 'opensearch'):
+        push_report_to_opensearch(reports, args.esdocument)
+    else:
+        push_report_to_null(reports)
 
 if __name__ == '__main__':
     sys.exit(main())

build_tools/check-sources.sh

@@ -17,12 +17,18 @@ if [ "$?" != "1" ]; then
   BAD=1
 fi
 
-git grep -n '<rocksdb/' -- ':!build_tools/check-sources.sh'
+git grep -n 'include <rocksdb/' -- ':!build_tools/check-sources.sh'
 if [ "$?" != "1" ]; then
   echo '^^^^^ Use double-quotes as in #include "rocksdb/something.h"'
   BAD=1
 fi
 
+git grep -n 'include "include/rocksdb/' -- ':!build_tools/check-sources.sh'
+if [ "$?" != "1" ]; then
+  echo '^^^^^ Use #include "rocksdb/something.h" instead of #include "include/rocksdb/something.h"'
+  BAD=1
+fi
+
 git grep -n 'using namespace' -- ':!build_tools' ':!docs' \
     ':!third-party/folly/folly/lang/Align.h' \
     ':!third-party/gtest-1.8.1/fused-src/gtest/gtest.h'

build_tools/dependencies_platform009.sh

@@ -6,7 +6,7 @@ GLIBC_BASE=/mnt/gvfs/third-party2/glibc/45ce3375cdc77ecb2520bbf8f0ecddd3f98efd7a
 SNAPPY_BASE=/mnt/gvfs/third-party2/snappy/be4de3205e029101b18aa8103daa696c2bef3b19/1.1.3/platform009/7f3b187
 ZLIB_BASE=/mnt/gvfs/third-party2/zlib/3c160ac5c67e257501e24c6c1d00ad5e01d73db6/1.2.8/platform009/7f3b187
 BZIP2_BASE=/mnt/gvfs/third-party2/bzip2/73a237ac5bc0a5f5d67b39b8d253cfebaab88684/1.0.6/platform009/7f3b187
-LZ4_BASE=/mnt/gvfs/third-party2/lz4/ec6573523b0ce55ef6373a4801189027cf07bb2c/1.9.1/platform009/7f3b187
+LZ4_BASE=/mnt/gvfs/third-party2/lz4/6ca38d3c390be2774d61a300f151464bbd632d62/1.9.1/platform009/7f3b187
 ZSTD_BASE=/mnt/gvfs/third-party2/zstd/64c58a207d2495e83abc57a500a956df09b79a7c/1.4.x/platform009/ba86d1f
 GFLAGS_BASE=/mnt/gvfs/third-party2/gflags/824d0a8a5abb5b121afd1b35fc3896407ea50092/2.2.0/platform009/7f3b187
 JEMALLOC_BASE=/mnt/gvfs/third-party2/jemalloc/b62912d333ef33f9760efa6219dbe3fe6abb3b0e/master/platform009/c305944

build_tools/format-diff.sh

@@ -170,11 +170,6 @@ echo "$diffs" |
   sed -e "s/\(^-.*$\)/`echo -e \"$COLOR_RED\1$COLOR_END\"`/" |
   sed -e "s/\(^+.*$\)/`echo -e \"$COLOR_GREEN\1$COLOR_END\"`/"
 
-if [[ "$OPT" == *"-DTRAVIS"* ]]
-then
-  exit 1
-fi
-
 echo -e "Would you like to fix the format automatically (y/n): \c"
 
 # Make sure under any mode, we can read user input.

build_tools/ubuntu20_image/Dockerfile

@@ -0,0 +1,56 @@
+# from official ubuntu 20.04
+FROM ubuntu:20.04
+# update system
+RUN apt-get update && apt-get upgrade -y
+# install basic tools
+RUN apt-get install -y vim wget curl
+# install tzdata noninteractive
+RUN DEBIAN_FRONTEND=noninteractive TZ=Etc/UTC apt-get -y install tzdata
+# install git and default compilers
+RUN apt-get install -y git gcc g++ clang clang-tools
+# install basic package
+RUN apt-get install -y lsb-release software-properties-common gnupg
+# install gflags, tbb
+RUN apt-get install -y libgflags-dev libtbb-dev
+# install compression libs
+RUN apt-get install -y libsnappy-dev zlib1g-dev libbz2-dev liblz4-dev libzstd-dev
+# install cmake
+RUN apt-get install -y cmake
+# install clang-13
+WORKDIR /root
+RUN wget https://apt.llvm.org/llvm.sh
+RUN chmod +x llvm.sh
+RUN ./llvm.sh 13 all
+# install gcc-7, 8, 10, 11, default is 9
+RUN apt-get install -y gcc-7 g++-7
+RUN apt-get install -y gcc-8 g++-8
+RUN apt-get install -y gcc-10 g++-10
+RUN add-apt-repository -y ppa:ubuntu-toolchain-r/test
+RUN apt-get install -y gcc-11 g++-11
+# install apt-get install -y valgrind
+RUN apt-get install -y valgrind
+# install folly depencencies
+RUN apt-get install -y libgoogle-glog-dev
+# install openjdk 8
+RUN apt-get install -y openjdk-8-jdk
+ENV JAVA_HOME /usr/lib/jvm/java-1.8.0-openjdk-amd64
+# install mingw
+RUN apt-get install -y mingw-w64
+
+# install gtest-parallel package
+RUN git clone --single-branch --branch master --depth 1 https://github.com/google/gtest-parallel.git ~/gtest-parallel
+ENV PATH $PATH:/root/gtest-parallel
+
+# install libprotobuf for fuzzers test
+RUN apt-get install -y ninja-build binutils liblzma-dev libz-dev pkg-config autoconf libtool
+RUN git clone --branch v1.0 https://github.com/google/libprotobuf-mutator.git ~/libprotobuf-mutator && cd ~/libprotobuf-mutator && git checkout ffd86a32874e5c08a143019aad1aaf0907294c9f && mkdir build && cd build && cmake .. -GNinja -DCMAKE_C_COMPILER=clang-13 -DCMAKE_CXX_COMPILER=clang++-13 -DCMAKE_BUILD_TYPE=Release -DLIB_PROTO_MUTATOR_DOWNLOAD_PROTOBUF=ON && ninja && ninja install
+ENV PKG_CONFIG_PATH /usr/local/OFF/:/root/libprotobuf-mutator/build/external.protobuf/lib/pkgconfig/
+ENV PROTOC_BIN /root/libprotobuf-mutator/build/external.protobuf/bin/protoc
+
+# install the latest google benchmark
+RUN git clone --depth 1 --branch v1.7.0 https://github.com/google/benchmark.git ~/benchmark
+RUN cd ~/benchmark && mkdir build && cd build && cmake .. -GNinja -DCMAKE_BUILD_TYPE=Release -DBENCHMARK_ENABLE_GTEST_TESTS=0 && ninja && ninja install
+
+# clean up
+RUN rm -rf /var/lib/apt/lists/*
+RUN rm -rf /root/benchmark

cache/cache.cc

@@ -33,6 +33,10 @@ static std::unordered_map<std::string, OptionTypeInfo>
          {offsetof(struct LRUCacheOptions, high_pri_pool_ratio),
           OptionType::kDouble, OptionVerificationType::kNormal,
           OptionTypeFlags::kMutable}},
+        {"low_pri_pool_ratio",
+         {offsetof(struct LRUCacheOptions, low_pri_pool_ratio),
+          OptionType::kDouble, OptionVerificationType::kNormal,
+          OptionTypeFlags::kMutable}},
 };
 
 static std::unordered_map<std::string, OptionTypeInfo>

cache/cache_bench_tool.cc

@@ -3,6 +3,7 @@
 //  COPYING file in the root directory) and Apache 2.0 License
 //  (found in the LICENSE.Apache file in the root directory).
 
+#include "cache_key.h"
 #ifdef GFLAGS
 #include <cinttypes>
 #include <cstddef>
@@ -12,6 +13,7 @@
 #include <set>
 #include <sstream>
 
+#include "cache/clock_cache.h"
 #include "cache/fast_lru_cache.h"
 #include "db/db_impl/db_impl.h"
 #include "monitoring/histogram.h"
@@ -72,6 +74,11 @@ DEFINE_uint32(
 DEFINE_uint32(gather_stats_entries_per_lock, 256,
               "For Cache::ApplyToAllEntries");
 DEFINE_bool(skewed, false, "If true, skew the key access distribution");
+
+DEFINE_bool(lean, false,
+            "If true, no additional computation is performed besides cache "
+            "operations.");
+
 #ifndef ROCKSDB_LITE
 DEFINE_string(secondary_cache_uri, "",
               "Full URI for creating a custom secondary cache object");
@@ -107,6 +114,8 @@ DEFINE_uint32(
     "(-stress_cache_key) Simulated file size in MiB, for accounting purposes");
 DEFINE_uint32(sck_reopen_nfiles, 100,
               "(-stress_cache_key) Simulate DB re-open average every n files");
+DEFINE_uint32(sck_newdb_nreopen, 1000,
+              "(-stress_cache_key) Simulate new DB average every n re-opens");
 DEFINE_uint32(sck_restarts_per_day, 24,
               "(-stress_cache_key) Average simulated process restarts per day "
               "(across DBs)");
@@ -214,7 +223,8 @@ struct KeyGen {
     EncodeFixed64(key_data + 10, key);
     key_data[18] = char{4};
     EncodeFixed64(key_data + 19, key);
-    return Slice(&key_data[off], sizeof(key_data) - off);
+    assert(27 >= kCacheKeySize);
+    return Slice(&key_data[off], kCacheKeySize);
   }
 };
 
@@ -282,7 +292,9 @@ class CacheBench {
     }
 
     if (FLAGS_cache_type == "clock_cache") {
-      cache_ = NewClockCache(FLAGS_cache_size, FLAGS_num_shard_bits);
+      cache_ = ExperimentalNewClockCache(
+          FLAGS_cache_size, FLAGS_value_bytes, FLAGS_num_shard_bits,
+          false /*strict_capacity_limit*/, kDefaultCacheMetadataChargePolicy);
       if (!cache_) {
         fprintf(stderr, "Clock cache not supported.\n");
         exit(1);
@@ -292,7 +304,9 @@ class CacheBench {
           FLAGS_cache_size, FLAGS_value_bytes, FLAGS_num_shard_bits,
           false /*strict_capacity_limit*/, kDefaultCacheMetadataChargePolicy);
     } else if (FLAGS_cache_type == "lru_cache") {
-      LRUCacheOptions opts(FLAGS_cache_size, FLAGS_num_shard_bits, false, 0.5);
+      LRUCacheOptions opts(FLAGS_cache_size, FLAGS_num_shard_bits,
+                           false /* strict_capacity_limit */,
+                           0.5 /* high_pri_pool_ratio */);
 #ifndef ROCKSDB_LITE
       if (!FLAGS_secondary_cache_uri.empty()) {
         Status s = SecondaryCache::CreateFromString(
@@ -321,8 +335,9 @@ class CacheBench {
     Random64 rnd(1);
     KeyGen keygen;
     for (uint64_t i = 0; i < 2 * FLAGS_cache_size; i += FLAGS_value_bytes) {
-      cache_->Insert(keygen.GetRand(rnd, max_key_, max_log_), createValue(rnd),
-                     &helper1, FLAGS_value_bytes);
+      Status s = cache_->Insert(keygen.GetRand(rnd, max_key_, max_log_),
+                                createValue(rnd), &helper1, FLAGS_value_bytes);
+      assert(s.ok());
     }
   }
 
@@ -516,7 +531,6 @@ class CacheBench {
     StopWatchNano timer(clock);
 
     for (uint64_t i = 0; i < FLAGS_ops_per_thread; i++) {
-      timer.Start();
       Slice key = gen.GetRand(thread->rnd, max_key_, max_log_);
       uint64_t random_op = thread->rnd.Next();
       Cache::CreateCallback create_cb = [](const void* buf, size_t size,
@@ -528,6 +542,8 @@ class CacheBench {
         return Status::OK();
       };
 
+      timer.Start();
+
       if (random_op < lookup_insert_threshold_) {
         if (handle) {
           cache_->Release(handle);
@@ -537,13 +553,16 @@ class CacheBench {
         handle = cache_->Lookup(key, &helper2, create_cb, Cache::Priority::LOW,
                                 true);
         if (handle) {
-          // do something with the data
-          result += NPHash64(static_cast<char*>(cache_->Value(handle)),
-                             FLAGS_value_bytes);
+          if (!FLAGS_lean) {
+            // do something with the data
+            result += NPHash64(static_cast<char*>(cache_->Value(handle)),
+                               FLAGS_value_bytes);
+          }
         } else {
           // do insert
-          cache_->Insert(key, createValue(thread->rnd), &helper2,
-                         FLAGS_value_bytes, &handle);
+          Status s = cache_->Insert(key, createValue(thread->rnd), &helper2,
+                                    FLAGS_value_bytes, &handle);
+          assert(s.ok());
         }
       } else if (random_op < insert_threshold_) {
         if (handle) {
@@ -551,8 +570,9 @@ class CacheBench {
           handle = nullptr;
         }
         // do insert
-        cache_->Insert(key, createValue(thread->rnd), &helper3,
-                       FLAGS_value_bytes, &handle);
+        Status s = cache_->Insert(key, createValue(thread->rnd), &helper3,
+                                  FLAGS_value_bytes, &handle);
+        assert(s.ok());
       } else if (random_op < lookup_threshold_) {
         if (handle) {
           cache_->Release(handle);
@@ -562,9 +582,11 @@ class CacheBench {
         handle = cache_->Lookup(key, &helper2, create_cb, Cache::Priority::LOW,
                                 true);
         if (handle) {
-          // do something with the data
-          result += NPHash64(static_cast<char*>(cache_->Value(handle)),
-                             FLAGS_value_bytes);
+          if (!FLAGS_lean) {
+            // do something with the data
+            result += NPHash64(static_cast<char*>(cache_->Value(handle)),
+                               FLAGS_value_bytes);
+          }
         }
       } else if (random_op < erase_threshold_) {
         // do erase
@@ -762,7 +784,7 @@ class StressCacheKey {
 
   void RunOnce() {
     // Re-initialized simulated state
-    const size_t db_count = FLAGS_sck_db_count;
+    const size_t db_count = std::max(size_t{FLAGS_sck_db_count}, size_t{1});
     dbs_.reset(new TableProperties[db_count]{});
     const size_t table_mask = (size_t{1} << FLAGS_sck_table_bits) - 1;
     table_.reset(new uint64_t[table_mask + 1]{});
@@ -779,13 +801,13 @@ class StressCacheKey {
 
     process_count_ = 0;
     session_count_ = 0;
-    ResetProcess();
+    newdb_count_ = 0;
+    ResetProcess(/*newdbs*/ true);
 
     Random64 r{std::random_device{}()};
 
     uint64_t max_file_count =
         uint64_t{FLAGS_sck_files_per_day} * FLAGS_sck_days_per_run;
-    uint64_t file_size = FLAGS_sck_file_size_mb * uint64_t{1024} * 1024U;
     uint32_t report_count = 0;
     uint32_t collisions_this_run = 0;
     size_t db_i = 0;
@@ -798,9 +820,9 @@ class StressCacheKey {
       }
       // Any other periodic actions before simulating next file
       if (!FLAGS_sck_footer_unique_id && r.OneIn(FLAGS_sck_reopen_nfiles)) {
-        ResetSession(db_i);
+        ResetSession(db_i, /*newdb*/ r.OneIn(FLAGS_sck_newdb_nreopen));
       } else if (r.OneIn(restart_nfiles_)) {
-        ResetProcess();
+        ResetProcess(/*newdbs*/ false);
       }
       // Simulate next file
       OffsetableCacheKey ock;
@@ -813,8 +835,7 @@ class StressCacheKey {
       }
       bool is_stable;
       BlockBasedTable::SetupBaseCacheKey(&dbs_[db_i], /* ignored */ "",
-                                         /* ignored */ 42, file_size, &ock,
-                                         &is_stable);
+                                         /* ignored */ 42, &ock, &is_stable);
       assert(is_stable);
       // Get a representative cache key, which later we analytically generalize
       // to a range.
@@ -824,13 +845,11 @@ class StressCacheKey {
         reduced_key = GetSliceHash64(ck.AsSlice()) >> shift_away;
       } else if (FLAGS_sck_footer_unique_id) {
         // Special case: keep only file number, not session counter
-        uint32_t a = DecodeFixed32(ck.AsSlice().data() + 4) >> shift_away_a;
-        uint32_t b = DecodeFixed32(ck.AsSlice().data() + 12) >> shift_away_b;
-        reduced_key = (uint64_t{a} << 32) + b;
+        reduced_key = DecodeFixed64(ck.AsSlice().data()) >> shift_away;
       } else {
         // Try to keep file number and session counter (shift away other bits)
         uint32_t a = DecodeFixed32(ck.AsSlice().data()) << shift_away_a;
-        uint32_t b = DecodeFixed32(ck.AsSlice().data() + 12) >> shift_away_b;
+        uint32_t b = DecodeFixed32(ck.AsSlice().data() + 4) >> shift_away_b;
         reduced_key = (uint64_t{a} << 32) + b;
       }
       if (reduced_key == 0) {
@@ -852,7 +871,7 @@ class StressCacheKey {
         // Our goal is to predict probability of no collisions, not expected
         // number of collisions. To make the distinction, we have to get rid
         // of observing correlated collisions, which this takes care of:
-        ResetProcess();
+        ResetProcess(/*newdbs*/ false);
       } else {
         // Replace (end of lifetime for file that was in this slot)
         table_[pos] = reduced_key;
@@ -870,10 +889,11 @@ class StressCacheKey {
         }
         // Report
         printf(
-            "%" PRIu64 " days, %" PRIu64 " proc, %" PRIu64
-            " sess, %u coll, occ %g%%, ejected %g%%   \r",
+            "%" PRIu64 " days, %" PRIu64 " proc, %" PRIu64 " sess, %" PRIu64
+            " newdb, %u coll, occ %g%%, ejected %g%%      \r",
             file_count / FLAGS_sck_files_per_day, process_count_,
-            session_count_, collisions_this_run, 100.0 * sampled_count / 1000.0,
+            session_count_, newdb_count_ - FLAGS_sck_db_count,
+            collisions_this_run, 100.0 * sampled_count / 1000.0,
             100.0 * (1.0 - sampled_count / 1000.0 * table_mask / file_count));
         fflush(stdout);
       }
@@ -881,16 +901,27 @@ class StressCacheKey {
     collisions_ += collisions_this_run;
   }
 
-  void ResetSession(size_t i) {
+  void ResetSession(size_t i, bool newdb) {
     dbs_[i].db_session_id = DBImpl::GenerateDbSessionId(nullptr);
+    if (newdb) {
+      ++newdb_count_;
+      if (FLAGS_sck_footer_unique_id) {
+        // Simulate how footer id would behave
+        dbs_[i].db_id = "none";
+      } else {
+        // db_id might be ignored, depending on the implementation details
+        dbs_[i].db_id = std::to_string(newdb_count_);
+        dbs_[i].orig_file_number = 0;
+      }
+    }
     session_count_++;
   }
 
-  void ResetProcess() {
+  void ResetProcess(bool newdbs) {
     process_count_++;
     DBImpl::TEST_ResetDbSessionIdGen();
     for (size_t i = 0; i < FLAGS_sck_db_count; ++i) {
-      ResetSession(i);
+      ResetSession(i, newdbs);
     }
     if (FLAGS_sck_footer_unique_id) {
       // For footer unique ID, this tracks process-wide generated SST file
@@ -905,6 +936,7 @@ class StressCacheKey {
   std::unique_ptr<uint64_t[]> table_;
   uint64_t process_count_ = 0;
   uint64_t session_count_ = 0;
+  uint64_t newdb_count_ = 0;
   uint64_t collisions_ = 0;
   uint32_t restart_nfiles_ = 0;
   double multiplier_ = 0.0;

cache/cache_entry_roles.cc

@@ -23,6 +23,7 @@ std::array<std::string, kNumCacheEntryRoles> kCacheEntryRoleToCamelString{{
     "FilterConstruction",
     "BlockBasedTableReader",
     "FileMetadata",
+    "BlobCache",
     "Misc",
 }};
 
@@ -38,6 +39,7 @@ std::array<std::string, kNumCacheEntryRoles> kCacheEntryRoleToHyphenString{{
     "filter-construction",
     "block-based-table-reader",
     "file-metadata",
+    "blob-cache",
     "misc",
 }};
 

cache/cache_helpers.h

@@ -84,6 +84,16 @@ class CacheHandleGuard {
   Cache::Handle* GetCacheHandle() const { return handle_; }
   T* GetValue() const { return value_; }
 
+  void TransferTo(Cleanable* cleanable) {
+    if (cleanable) {
+      if (handle_ != nullptr) {
+        assert(cache_);
+        cleanable->RegisterCleanup(&ReleaseCacheHandle, cache_, handle_);
+      }
+    }
+    ResetFields();
+  }
+
   void Reset() {
     ReleaseHandle();
     ResetFields();
@@ -105,6 +115,16 @@ class CacheHandleGuard {
     value_ = nullptr;
   }
 
+  static void ReleaseCacheHandle(void* arg1, void* arg2) {
+    Cache* const cache = static_cast<Cache*>(arg1);
+    assert(cache);
+
+    Cache::Handle* const cache_handle = static_cast<Cache::Handle*>(arg2);
+    assert(cache_handle);
+
+    cache->Release(cache_handle);
+  }
+
  private:
   Cache* cache_ = nullptr;
   Cache::Handle* handle_ = nullptr;

cache/cache_key.cc

@@ -17,7 +17,7 @@ namespace ROCKSDB_NAMESPACE {
 
 // Value space plan for CacheKey:
 //
-// session_etc64_ | offset_etc64_ | Only generated by
+// file_num_etc64_ | offset_etc64_ | Only generated by
 // ---------------+---------------+------------------------------------------
 //              0 |             0 | Reserved for "empty" CacheKey()
 //              0 |  > 0, < 1<<63 | CreateUniqueForCacheLifetime
@@ -44,7 +44,7 @@ CacheKey CacheKey::CreateUniqueForProcessLifetime() {
   return CacheKey(0, id);
 }
 
-// Value plan for CacheKeys from OffsetableCacheKey, assuming that
+// How we generate CacheKeys and base OffsetableCacheKey, assuming that
 // db_session_ids are generated from a base_session_id and
 // session_id_counter (by SemiStructuredUniqueIdGen+EncodeSessionId
 // in DBImpl::GenerateDbSessionId):
@@ -56,63 +56,108 @@ CacheKey CacheKey::CreateUniqueForProcessLifetime() {
 //   base_session_id         (unstructured, from GenerateRawUniqueId)
 //   session_id_counter      (structured)
 //                           * usually much smaller than 2**24
-//   file_number             (structured)
+//   orig_file_number        (structured)
 //                           * usually smaller than 2**24
 //   offset_in_file          (structured, might skip lots of values)
 //                           * usually smaller than 2**32
-//   max_offset              determines placement of file_number to prevent
-//                           overlapping with offset
 //
-// Outputs come from bitwise-xor of the constituent pieces, low bits on left:
+// Overall approach (see https://github.com/pdillinger/unique_id for
+// background):
 //
-// |------------------------- session_etc64 -------------------------|
-// | +++++++++++++++ base_session_id (lower 64 bits) +++++++++++++++ |
+// First, we have three "structured" values, up to 64 bits each, that we
+// need to fit, without losses, into 128 bits. In practice, the values will
+// be small enough that they should fit. For example, applications generating
+// large SST files (large offsets) will naturally produce fewer files (small
+// file numbers). But we don't know ahead of time what bounds the values will
+// have.
+//
+// Second, we have unstructured inputs that enable distinct RocksDB processes
+// to pick a random point in space, likely very different from others. Xoring
+// the structured with the unstructured give us a cache key that is
+// structurally distinct between related keys (e.g. same file or same RocksDB
+// process) and distinct with high probability between unrelated keys.
+//
+// The problem of packing three structured values into the space for two is
+// complicated by the fact that we want to derive cache keys from SST unique
+// IDs, which have already combined structured and unstructured inputs in a
+// practically inseparable way. And we want a base cache key that works
+// with an offset of any size. So basically, we need to encode these three
+// structured values, each up to 64 bits, into 128 bits without knowing any
+// of their sizes. The DownwardInvolution() function gives us a mechanism to
+// accomplish this. (See its properties in math.h.) Specifically, for inputs
+// a, b, and c:
+//   lower64 = DownwardInvolution(a) ^ ReverseBits(b);
+//   upper64 = c ^ ReverseBits(a);
+// The 128-bit output is unique assuming there exist some i, j, and k
+// where a < 2**i, b < 2**j, c < 2**k, i <= 64, j <= 64, k <= 64, and
+// i + j + k <= 128. In other words, as long as there exist some bounds
+// that would allow us to pack the bits of a, b, and c into the output
+// if we know the bound, we can generate unique outputs without knowing
+// those bounds. To validate this claim, the inversion function (given
+// the bounds) has been implemented in CacheKeyDecoder in
+// db_block_cache_test.cc.
+//
+// With that in mind, the outputs in terms of the conceptual inputs look
+// like this, using bitwise-xor of the constituent pieces, low bits on left:
+//
+// |------------------------- file_num_etc64 -------------------------|
+// | +++++++++ base_session_id (lower 64 bits, involution) +++++++++ |
 // |-----------------------------------------------------------------|
-// | session_id_counter ...|                                         |
+// | session_id_counter (involution) ..... |                         |
 // |-----------------------------------------------------------------|
-// |                                               | ... file_number |
-// |                                               | overflow & meta |
-// |-----------------------------------------------------------------|
-//
-//
-// |------------------------- offset_etc64 --------------------------|
 // | hash of: ++++++++++++++++++++++++++++++++++++++++++++++++++++++ |
 // |  * base_session_id (upper ~39 bits)                             |
 // |  * db_id (~122 bits entropy)                                    |
 // |-----------------------------------------------------------------|
+// |                             | ..... orig_file_number (reversed) |
+// |-----------------------------------------------------------------|
+//
+//
+// |------------------------- offset_etc64 --------------------------|
+// | ++++++++++ base_session_id (lower 64 bits, reversed) ++++++++++ |
+// |-----------------------------------------------------------------|
+// |                           | ..... session_id_counter (reversed) |
+// |-----------------------------------------------------------------|
 // | offset_in_file ............... |                                |
 // |-----------------------------------------------------------------|
-// |                                              | file_number, 0-3 |
-// |                                              | lower bytes      |
-// |-----------------------------------------------------------------|
 //
-// Based on max_offset, a maximal number of bytes 0..3 is chosen for
-// including from lower bits of file_number in offset_etc64. The choice
-// is encoded in two bits of metadata going into session_etc64, though
-// the common case of 3 bytes is encoded as 0 so that session_etc64
-// is unmodified by file_number concerns in the common case.
+// Some oddities or inconveniences of this layout are due to deriving
+// the "base" cache key (without offset) from the SST unique ID (see
+// GetSstInternalUniqueId). Specifically,
+// * Lower 64 of base_session_id occurs in both output words (ok but
+//   weird)
+// * The inclusion of db_id is bad for the conditions under which we
+//   can guarantee uniqueness, but could be useful in some cases with
+//   few small files per process, to make up for db session id only having
+//   ~103 bits of entropy.
 //
-// There is nothing preventing "file number overflow & meta" from meeting
-// and overlapping with session_id_counter, but reaching such a case requires
-// an intractable combination of large file offsets (thus at least some large
-// files), large file numbers (thus large number of files generated), and
-// large number of session IDs generated in a single process. A trillion each
-// (2**40) of session ids, offsets, and file numbers comes to 120 bits.
-// With two bits of metadata and byte granularity, this is on the verge of
-// overlap, but even in the overlap case, it doesn't seem likely that
-// a file from billions of files or session ids ago will still be live
-// or cached.
+// In fact, if DB ids were not involved, we would be guaranteed unique
+// cache keys for files generated in a single process until total bits for
+// biggest session_id_counter, orig_file_number, and offset_in_file
+// reach 128 bits.
 //
-// In fact, if our SST files are all < 4TB (see
-// BlockBasedTable::kMaxFileSizeStandardEncoding), then SST files generated
-// in a single process are guaranteed to have unique cache keys, unless/until
-// number session ids * max file number = 2**86, e.g. 1 trillion DB::Open in
-// a single process and 64 trillion files generated. Even at that point, to
-// see a collision we would need a miraculous re-synchronization of session
-// id and file number, along with a live file or stale cache entry from
-// trillions of files ago.
+// With the DB id limitation, we only have nice guaranteed unique cache
+// keys for files generated in a single process until biggest
+// session_id_counter and offset_in_file reach combined 64 bits. This
+// is quite good in practice because we can have millions of DB Opens
+// with terabyte size SST files, or billions of DB Opens with gigabyte
+// size SST files.
 //
-// How https://github.com/pdillinger/unique_id applies here:
+// One of the considerations in the translation between existing SST unique
+// IDs and base cache keys is supporting better SST unique IDs in a future
+// format_version. If we use a process-wide file counter instead of
+// session counter and file numbers, we only need to combine two 64-bit values
+// instead of three. But we don't want to track unique ID versions in the
+// manifest, so we want to keep the same translation layer between SST unique
+// IDs and base cache keys, even with updated SST unique IDs. If the new
+// unique IDs put the file counter where the orig_file_number was, and
+// use no structured field where session_id_counter was, then our translation
+// layer works fine for two structured fields as well as three (for
+// compatibility). The small computation for the translation (one
+// DownwardInvolution(), two ReverseBits(), both ~log(64) instructions deep)
+// is negligible for computing as part of SST file reader open.
+//
+// More on how https://github.com/pdillinger/unique_id applies here:
 // Every bit of output always includes "unstructured" uniqueness bits and
 // often combines with "structured" uniqueness bits. The "unstructured" bits
 // change infrequently: only when we cannot guarantee our state tracking for
@@ -141,12 +186,11 @@ CacheKey CacheKey::CreateUniqueForProcessLifetime() {
 // 128 bits cache key size
 // - 55 <- ideal size for byte offsets + file numbers
 // -  2 <- bits for offsets and file numbers not exactly powers of two
-// -  2 <- bits for file number encoding metadata
 // +  2 <- bits saved not using byte offsets in BlockBasedTable::GetCacheKey
 // ----
-//   71 <- bits remaining for distinguishing session IDs
-// The probability of a collision in 71 bits of session ID data is less than
-// 1 in 2**(71 - (2 * 16)), or roughly 1 in a trillion. And this assumes all
+//   73 <- bits remaining for distinguishing session IDs
+// The probability of a collision in 73 bits of session ID data is less than
+// 1 in 2**(73 - (2 * 16)), or roughly 1 in a trillion. And this assumes all
 // data from the last 180 days is in cache for potential collision, and that
 // cache keys under each session id exhaustively cover the remaining 57 bits
 // while in reality they'll only cover a small fraction of it.
@@ -160,7 +204,7 @@ CacheKey CacheKey::CreateUniqueForProcessLifetime() {
 // Now suppose we have many DBs per host, say 2**10, with same host-wide write
 // rate and process/session lifetime. File numbers will be ~10 bits smaller
 // and we will have 2**10 times as many session IDs because of simultaneous
-// lifetimes. So now collision chance is less than 1 in 2**(81 - (2 * 26)),
+// lifetimes. So now collision chance is less than 1 in 2**(83 - (2 * 26)),
 // or roughly 1 in a billion.
 //
 // Suppose instead we generated random or hashed cache keys for each
@@ -176,17 +220,17 @@ CacheKey CacheKey::CreateUniqueForProcessLifetime() {
 // activity over many months, by making some pessimistic simplifying
 // assumptions. See class StressCacheKey in cache_bench_tool.cc for details.
 // Here is some sample output with
-// `./cache_bench -stress_cache_key -sck_keep_bits=40`:
+// `./cache_bench -stress_cache_key -sck_keep_bits=43`:
 //
 //   Total cache or DBs size: 32TiB  Writing 925.926 MiB/s or 76.2939TiB/day
-//   Multiply by 9.22337e+18 to correct for simulation losses (but still
+//   Multiply by 1.15292e+18 to correct for simulation losses (but still
 //   assume whole file cached)
 //
 // These come from default settings of 2.5M files per day of 32 MB each, and
-// `-sck_keep_bits=40` means that to represent a single file, we are only
-// keeping 40 bits of the 128-bit (base) cache key.  With file size of 2**25
-// contiguous keys (pessimistic), our simulation is about 2\*\*(128-40-25) or
-// about 9 billion billion times more prone to collision than reality.
+// `-sck_keep_bits=43` means that to represent a single file, we are only
+// keeping 43 bits of the 128-bit (base) cache key.  With file size of 2**25
+// contiguous keys (pessimistic), our simulation is about 2\*\*(128-43-25) or
+// about 1 billion billion times more prone to collision than reality.
 //
 // More default assumptions, relatively pessimistic:
 // * 100 DBs in same process (doesn't matter much)
@@ -194,49 +238,55 @@ CacheKey CacheKey::CreateUniqueForProcessLifetime() {
 // average every 100 files generated
 // * Restart process (all new session IDs unrelated to old) 24 times per day
 //
-// After enough data, we get a result at the end (-sck_keep_bits=40):
+// After enough data, we get a result at the end (-sck_keep_bits=43):
 //
-//   (keep 40 bits)  17 collisions after 2 x 90 days, est 10.5882 days between
-//                   (9.76592e+19 corrected)
+//   (keep 43 bits)  18 collisions after 2 x 90 days, est 10 days between
+//                   (1.15292e+19 corrected)
 //
 // If we believe the (pessimistic) simulation and the mathematical
-// extrapolation, we would need to run a billion machines all for 97 billion
+// extrapolation, we would need to run a billion machines all for 11 billion
 // days to expect a cache key collision. To help verify that our extrapolation
-// ("corrected") is robust, we can make our simulation more precise with
-// `-sck_keep_bits=41` and `42`, which takes more running time to get enough
+// ("corrected") is robust, we can make our simulation more precise by
+// increasing the "keep" bits, which takes more running time to get enough
 // collision data:
 //
-//   (keep 41 bits)  16 collisions after 4 x 90 days, est 22.5 days between
-//                   (1.03763e+20 corrected)
-//   (keep 42 bits)  19 collisions after 10 x 90 days, est 47.3684 days between
-//                   (1.09224e+20 corrected)
+//   (keep 44 bits)  16 collisions after 5 x 90 days, est 28.125 days between
+//                   (1.6213e+19 corrected)
+//   (keep 45 bits)  15 collisions after 7 x 90 days, est 42 days between
+//                   (1.21057e+19 corrected)
+//   (keep 46 bits)  15 collisions after 17 x 90 days, est 102 days between
+//                   (1.46997e+19 corrected)
+//   (keep 47 bits)  15 collisions after 49 x 90 days, est 294 days between
+//                   (2.11849e+19 corrected)
 //
-// The extrapolated prediction is very close. If anything, we might have some
-// very small losses of structured data (see class StressCacheKey in
-// cache_bench_tool.cc) leading to more accurate & more attractive prediction
-// with more bits kept.
+// The extrapolated prediction seems to be within noise (sampling error).
 //
 // With the `-sck_randomize` option, we can see that typical workloads like
 // above have lower collision probability than "random" cache keys (note:
-// offsets still non-randomized) by a modest amount (roughly 20x less collision
-// prone than random), which should make us reasonably comfortable even in
-// "degenerate" cases (e.g. repeatedly launch a process to generate 1 file
-// with SstFileWriter):
+// offsets still non-randomized) by a modest amount (roughly 2-3x less
+// collision prone than random), which should make us reasonably comfortable
+// even in "degenerate" cases (e.g. repeatedly launch a process to generate
+// one file with SstFileWriter):
 //
-//   (rand 40 bits) 197 collisions after 1 x 90 days, est 0.456853 days between
-//                  (4.21372e+18 corrected)
+//   (rand 43 bits) 22 collisions after 1 x 90 days, est 4.09091 days between
+//                  (4.7165e+18 corrected)
 //
-// We can see that with more frequent process restarts (all new session IDs),
-// we get closer to the "random" cache key performance:
+// We can see that with more frequent process restarts,
+// -sck_restarts_per_day=5000, which means more all-new session IDs, we get
+// closer to the "random" cache key performance:
 //
-//   (-sck_restarts_per_day=5000): 140 collisions after 1 x 90 days, ...
-//                  (5.92931e+18 corrected)
+// 15 collisions after 1 x 90 days, est 6 days between (6.91753e+18 corrected)
+//
+// And with less frequent process restarts and re-opens,
+// -sck_restarts_per_day=1 -sck_reopen_nfiles=1000, we get lower collision
+// probability:
+//
+// 18 collisions after 8 x 90 days, est 40 days between (4.61169e+19 corrected)
 //
 // Other tests have been run to validate other conditions behave as expected,
 // never behaving "worse than random" unless we start chopping off structured
 // data.
 //
-//
 // Conclusion: Even in extreme cases, rapidly burning through "all new" IDs
 // that only arise when a new process is started, the chance of any cache key
 // collisions in a giant fleet of machines is negligible. Especially when
@@ -249,96 +299,66 @@ CacheKey CacheKey::CreateUniqueForProcessLifetime() {
 // quantify) block cache corruptions, including collisions, should be added.
 OffsetableCacheKey::OffsetableCacheKey(const std::string &db_id,
                                        const std::string &db_session_id,
-                                       uint64_t file_number,
-                                       uint64_t max_offset) {
+                                       uint64_t file_number) {
+  UniqueId64x2 internal_id;
+  Status s = GetSstInternalUniqueId(db_id, db_session_id, file_number,
+                                    &internal_id, /*force=*/true);
+  assert(s.ok());
+  *this = FromInternalUniqueId(&internal_id);
+}
+
+OffsetableCacheKey OffsetableCacheKey::FromInternalUniqueId(UniqueIdPtr id) {
+  uint64_t session_lower = id.ptr[0];
+  uint64_t file_num_etc = id.ptr[1];
+
 #ifndef NDEBUG
-  max_offset_ = max_offset;
+  bool is_empty = session_lower == 0 && file_num_etc == 0;
 #endif
-  // Closely related to GetSstInternalUniqueId, but only need 128 bits and
-  // need to include an offset within the file.
-  // See also https://github.com/pdillinger/unique_id for background.
-  uint64_t session_upper = 0;  // Assignment to appease clang-analyze
-  uint64_t session_lower = 0;  // Assignment to appease clang-analyze
-  {
-    Status s = DecodeSessionId(db_session_id, &session_upper, &session_lower);
-    if (!s.ok()) {
-      // A reasonable fallback in case malformed
-      Hash2x64(db_session_id.data(), db_session_id.size(), &session_upper,
-               &session_lower);
-    }
-  }
-
-  // Hash the session upper (~39 bits entropy) and DB id (120+ bits entropy)
-  // for more global uniqueness entropy.
-  // (It is possible that many DBs descended from one common DB id are copied
-  // around and proliferate, in which case session id is critical, but it is
-  // more common for different DBs to have different DB ids.)
-  uint64_t db_hash = Hash64(db_id.data(), db_id.size(), session_upper);
-
-  // This establishes the db+session id part of the cache key.
-  //
-  // Exactly preserve (in common cases; see modifiers below) session lower to
-  // ensure that session ids generated during the same process lifetime are
-  // guaranteed unique.
-  //
-  // We put this first for CommonPrefixSlice(), so that a small-ish set of
-  // cache key prefixes to cover entries relevant to any DB.
-  session_etc64_ = session_lower;
-  // This provides extra entopy in case of different DB id or process
-  // generating a session id, but is also partly/variably obscured by
-  // file_number and offset (see below).
-  offset_etc64_ = db_hash;
-
-  // Into offset_etc64_ we are (eventually) going to pack & xor in an offset and
-  // a file_number, but we might need the file_number to overflow into
-  // session_etc64_. (There must only be one session_etc64_ value per
-  // file, and preferably shared among many files.)
-  //
-  // Figure out how many bytes of file_number we are going to be able to
-  // pack in with max_offset, though our encoding will only support packing
-  // in up to 3 bytes of file_number. (16M file numbers is enough for a new
-  // file number every second for half a year.)
-  int file_number_bytes_in_offset_etc =
-      (63 - FloorLog2(max_offset | 0x100000000U)) / 8;
-  int file_number_bits_in_offset_etc = file_number_bytes_in_offset_etc * 8;
-
-  // Assert two bits of metadata
-  assert(file_number_bytes_in_offset_etc >= 0 &&
-         file_number_bytes_in_offset_etc <= 3);
-  // Assert we couldn't have used a larger allowed number of bytes (shift
-  // would chop off bytes).
-  assert(file_number_bytes_in_offset_etc == 3 ||
-         (max_offset << (file_number_bits_in_offset_etc + 8) >>
-          (file_number_bits_in_offset_etc + 8)) != max_offset);
-
-  uint64_t mask = (uint64_t{1} << (file_number_bits_in_offset_etc)) - 1;
-  // Pack into high bits of etc so that offset can go in low bits of etc
-  // TODO: could be EndianSwapValue?
-  uint64_t offset_etc_modifier = ReverseBits(file_number & mask);
-  assert(offset_etc_modifier << file_number_bits_in_offset_etc == 0U);
-
-  // Overflow and 3 - byte count (likely both zero) go into session_id part
-  uint64_t session_etc_modifier =
-      (file_number >> file_number_bits_in_offset_etc << 2) |
-      static_cast<uint64_t>(3 - file_number_bytes_in_offset_etc);
-  // Packed into high bits to minimize interference with session id counter.
-  session_etc_modifier = ReverseBits(session_etc_modifier);
-
-  // Assert session_id part is only modified in extreme cases
-  assert(session_etc_modifier == 0 || file_number > /*3 bytes*/ 0xffffffU ||
-         max_offset > /*5 bytes*/ 0xffffffffffU);
-
-  // Xor in the modifiers
-  session_etc64_ ^= session_etc_modifier;
-  offset_etc64_ ^= offset_etc_modifier;
 
   // Although DBImpl guarantees (in recent versions) that session_lower is not
-  // zero, that's not entirely sufficient to guarantee that session_etc64_ is
+  // zero, that's not entirely sufficient to guarantee that file_num_etc64_ is
   // not zero (so that the 0 case can be used by CacheKey::CreateUnique*)
-  if (session_etc64_ == 0U) {
-    session_etc64_ = session_upper | 1U;
+  // However, if we are given an "empty" id as input, then we should produce
+  // "empty" as output.
+  // As a consequence, this function is only bijective assuming
+  // id[0] == 0 only if id[1] == 0.
+  if (session_lower == 0U) {
+    session_lower = file_num_etc;
   }
-  assert(session_etc64_ != 0);
+
+  // See comments above for how DownwardInvolution and ReverseBits
+  // make this function invertible under various assumptions.
+  OffsetableCacheKey rv;
+  rv.file_num_etc64_ =
+      DownwardInvolution(session_lower) ^ ReverseBits(file_num_etc);
+  rv.offset_etc64_ = ReverseBits(session_lower);
+
+  // Because of these transformations and needing to allow arbitrary
+  // offset (thus, second 64 bits of cache key might be 0), we need to
+  // make some correction to ensure the first 64 bits is not 0.
+  // Fortunately, the transformation ensures the second 64 bits is not 0
+  // for non-empty base key, so we can swap in the case one is 0 without
+  // breaking bijectivity (assuming condition above).
+  assert(is_empty || rv.offset_etc64_ > 0);
+  if (rv.file_num_etc64_ == 0) {
+    std::swap(rv.file_num_etc64_, rv.offset_etc64_);
+  }
+  assert(is_empty || rv.file_num_etc64_ > 0);
+  return rv;
+}
+
+// Inverse of FromInternalUniqueId (assuming file_num_etc64 == 0 only if
+// offset_etc64 == 0)
+UniqueId64x2 OffsetableCacheKey::ToInternalUniqueId() {
+  uint64_t a = file_num_etc64_;
+  uint64_t b = offset_etc64_;
+  if (b == 0) {
+    std::swap(a, b);
+  }
+  UniqueId64x2 rv;
+  rv[0] = ReverseBits(b);
+  rv[1] = ReverseBits(a ^ DownwardInvolution(rv[0]));
+  return rv;
 }
 
 }  // namespace ROCKSDB_NAMESPACE

cache/cache_key.h

@@ -9,6 +9,7 @@
 
 #include "rocksdb/rocksdb_namespace.h"
 #include "rocksdb/slice.h"
+#include "table/unique_id_impl.h"
 
 namespace ROCKSDB_NAMESPACE {
 
@@ -33,10 +34,10 @@ class CacheKey {
  public:
   // For convenience, constructs an "empty" cache key that is never returned
   // by other means.
-  inline CacheKey() : session_etc64_(), offset_etc64_() {}
+  inline CacheKey() : file_num_etc64_(), offset_etc64_() {}
 
   inline bool IsEmpty() const {
-    return (session_etc64_ == 0) & (offset_etc64_ == 0);
+    return (file_num_etc64_ == 0) & (offset_etc64_ == 0);
   }
 
   // Use this cache key as a Slice (byte order is endianness-dependent)
@@ -59,12 +60,14 @@ class CacheKey {
 
  protected:
   friend class OffsetableCacheKey;
-  CacheKey(uint64_t session_etc64, uint64_t offset_etc64)
-      : session_etc64_(session_etc64), offset_etc64_(offset_etc64) {}
-  uint64_t session_etc64_;
+  CacheKey(uint64_t file_num_etc64, uint64_t offset_etc64)
+      : file_num_etc64_(file_num_etc64), offset_etc64_(offset_etc64) {}
+  uint64_t file_num_etc64_;
   uint64_t offset_etc64_;
 };
 
+constexpr uint8_t kCacheKeySize = static_cast<uint8_t>(sizeof(CacheKey));
+
 // A file-specific generator of cache keys, sometimes referred to as the
 // "base" cache key for a file because all the cache keys for various offsets
 // within the file are computed using simple arithmetic. The basis for the
@@ -83,50 +86,58 @@ class OffsetableCacheKey : private CacheKey {
   inline OffsetableCacheKey() : CacheKey() {}
 
   // Constructs an OffsetableCacheKey with the given information about a file.
-  // max_offset is based on file size (see WithOffset) and is required here to
-  // choose an appropriate (sub-)encoding. This constructor never generates an
-  // "empty" base key.
+  // This constructor never generates an "empty" base key.
   OffsetableCacheKey(const std::string &db_id, const std::string &db_session_id,
-                     uint64_t file_number, uint64_t max_offset);
+                     uint64_t file_number);
+
+  // Creates an OffsetableCacheKey from an SST unique ID, so that cache keys
+  // can be derived from DB manifest data before reading the file from
+  // storage--so that every part of the file can potentially go in a persistent
+  // cache.
+  //
+  // Calling GetSstInternalUniqueId() on a db_id, db_session_id, and
+  // file_number and passing the result to this function produces the same
+  // base cache key as feeding those inputs directly to the constructor.
+  //
+  // This is a bijective transformation assuming either id is empty or
+  // lower 64 bits is non-zero:
+  // * Empty (all zeros) input -> empty (all zeros) output
+  // * Lower 64 input is non-zero -> lower 64 output (file_num_etc64_) is
+  //   non-zero
+  static OffsetableCacheKey FromInternalUniqueId(UniqueIdPtr id);
+
+  // This is the inverse transformation to the above, assuming either empty
+  // or lower 64 bits (file_num_etc64_) is non-zero. Perhaps only useful for
+  // testing.
+  UniqueId64x2 ToInternalUniqueId();
 
   inline bool IsEmpty() const {
-    bool result = session_etc64_ == 0;
+    bool result = file_num_etc64_ == 0;
     assert(!(offset_etc64_ > 0 && result));
     return result;
   }
 
-  // Construct a CacheKey for an offset within a file, which must be
-  // <= max_offset provided in constructor. An offset is not necessarily a
-  // byte offset if a smaller unique identifier of keyable offsets is used.
+  // Construct a CacheKey for an offset within a file. An offset is not
+  // necessarily a byte offset if a smaller unique identifier of keyable
+  // offsets is used.
   //
   // This class was designed to make this hot code extremely fast.
   inline CacheKey WithOffset(uint64_t offset) const {
     assert(!IsEmpty());
-    assert(offset <= max_offset_);
-    return CacheKey(session_etc64_, offset_etc64_ ^ offset);
+    return CacheKey(file_num_etc64_, offset_etc64_ ^ offset);
   }
 
-  // The "common prefix" is a shared prefix for all the returned CacheKeys,
-  // that also happens to usually be the same among many files in the same DB,
-  // so is efficient and highly accurate (not perfectly) for DB-specific cache
-  // dump selection (but not file-specific).
+  // The "common prefix" is a shared prefix for all the returned CacheKeys.
+  // It is specific to the file but the same for all offsets within the file.
   static constexpr size_t kCommonPrefixSize = 8;
   inline Slice CommonPrefixSlice() const {
-    static_assert(sizeof(session_etc64_) == kCommonPrefixSize,
+    static_assert(sizeof(file_num_etc64_) == kCommonPrefixSize,
                   "8 byte common prefix expected");
     assert(!IsEmpty());
-    assert(&this->session_etc64_ == static_cast<const void *>(this));
+    assert(&this->file_num_etc64_ == static_cast<const void *>(this));
 
     return Slice(reinterpret_cast<const char *>(this), kCommonPrefixSize);
   }
-
-  // For any max_offset <= this value, the same encoding scheme is guaranteed.
-  static constexpr uint64_t kMaxOffsetStandardEncoding = 0xffffffffffU;
-
- private:
-#ifndef NDEBUG
-  uint64_t max_offset_ = 0;
-#endif
 };
 
 }  // namespace ROCKSDB_NAMESPACE

cache/cache_reservation_manager.cc

@@ -181,4 +181,5 @@ template class CacheReservationManagerImpl<CacheEntryRole::kFilterConstruction>;
 template class CacheReservationManagerImpl<CacheEntryRole::kMisc>;
 template class CacheReservationManagerImpl<CacheEntryRole::kWriteBuffer>;
 template class CacheReservationManagerImpl<CacheEntryRole::kFileMetadata>;
+template class CacheReservationManagerImpl<CacheEntryRole::kBlobCache>;
 }  // namespace ROCKSDB_NAMESPACE

cache/cache_reservation_manager_test.cc

@@ -48,13 +48,13 @@ TEST_F(CacheReservationManagerTest, GenerateCacheKey) {
   // Next unique Cache key
   CacheKey ckey = CacheKey::CreateUniqueForCacheLifetime(cache.get());
   // Get to the underlying values
-  using PairU64 = std::array<uint64_t, 2>;
-  auto& ckey_pair = *reinterpret_cast<PairU64*>(&ckey);
+  uint64_t* ckey_data = reinterpret_cast<uint64_t*>(&ckey);
   // Back it up to the one used by CRM (using CacheKey implementation details)
-  ckey_pair[1]--;
+  ckey_data[1]--;
 
   // Specific key (subject to implementation details)
-  EXPECT_EQ(ckey_pair, PairU64({0, 2}));
+  EXPECT_EQ(ckey_data[0], 0);
+  EXPECT_EQ(ckey_data[1], 2);
 
   Cache::Handle* handle = cache->Lookup(ckey.AsSlice());
   EXPECT_NE(handle, nullptr)
@@ -147,7 +147,7 @@ TEST(CacheReservationManagerIncreaseReservcationOnFullCacheTest,
 
   std::size_t new_mem_used = kSmallCacheCapacity + 1;
   Status s = test_cache_rev_mng->UpdateCacheReservation(new_mem_used);
-  EXPECT_EQ(s, Status::Incomplete())
+  EXPECT_EQ(s, Status::MemoryLimit())
       << "Failed to return status to indicate failure of dummy entry insertion "
          "during cache reservation on full cache";
   EXPECT_GE(test_cache_rev_mng->GetTotalReservedCacheSize(),
@@ -192,7 +192,7 @@ TEST(CacheReservationManagerIncreaseReservcationOnFullCacheTest,
   // Create cache full again for subsequent tests
   new_mem_used = kSmallCacheCapacity + 1;
   s = test_cache_rev_mng->UpdateCacheReservation(new_mem_used);
-  EXPECT_EQ(s, Status::Incomplete())
+  EXPECT_EQ(s, Status::MemoryLimit())
       << "Failed to return status to indicate failure of dummy entry insertion "
          "during cache reservation on full cache";
   EXPECT_GE(test_cache_rev_mng->GetTotalReservedCacheSize(),

cache/cache_test.cc

@@ -23,6 +23,11 @@
 #include "util/coding.h"
 #include "util/string_util.h"
 
+// FastLRUCache and ClockCache only support 16-byte keys, so some of
+// the tests originally wrote for LRUCache do not work on the other caches.
+// Those tests were adapted to use 16-byte keys. We kept the original ones.
+// TODO: Remove the original tests if they ever become unused.
+
 namespace ROCKSDB_NAMESPACE {
 
 namespace {
@@ -58,17 +63,22 @@ int DecodeValue(void* v) {
   return static_cast<int>(reinterpret_cast<uintptr_t>(v));
 }
 
-const std::string kLRU = "lru";
-const std::string kClock = "clock";
-const std::string kFast = "fast";
+void DumbDeleter(const Slice& /*key*/, void* /*value*/) {}
 
-void dumbDeleter(const Slice& /*key*/, void* /*value*/) {}
-
-void eraseDeleter(const Slice& /*key*/, void* value) {
+void EraseDeleter1(const Slice& /*key*/, void* value) {
   Cache* cache = reinterpret_cast<Cache*>(value);
   cache->Erase("foo");
 }
 
+void EraseDeleter2(const Slice& /*key*/, void* value) {
+  Cache* cache = reinterpret_cast<Cache*>(value);
+  cache->Erase(EncodeKey16Bytes(1234));
+}
+
+const std::string kLRU = "lru";
+const std::string kClock = "clock";
+const std::string kFast = "fast";
+
 }  // anonymous namespace
 
 class CacheTest : public testing::TestWithParam<std::string> {
@@ -77,7 +87,7 @@ class CacheTest : public testing::TestWithParam<std::string> {
   static std::string type_;
 
   static void Deleter(const Slice& key, void* v) {
-    if (type_ == kFast) {
+    if (type_ == kFast || type_ == kClock) {
       current_->deleted_keys_.push_back(DecodeKey16Bytes(key));
     } else {
       current_->deleted_keys_.push_back(DecodeKey32Bits(key));
@@ -111,7 +121,9 @@ class CacheTest : public testing::TestWithParam<std::string> {
       return NewLRUCache(capacity);
     }
     if (type == kClock) {
-      return NewClockCache(capacity);
+      return ExperimentalNewClockCache(
+          capacity, 1 /*estimated_value_size*/, -1 /*num_shard_bits*/,
+          false /*strict_capacity_limit*/, kDefaultCacheMetadataChargePolicy);
     }
     if (type == kFast) {
       return NewFastLRUCache(
@@ -135,8 +147,9 @@ class CacheTest : public testing::TestWithParam<std::string> {
       return NewLRUCache(co);
     }
     if (type == kClock) {
-      return NewClockCache(capacity, num_shard_bits, strict_capacity_limit,
-                           charge_policy);
+      return ExperimentalNewClockCache(capacity, 1 /*estimated_value_size*/,
+                                       num_shard_bits, strict_capacity_limit,
+                                       charge_policy);
     }
     if (type == kFast) {
       return NewFastLRUCache(capacity, 1 /*estimated_value_size*/,
@@ -152,7 +165,8 @@ class CacheTest : public testing::TestWithParam<std::string> {
   // LRUCache and ClockCache don't, so the encoding depends on
   // the cache type.
   std::string EncodeKey(int k) {
-    if (GetParam() == kFast) {
+    auto type = GetParam();
+    if (type == kFast || type == kClock) {
       return EncodeKey16Bytes(k);
     } else {
       return EncodeKey32Bits(k);
@@ -160,7 +174,8 @@ class CacheTest : public testing::TestWithParam<std::string> {
   }
 
   int DecodeKey(const Slice& k) {
-    if (GetParam() == kFast) {
+    auto type = GetParam();
+    if (type == kFast || type == kClock) {
       return DecodeKey16Bytes(k);
     } else {
       return DecodeKey32Bits(k);
@@ -217,13 +232,10 @@ std::string CacheTest::type_;
 class LRUCacheTest : public CacheTest {};
 
 TEST_P(CacheTest, UsageTest) {
-  if (GetParam() == kFast) {
-    ROCKSDB_GTEST_BYPASS("FastLRUCache requires 16 byte keys.");
-    return;
-  }
+  auto type = GetParam();
 
   // cache is std::shared_ptr and will be automatically cleaned up.
-  const uint64_t kCapacity = 100000;
+  const size_t kCapacity = 100000;
   auto cache = NewCache(kCapacity, 8, false, kDontChargeCacheMetadata);
   auto precise_cache = NewCache(kCapacity, 0, false, kFullChargeCacheMetadata);
   ASSERT_EQ(0, cache->GetUsage());
@@ -233,12 +245,17 @@ TEST_P(CacheTest, UsageTest) {
   char value[10] = "abcdef";
   // make sure everything will be cached
   for (int i = 1; i < 100; ++i) {
-    std::string key(i, 'a');
+    std::string key;
+    if (type == kLRU) {
+      key = std::string(i, 'a');
+    } else {
+      key = EncodeKey(i);
+    }
     auto kv_size = key.size() + 5;
     ASSERT_OK(cache->Insert(key, reinterpret_cast<void*>(value), kv_size,
-                            dumbDeleter));
+                            DumbDeleter));
     ASSERT_OK(precise_cache->Insert(key, reinterpret_cast<void*>(value),
-                                    kv_size, dumbDeleter));
+                                    kv_size, DumbDeleter));
     usage += kv_size;
     ASSERT_EQ(usage, cache->GetUsage());
     ASSERT_LT(usage, precise_cache->GetUsage());
@@ -250,12 +267,17 @@ TEST_P(CacheTest, UsageTest) {
   ASSERT_EQ(0, precise_cache->GetUsage());
 
   // make sure the cache will be overloaded
-  for (uint64_t i = 1; i < kCapacity; ++i) {
-    auto key = std::to_string(i);
+  for (size_t i = 1; i < kCapacity; ++i) {
+    std::string key;
+    if (type == kLRU) {
+      key = std::to_string(i);
+    } else {
+      key = EncodeKey(static_cast<int>(1000 + i));
+    }
     ASSERT_OK(cache->Insert(key, reinterpret_cast<void*>(value), key.size() + 5,
-                            dumbDeleter));
+                            DumbDeleter));
     ASSERT_OK(precise_cache->Insert(key, reinterpret_cast<void*>(value),
-                                    key.size() + 5, dumbDeleter));
+                                    key.size() + 5, DumbDeleter));
   }
 
   // the usage should be close to the capacity
@@ -265,14 +287,18 @@ TEST_P(CacheTest, UsageTest) {
   ASSERT_LT(kCapacity * 0.95, precise_cache->GetUsage());
 }
 
+// TODO: This test takes longer than expected on ClockCache. This is
+// because the values size estimate at construction is too sloppy.
+// Fix this.
+// Why is it so slow? The cache is constructed with an estimate of 1, but
+// then the charge is claimed to be 21. This will cause the hash table
+// to be extremely sparse, which in turn means clock needs to scan too
+// many slots to find victims.
 TEST_P(CacheTest, PinnedUsageTest) {
-  if (GetParam() == kFast) {
-    ROCKSDB_GTEST_BYPASS("FastLRUCache requires 16 byte keys.");
-    return;
-  }
+  auto type = GetParam();
 
   // cache is std::shared_ptr and will be automatically cleaned up.
-  const uint64_t kCapacity = 200000;
+  const size_t kCapacity = 200000;
   auto cache = NewCache(kCapacity, 8, false, kDontChargeCacheMetadata);
   auto precise_cache = NewCache(kCapacity, 8, false, kFullChargeCacheMetadata);
 
@@ -285,15 +311,20 @@ TEST_P(CacheTest, PinnedUsageTest) {
   // Add entries. Unpin some of them after insertion. Then, pin some of them
   // again. Check GetPinnedUsage().
   for (int i = 1; i < 100; ++i) {
-    std::string key(i, 'a');
+    std::string key;
+    if (type == kLRU) {
+      key = std::string(i, 'a');
+    } else {
+      key = EncodeKey(i);
+    }
     auto kv_size = key.size() + 5;
     Cache::Handle* handle;
     Cache::Handle* handle_in_precise_cache;
     ASSERT_OK(cache->Insert(key, reinterpret_cast<void*>(value), kv_size,
-                            dumbDeleter, &handle));
+                            DumbDeleter, &handle));
     assert(handle);
     ASSERT_OK(precise_cache->Insert(key, reinterpret_cast<void*>(value),
-                                    kv_size, dumbDeleter,
+                                    kv_size, DumbDeleter,
                                     &handle_in_precise_cache));
     assert(handle_in_precise_cache);
     pinned_usage += kv_size;
@@ -327,12 +358,17 @@ TEST_P(CacheTest, PinnedUsageTest) {
   ASSERT_LT(pinned_usage, precise_cache_pinned_usage);
 
   // check that overloading the cache does not change the pinned usage
-  for (uint64_t i = 1; i < 2 * kCapacity; ++i) {
-    auto key = std::to_string(i);
+  for (size_t i = 1; i < 2 * kCapacity; ++i) {
+    std::string key;
+    if (type == kLRU) {
+      key = std::to_string(i);
+    } else {
+      key = EncodeKey(static_cast<int>(1000 + i));
+    }
     ASSERT_OK(cache->Insert(key, reinterpret_cast<void*>(value), key.size() + 5,
-                            dumbDeleter));
+                            DumbDeleter));
     ASSERT_OK(precise_cache->Insert(key, reinterpret_cast<void*>(value),
-                                    key.size() + 5, dumbDeleter));
+                                    key.size() + 5, DumbDeleter));
   }
   ASSERT_EQ(pinned_usage, cache->GetPinnedUsage());
   ASSERT_EQ(precise_cache_pinned_usage, precise_cache->GetPinnedUsage());
@@ -440,7 +476,7 @@ TEST_P(CacheTest, EvictionPolicy) {
   Insert(200, 201);
 
   // Frequently used entry must be kept around
-  for (int i = 0; i < kCacheSize * 2; i++) {
+  for (int i = 0; i < 2 * kCacheSize; i++) {
     Insert(1000+i, 2000+i);
     ASSERT_EQ(101, Lookup(100));
   }
@@ -492,8 +528,8 @@ TEST_P(CacheTest, EvictionPolicyRef) {
   Insert(302, 103);
   Insert(303, 104);
 
-  // Insert entries much more than Cache capacity
-  for (int i = 0; i < kCacheSize * 2; i++) {
+  // Insert entries much more than cache capacity.
+  for (int i = 0; i < 100 * kCacheSize; i++) {
     Insert(1000 + i, 2000 + i);
   }
 
@@ -523,30 +559,41 @@ TEST_P(CacheTest, EvictionPolicyRef) {
 }
 
 TEST_P(CacheTest, EvictEmptyCache) {
-  if (GetParam() == kFast) {
-    ROCKSDB_GTEST_BYPASS("FastLRUCache requires 16 byte keys.");
-    return;
-  }
+  auto type = GetParam();
 
   // Insert item large than capacity to trigger eviction on empty cache.
   auto cache = NewCache(1, 0, false);
-  ASSERT_OK(cache->Insert("foo", nullptr, 10, dumbDeleter));
+  if (type == kLRU) {
+    ASSERT_OK(cache->Insert("foo", nullptr, 10, DumbDeleter));
+  } else {
+    ASSERT_OK(cache->Insert(EncodeKey(1000), nullptr, 10, DumbDeleter));
+  }
 }
 
 TEST_P(CacheTest, EraseFromDeleter) {
-  if (GetParam() == kFast) {
-    ROCKSDB_GTEST_BYPASS("FastLRUCache requires 16 byte keys.");
-    return;
-  }
+  auto type = GetParam();
 
   // Have deleter which will erase item from cache, which will re-enter
   // the cache at that point.
   std::shared_ptr<Cache> cache = NewCache(10, 0, false);
-  ASSERT_OK(cache->Insert("foo", nullptr, 1, dumbDeleter));
-  ASSERT_OK(cache->Insert("bar", cache.get(), 1, eraseDeleter));
-  cache->Erase("bar");
-  ASSERT_EQ(nullptr, cache->Lookup("foo"));
-  ASSERT_EQ(nullptr, cache->Lookup("bar"));
+  std::string foo, bar;
+  Cache::DeleterFn erase_deleter;
+  if (type == kLRU) {
+    foo = "foo";
+    bar = "bar";
+    erase_deleter = EraseDeleter1;
+  } else {
+    foo = EncodeKey(1234);
+    bar = EncodeKey(5678);
+    erase_deleter = EraseDeleter2;
+  }
+
+  ASSERT_OK(cache->Insert(foo, nullptr, 1, DumbDeleter));
+  ASSERT_OK(cache->Insert(bar, cache.get(), 1, erase_deleter));
+
+  cache->Erase(bar);
+  ASSERT_EQ(nullptr, cache->Lookup(foo));
+  ASSERT_EQ(nullptr, cache->Lookup(bar));
 }
 
 TEST_P(CacheTest, ErasedHandleState) {
@@ -579,9 +626,9 @@ TEST_P(CacheTest, HeavyEntries) {
   const int kHeavy = 10;
   int added = 0;
   int index = 0;
-  while (added < 2*kCacheSize) {
+  while (added < 2 * kCacheSize) {
     const int weight = (index & 1) ? kLight : kHeavy;
-    Insert(index, 1000+index, weight);
+    Insert(index, 1000 + index, weight);
     added += weight;
     index++;
   }
@@ -592,7 +639,7 @@ TEST_P(CacheTest, HeavyEntries) {
     int r = Lookup(i);
     if (r >= 0) {
       cached_weight += weight;
-      ASSERT_EQ(1000+i, r);
+      ASSERT_EQ(1000 + i, r);
     }
   }
   ASSERT_LE(cached_weight, kCacheSize + kCacheSize/10);
@@ -604,7 +651,6 @@ TEST_P(CacheTest, NewId) {
   ASSERT_NE(a, b);
 }
 
-
 class Value {
  public:
   explicit Value(int v) : v_(v) {}
@@ -650,6 +696,13 @@ TEST_P(CacheTest, ReleaseWithoutErase) {
 }
 
 TEST_P(CacheTest, SetCapacity) {
+  auto type = GetParam();
+  if (type == kFast || type == kClock) {
+    ROCKSDB_GTEST_BYPASS(
+        "FastLRUCache and ClockCache don't support arbitrary capacity "
+        "adjustments.");
+    return;
+  }
   // test1: increase capacity
   // lets create a cache with capacity 5,
   // then, insert 5 elements, then increase capacity
@@ -698,6 +751,14 @@ TEST_P(CacheTest, SetCapacity) {
 }
 
 TEST_P(LRUCacheTest, SetStrictCapacityLimit) {
+  auto type = GetParam();
+  if (type == kFast) {
+    ROCKSDB_GTEST_BYPASS(
+        "FastLRUCache only supports a limited number of "
+        "inserts beyond "
+        "capacity.");
+    return;
+  }
   // test1: set the flag to false. Insert more keys than capacity. See if they
   // all go through.
   std::shared_ptr<Cache> cache = NewCache(5, 0, false);
@@ -717,7 +778,7 @@ TEST_P(LRUCacheTest, SetStrictCapacityLimit) {
   cache->SetStrictCapacityLimit(true);
   Cache::Handle* handle;
   s = cache->Insert(extra_key, extra_value, 1, &deleter, &handle);
-  ASSERT_TRUE(s.IsIncomplete());
+  ASSERT_TRUE(s.IsMemoryLimit());
   ASSERT_EQ(nullptr, handle);
   ASSERT_EQ(10, cache->GetUsage());
 
@@ -734,7 +795,7 @@ TEST_P(LRUCacheTest, SetStrictCapacityLimit) {
     ASSERT_NE(nullptr, handles[i]);
   }
   s = cache2->Insert(extra_key, extra_value, 1, &deleter, &handle);
-  ASSERT_TRUE(s.IsIncomplete());
+  ASSERT_TRUE(s.IsMemoryLimit());
   ASSERT_EQ(nullptr, handle);
   // test insert without handle
   s = cache2->Insert(extra_key, extra_value, 1, &deleter);
@@ -749,6 +810,11 @@ TEST_P(LRUCacheTest, SetStrictCapacityLimit) {
 }
 
 TEST_P(CacheTest, OverCapacity) {
+  auto type = GetParam();
+  if (type == kClock) {
+    ROCKSDB_GTEST_BYPASS("Requires LRU eviction policy.");
+    return;
+  }
   size_t n = 10;
 
   // a LRUCache with n entries and one shard only
@@ -924,15 +990,11 @@ TEST_P(CacheTest, GetChargeAndDeleter) {
   cache_->Release(h1);
 }
 
-#ifdef SUPPORT_CLOCK_CACHE
-std::shared_ptr<Cache> (*new_clock_cache_func)(
-    size_t, int, bool, CacheMetadataChargePolicy) = NewClockCache;
+std::shared_ptr<Cache> (*new_clock_cache_func)(size_t, size_t, int, bool,
+                                               CacheMetadataChargePolicy) =
+    ExperimentalNewClockCache;
 INSTANTIATE_TEST_CASE_P(CacheTestInstance, CacheTest,
                         testing::Values(kLRU, kClock, kFast));
-#else
-INSTANTIATE_TEST_CASE_P(CacheTestInstance, CacheTest,
-                        testing::Values(kLRU, kFast));
-#endif  // SUPPORT_CLOCK_CACHE
 INSTANTIATE_TEST_CASE_P(CacheTestInstance, LRUCacheTest,
                         testing::Values(kLRU, kFast));
 

cache/charged_cache.cc

@@ -0,0 +1,117 @@
+//  Copyright (c) Meta Platforms, Inc. and affiliates.
+//  This source code is licensed under both the GPLv2 (found in the
+//  COPYING file in the root directory) and Apache 2.0 License
+//  (found in the LICENSE.Apache file in the root directory).
+
+#include "cache/charged_cache.h"
+
+#include "cache/cache_reservation_manager.h"
+
+namespace ROCKSDB_NAMESPACE {
+
+ChargedCache::ChargedCache(std::shared_ptr<Cache> cache,
+                           std::shared_ptr<Cache> block_cache)
+    : cache_(cache),
+      cache_res_mgr_(std::make_shared<ConcurrentCacheReservationManager>(
+          std::make_shared<
+              CacheReservationManagerImpl<CacheEntryRole::kBlobCache>>(
+              block_cache))) {}
+
+Status ChargedCache::Insert(const Slice& key, void* value, size_t charge,
+                            DeleterFn deleter, Handle** handle,
+                            Priority priority) {
+  Status s = cache_->Insert(key, value, charge, deleter, handle, priority);
+  if (s.ok()) {
+    // Insert may cause the cache entry eviction if the cache is full. So we
+    // directly call the reservation manager to update the total memory used
+    // in the cache.
+    assert(cache_res_mgr_);
+    cache_res_mgr_->UpdateCacheReservation(cache_->GetUsage())
+        .PermitUncheckedError();
+  }
+  return s;
+}
+
+Status ChargedCache::Insert(const Slice& key, void* value,
+                            const CacheItemHelper* helper, size_t charge,
+                            Handle** handle, Priority priority) {
+  Status s = cache_->Insert(key, value, helper, charge, handle, priority);
+  if (s.ok()) {
+    // Insert may cause the cache entry eviction if the cache is full. So we
+    // directly call the reservation manager to update the total memory used
+    // in the cache.
+    assert(cache_res_mgr_);
+    cache_res_mgr_->UpdateCacheReservation(cache_->GetUsage())
+        .PermitUncheckedError();
+  }
+  return s;
+}
+
+Cache::Handle* ChargedCache::Lookup(const Slice& key, Statistics* stats) {
+  return cache_->Lookup(key, stats);
+}
+
+Cache::Handle* ChargedCache::Lookup(const Slice& key,
+                                    const CacheItemHelper* helper,
+                                    const CreateCallback& create_cb,
+                                    Priority priority, bool wait,
+                                    Statistics* stats) {
+  auto handle = cache_->Lookup(key, helper, create_cb, priority, wait, stats);
+  // Lookup may promote the KV pair from the secondary cache to the primary
+  // cache. So we directly call the reservation manager to update the total
+  // memory used in the cache.
+  assert(cache_res_mgr_);
+  cache_res_mgr_->UpdateCacheReservation(cache_->GetUsage())
+      .PermitUncheckedError();
+  return handle;
+}
+
+bool ChargedCache::Release(Cache::Handle* handle, bool useful,
+                           bool erase_if_last_ref) {
+  size_t memory_used_delta = cache_->GetUsage(handle);
+  bool erased = cache_->Release(handle, useful, erase_if_last_ref);
+  if (erased) {
+    assert(cache_res_mgr_);
+    cache_res_mgr_
+        ->UpdateCacheReservation(memory_used_delta, /* increase */ false)
+        .PermitUncheckedError();
+  }
+  return erased;
+}
+
+bool ChargedCache::Release(Cache::Handle* handle, bool erase_if_last_ref) {
+  size_t memory_used_delta = cache_->GetUsage(handle);
+  bool erased = cache_->Release(handle, erase_if_last_ref);
+  if (erased) {
+    assert(cache_res_mgr_);
+    cache_res_mgr_
+        ->UpdateCacheReservation(memory_used_delta, /* increase */ false)
+        .PermitUncheckedError();
+  }
+  return erased;
+}
+
+void ChargedCache::Erase(const Slice& key) {
+  cache_->Erase(key);
+  assert(cache_res_mgr_);
+  cache_res_mgr_->UpdateCacheReservation(cache_->GetUsage())
+      .PermitUncheckedError();
+}
+
+void ChargedCache::EraseUnRefEntries() {
+  cache_->EraseUnRefEntries();
+  assert(cache_res_mgr_);
+  cache_res_mgr_->UpdateCacheReservation(cache_->GetUsage())
+      .PermitUncheckedError();
+}
+
+void ChargedCache::SetCapacity(size_t capacity) {
+  cache_->SetCapacity(capacity);
+  // SetCapacity can result in evictions when the cache capacity is decreased,
+  // so we would want to update the cache reservation here as well.
+  assert(cache_res_mgr_);
+  cache_res_mgr_->UpdateCacheReservation(cache_->GetUsage())
+      .PermitUncheckedError();
+}
+
+}  // namespace ROCKSDB_NAMESPACE

cache/charged_cache.h

@@ -0,0 +1,121 @@
+//  Copyright (c) Meta Platforms, Inc. and affiliates.
+//  This source code is licensed under both the GPLv2 (found in the
+//  COPYING file in the root directory) and Apache 2.0 License
+//  (found in the LICENSE.Apache file in the root directory).
+
+#pragma once
+
+#include <string>
+
+#include "port/port.h"
+#include "rocksdb/cache.h"
+
+namespace ROCKSDB_NAMESPACE {
+
+class ConcurrentCacheReservationManager;
+
+// A cache interface which wraps around another cache and takes care of
+// reserving space in block cache towards a single global memory limit, and
+// forwards all the calls to the underlying cache.
+class ChargedCache : public Cache {
+ public:
+  ChargedCache(std::shared_ptr<Cache> cache,
+               std::shared_ptr<Cache> block_cache);
+  ~ChargedCache() override = default;
+
+  Status Insert(const Slice& key, void* value, size_t charge, DeleterFn deleter,
+                Handle** handle, Priority priority) override;
+  Status Insert(const Slice& key, void* value, const CacheItemHelper* helper,
+                size_t charge, Handle** handle = nullptr,
+                Priority priority = Priority::LOW) override;
+
+  Cache::Handle* Lookup(const Slice& key, Statistics* stats) override;
+  Cache::Handle* Lookup(const Slice& key, const CacheItemHelper* helper,
+                        const CreateCallback& create_cb, Priority priority,
+                        bool wait, Statistics* stats = nullptr) override;
+
+  bool Release(Cache::Handle* handle, bool useful,
+               bool erase_if_last_ref = false) override;
+  bool Release(Cache::Handle* handle, bool erase_if_last_ref = false) override;
+
+  void Erase(const Slice& key) override;
+  void EraseUnRefEntries() override;
+
+  static const char* kClassName() { return "ChargedCache"; }
+  const char* Name() const override { return kClassName(); }
+
+  uint64_t NewId() override { return cache_->NewId(); }
+
+  void SetCapacity(size_t capacity) override;
+
+  void SetStrictCapacityLimit(bool strict_capacity_limit) override {
+    cache_->SetStrictCapacityLimit(strict_capacity_limit);
+  }
+
+  bool HasStrictCapacityLimit() const override {
+    return cache_->HasStrictCapacityLimit();
+  }
+
+  void* Value(Cache::Handle* handle) override { return cache_->Value(handle); }
+
+  bool IsReady(Cache::Handle* handle) override {
+    return cache_->IsReady(handle);
+  }
+
+  void Wait(Cache::Handle* handle) override { cache_->Wait(handle); }
+
+  void WaitAll(std::vector<Handle*>& handles) override {
+    cache_->WaitAll(handles);
+  }
+
+  bool Ref(Cache::Handle* handle) override { return cache_->Ref(handle); }
+
+  size_t GetCapacity() const override { return cache_->GetCapacity(); }
+
+  size_t GetUsage() const override { return cache_->GetUsage(); }
+
+  size_t GetUsage(Cache::Handle* handle) const override {
+    return cache_->GetUsage(handle);
+  }
+
+  size_t GetPinnedUsage() const override { return cache_->GetPinnedUsage(); }
+
+  size_t GetCharge(Cache::Handle* handle) const override {
+    return cache_->GetCharge(handle);
+  }
+
+  Cache::DeleterFn GetDeleter(Cache::Handle* handle) const override {
+    return cache_->GetDeleter(handle);
+  }
+
+  void ApplyToAllEntries(
+      const std::function<void(const Slice& key, void* value, size_t charge,
+                               Cache::DeleterFn deleter)>& callback,
+      const Cache::ApplyToAllEntriesOptions& opts) override {
+    cache_->ApplyToAllEntries(callback, opts);
+  }
+
+  void ApplyToAllCacheEntries(void (*callback)(void* value, size_t charge),
+                              bool thread_safe) override {
+    cache_->ApplyToAllCacheEntries(callback, thread_safe);
+  }
+
+  std::string GetPrintableOptions() const override {
+    return cache_->GetPrintableOptions();
+  }
+
+  void DisownData() override { return cache_->DisownData(); }
+
+  inline Cache* GetCache() const { return cache_.get(); }
+
+  inline ConcurrentCacheReservationManager* TEST_GetCacheReservationManager()
+      const {
+    return cache_res_mgr_.get();
+  }
+
+ private:
+  std::shared_ptr<Cache> cache_;
+  std::shared_ptr<ConcurrentCacheReservationManager> cache_res_mgr_;
+};
+
+}  // namespace ROCKSDB_NAMESPACE

cache/clock_cache.h

@@ -9,8 +9,829 @@
 
 #pragma once
 
-#include "rocksdb/cache.h"
+#include <sys/types.h>
 
-#if defined(TBB) && !defined(ROCKSDB_LITE)
-#define SUPPORT_CLOCK_CACHE
+#include <array>
+#include <atomic>
+#include <cstdint>
+#include <memory>
+#include <string>
+
+#include "cache/cache_key.h"
+#include "cache/sharded_cache.h"
+#include "port/lang.h"
+#include "port/malloc.h"
+#include "port/port.h"
+#include "rocksdb/cache.h"
+#include "rocksdb/secondary_cache.h"
+#include "util/autovector.h"
+
+namespace ROCKSDB_NAMESPACE {
+
+namespace clock_cache {
+
+// Forward declaration of friend class.
+class ClockCacheTest;
+
+// An experimental alternative to LRUCache, using a lock-free, open-addressed
+// hash table and clock eviction.
+
+// ----------------------------------------------------------------------------
+// 1. INTRODUCTION
+//
+// In RocksDB, a Cache is a concurrent unordered dictionary that supports
+// external references (a.k.a. user references). A ClockCache is a type of Cache
+// that uses the clock algorithm as its eviction policy. Internally, a
+// ClockCache is an open-addressed hash table that stores all KV pairs in a
+// large array. Every slot in the hash table is a ClockHandle, which holds a KV
+// pair plus some additional metadata that controls the different aspects of the
+// cache: external references, the hashing mechanism, concurrent access and the
+// clock algorithm.
+//
+//
+// 2. EXTERNAL REFERENCES
+//
+// An externally referenced handle can't be deleted (either evicted by the clock
+// algorithm, or explicitly deleted) or replaced by a new version (via an insert
+// of the same key) until all external references to it have been released by
+// the users. ClockHandles have two members to support external references:
+// - EXTERNAL_REFS counter: The number of external refs. When EXTERNAL_REFS > 0,
+//    the handle is externally referenced. Updates that intend to modify the
+//    handle will refrain from doing so. Eventually, when all references are
+//    released, we have EXTERNAL_REFS == 0, and updates can operate normally on
+//    the handle.
+// - WILL_BE_DELETED flag: An handle is marked for deletion when an operation
+//    decides the handle should be deleted. This happens either when the last
+//    reference to a handle is released (and the release operation is instructed
+//    to delete on last reference) or on when a delete operation is called on
+//    the item. This flag is needed because an externally referenced handle
+//    can't be immediately deleted. In these cases, the flag will be later read
+//    and acted upon by the eviction algorithm. Importantly, WILL_BE_DELETED is
+//    used not only to defer deletions, but also as a barrier for external
+//    references: once WILL_BE_DELETED is set, lookups (which are the most
+//    common way to acquire new external references) will ignore the handle.
+//    For this reason, when WILL_BE_DELETED is set, we say the handle is
+//    invisible (and, otherwise, that it's visible).
+//
+//
+// 3. HASHING AND COLLISION RESOLUTION
+//
+// ClockCache uses an open-addressed hash table to store the handles.
+// We use a variant of tombstones to manage collisions: every slot keeps a
+// count of how many KV pairs that are currently in the cache have probed the
+// slot in an attempt to insert. Probes are generated with double-hashing
+// (although the code can be easily modified to use other probing schemes, like
+// linear probing).
+//
+// A slot in the hash table can be in a few different states:
+// - Element: The slot contains an element. This is indicated with the
+//    IS_ELEMENT flag. Element can be sub-classified depending on the
+//    value of WILL_BE_DELETED:
+//    * Visible element.
+//    * Invisible element.
+// - Tombstone: The slot doesn't contain an element, but there is some other
+//    element that probed this slot during its insertion.
+// - Empty: The slot is unused---it's neither an element nor a tombstone.
+//
+// A slot cycles through the following sequence of states:
+// empty or tombstone --> visible element --> invisible element -->
+// empty or tombstone. Initially a slot is available---it's either
+// empty or a tombstone. As soon as a KV pair is written into the slot, it
+// becomes a visible element. At some point, the handle will be deleted
+// by an explicit delete operation, the eviction algorithm, or an overwriting
+// insert. In either case, the handle is marked for deletion. When the an
+// attempt to delete the element finally succeeds, the slot is freed up
+// and becomes available again.
+//
+//
+// 4. CONCURRENCY
+//
+// ClockCache is lock-free. At a high level, we synchronize the operations
+// using a read-prioritized, non-blocking variant of RW locks on every slot of
+// the hash table. To do this we generalize the concept of reference:
+// - Internal reference: Taken by a thread that is attempting to read a slot
+//    or do a very precise type of update.
+// - Exclusive reference: Taken by a thread that is attempting to write a
+//    a slot extensively.
+//
+// We defer the precise definitions to the comments in the code below.
+// A crucial feature of our references is that attempting to take one never
+// blocks the thread. Another important feature is that readers are
+// prioritized, as they use extremely fast synchronization primitives---they
+// use atomic arithmetic/bit operations, but no compare-and-swaps (which are
+// much slower).
+//
+// Internal references are used by threads to read slots during a probing
+// sequence, making them the most common references (probing is performed
+// in almost every operation, not just lookups). During a lookup, once
+// the target element is found, and just before the handle is handed over
+// to the user, an internal reference is converted into an external reference.
+// During an update operation, once the target slot is found, an internal
+// reference is converted into an exclusive reference. Interestingly, we
+// can't atomically upgrade from internal to exclusive, or we may run into a
+// deadlock. Releasing the internal reference and then taking an exclusive
+// reference avoids the deadlock, but then the handle may change inbetween.
+// One of the key observations we use in our implementation is that we can
+// make up for this lack of atomicity using IS_ELEMENT and WILL_BE_DELETED.
+//
+// Distinguishing internal from external references is useful for two reasons:
+// - Internal references are short lived, but external references are typically
+//    not. This is helpful when acquiring an exclusive ref: if there are any
+//    external references to the item, it's probably not worth waiting until
+//    they go away.
+// - We can precisely determine when there are no more external references to a
+//    handle, and proceed to mark it for deletion. This is useful when users
+//    release external references.
+//
+//
+// 5. CLOCK ALGORITHM
+//
+// The clock algorithm circularly sweeps through the hash table to find the next
+// victim. Recall that handles that are referenced are not evictable; the clock
+// algorithm never picks those. We use different clock priorities: NONE, LOW,
+// MEDIUM and HIGH. Priorities LOW, MEDIUM and HIGH represent how close an
+// element is from being evicted, LOW being the closest to evicted. NONE means
+// the slot is not evictable. NONE priority is used in one of the following
+// cases:
+// (a) the slot doesn't contain an element, or
+// (b) the slot contains an externally referenced element, or
+// (c) the slot contains an element that used to be externally referenced,
+//      and the clock pointer has not swept through the slot since the element
+//      stopped being externally referenced.
+// ----------------------------------------------------------------------------
+
+// The load factor p is a real number in (0, 1) such that at all
+// times at most a fraction p of all slots, without counting tombstones,
+// are occupied by elements. This means that the probability that a
+// random probe hits an empty slot is at most p, and thus at most 1/p probes
+// are required on average. For example, p = 70% implies that between 1 and 2
+// probes are needed on average (bear in mind that this reasoning doesn't
+// consider the effects of clustering over time).
+// Because the size of the hash table is always rounded up to the next
+// power of 2, p is really an upper bound on the actual load factor---the
+// actual load factor is anywhere between p/2 and p. This is a bit wasteful,
+// but bear in mind that slots only hold metadata, not actual values.
+// Since space cost is dominated by the values (the LSM blocks),
+// overprovisioning the table with metadata only increases the total cache space
+// usage by a tiny fraction.
+constexpr double kLoadFactor = 0.35;
+
+// The user can exceed kLoadFactor if the sizes of the inserted values don't
+// match estimated_value_size, or if strict_capacity_limit == false. To
+// avoid a performance drop, we set a strict upper bound on the load factor.
+constexpr double kStrictLoadFactor = 0.7;
+
+// Maximum number of spins when trying to acquire a ref.
+// TODO(Guido) This value was set arbitrarily. Is it appropriate?
+// What's the best way to bound the spinning?
+constexpr uint32_t kSpinsPerTry = 100000;
+
+// Arbitrary seeds.
+constexpr uint32_t kProbingSeed1 = 0xbc9f1d34;
+constexpr uint32_t kProbingSeed2 = 0x7a2bb9d5;
+
+struct ClockHandle {
+  void* value;
+  Cache::DeleterFn deleter;
+  uint32_t hash;
+  size_t total_charge;
+  std::array<char, kCacheKeySize> key_data;
+
+  static constexpr uint8_t kIsElementOffset = 0;
+  static constexpr uint8_t kClockPriorityOffset = 1;
+  static constexpr uint8_t kIsHitOffset = 3;
+  static constexpr uint8_t kCachePriorityOffset = 4;
+
+  enum Flags : uint8_t {
+    // Whether the slot is in use by an element.
+    IS_ELEMENT = 1 << kIsElementOffset,
+    // Clock priorities. Represents how close a handle is from being evictable.
+    CLOCK_PRIORITY = 3 << kClockPriorityOffset,
+    // Whether the handle has been looked up after its insertion.
+    HAS_HIT = 1 << kIsHitOffset,
+    // The value of Cache::Priority of the handle.
+    CACHE_PRIORITY = 1 << kCachePriorityOffset,
+  };
+
+  std::atomic<uint8_t> flags;
+
+  enum ClockPriority : uint8_t {
+    NONE = (0 << kClockPriorityOffset),
+    LOW = (1 << kClockPriorityOffset),
+    MEDIUM = (2 << kClockPriorityOffset),
+    HIGH = (3 << kClockPriorityOffset)
+  };
+
+  // The number of elements that hash to this slot or a lower one, but wind
+  // up in this slot or a higher one.
+  std::atomic<uint32_t> displacements;
+
+  static constexpr uint8_t kExternalRefsOffset = 0;
+  static constexpr uint8_t kSharedRefsOffset = 15;
+  static constexpr uint8_t kExclusiveRefOffset = 30;
+  static constexpr uint8_t kWillBeDeletedOffset = 31;
+
+  enum Refs : uint32_t {
+    // Synchronization model:
+    // - An external reference guarantees that hash, value, key_data
+    //    and the IS_ELEMENT flag are not modified. Doesn't allow
+    //    any writes.
+    // - An internal reference has the same guarantees as an
+    //    external reference, and additionally allows the following
+    //    idempotent updates on the handle:
+    //      * set CLOCK_PRIORITY to NONE;
+    //      * set the HAS_HIT bit;
+    //      * set the WILL_BE_DELETED bit.
+    // - A shared reference is either an external reference or an
+    //    internal reference.
+    // - An exclusive reference guarantees that no other thread has a shared
+    //    or exclusive reference to the handle, and allows writes
+    //    on the handle.
+
+    // Number of external references to the slot.
+    EXTERNAL_REFS = ((uint32_t{1} << 15) - 1)
+                    << kExternalRefsOffset,  // Bits 0, ..., 14
+    // Number of internal references plus external references to the slot.
+    SHARED_REFS = ((uint32_t{1} << 15) - 1)
+                  << kSharedRefsOffset,  // Bits 15, ..., 29
+    // Whether a thread has an exclusive reference to the slot.
+    EXCLUSIVE_REF = uint32_t{1} << kExclusiveRefOffset,  // Bit 30
+    // Whether the handle will be deleted soon. When this bit is set, new
+    // internal references to this handle stop being accepted.
+    // External references may still be granted---they can be created from
+    // existing external references, or converting from existing internal
+    // references.
+    WILL_BE_DELETED = uint32_t{1} << kWillBeDeletedOffset  // Bit 31
+
+    // Having these 4 fields in a single variable allows us to support the
+    // following operations efficiently:
+    // - Convert an internal reference into an external reference in a single
+    //    atomic arithmetic operation.
+    // - Attempt to take a shared reference using a single atomic arithmetic
+    //    operation. This is because we can increment the internal ref count
+    //    as well as checking whether the entry is marked for deletion using a
+    //    single atomic arithmetic operation (and one non-atomic comparison).
+  };
+
+  static constexpr uint32_t kOneInternalRef = 0x8000;
+  static constexpr uint32_t kOneExternalRef = 0x8001;
+
+  std::atomic<uint32_t> refs;
+
+  // True iff the handle is allocated separately from hash table.
+  bool detached;
+
+  ClockHandle()
+      : value(nullptr),
+        deleter(nullptr),
+        hash(0),
+        total_charge(0),
+        flags(0),
+        displacements(0),
+        refs(0),
+        detached(false) {
+    SetWillBeDeleted(false);
+    SetIsElement(false);
+    SetClockPriority(ClockPriority::NONE);
+    SetCachePriority(Cache::Priority::LOW);
+    key_data.fill(0);
+  }
+
+  // The copy ctor and assignment operator are only used to copy a handle
+  // for immediate deletion. (We need to copy because the slot may become
+  // re-used before the deletion is completed.) We only copy the necessary
+  // members to carry out the deletion. In particular, we don't need
+  // the atomic members.
+  ClockHandle(const ClockHandle& other) { *this = other; }
+
+  void operator=(const ClockHandle& other) {
+    value = other.value;
+    deleter = other.deleter;
+    key_data = other.key_data;
+    hash = other.hash;
+    total_charge = other.total_charge;
+  }
+
+  Slice key() const { return Slice(key_data.data(), kCacheKeySize); }
+
+  void FreeData() {
+    if (deleter) {
+      (*deleter)(key(), value);
+    }
+  }
+
+  // Calculate the memory usage by metadata.
+  inline size_t CalcMetaCharge(
+      CacheMetadataChargePolicy metadata_charge_policy) const {
+    if (metadata_charge_policy != kFullChargeCacheMetadata) {
+      return 0;
+    } else {
+      // #ifdef ROCKSDB_MALLOC_USABLE_SIZE
+      //       return malloc_usable_size(
+      //           const_cast<void*>(static_cast<const void*>(this)));
+      // #else
+      // TODO(Guido) malloc_usable_size only works when we call it on
+      // a pointer allocated with malloc. Because our handles are all
+      // allocated in a single shot as an array, the user can't call
+      // CalcMetaCharge (or CalcTotalCharge or GetCharge) on a handle
+      // pointer returned by the cache. Moreover, malloc_usable_size
+      // expects a heap-allocated handle, but sometimes in our code we
+      // wish to pass a stack-allocated handle (this is only a performance
+      // concern).
+      // What is the right way to compute metadata charges with pre-allocated
+      // handles?
+      return sizeof(ClockHandle);
+      // #endif
+    }
+  }
+
+  inline void CalcTotalCharge(
+      size_t charge, CacheMetadataChargePolicy metadata_charge_policy) {
+    total_charge = charge + CalcMetaCharge(metadata_charge_policy);
+  }
+
+  inline size_t GetCharge(
+      CacheMetadataChargePolicy metadata_charge_policy) const {
+    size_t meta_charge = CalcMetaCharge(metadata_charge_policy);
+    assert(total_charge >= meta_charge);
+    return total_charge - meta_charge;
+  }
+
+  // flags functions.
+
+  bool IsElement() const { return flags & Flags::IS_ELEMENT; }
+
+  void SetIsElement(bool is_element) {
+    if (is_element) {
+      flags |= Flags::IS_ELEMENT;
+    } else {
+      flags &= static_cast<uint8_t>(~Flags::IS_ELEMENT);
+    }
+  }
+
+  bool HasHit() const { return flags & HAS_HIT; }
+
+  void SetHit() { flags |= HAS_HIT; }
+
+  Cache::Priority GetCachePriority() const {
+    return static_cast<Cache::Priority>(flags & CACHE_PRIORITY);
+  }
+
+  void SetCachePriority(Cache::Priority priority) {
+    if (priority == Cache::Priority::HIGH) {
+      flags |= Flags::CACHE_PRIORITY;
+    } else {
+      flags &= static_cast<uint8_t>(~Flags::CACHE_PRIORITY);
+    }
+  }
+
+  bool IsInClock() const {
+    return GetClockPriority() != ClockHandle::ClockPriority::NONE;
+  }
+
+  ClockPriority GetClockPriority() const {
+    return static_cast<ClockPriority>(flags & Flags::CLOCK_PRIORITY);
+  }
+
+  void SetClockPriority(ClockPriority priority) {
+    flags &= static_cast<uint8_t>(~Flags::CLOCK_PRIORITY);
+    flags |= priority;
+  }
+
+  void DecreaseClockPriority() {
+    uint8_t p = static_cast<uint8_t>(flags & Flags::CLOCK_PRIORITY) >>
+                kClockPriorityOffset;
+    assert(p > 0);
+    p--;
+    flags &= static_cast<uint8_t>(~Flags::CLOCK_PRIORITY);
+    ClockPriority new_priority =
+        static_cast<ClockPriority>(p << kClockPriorityOffset);
+    flags |= new_priority;
+  }
+
+  bool IsDetached() { return detached; }
+
+  void SetDetached() { detached = true; }
+
+  inline bool IsEmpty() const {
+    return !this->IsElement() && this->displacements == 0;
+  }
+
+  inline bool IsTombstone() const {
+    return !this->IsElement() && this->displacements > 0;
+  }
+
+  inline bool Matches(const Slice& some_key, uint32_t some_hash) const {
+    return this->hash == some_hash && this->key() == some_key;
+  }
+
+  // refs functions.
+
+  inline bool WillBeDeleted() const { return refs & WILL_BE_DELETED; }
+
+  void SetWillBeDeleted(bool will_be_deleted) {
+    if (will_be_deleted) {
+      refs |= WILL_BE_DELETED;
+    } else {
+      refs &= ~WILL_BE_DELETED;
+    }
+  }
+
+  uint32_t ExternalRefs() const {
+    return (refs & EXTERNAL_REFS) >> kExternalRefsOffset;
+  }
+
+  // Tries to take an internal ref. Returns true iff it succeeds.
+  inline bool TryInternalRef() {
+    if (!((refs += kOneInternalRef) & (EXCLUSIVE_REF | WILL_BE_DELETED))) {
+      return true;
+    }
+    refs -= kOneInternalRef;
+    return false;
+  }
+
+  // Tries to take an external ref. Returns true iff it succeeds.
+  inline bool TryExternalRef() {
+    if (!((refs += kOneExternalRef) & EXCLUSIVE_REF)) {
+      return true;
+    }
+    refs -= kOneExternalRef;
+    return false;
+  }
+
+  // Tries to take an exclusive ref. Returns true iff it succeeds.
+  // TODO(Guido) After every TryExclusiveRef call, we always call
+  // WillBeDeleted(). We could save an atomic read by having an output parameter
+  // with the last value of refs.
+  inline bool TryExclusiveRef() {
+    uint32_t will_be_deleted = refs & WILL_BE_DELETED;
+    uint32_t expected = will_be_deleted;
+    return refs.compare_exchange_strong(expected,
+                                        EXCLUSIVE_REF | will_be_deleted);
+  }
+
+  // Repeatedly tries to take an exclusive reference, but aborts as soon
+  // as an external or exclusive reference is detected (since the wait
+  // would presumably be too long).
+  inline bool SpinTryExclusiveRef() {
+    uint32_t expected = 0;
+    uint32_t will_be_deleted = 0;
+    uint32_t spins = kSpinsPerTry;
+    while (!refs.compare_exchange_strong(expected,
+                                         EXCLUSIVE_REF | will_be_deleted) &&
+           spins--) {
+      std::this_thread::yield();
+      if (expected & (EXTERNAL_REFS | EXCLUSIVE_REF)) {
+        return false;
+      }
+      will_be_deleted = expected & WILL_BE_DELETED;
+      expected = will_be_deleted;
+    }
+    return true;
+  }
+
+  // Take an external ref, assuming there is already one external ref
+  // to the handle.
+  void Ref() {
+    // TODO(Guido) Is it okay to assume that the existing external reference
+    // survives until this function returns?
+    refs += kOneExternalRef;
+  }
+
+  inline void ReleaseExternalRef() { refs -= kOneExternalRef; }
+
+  inline void ReleaseInternalRef() { refs -= kOneInternalRef; }
+
+  inline void ReleaseExclusiveRef() { refs.fetch_and(~EXCLUSIVE_REF); }
+
+  // Downgrade an exclusive ref to external.
+  inline void ExclusiveToExternalRef() {
+    refs += kOneExternalRef;
+    ReleaseExclusiveRef();
+  }
+
+  // Convert an internal ref into external.
+  inline void InternalToExternalRef() {
+    refs += kOneExternalRef - kOneInternalRef;
+  }
+
+};  // struct ClockHandle
+
+class ClockHandleTable {
+ public:
+  explicit ClockHandleTable(size_t capacity, int hash_bits);
+  ~ClockHandleTable();
+
+  // Returns a pointer to a visible handle matching the key/hash, or
+  // nullptr if not present. When an actual handle is produced, an
+  // internal reference is handed over.
+  ClockHandle* Lookup(const Slice& key, uint32_t hash);
+
+  // Inserts a copy of h into the hash table. Returns a pointer to the
+  // inserted handle, or nullptr if no available slot was found. Every
+  // existing visible handle matching the key is already present in the
+  // hash table is marked as WILL_BE_DELETED. The deletion is also attempted,
+  // and, if the attempt is successful, the handle is inserted into the
+  // autovector deleted. When take_reference is true, the function hands
+  // over an external reference on the handle, and otherwise no reference is
+  // produced.
+  ClockHandle* Insert(ClockHandle* h, autovector<ClockHandle>* deleted,
+                      bool take_reference);
+
+  // Assigns h the appropriate clock priority, making it evictable.
+  void ClockOn(ClockHandle* h);
+
+  // Makes h non-evictable.
+  void ClockOff(ClockHandle* h);
+
+  // Runs the clock eviction algorithm until usage_ + charge is at most
+  // capacity_.
+  void ClockRun(size_t charge);
+
+  // Remove h from the hash table. Requires an exclusive ref to h.
+  void Remove(ClockHandle* h, autovector<ClockHandle>* deleted);
+
+  // Remove from the hash table all handles with matching key/hash along a
+  // probe sequence, starting from the given probe number. Doesn't
+  // require any references.
+  void RemoveAll(const Slice& key, uint32_t hash, uint32_t& probe,
+                 autovector<ClockHandle>* deleted);
+
+  void RemoveAll(const Slice& key, uint32_t hash,
+                 autovector<ClockHandle>* deleted) {
+    uint32_t probe = 0;
+    RemoveAll(key, hash, probe, deleted);
+  }
+
+  // Tries to remove h from the hash table. If the attempt is successful,
+  // the function hands over an exclusive ref to h.
+  bool TryRemove(ClockHandle* h, autovector<ClockHandle>* deleted);
+
+  // Similar to TryRemove, except that it spins, increasing the chances of
+  // success. Requires that the caller thread has no shared ref to h.
+  bool SpinTryRemove(ClockHandle* h, autovector<ClockHandle>* deleted);
+
+  // Call this function after an Insert, Remove, RemoveAll, TryRemove
+  // or SpinTryRemove. It frees the deleted values and updates the hash table
+  // metadata.
+  void Free(autovector<ClockHandle>* deleted);
+
+  void ApplyToEntriesRange(std::function<void(ClockHandle*)> func,
+                           uint32_t index_begin, uint32_t index_end,
+                           bool apply_if_will_be_deleted) {
+    for (uint32_t i = index_begin; i < index_end; i++) {
+      ClockHandle* h = &array_[i];
+      if (h->TryExclusiveRef()) {
+        if (h->IsElement() &&
+            (apply_if_will_be_deleted || !h->WillBeDeleted())) {
+          func(h);
+        }
+        h->ReleaseExclusiveRef();
+      }
+    }
+  }
+
+  void ConstApplyToEntriesRange(std::function<void(const ClockHandle*)> func,
+                                uint32_t index_begin, uint32_t index_end,
+                                bool apply_if_will_be_deleted) const {
+    for (uint32_t i = index_begin; i < index_end; i++) {
+      ClockHandle* h = &array_[i];
+      // We take an external ref because we are handing over control
+      // to a user-defined function, and because the handle will not be
+      // modified.
+      if (h->TryExternalRef()) {
+        if (h->IsElement() &&
+            (apply_if_will_be_deleted || !h->WillBeDeleted())) {
+          func(h);
+        }
+        h->ReleaseExternalRef();
+      }
+    }
+  }
+
+  uint32_t GetTableSize() const { return uint32_t{1} << length_bits_; }
+
+  int GetLengthBits() const { return length_bits_; }
+
+  uint32_t GetOccupancyLimit() const { return occupancy_limit_; }
+
+  uint32_t GetOccupancy() const { return occupancy_; }
+
+  size_t GetUsage() const { return usage_; }
+
+  size_t GetCapacity() const { return capacity_; }
+
+  void SetCapacity(size_t capacity) { capacity_ = capacity; }
+
+  // Returns x mod 2^{length_bits_}.
+  uint32_t ModTableSize(uint32_t x) { return x & length_bits_mask_; }
+
+ private:
+  // Extracts the element information from a handle (src), and assigns it
+  // to a hash table slot (dst). Doesn't touch displacements and refs,
+  // which are maintained by the hash table algorithm.
+  void Assign(ClockHandle* dst, ClockHandle* src);
+
+  // Returns the first slot in the probe sequence, starting from the given
+  // probe number, with a handle e such that match(e) is true. At every
+  // step, the function first tests whether match(e) holds. If this is false,
+  // it evaluates abort(e) to decide whether the search should be aborted,
+  // and in the affirmative returns -1. For every handle e probed except
+  // the last one, the function runs update(e).
+  // The probe parameter is modified as follows. We say a probe to a handle
+  // e is aborting if match(e) is false and abort(e) is true. Then the final
+  // value of probe is one more than the last non-aborting probe during the
+  // call. This is so that that the variable can be used to keep track of
+  // progress across consecutive calls to FindSlot.
+  inline ClockHandle* FindSlot(const Slice& key,
+                               std::function<bool(ClockHandle*)> match,
+                               std::function<bool(ClockHandle*)> stop,
+                               std::function<void(ClockHandle*)> update,
+                               uint32_t& probe);
+
+  // Returns an available slot for the given key. All copies of the
+  // key found along the probing sequence until an available slot is
+  // found are marked for deletion. On each of them, a deletion is
+  // attempted, and when the attempt succeeds the slot is assigned to
+  // the new copy of the element.
+  ClockHandle* FindAvailableSlot(const Slice& key, uint32_t hash,
+                                 uint32_t& probe,
+                                 autovector<ClockHandle>* deleted);
+
+  // After a failed FindSlot call (i.e., with answer -1) in
+  // FindAvailableSlot, this function fixes all displacements's
+  // starting from the 0-th probe, until the given probe.
+  void Rollback(const Slice& key, uint32_t probe);
+
+  // Number of hash bits used for table index.
+  // The size of the table is 1 << length_bits_.
+  const int length_bits_;
+
+  // For faster computation of ModTableSize.
+  const uint32_t length_bits_mask_;
+
+  // Maximum number of elements the user can store in the table.
+  const uint32_t occupancy_limit_;
+
+  // Maximum total charge of all elements stored in the table.
+  size_t capacity_;
+
+  // We partition the following members into different cache lines
+  // to avoid false sharing among Lookup, Release, Erase and Insert
+  // operations in ClockCacheShard.
+
+  ALIGN_AS(CACHE_LINE_SIZE)
+  // Array of slots comprising the hash table.
+  std::unique_ptr<ClockHandle[]> array_;
+
+  ALIGN_AS(CACHE_LINE_SIZE)
+  // Clock algorithm sweep pointer.
+  std::atomic<uint32_t> clock_pointer_;
+
+  ALIGN_AS(CACHE_LINE_SIZE)
+  // Number of elements in the table.
+  std::atomic<uint32_t> occupancy_;
+
+  // Memory size for entries residing in the cache.
+  std::atomic<size_t> usage_;
+};  // class ClockHandleTable
+
+// A single shard of sharded cache.
+class ALIGN_AS(CACHE_LINE_SIZE) ClockCacheShard final : public CacheShard {
+ public:
+  ClockCacheShard(size_t capacity, size_t estimated_value_size,
+                  bool strict_capacity_limit,
+                  CacheMetadataChargePolicy metadata_charge_policy);
+  ~ClockCacheShard() override = default;
+
+  // Separate from constructor so caller can easily make an array of ClockCache
+  // if current usage is more than new capacity, the function will attempt to
+  // free the needed space.
+  void SetCapacity(size_t capacity) override;
+
+  // Set the flag to reject insertion if cache if full.
+  void SetStrictCapacityLimit(bool strict_capacity_limit) override;
+
+  // Like Cache methods, but with an extra "hash" parameter.
+  // Insert an item into the hash table and, if handle is null, make it
+  // evictable by the clock algorithm. Older items are evicted as necessary.
+  // If the cache is full and free_handle_on_fail is true, the item is deleted
+  // and handle is set to nullptr.
+  Status Insert(const Slice& key, uint32_t hash, void* value, size_t charge,
+                Cache::DeleterFn deleter, Cache::Handle** handle,
+                Cache::Priority priority) override;
+
+  Status Insert(const Slice& key, uint32_t hash, void* value,
+                const Cache::CacheItemHelper* helper, size_t charge,
+                Cache::Handle** handle, Cache::Priority priority) override {
+    return Insert(key, hash, value, charge, helper->del_cb, handle, priority);
+  }
+
+  Cache::Handle* Lookup(const Slice& key, uint32_t hash,
+                        const Cache::CacheItemHelper* /*helper*/,
+                        const Cache::CreateCallback& /*create_cb*/,
+                        Cache::Priority /*priority*/, bool /*wait*/,
+                        Statistics* /*stats*/) override {
+    return Lookup(key, hash);
+  }
+
+  Cache::Handle* Lookup(const Slice& key, uint32_t hash) override;
+
+  bool Release(Cache::Handle* handle, bool /*useful*/,
+               bool erase_if_last_ref) override {
+    return Release(handle, erase_if_last_ref);
+  }
+
+  bool IsReady(Cache::Handle* /*handle*/) override { return true; }
+
+  void Wait(Cache::Handle* /*handle*/) override {}
+
+  bool Ref(Cache::Handle* handle) override;
+
+  bool Release(Cache::Handle* handle, bool erase_if_last_ref = false) override;
+
+  void Erase(const Slice& key, uint32_t hash) override;
+
+  size_t GetUsage() const override;
+
+  size_t GetPinnedUsage() const override;
+
+  void ApplyToSomeEntries(
+      const std::function<void(const Slice& key, void* value, size_t charge,
+                               DeleterFn deleter)>& callback,
+      uint32_t average_entries_per_lock, uint32_t* state) override;
+
+  void EraseUnRefEntries() override;
+
+  std::string GetPrintableOptions() const override { return std::string{}; }
+
+ private:
+  friend class ClockCache;
+  friend class ClockCacheTest;
+
+  ClockHandle* DetachedInsert(ClockHandle* h);
+
+  // Returns the charge of a single handle.
+  static size_t CalcEstimatedHandleCharge(
+      size_t estimated_value_size,
+      CacheMetadataChargePolicy metadata_charge_policy);
+
+  // Returns the number of bits used to hash an element in the hash
+  // table.
+  static int CalcHashBits(size_t capacity, size_t estimated_value_size,
+                          CacheMetadataChargePolicy metadata_charge_policy);
+
+  // Whether to reject insertion if cache reaches its full capacity.
+  std::atomic<bool> strict_capacity_limit_;
+
+  // Handles allocated separately from the table.
+  std::atomic<size_t> detached_usage_;
+
+  ClockHandleTable table_;
+};  // class ClockCacheShard
+
+class ClockCache
+#ifdef NDEBUG
+    final
 #endif
+    : public ShardedCache {
+ public:
+  ClockCache(size_t capacity, size_t estimated_value_size, int num_shard_bits,
+             bool strict_capacity_limit,
+             CacheMetadataChargePolicy metadata_charge_policy =
+                 kDontChargeCacheMetadata);
+
+  ~ClockCache() override;
+
+  const char* Name() const override { return "ClockCache"; }
+
+  CacheShard* GetShard(uint32_t shard) override;
+
+  const CacheShard* GetShard(uint32_t shard) const override;
+
+  void* Value(Handle* handle) override;
+
+  size_t GetCharge(Handle* handle) const override;
+
+  uint32_t GetHash(Handle* handle) const override;
+
+  DeleterFn GetDeleter(Handle* handle) const override;
+
+  void DisownData() override;
+
+ private:
+  ClockCacheShard* shards_ = nullptr;
+
+  int num_shards_;
+};  // class ClockCache
+
+}  // namespace clock_cache
+
+// Only for internal testing, temporarily replacing NewClockCache.
+// TODO(Guido) Remove once NewClockCache constructs a ClockCache again.
+extern std::shared_ptr<Cache> ExperimentalNewClockCache(
+    size_t capacity, size_t estimated_value_size, int num_shard_bits,
+    bool strict_capacity_limit,
+    CacheMetadataChargePolicy metadata_charge_policy);
+
+}  // namespace ROCKSDB_NAMESPACE

cache/compressed_secondary_cache.cc

@@ -5,6 +5,8 @@
 
 #include "cache/compressed_secondary_cache.h"
 
+#include <algorithm>
+#include <cstdint>
 #include <memory>
 
 #include "memory/memory_allocator.h"
@@ -13,28 +15,20 @@
 
 namespace ROCKSDB_NAMESPACE {
 
-namespace {
-
-void DeletionCallback(const Slice& /*key*/, void* obj) {
-  delete reinterpret_cast<CacheAllocationPtr*>(obj);
-  obj = nullptr;
-}
-
-}  // namespace
-
 CompressedSecondaryCache::CompressedSecondaryCache(
     size_t capacity, int num_shard_bits, bool strict_capacity_limit,
-    double high_pri_pool_ratio,
+    double high_pri_pool_ratio, double low_pri_pool_ratio,
     std::shared_ptr<MemoryAllocator> memory_allocator, bool use_adaptive_mutex,
     CacheMetadataChargePolicy metadata_charge_policy,
     CompressionType compression_type, uint32_t compress_format_version)
     : cache_options_(capacity, num_shard_bits, strict_capacity_limit,
                      high_pri_pool_ratio, memory_allocator, use_adaptive_mutex,
                      metadata_charge_policy, compression_type,
-                     compress_format_version) {
-  cache_ = NewLRUCache(capacity, num_shard_bits, strict_capacity_limit,
-                       high_pri_pool_ratio, memory_allocator,
-                       use_adaptive_mutex, metadata_charge_policy);
+                     compress_format_version, low_pri_pool_ratio) {
+  cache_ =
+      NewLRUCache(capacity, num_shard_bits, strict_capacity_limit,
+                  high_pri_pool_ratio, memory_allocator, use_adaptive_mutex,
+                  metadata_charge_policy, low_pri_pool_ratio);
 }
 
 CompressedSecondaryCache::~CompressedSecondaryCache() { cache_.reset(); }
@@ -49,26 +43,29 @@ std::unique_ptr<SecondaryCacheResultHandle> CompressedSecondaryCache::Lookup(
     return handle;
   }
 
-  CacheAllocationPtr* ptr =
-      reinterpret_cast<CacheAllocationPtr*>(cache_->Value(lru_handle));
-  void* value = nullptr;
-  size_t charge = 0;
-  Status s;
+  CacheValueChunk* handle_value =
+      reinterpret_cast<CacheValueChunk*>(cache_->Value(lru_handle));
+  size_t handle_value_charge{0};
+  CacheAllocationPtr merged_value =
+      MergeChunksIntoValue(handle_value, handle_value_charge);
 
+  Status s;
+  void* value{nullptr};
+  size_t charge{0};
   if (cache_options_.compression_type == kNoCompression) {
-    s = create_cb(ptr->get(), cache_->GetCharge(lru_handle), &value, &charge);
+    s = create_cb(merged_value.get(), handle_value_charge, &value, &charge);
   } else {
     UncompressionContext uncompression_context(cache_options_.compression_type);
     UncompressionInfo uncompression_info(uncompression_context,
                                          UncompressionDict::GetEmptyDict(),
                                          cache_options_.compression_type);
 
-    size_t uncompressed_size = 0;
+    size_t uncompressed_size{0};
     CacheAllocationPtr uncompressed;
-    uncompressed = UncompressData(
-        uncompression_info, (char*)ptr->get(), cache_->GetCharge(lru_handle),
-        &uncompressed_size, cache_options_.compress_format_version,
-        cache_options_.memory_allocator.get());
+    uncompressed = UncompressData(uncompression_info, (char*)merged_value.get(),
+                                  handle_value_charge, &uncompressed_size,
+                                  cache_options_.compress_format_version,
+                                  cache_options_.memory_allocator.get());
 
     if (!uncompressed) {
       cache_->Release(lru_handle, /* erase_if_last_ref */ true);
@@ -104,7 +101,7 @@ Status CompressedSecondaryCache::Insert(const Slice& key, void* value,
   if (cache_options_.compression_type != kNoCompression) {
     CompressionOptions compression_opts;
     CompressionContext compression_context(cache_options_.compression_type);
-    uint64_t sample_for_compression = 0;
+    uint64_t sample_for_compression{0};
     CompressionInfo compression_info(
         compression_opts, compression_context, CompressionDict::GetEmptyDict(),
         cache_options_.compression_type, sample_for_compression);
@@ -118,14 +115,12 @@ Status CompressedSecondaryCache::Insert(const Slice& key, void* value,
     }
 
     val = Slice(compressed_val);
-    size = compressed_val.size();
-    ptr = AllocateBlock(size, cache_options_.memory_allocator.get());
-    memcpy(ptr.get(), compressed_val.data(), size);
   }
 
-  CacheAllocationPtr* buf = new CacheAllocationPtr(std::move(ptr));
-
-  return cache_->Insert(key, buf, size, DeletionCallback);
+  size_t charge{0};
+  CacheValueChunk* value_chunks_head =
+      SplitValueIntoChunks(val, cache_options_.compression_type, charge);
+  return cache_->Insert(key, value_chunks_head, charge, DeletionCallback);
 }
 
 void CompressedSecondaryCache::Erase(const Slice& key) { cache_->Erase(key); }
@@ -133,28 +128,110 @@ void CompressedSecondaryCache::Erase(const Slice& key) { cache_->Erase(key); }
 std::string CompressedSecondaryCache::GetPrintableOptions() const {
   std::string ret;
   ret.reserve(20000);
-  const int kBufferSize = 200;
+  const int kBufferSize{200};
   char buffer[kBufferSize];
   ret.append(cache_->GetPrintableOptions());
   snprintf(buffer, kBufferSize, "    compression_type : %s\n",
            CompressionTypeToString(cache_options_.compression_type).c_str());
   ret.append(buffer);
-  snprintf(buffer, kBufferSize, "    compression_type : %d\n",
+  snprintf(buffer, kBufferSize, "    compress_format_version : %d\n",
            cache_options_.compress_format_version);
   ret.append(buffer);
   return ret;
 }
 
+CompressedSecondaryCache::CacheValueChunk*
+CompressedSecondaryCache::SplitValueIntoChunks(
+    const Slice& value, const CompressionType compression_type,
+    size_t& charge) {
+  assert(!value.empty());
+  const char* src_ptr = value.data();
+  size_t src_size{value.size()};
+
+  CacheValueChunk dummy_head = CacheValueChunk();
+  CacheValueChunk* current_chunk = &dummy_head;
+  // Do not split when value size is large or there is no compression.
+  size_t predicted_chunk_size{0};
+  size_t actual_chunk_size{0};
+  size_t tmp_size{0};
+  while (src_size > 0) {
+    predicted_chunk_size = sizeof(CacheValueChunk) - 1 + src_size;
+    auto upper =
+        std::upper_bound(malloc_bin_sizes_.begin(), malloc_bin_sizes_.end(),
+                         predicted_chunk_size);
+    // Do not split when value size is too small, too large, close to a bin
+    // size, or there is no compression.
+    if (upper == malloc_bin_sizes_.begin() ||
+        upper == malloc_bin_sizes_.end() ||
+        *upper - predicted_chunk_size < malloc_bin_sizes_.front() ||
+        compression_type == kNoCompression) {
+      tmp_size = predicted_chunk_size;
+    } else {
+      tmp_size = *(--upper);
+    }
+
+    CacheValueChunk* new_chunk =
+        reinterpret_cast<CacheValueChunk*>(new char[tmp_size]);
+    current_chunk->next = new_chunk;
+    current_chunk = current_chunk->next;
+    actual_chunk_size = tmp_size - sizeof(CacheValueChunk) + 1;
+    memcpy(current_chunk->data, src_ptr, actual_chunk_size);
+    current_chunk->size = actual_chunk_size;
+    src_ptr += actual_chunk_size;
+    src_size -= actual_chunk_size;
+    charge += tmp_size;
+  }
+  current_chunk->next = nullptr;
+
+  return dummy_head.next;
+}
+
+CacheAllocationPtr CompressedSecondaryCache::MergeChunksIntoValue(
+    const void* chunks_head, size_t& charge) {
+  const CacheValueChunk* head =
+      reinterpret_cast<const CacheValueChunk*>(chunks_head);
+  const CacheValueChunk* current_chunk = head;
+  charge = 0;
+  while (current_chunk != nullptr) {
+    charge += current_chunk->size;
+    current_chunk = current_chunk->next;
+  }
+
+  CacheAllocationPtr ptr =
+      AllocateBlock(charge, cache_options_.memory_allocator.get());
+  current_chunk = head;
+  size_t pos{0};
+  while (current_chunk != nullptr) {
+    memcpy(ptr.get() + pos, current_chunk->data, current_chunk->size);
+    pos += current_chunk->size;
+    current_chunk = current_chunk->next;
+  }
+
+  return ptr;
+}
+
+void CompressedSecondaryCache::DeletionCallback(const Slice& /*key*/,
+                                                void* obj) {
+  CacheValueChunk* chunks_head = reinterpret_cast<CacheValueChunk*>(obj);
+  while (chunks_head != nullptr) {
+    CacheValueChunk* tmp_chunk = chunks_head;
+    chunks_head = chunks_head->next;
+    tmp_chunk->Free();
+  }
+  obj = nullptr;
+}
+
 std::shared_ptr<SecondaryCache> NewCompressedSecondaryCache(
     size_t capacity, int num_shard_bits, bool strict_capacity_limit,
     double high_pri_pool_ratio,
     std::shared_ptr<MemoryAllocator> memory_allocator, bool use_adaptive_mutex,
     CacheMetadataChargePolicy metadata_charge_policy,
-    CompressionType compression_type, uint32_t compress_format_version) {
+    CompressionType compression_type, uint32_t compress_format_version,
+    double low_pri_pool_ratio) {
   return std::make_shared<CompressedSecondaryCache>(
       capacity, num_shard_bits, strict_capacity_limit, high_pri_pool_ratio,
-      memory_allocator, use_adaptive_mutex, metadata_charge_policy,
-      compression_type, compress_format_version);
+      low_pri_pool_ratio, memory_allocator, use_adaptive_mutex,
+      metadata_charge_policy, compression_type, compress_format_version);
 }
 
 std::shared_ptr<SecondaryCache> NewCompressedSecondaryCache(
@@ -165,7 +242,7 @@ std::shared_ptr<SecondaryCache> NewCompressedSecondaryCache(
       opts.capacity, opts.num_shard_bits, opts.strict_capacity_limit,
       opts.high_pri_pool_ratio, opts.memory_allocator, opts.use_adaptive_mutex,
       opts.metadata_charge_policy, opts.compression_type,
-      opts.compress_format_version);
+      opts.compress_format_version, opts.low_pri_pool_ratio);
 }
 
 }  // namespace ROCKSDB_NAMESPACE

cache/compressed_secondary_cache.h

@@ -5,6 +5,8 @@
 
 #pragma once
 
+#include <array>
+#include <cstddef>
 #include <memory>
 
 #include "cache/lru_cache.h"
@@ -54,11 +56,11 @@ class CompressedSecondaryCache : public SecondaryCache {
  public:
   CompressedSecondaryCache(
       size_t capacity, int num_shard_bits, bool strict_capacity_limit,
-      double high_pri_pool_ratio,
+      double high_pri_pool_ratio, double low_pri_pool_ratio,
       std::shared_ptr<MemoryAllocator> memory_allocator = nullptr,
       bool use_adaptive_mutex = kDefaultToAdaptiveMutex,
       CacheMetadataChargePolicy metadata_charge_policy =
-          kDontChargeCacheMetadata,
+          kDefaultCacheMetadataChargePolicy,
       CompressionType compression_type = CompressionType::kLZ4Compression,
       uint32_t compress_format_version = 2);
   virtual ~CompressedSecondaryCache() override;
@@ -79,6 +81,36 @@ class CompressedSecondaryCache : public SecondaryCache {
   std::string GetPrintableOptions() const override;
 
  private:
+  friend class CompressedSecondaryCacheTest;
+  static constexpr std::array<uint16_t, 33> malloc_bin_sizes_{
+      32,   64,   96,   128,  160,  192,  224,   256,   320,   384,   448,
+      512,  640,  768,  896,  1024, 1280, 1536,  1792,  2048,  2560,  3072,
+      3584, 4096, 5120, 6144, 7168, 8192, 10240, 12288, 14336, 16384, 32768};
+
+  struct CacheValueChunk {
+    // TODO try "CacheAllocationPtr next;".
+    CacheValueChunk* next;
+    size_t size;
+    // Beginning of the chunk data (MUST BE THE LAST FIELD IN THIS STRUCT!)
+    char data[1];
+
+    void Free() { delete[] reinterpret_cast<char*>(this); }
+  };
+
+  // Split value into chunks to better fit into jemalloc bins. The chunks
+  // are stored in CacheValueChunk and extra charge is needed for each chunk,
+  // so the cache charge is recalculated here.
+  CacheValueChunk* SplitValueIntoChunks(const Slice& value,
+                                        const CompressionType compression_type,
+                                        size_t& charge);
+
+  // After merging chunks, the extra charge for each chunk is removed, so
+  // the charge is recalculated.
+  CacheAllocationPtr MergeChunksIntoValue(const void* chunks_head,
+                                          size_t& charge);
+
+  // An implementation of Cache::DeleterFn.
+  static void DeletionCallback(const Slice& /*key*/, void* obj);
   std::shared_ptr<Cache> cache_;
   CompressedSecondaryCacheOptions cache_options_;
 };

cache/compressed_secondary_cache_test.cc

@@ -7,9 +7,12 @@
 
 #include <algorithm>
 #include <cstdint>
+#include <iterator>
 
+#include "cache/lru_cache.h"
 #include "memory/jemalloc_nodump_allocator.h"
 #include "memory/memory_allocator.h"
+#include "rocksdb/compression_type.h"
 #include "rocksdb/convenience.h"
 #include "rocksdb/secondary_cache.h"
 #include "test_util/testharness.h"
@@ -136,7 +139,6 @@ class CompressedSecondaryCacheTest : public testing::Test {
     CompressedSecondaryCacheOptions opts;
     opts.capacity = 2048;
     opts.num_shard_bits = 0;
-    opts.metadata_charge_policy = kDontChargeCacheMetadata;
 
     if (sec_cache_is_compressed) {
       if (!LZ4_Supported()) {
@@ -162,6 +164,8 @@ class CompressedSecondaryCacheTest : public testing::Test {
     }
     std::shared_ptr<SecondaryCache> sec_cache =
         NewCompressedSecondaryCache(opts);
+
+    BasicTestHelper(sec_cache);
   }
 
   void FailsTest(bool sec_cache_is_compressed) {
@@ -177,7 +181,6 @@ class CompressedSecondaryCacheTest : public testing::Test {
 
     secondary_cache_opts.capacity = 1100;
     secondary_cache_opts.num_shard_bits = 0;
-    secondary_cache_opts.metadata_charge_policy = kDontChargeCacheMetadata;
     std::shared_ptr<SecondaryCache> sec_cache =
         NewCompressedSecondaryCache(secondary_cache_opts);
 
@@ -235,34 +238,37 @@ class CompressedSecondaryCacheTest : public testing::Test {
 
     secondary_cache_opts.capacity = 2300;
     secondary_cache_opts.num_shard_bits = 0;
-    secondary_cache_opts.metadata_charge_policy = kDontChargeCacheMetadata;
     std::shared_ptr<SecondaryCache> secondary_cache =
         NewCompressedSecondaryCache(secondary_cache_opts);
-    LRUCacheOptions lru_cache_opts(1024, 0, false, 0.5, nullptr,
-                                   kDefaultToAdaptiveMutex,
-                                   kDontChargeCacheMetadata);
+    LRUCacheOptions lru_cache_opts(
+        1300 /* capacity */, 0 /* num_shard_bits */,
+        false /* strict_capacity_limit */, 0.5 /* high_pri_pool_ratio */,
+        nullptr /* memory_allocator */, kDefaultToAdaptiveMutex,
+        kDefaultCacheMetadataChargePolicy);
     lru_cache_opts.secondary_cache = secondary_cache;
     std::shared_ptr<Cache> cache = NewLRUCache(lru_cache_opts);
     std::shared_ptr<Statistics> stats = CreateDBStatistics();
 
     Random rnd(301);
 
-    std::string str1 = rnd.RandomString(1010);
+    std::string str1;
+    test::CompressibleString(&rnd, 0.5, 1001, &str1);
     std::string str1_clone{str1};
     TestItem* item1 = new TestItem(str1.data(), str1.length());
     ASSERT_OK(cache->Insert("k1", item1, &CompressedSecondaryCacheTest::helper_,
                             str1.length()));
 
-    std::string str2 = rnd.RandomString(1020);
+    std::string str2;
+    test::CompressibleString(&rnd, 0.5, 1012, &str2);
     TestItem* item2 = new TestItem(str2.data(), str2.length());
-    // After Insert, lru cache contains k2 and secondary cache contains k1.
+    // After Insert, cache contains k2 and secondary cache contains k1.
     ASSERT_OK(cache->Insert("k2", item2, &CompressedSecondaryCacheTest::helper_,
                             str2.length()));
 
-    std::string str3 = rnd.RandomString(1020);
+    std::string str3;
+    test::CompressibleString(&rnd, 0.5, 1024, &str3);
     TestItem* item3 = new TestItem(str3.data(), str3.length());
-    // After Insert, lru cache contains k3 and secondary cache contains k1 and
-    // k2
+    // After Insert, cache contains k3 and secondary cache contains k1 and k2.
     ASSERT_OK(cache->Insert("k3", item3, &CompressedSecondaryCacheTest::helper_,
                             str3.length()));
 
@@ -287,7 +293,6 @@ class CompressedSecondaryCacheTest : public testing::Test {
     handle = cache->Lookup("k1", &CompressedSecondaryCacheTest::helper_,
                            test_item_creator, Cache::Priority::LOW, true,
                            stats.get());
-
     ASSERT_NE(handle, nullptr);
     TestItem* val1_1 = static_cast<TestItem*>(cache->Value(handle));
     ASSERT_NE(val1_1, nullptr);
@@ -316,19 +321,22 @@ class CompressedSecondaryCacheTest : public testing::Test {
       secondary_cache_opts.compression_type = CompressionType::kNoCompression;
     }
 
-    secondary_cache_opts.capacity = 2048;
+    secondary_cache_opts.capacity = 2300;
     secondary_cache_opts.num_shard_bits = 0;
-    secondary_cache_opts.metadata_charge_policy = kDontChargeCacheMetadata;
     std::shared_ptr<SecondaryCache> secondary_cache =
         NewCompressedSecondaryCache(secondary_cache_opts);
 
-    LRUCacheOptions opts(1024, 0, false, 0.5, nullptr, kDefaultToAdaptiveMutex,
-                         kDontChargeCacheMetadata);
+    LRUCacheOptions opts(
+        1024 /* capacity */, 0 /* num_shard_bits */,
+        false /* strict_capacity_limit */, 0.5 /* high_pri_pool_ratio */,
+        nullptr /* memory_allocator */, kDefaultToAdaptiveMutex,
+        kDefaultCacheMetadataChargePolicy);
     opts.secondary_cache = secondary_cache;
     std::shared_ptr<Cache> cache = NewLRUCache(opts);
 
     Random rnd(301);
-    std::string str1 = rnd.RandomString(1020);
+    std::string str1;
+    test::CompressibleString(&rnd, 0.5, 1001, &str1);
     auto item1 =
         std::unique_ptr<TestItem>(new TestItem(str1.data(), str1.length()));
     ASSERT_NOK(cache->Insert("k1", item1.get(), nullptr, str1.length()));
@@ -361,25 +369,30 @@ class CompressedSecondaryCacheTest : public testing::Test {
       secondary_cache_opts.compression_type = CompressionType::kNoCompression;
     }
 
-    secondary_cache_opts.capacity = 2048;
+    secondary_cache_opts.capacity = 2300;
     secondary_cache_opts.num_shard_bits = 0;
-    secondary_cache_opts.metadata_charge_policy = kDontChargeCacheMetadata;
 
     std::shared_ptr<SecondaryCache> secondary_cache =
         NewCompressedSecondaryCache(secondary_cache_opts);
 
-    LRUCacheOptions opts(1024, 0, false, 0.5, nullptr, kDefaultToAdaptiveMutex,
-                         kDontChargeCacheMetadata);
+    LRUCacheOptions opts(
+        1200 /* capacity */, 0 /* num_shard_bits */,
+        false /* strict_capacity_limit */, 0.5 /* high_pri_pool_ratio */,
+        nullptr /* memory_allocator */, kDefaultToAdaptiveMutex,
+        kDefaultCacheMetadataChargePolicy);
     opts.secondary_cache = secondary_cache;
     std::shared_ptr<Cache> cache = NewLRUCache(opts);
 
     Random rnd(301);
-    std::string str1 = rnd.RandomString(1020);
+    std::string str1;
+    test::CompressibleString(&rnd, 0.5, 1001, &str1);
     TestItem* item1 = new TestItem(str1.data(), str1.length());
     ASSERT_OK(cache->Insert("k1", item1,
                             &CompressedSecondaryCacheTest::helper_fail_,
                             str1.length()));
-    std::string str2 = rnd.RandomString(1020);
+
+    std::string str2;
+    test::CompressibleString(&rnd, 0.5, 1002, &str2);
     TestItem* item2 = new TestItem(str2.data(), str2.length());
     // k1 should be demoted to the secondary cache.
     ASSERT_OK(cache->Insert("k2", item2,
@@ -417,25 +430,29 @@ class CompressedSecondaryCacheTest : public testing::Test {
       secondary_cache_opts.compression_type = CompressionType::kNoCompression;
     }
 
-    secondary_cache_opts.capacity = 2048;
+    secondary_cache_opts.capacity = 2300;
     secondary_cache_opts.num_shard_bits = 0;
-    secondary_cache_opts.metadata_charge_policy = kDontChargeCacheMetadata;
 
     std::shared_ptr<SecondaryCache> secondary_cache =
         NewCompressedSecondaryCache(secondary_cache_opts);
 
-    LRUCacheOptions opts(1024, 0, false, 0.5, nullptr, kDefaultToAdaptiveMutex,
-                         kDontChargeCacheMetadata);
+    LRUCacheOptions opts(
+        1200 /* capacity */, 0 /* num_shard_bits */,
+        false /* strict_capacity_limit */, 0.5 /* high_pri_pool_ratio */,
+        nullptr /* memory_allocator */, kDefaultToAdaptiveMutex,
+        kDefaultCacheMetadataChargePolicy);
     opts.secondary_cache = secondary_cache;
     std::shared_ptr<Cache> cache = NewLRUCache(opts);
 
     Random rnd(301);
-    std::string str1 = rnd.RandomString(1020);
+    std::string str1;
+    test::CompressibleString(&rnd, 0.5, 1001, &str1);
     TestItem* item1 = new TestItem(str1.data(), str1.length());
     ASSERT_OK(cache->Insert("k1", item1, &CompressedSecondaryCacheTest::helper_,
                             str1.length()));
 
-    std::string str2 = rnd.RandomString(1020);
+    std::string str2;
+    test::CompressibleString(&rnd, 0.5, 1002, &str2);
     TestItem* item2 = new TestItem(str2.data(), str2.length());
     // k1 should be demoted to the secondary cache.
     ASSERT_OK(cache->Insert("k2", item2, &CompressedSecondaryCacheTest::helper_,
@@ -473,24 +490,30 @@ class CompressedSecondaryCacheTest : public testing::Test {
       secondary_cache_opts.compression_type = CompressionType::kNoCompression;
     }
 
-    secondary_cache_opts.capacity = 2048;
+    secondary_cache_opts.capacity = 2300;
     secondary_cache_opts.num_shard_bits = 0;
-    secondary_cache_opts.metadata_charge_policy = kDontChargeCacheMetadata;
 
     std::shared_ptr<SecondaryCache> secondary_cache =
         NewCompressedSecondaryCache(secondary_cache_opts);
 
-    LRUCacheOptions opts(1024, 0, /*_strict_capacity_limit=*/true, 0.5, nullptr,
-                         kDefaultToAdaptiveMutex, kDontChargeCacheMetadata);
+    LRUCacheOptions opts(
+        1200 /* capacity */, 0 /* num_shard_bits */,
+        true /* strict_capacity_limit */, 0.5 /* high_pri_pool_ratio */,
+        nullptr /* memory_allocator */, kDefaultToAdaptiveMutex,
+        kDefaultCacheMetadataChargePolicy);
     opts.secondary_cache = secondary_cache;
     std::shared_ptr<Cache> cache = NewLRUCache(opts);
 
     Random rnd(301);
-    std::string str1 = rnd.RandomString(1020);
+    std::string str1;
+    test::CompressibleString(&rnd, 0.5, 1001, &str1);
     TestItem* item1 = new TestItem(str1.data(), str1.length());
     ASSERT_OK(cache->Insert("k1", item1, &CompressedSecondaryCacheTest::helper_,
                             str1.length()));
-    std::string str2 = rnd.RandomString(1020);
+
+    std::string str2;
+    test::CompressibleString(&rnd, 0.5, 1002, &str2);
+    std::string str2_clone{str2};
     TestItem* item2 = new TestItem(str2.data(), str2.length());
     // k1 should be demoted to the secondary cache.
     ASSERT_OK(cache->Insert("k2", item2, &CompressedSecondaryCacheTest::helper_,
@@ -501,8 +524,9 @@ class CompressedSecondaryCacheTest : public testing::Test {
                             test_item_creator, Cache::Priority::LOW, true);
     ASSERT_NE(handle2, nullptr);
     cache->Release(handle2);
-    // k1 promotion should fail due to the block cache being at capacity,
-    // but the lookup should still succeed
+
+    // k1 promotion should fail because cache is at capacity and
+    // strict_capacity_limit is true, but the lookup should still succeed.
     Cache::Handle* handle1;
     handle1 = cache->Lookup("k1", &CompressedSecondaryCacheTest::helper_,
                             test_item_creator, Cache::Priority::LOW, true);
@@ -519,6 +543,119 @@ class CompressedSecondaryCacheTest : public testing::Test {
     secondary_cache.reset();
   }
 
+  void SplitValueIntoChunksTest() {
+    JemallocAllocatorOptions jopts;
+    std::shared_ptr<MemoryAllocator> allocator;
+    std::string msg;
+    if (JemallocNodumpAllocator::IsSupported(&msg)) {
+      Status s = NewJemallocNodumpAllocator(jopts, &allocator);
+      if (!s.ok()) {
+        ROCKSDB_GTEST_BYPASS("JEMALLOC not supported");
+      }
+    } else {
+      ROCKSDB_GTEST_BYPASS("JEMALLOC not supported");
+    }
+
+    using CacheValueChunk = CompressedSecondaryCache::CacheValueChunk;
+    std::unique_ptr<CompressedSecondaryCache> sec_cache =
+        std::make_unique<CompressedSecondaryCache>(1000, 0, true, 0.5, 0.0,
+                                                   allocator);
+    Random rnd(301);
+    // 10000 = 8169 + 1769 + 62 , so there should be 3 chunks after split.
+    size_t str_size{10000};
+    std::string str = rnd.RandomString(static_cast<int>(str_size));
+    size_t charge{0};
+    CacheValueChunk* chunks_head =
+        sec_cache->SplitValueIntoChunks(str, kLZ4Compression, charge);
+    ASSERT_EQ(charge, str_size + 3 * (sizeof(CacheValueChunk) - 1));
+
+    CacheValueChunk* current_chunk = chunks_head;
+    ASSERT_EQ(current_chunk->size, 8192 - sizeof(CacheValueChunk) + 1);
+    current_chunk = current_chunk->next;
+    ASSERT_EQ(current_chunk->size, 1792 - sizeof(CacheValueChunk) + 1);
+    current_chunk = current_chunk->next;
+    ASSERT_EQ(current_chunk->size, 62);
+
+    sec_cache->DeletionCallback("dummy", chunks_head);
+  }
+
+  void MergeChunksIntoValueTest() {
+    using CacheValueChunk = CompressedSecondaryCache::CacheValueChunk;
+    Random rnd(301);
+    size_t size1{2048};
+    std::string str1 = rnd.RandomString(static_cast<int>(size1));
+    CacheValueChunk* current_chunk = reinterpret_cast<CacheValueChunk*>(
+        new char[sizeof(CacheValueChunk) - 1 + size1]);
+    CacheValueChunk* chunks_head = current_chunk;
+    memcpy(current_chunk->data, str1.data(), size1);
+    current_chunk->size = size1;
+
+    size_t size2{256};
+    std::string str2 = rnd.RandomString(static_cast<int>(size2));
+    current_chunk->next = reinterpret_cast<CacheValueChunk*>(
+        new char[sizeof(CacheValueChunk) - 1 + size2]);
+    current_chunk = current_chunk->next;
+    memcpy(current_chunk->data, str2.data(), size2);
+    current_chunk->size = size2;
+
+    size_t size3{31};
+    std::string str3 = rnd.RandomString(static_cast<int>(size3));
+    current_chunk->next = reinterpret_cast<CacheValueChunk*>(
+        new char[sizeof(CacheValueChunk) - 1 + size3]);
+    current_chunk = current_chunk->next;
+    memcpy(current_chunk->data, str3.data(), size3);
+    current_chunk->size = size3;
+    current_chunk->next = nullptr;
+
+    std::string str = str1 + str2 + str3;
+
+    std::unique_ptr<CompressedSecondaryCache> sec_cache =
+        std::make_unique<CompressedSecondaryCache>(1000, 0, true, 0.5, 0.0);
+    size_t charge{0};
+    CacheAllocationPtr value =
+        sec_cache->MergeChunksIntoValue(chunks_head, charge);
+    ASSERT_EQ(charge, size1 + size2 + size3);
+    std::string value_str{value.get(), charge};
+    ASSERT_EQ(strcmp(value_str.data(), str.data()), 0);
+
+    sec_cache->DeletionCallback("dummy", chunks_head);
+  }
+
+  void SplictValueAndMergeChunksTest() {
+    JemallocAllocatorOptions jopts;
+    std::shared_ptr<MemoryAllocator> allocator;
+    std::string msg;
+    if (JemallocNodumpAllocator::IsSupported(&msg)) {
+      Status s = NewJemallocNodumpAllocator(jopts, &allocator);
+      if (!s.ok()) {
+        ROCKSDB_GTEST_BYPASS("JEMALLOC not supported");
+      }
+    } else {
+      ROCKSDB_GTEST_BYPASS("JEMALLOC not supported");
+    }
+
+    using CacheValueChunk = CompressedSecondaryCache::CacheValueChunk;
+    std::unique_ptr<CompressedSecondaryCache> sec_cache =
+        std::make_unique<CompressedSecondaryCache>(1000, 0, true, 0.5, 0.0,
+                                                   allocator);
+    Random rnd(301);
+    // 10000 = 8169 + 1769 + 62 , so there should be 3 chunks after split.
+    size_t str_size{10000};
+    std::string str = rnd.RandomString(static_cast<int>(str_size));
+    size_t charge{0};
+    CacheValueChunk* chunks_head =
+        sec_cache->SplitValueIntoChunks(str, kLZ4Compression, charge);
+    ASSERT_EQ(charge, str_size + 3 * (sizeof(CacheValueChunk) - 1));
+
+    CacheAllocationPtr value =
+        sec_cache->MergeChunksIntoValue(chunks_head, charge);
+    ASSERT_EQ(charge, str_size);
+    std::string value_str{value.get(), charge};
+    ASSERT_EQ(strcmp(value_str.data(), str.data()), 0);
+
+    sec_cache->DeletionCallback("dummy", chunks_head);
+  }
+
  private:
   bool fail_create_;
 };
@@ -639,6 +776,18 @@ TEST_F(CompressedSecondaryCacheTest,
   IntegrationFullCapacityTest(true);
 }
 
+TEST_F(CompressedSecondaryCacheTest, SplitValueIntoChunksTest) {
+  SplitValueIntoChunksTest();
+}
+
+TEST_F(CompressedSecondaryCacheTest, MergeChunksIntoValueTest) {
+  MergeChunksIntoValueTest();
+}
+
+TEST_F(CompressedSecondaryCacheTest, SplictValueAndMergeChunksTest) {
+  SplictValueAndMergeChunksTest();
+}
+
 }  // namespace ROCKSDB_NAMESPACE
 
 int main(int argc, char** argv) {

cache/fast_lru_cache.cc

@@ -12,15 +12,15 @@
 #include <cassert>
 #include <cstdint>
 #include <cstdio>
+#include <functional>
 
 #include "monitoring/perf_context_imp.h"
 #include "monitoring/statistics.h"
 #include "port/lang.h"
 #include "util/distributed_mutex.h"
-
-#define KEY_LENGTH \
-  16  // TODO(guido) Make use of this symbol in other parts of the source code
-      // (e.g., cache_key.h, cache_test.cc, etc.)
+#include "util/hash.h"
+#include "util/math.h"
+#include "util/random.h"
 
 namespace ROCKSDB_NAMESPACE {
 
@@ -28,58 +28,155 @@ namespace fast_lru_cache {
 
 LRUHandleTable::LRUHandleTable(int hash_bits)
     : length_bits_(hash_bits),
-      list_(new LRUHandle* [size_t{1} << length_bits_] {}) {}
+      length_bits_mask_((uint32_t{1} << length_bits_) - 1),
+      occupancy_(0),
+      occupancy_limit_(static_cast<uint32_t>((uint32_t{1} << length_bits_) *
+                                             kStrictLoadFactor)),
+      array_(new LRUHandle[size_t{1} << length_bits_]) {
+  assert(hash_bits <= 32);
+}
 
 LRUHandleTable::~LRUHandleTable() {
-  ApplyToEntriesRange(
-      [](LRUHandle* h) {
-        if (!h->HasRefs()) {
-          h->Free();
-        }
-      },
-      0, uint32_t{1} << length_bits_);
+  ApplyToEntriesRange([](LRUHandle* h) { h->FreeData(); }, 0, GetTableSize());
 }
 
 LRUHandle* LRUHandleTable::Lookup(const Slice& key, uint32_t hash) {
-  return *FindPointer(key, hash);
+  int probe = 0;
+  int slot = FindVisibleElement(key, hash, probe, 0);
+  return (slot == -1) ? nullptr : &array_[slot];
 }
 
-inline LRUHandle** LRUHandleTable::Head(uint32_t hash) {
-  return &list_[hash >> (32 - length_bits_)];
-}
-
-LRUHandle* LRUHandleTable::Insert(LRUHandle* h) {
-  LRUHandle** ptr = FindPointer(h->key(), h->hash);
-  LRUHandle* old = *ptr;
-  h->next_hash = (old == nullptr ? nullptr : old->next_hash);
-  *ptr = h;
-  return old;
-}
-
-LRUHandle* LRUHandleTable::Remove(const Slice& key, uint32_t hash) {
-  LRUHandle** ptr = FindPointer(key, hash);
-  LRUHandle* result = *ptr;
-  if (result != nullptr) {
-    *ptr = result->next_hash;
+LRUHandle* LRUHandleTable::Insert(LRUHandle* h, LRUHandle** old) {
+  int probe = 0;
+  int slot = FindVisibleElementOrAvailableSlot(h->key(), h->hash, probe,
+                                               1 /*displacement*/);
+  *old = nullptr;
+  if (slot == -1) {
+    // TODO(Guido) Don't we need to roll back displacements here?
+    return nullptr;
+  }
+
+  if (array_[slot].IsEmpty() || array_[slot].IsTombstone()) {
+    bool empty = array_[slot].IsEmpty();
+    Assign(slot, h);
+    LRUHandle* new_entry = &array_[slot];
+    if (empty) {
+      // This used to be an empty slot.
+      return new_entry;
+    }
+    // It used to be a tombstone, so there may already be a copy of the
+    // key in the table.
+    slot = FindVisibleElement(h->key(), h->hash, probe, 0 /*displacement*/);
+    if (slot == -1) {
+      // No existing copy of the key.
+      return new_entry;
+    }
+    *old = &array_[slot];
+    return new_entry;
+  } else {
+    // There is an existing copy of the key.
+    *old = &array_[slot];
+    // Find an available slot for the new element.
+    array_[slot].displacements++;
+    slot = FindAvailableSlot(h->key(), probe, 1 /*displacement*/);
+    if (slot == -1) {
+      // No available slots. Roll back displacements.
+      probe = 0;
+      slot = FindVisibleElement(h->key(), h->hash, probe, -1);
+      array_[slot].displacements--;
+      FindAvailableSlot(h->key(), probe, -1);
+      return nullptr;
+    }
+    Assign(slot, h);
+    return &array_[slot];
   }
-  return result;
 }
 
-LRUHandle** LRUHandleTable::FindPointer(const Slice& key, uint32_t hash) {
-  LRUHandle** ptr = &list_[hash >> (32 - length_bits_)];
-  while (*ptr != nullptr && ((*ptr)->hash != hash || key != (*ptr)->key())) {
-    ptr = &(*ptr)->next_hash;
+void LRUHandleTable::Remove(LRUHandle* h) {
+  assert(h->next == nullptr &&
+         h->prev == nullptr);  // Already off the LRU list.
+  int probe = 0;
+  FindSlot(
+      h->key(), [&h](LRUHandle* e) { return e == h; }, probe,
+      -1 /*displacement*/);
+  h->SetIsVisible(false);
+  h->SetIsElement(false);
+  occupancy_--;
+}
+
+void LRUHandleTable::Assign(int slot, LRUHandle* h) {
+  LRUHandle* dst = &array_[slot];
+  uint32_t disp = dst->displacements;
+  *dst = *h;
+  dst->displacements = disp;
+  dst->SetIsVisible(true);
+  dst->SetIsElement(true);
+  occupancy_++;
+}
+
+void LRUHandleTable::Exclude(LRUHandle* h) { h->SetIsVisible(false); }
+
+int LRUHandleTable::FindVisibleElement(const Slice& key, uint32_t hash,
+                                       int& probe, int displacement) {
+  return FindSlot(
+      key,
+      [&](LRUHandle* h) { return h->Matches(key, hash) && h->IsVisible(); },
+      probe, displacement);
+}
+
+int LRUHandleTable::FindAvailableSlot(const Slice& key, int& probe,
+                                      int displacement) {
+  return FindSlot(
+      key, [](LRUHandle* h) { return h->IsEmpty() || h->IsTombstone(); }, probe,
+      displacement);
+}
+
+int LRUHandleTable::FindVisibleElementOrAvailableSlot(const Slice& key,
+                                                      uint32_t hash, int& probe,
+                                                      int displacement) {
+  return FindSlot(
+      key,
+      [&](LRUHandle* h) {
+        return h->IsEmpty() || h->IsTombstone() ||
+               (h->Matches(key, hash) && h->IsVisible());
+      },
+      probe, displacement);
+}
+
+inline int LRUHandleTable::FindSlot(const Slice& key,
+                                    std::function<bool(LRUHandle*)> cond,
+                                    int& probe, int displacement) {
+  uint32_t base = ModTableSize(Hash(key.data(), key.size(), kProbingSeed1));
+  uint32_t increment =
+      ModTableSize((Hash(key.data(), key.size(), kProbingSeed2) << 1) | 1);
+  uint32_t current = ModTableSize(base + probe * increment);
+  while (true) {
+    LRUHandle* h = &array_[current];
+    probe++;
+    if (current == base && probe > 1) {
+      // We looped back.
+      return -1;
+    }
+    if (cond(h)) {
+      return current;
+    }
+    if (h->IsEmpty()) {
+      // We check emptyness after the condition, because
+      // the condition may be emptyness.
+      return -1;
+    }
+    h->displacements += displacement;
+    current = ModTableSize(current + increment);
   }
-  return ptr;
 }
 
 LRUCacheShard::LRUCacheShard(size_t capacity, size_t estimated_value_size,
                              bool strict_capacity_limit,
                              CacheMetadataChargePolicy metadata_charge_policy)
-    : capacity_(0),
+    : capacity_(capacity),
       strict_capacity_limit_(strict_capacity_limit),
       table_(
-          GetHashBits(capacity, estimated_value_size, metadata_charge_policy)),
+          CalcHashBits(capacity, estimated_value_size, metadata_charge_policy)),
       usage_(0),
       lru_usage_(0) {
   set_metadata_charge_policy(metadata_charge_policy);
@@ -87,29 +184,27 @@ LRUCacheShard::LRUCacheShard(size_t capacity, size_t estimated_value_size,
   lru_.next = &lru_;
   lru_.prev = &lru_;
   lru_low_pri_ = &lru_;
-  SetCapacity(capacity);
 }
 
 void LRUCacheShard::EraseUnRefEntries() {
-  autovector<LRUHandle*> last_reference_list;
+  autovector<LRUHandle> last_reference_list;
   {
     DMutexLock l(mutex_);
     while (lru_.next != &lru_) {
       LRUHandle* old = lru_.next;
       // LRU list contains only elements which can be evicted.
-      assert(old->InCache() && !old->HasRefs());
+      assert(old->IsVisible() && !old->HasRefs());
       LRU_Remove(old);
-      table_.Remove(old->key(), old->hash);
-      old->SetInCache(false);
+      table_.Remove(old);
       assert(usage_ >= old->total_charge);
       usage_ -= old->total_charge;
-      last_reference_list.push_back(old);
+      last_reference_list.push_back(*old);
     }
   }
 
   // Free the entries here outside of mutex for performance reasons.
-  for (auto entry : last_reference_list) {
-    entry->Free();
+  for (auto& h : last_reference_list) {
+    h.FreeData();
   }
 }
 
@@ -122,7 +217,7 @@ void LRUCacheShard::ApplyToSomeEntries(
   // hash bits for table indexes.
   DMutexLock l(mutex_);
   uint32_t length_bits = table_.GetLengthBits();
-  uint32_t length = uint32_t{1} << length_bits;
+  uint32_t length = table_.GetTableSize();
 
   assert(average_entries_per_lock > 0);
   // Assuming we are called with same average_entries_per_lock repeatedly,
@@ -148,74 +243,75 @@ void LRUCacheShard::ApplyToSomeEntries(
       index_begin, index_end);
 }
 
-void LRUCacheShard::LRU_Remove(LRUHandle* e) {
-  assert(e->next != nullptr);
-  assert(e->prev != nullptr);
-  e->next->prev = e->prev;
-  e->prev->next = e->next;
-  e->prev = e->next = nullptr;
-  assert(lru_usage_ >= e->total_charge);
-  lru_usage_ -= e->total_charge;
+void LRUCacheShard::LRU_Remove(LRUHandle* h) {
+  assert(h->next != nullptr);
+  assert(h->prev != nullptr);
+  h->next->prev = h->prev;
+  h->prev->next = h->next;
+  h->prev = h->next = nullptr;
+  assert(lru_usage_ >= h->total_charge);
+  lru_usage_ -= h->total_charge;
 }
 
-void LRUCacheShard::LRU_Insert(LRUHandle* e) {
-  assert(e->next == nullptr);
-  assert(e->prev == nullptr);
-  // Inset "e" to head of LRU list.
-  e->next = &lru_;
-  e->prev = lru_.prev;
-  e->prev->next = e;
-  e->next->prev = e;
-  lru_usage_ += e->total_charge;
+void LRUCacheShard::LRU_Insert(LRUHandle* h) {
+  assert(h->next == nullptr);
+  assert(h->prev == nullptr);
+  // Insert h to head of LRU list.
+  h->next = &lru_;
+  h->prev = lru_.prev;
+  h->prev->next = h;
+  h->next->prev = h;
+  lru_usage_ += h->total_charge;
 }
 
 void LRUCacheShard::EvictFromLRU(size_t charge,
-                                 autovector<LRUHandle*>* deleted) {
+                                 autovector<LRUHandle>* deleted) {
   while ((usage_ + charge) > capacity_ && lru_.next != &lru_) {
     LRUHandle* old = lru_.next;
     // LRU list contains only elements which can be evicted.
-    assert(old->InCache() && !old->HasRefs());
+    assert(old->IsVisible() && !old->HasRefs());
     LRU_Remove(old);
-    table_.Remove(old->key(), old->hash);
-    old->SetInCache(false);
+    table_.Remove(old);
     assert(usage_ >= old->total_charge);
     usage_ -= old->total_charge;
-    deleted->push_back(old);
+    deleted->push_back(*old);
   }
 }
 
-int LRUCacheShard::GetHashBits(
+size_t LRUCacheShard::CalcEstimatedHandleCharge(
+    size_t estimated_value_size,
+    CacheMetadataChargePolicy metadata_charge_policy) {
+  LRUHandle h;
+  h.CalcTotalCharge(estimated_value_size, metadata_charge_policy);
+  return h.total_charge;
+}
+
+int LRUCacheShard::CalcHashBits(
     size_t capacity, size_t estimated_value_size,
     CacheMetadataChargePolicy metadata_charge_policy) {
-  LRUHandle* e = reinterpret_cast<LRUHandle*>(
-      new char[sizeof(LRUHandle) - 1 + KEY_LENGTH]);
-  e->key_length = KEY_LENGTH;
-  e->deleter = nullptr;
-  e->refs = 0;
-  e->flags = 0;
-  e->refs = 0;
-
-  e->CalcTotalCharge(estimated_value_size, metadata_charge_policy);
-  size_t num_entries = capacity / e->total_charge;
-  e->Free();
-  int num_hash_bits = 0;
-  while (num_entries >>= 1) {
-    ++num_hash_bits;
-  }
-  return num_hash_bits;
+  size_t handle_charge =
+      CalcEstimatedHandleCharge(estimated_value_size, metadata_charge_policy);
+  assert(handle_charge > 0);
+  uint32_t num_entries =
+      static_cast<uint32_t>(capacity / (kLoadFactor * handle_charge)) + 1;
+  assert(num_entries <= uint32_t{1} << 31);
+  return FloorLog2((num_entries << 1) - 1);
 }
 
 void LRUCacheShard::SetCapacity(size_t capacity) {
-  autovector<LRUHandle*> last_reference_list;
+  autovector<LRUHandle> last_reference_list;
   {
     DMutexLock l(mutex_);
+    if (capacity > capacity_) {
+      assert(false);  // Not supported.
+    }
     capacity_ = capacity;
     EvictFromLRU(0, &last_reference_list);
   }
 
   // Free the entries here outside of mutex for performance reasons.
-  for (auto entry : last_reference_list) {
-    entry->Free();
+  for (auto& h : last_reference_list) {
+    h.FreeData();
   }
 }
 
@@ -224,83 +320,124 @@ void LRUCacheShard::SetStrictCapacityLimit(bool strict_capacity_limit) {
   strict_capacity_limit_ = strict_capacity_limit;
 }
 
-Status LRUCacheShard::InsertItem(LRUHandle* e, Cache::Handle** handle,
-                                 bool free_handle_on_fail) {
+Status LRUCacheShard::Insert(const Slice& key, uint32_t hash, void* value,
+                             size_t charge, Cache::DeleterFn deleter,
+                             Cache::Handle** handle,
+                             Cache::Priority /*priority*/) {
+  if (key.size() != kCacheKeySize) {
+    return Status::NotSupported("FastLRUCache only supports key size " +
+                                std::to_string(kCacheKeySize) + "B");
+  }
+
+  LRUHandle tmp;
+  tmp.value = value;
+  tmp.deleter = deleter;
+  tmp.hash = hash;
+  tmp.CalcTotalCharge(charge, metadata_charge_policy_);
+  for (int i = 0; i < kCacheKeySize; i++) {
+    tmp.key_data[i] = key.data()[i];
+  }
+
   Status s = Status::OK();
-  autovector<LRUHandle*> last_reference_list;
+  autovector<LRUHandle> last_reference_list;
   {
     DMutexLock l(mutex_);
+    assert(table_.GetOccupancy() <= table_.GetOccupancyLimit());
 
     // Free the space following strict LRU policy until enough space
     // is freed or the lru list is empty.
-    EvictFromLRU(e->total_charge, &last_reference_list);
+    EvictFromLRU(tmp.total_charge, &last_reference_list);
+    if ((usage_ + tmp.total_charge > capacity_ &&
+         (strict_capacity_limit_ || handle == nullptr)) ||
+        table_.GetOccupancy() == table_.GetOccupancyLimit()) {
+      // There are two measures of capacity:
+      // - Space (or charge) capacity: The maximum possible sum of the charges
+      //    of the elements.
+      // - Table capacity: The number of slots in the hash table.
+      // These are incomparable, in the sense that one doesn't imply the other.
+      // Typically we will reach space capacity before table capacity---
+      // if the user always inserts values with size equal to
+      // estimated_value_size, then at most a kLoadFactor fraction of slots
+      // will ever be occupied. But in some cases we may reach table capacity
+      // before space capacity---if the user initially claims a very large
+      // estimated_value_size but then inserts tiny values, more elements than
+      // initially estimated will be inserted.
 
-    if ((usage_ + e->total_charge) > capacity_ &&
-        (strict_capacity_limit_ || handle == nullptr)) {
-      e->SetInCache(false);
+      // TODO(Guido) Some tests (at least two from cache_test, as well as the
+      // stress tests) currently assume the table capacity is unbounded.
       if (handle == nullptr) {
         // Don't insert the entry but still return ok, as if the entry inserted
         // into cache and get evicted immediately.
-        last_reference_list.push_back(e);
+        last_reference_list.push_back(tmp);
       } else {
-        if (free_handle_on_fail) {
-          delete[] reinterpret_cast<char*>(e);
-          *handle = nullptr;
+        if (table_.GetOccupancy() == table_.GetOccupancyLimit()) {
+          // TODO: Consider using a distinct status for this case, but usually
+          // it will be handled the same way as reaching charge capacity limit
+          s = Status::MemoryLimit(
+              "Insert failed because all slots in the hash table are full.");
+        } else {
+          s = Status::MemoryLimit(
+              "Insert failed because the total charge has exceeded the "
+              "capacity.");
         }
-        s = Status::Incomplete("Insert failed due to LRU cache being full.");
       }
     } else {
       // Insert into the cache. Note that the cache might get larger than its
       // capacity if not enough space was freed up.
-      LRUHandle* old = table_.Insert(e);
-      usage_ += e->total_charge;
+      LRUHandle* old;
+      LRUHandle* h = table_.Insert(&tmp, &old);
+      assert(h != nullptr);  // We're below occupancy, so this insertion should
+                             // never fail.
+      usage_ += h->total_charge;
       if (old != nullptr) {
         s = Status::OkOverwritten();
-        assert(old->InCache());
-        old->SetInCache(false);
+        assert(old->IsVisible());
+        table_.Exclude(old);
         if (!old->HasRefs()) {
           // old is on LRU because it's in cache and its reference count is 0.
           LRU_Remove(old);
+          table_.Remove(old);
           assert(usage_ >= old->total_charge);
           usage_ -= old->total_charge;
-          last_reference_list.push_back(old);
+          last_reference_list.push_back(*old);
         }
       }
       if (handle == nullptr) {
-        LRU_Insert(e);
+        LRU_Insert(h);
       } else {
         // If caller already holds a ref, no need to take one here.
-        if (!e->HasRefs()) {
-          e->Ref();
+        if (!h->HasRefs()) {
+          h->Ref();
         }
-        *handle = reinterpret_cast<Cache::Handle*>(e);
+        *handle = reinterpret_cast<Cache::Handle*>(h);
       }
     }
   }
 
   // Free the entries here outside of mutex for performance reasons.
-  for (auto entry : last_reference_list) {
-    entry->Free();
+  for (auto& h : last_reference_list) {
+    h.FreeData();
   }
 
   return s;
 }
 
 Cache::Handle* LRUCacheShard::Lookup(const Slice& key, uint32_t hash) {
-  LRUHandle* e = nullptr;
+  LRUHandle* h = nullptr;
   {
     DMutexLock l(mutex_);
-    e = table_.Lookup(key, hash);
-    if (e != nullptr) {
-      assert(e->InCache());
-      if (!e->HasRefs()) {
-        // The entry is in LRU since it's in hash and has no external references
-        LRU_Remove(e);
+    h = table_.Lookup(key, hash);
+    if (h != nullptr) {
+      assert(h->IsVisible());
+      if (!h->HasRefs()) {
+        // The entry is in LRU since it's in hash and has no external
+        // references.
+        LRU_Remove(h);
       }
-      e->Ref();
+      h->Ref();
     }
   }
-  return reinterpret_cast<Cache::Handle*>(e);
+  return reinterpret_cast<Cache::Handle*>(h);
 }
 
 bool LRUCacheShard::Ref(Cache::Handle* h) {
@@ -316,91 +453,64 @@ bool LRUCacheShard::Release(Cache::Handle* handle, bool erase_if_last_ref) {
   if (handle == nullptr) {
     return false;
   }
-  LRUHandle* e = reinterpret_cast<LRUHandle*>(handle);
+  LRUHandle* h = reinterpret_cast<LRUHandle*>(handle);
+  LRUHandle copy;
   bool last_reference = false;
   {
     DMutexLock l(mutex_);
-    last_reference = e->Unref();
-    if (last_reference && e->InCache()) {
+    last_reference = h->Unref();
+    if (last_reference && h->IsVisible()) {
       // The item is still in cache, and nobody else holds a reference to it.
       if (usage_ > capacity_ || erase_if_last_ref) {
         // The LRU list must be empty since the cache is full.
         assert(lru_.next == &lru_ || erase_if_last_ref);
         // Take this opportunity and remove the item.
-        table_.Remove(e->key(), e->hash);
-        e->SetInCache(false);
+        table_.Remove(h);
       } else {
         // Put the item back on the LRU list, and don't free it.
-        LRU_Insert(e);
+        LRU_Insert(h);
         last_reference = false;
       }
     }
     // If it was the last reference, then decrement the cache usage.
     if (last_reference) {
-      assert(usage_ >= e->total_charge);
-      usage_ -= e->total_charge;
+      assert(usage_ >= h->total_charge);
+      usage_ -= h->total_charge;
+      copy = *h;
     }
   }
 
   // Free the entry here outside of mutex for performance reasons.
   if (last_reference) {
-    e->Free();
+    copy.FreeData();
   }
   return last_reference;
 }
 
-Status LRUCacheShard::Insert(const Slice& key, uint32_t hash, void* value,
-                             size_t charge, Cache::DeleterFn deleter,
-                             Cache::Handle** handle,
-                             Cache::Priority /*priority*/) {
-  if (key.size() != KEY_LENGTH) {
-    return Status::NotSupported("FastLRUCache only supports key size " +
-                                std::to_string(KEY_LENGTH) + "B");
-  }
-
-  // Allocate the memory here outside of the mutex.
-  // If the cache is full, we'll have to release it.
-  // It shouldn't happen very often though.
-  LRUHandle* e = reinterpret_cast<LRUHandle*>(
-      new char[sizeof(LRUHandle) - 1 + key.size()]);
-
-  e->value = value;
-  e->flags = 0;
-  e->deleter = deleter;
-  e->key_length = key.size();
-  e->hash = hash;
-  e->refs = 0;
-  e->next = e->prev = nullptr;
-  e->SetInCache(true);
-  e->CalcTotalCharge(charge, metadata_charge_policy_);
-  memcpy(e->key_data, key.data(), key.size());
-
-  return InsertItem(e, handle, /* free_handle_on_fail */ true);
-}
-
 void LRUCacheShard::Erase(const Slice& key, uint32_t hash) {
-  LRUHandle* e;
+  LRUHandle copy;
   bool last_reference = false;
   {
     DMutexLock l(mutex_);
-    e = table_.Remove(key, hash);
-    if (e != nullptr) {
-      assert(e->InCache());
-      e->SetInCache(false);
-      if (!e->HasRefs()) {
-        // The entry is in LRU since it's in hash and has no external references
-        LRU_Remove(e);
-        assert(usage_ >= e->total_charge);
-        usage_ -= e->total_charge;
+    LRUHandle* h = table_.Lookup(key, hash);
+    if (h != nullptr) {
+      table_.Exclude(h);
+      if (!h->HasRefs()) {
+        // The entry is in LRU since it's in cache and has no external
+        // references.
+        LRU_Remove(h);
+        table_.Remove(h);
+        assert(usage_ >= h->total_charge);
+        usage_ -= h->total_charge;
         last_reference = true;
+        copy = *h;
       }
     }
   }
-
   // Free the entry here outside of mutex for performance reasons.
   // last_reference will only be true if e != nullptr.
   if (last_reference) {
-    e->Free();
+    copy.FreeData();
   }
 }
 
@@ -421,6 +531,8 @@ LRUCache::LRUCache(size_t capacity, size_t estimated_value_size,
                    int num_shard_bits, bool strict_capacity_limit,
                    CacheMetadataChargePolicy metadata_charge_policy)
     : ShardedCache(capacity, num_shard_bits, strict_capacity_limit) {
+  assert(estimated_value_size > 0 ||
+         metadata_charge_policy != kDontChargeCacheMetadata);
   num_shards_ = 1 << num_shard_bits;
   shards_ = reinterpret_cast<LRUCacheShard*>(
       port::cacheline_aligned_alloc(sizeof(LRUCacheShard) * num_shards_));

cache/fast_lru_cache.h

@@ -8,9 +8,11 @@
 // found in the LICENSE file. See the AUTHORS file for names of contributors.
 #pragma once
 
+#include <array>
 #include <memory>
 #include <string>
 
+#include "cache/cache_key.h"
 #include "cache/sharded_cache.h"
 #include "port/lang.h"
 #include "port/malloc.h"
@@ -20,33 +22,124 @@
 #include "util/distributed_mutex.h"
 
 namespace ROCKSDB_NAMESPACE {
+
 namespace fast_lru_cache {
 
+// Forward declaration of friend class.
+class FastLRUCacheTest;
+
+// LRU cache implementation using an open-address hash table.
+//
+// Every slot in the hash table is an LRUHandle. Because handles can be
+// referenced externally, we can't discard them immediately once they are
+// deleted (via a delete or an LRU eviction) or replaced by a new version
+// (via an insert of the same key). The state of an element is defined by
+// the following two properties:
+// (R) Referenced: An element can be referenced externally (refs > 0), or not.
+//    Importantly, an element can be evicted if and only if it's not
+//    referenced. In particular, when an element becomes referenced, it's
+//    temporarily taken out of the LRU list until all references to it
+//    are dropped.
+// (V) Visible: An element can visible for lookups (IS_VISIBLE set), or not.
+//    Initially, every element is visible. An element that is not visible is
+//    called a ghost.
+// These properties induce 4 different states, with transitions defined as
+// follows:
+// - V --> not V: When a visible element is deleted or replaced by a new
+//    version.
+// - Not V --> V: This cannot happen. A ghost remains in that state until it's
+//    not referenced any more, at which point it's ready to be removed from the
+//    hash table. (A ghost simply waits to transition to the afterlife---it will
+//    never be visible again.)
+// - R --> not R: When all references to an element are dropped.
+// - Not R --> R: When an unreferenced element becomes referenced. This can only
+//    happen if the element is V, since references to an element can only be
+//    created when it's visible.
+//
+// Internally, the cache uses an open-addressed hash table to index the handles.
+// We use tombstone counters to keep track of displacements.
+// Because of the tombstones and the two possible visibility states of an
+// element, the table slots can be in 4 different states:
+// 1. Visible element (IS_ELEMENT set and IS_VISIBLE set): The slot contains a
+//    key-value element.
+// 2. Ghost element (IS_ELEMENT set and IS_VISIBLE unset): The slot contains an
+//    element that has been removed, but it's still referenced. It's invisible
+//    to lookups.
+// 3. Tombstone (IS_ELEMENT unset and displacements > 0): The slot contains a
+//    tombstone.
+// 4. Empty (IS_ELEMENT unset and displacements == 0): The slot is unused.
+//    A slot that is an element can further have IS_VISIBLE set or not.
+// When a ghost is removed from the table, it can either transition to being a
+// tombstone or an empty slot, depending on the number of displacements of the
+// slot. In any case, the slot becomes available. When a handle is inserted
+// into that slot, it becomes a visible element again.
+
+// The load factor p is a real number in (0, 1) such that at all
+// times at most a fraction p of all slots, without counting tombstones,
+// are occupied by elements. This means that the probability that a
+// random probe hits an empty slot is at most p, and thus at most 1/p probes
+// are required on average. For example, p = 70% implies that between 1 and 2
+// probes are needed on average (bear in mind that this reasoning doesn't
+// consider the effects of clustering over time).
+// Because the size of the hash table is always rounded up to the next
+// power of 2, p is really an upper bound on the actual load factor---the
+// actual load factor is anywhere between p/2 and p. This is a bit wasteful,
+// but bear in mind that slots only hold metadata, not actual values.
+// Since space cost is dominated by the values (the LSM blocks),
+// overprovisioning the table with metadata only increases the total cache space
+// usage by a tiny fraction.
+constexpr double kLoadFactor = 0.35;
+
+// The user can exceed kLoadFactor if the sizes of the inserted values don't
+// match estimated_value_size, or if strict_capacity_limit == false. To
+// avoid performance to plunge, we set a strict upper bound on the load factor.
+constexpr double kStrictLoadFactor = 0.7;
+
+// Arbitrary seeds.
+constexpr uint32_t kProbingSeed1 = 0xbc9f1d34;
+constexpr uint32_t kProbingSeed2 = 0x7a2bb9d5;
+
 // An experimental (under development!) alternative to LRUCache
 
 struct LRUHandle {
   void* value;
   Cache::DeleterFn deleter;
-  LRUHandle* next_hash;
   LRUHandle* next;
   LRUHandle* prev;
   size_t total_charge;  // TODO(opt): Only allow uint32_t?
-  size_t key_length;
   // The hash of key(). Used for fast sharding and comparisons.
   uint32_t hash;
-  // The number of external refs to this entry. The cache itself is not counted.
+  // The number of external refs to this entry.
   uint32_t refs;
 
   enum Flags : uint8_t {
-    // Whether this entry is referenced by the hash table.
-    IN_CACHE = (1 << 0),
+    // Whether the handle is visible to Lookups.
+    IS_VISIBLE = (1 << 0),
+    // Whether the slot is in use by an element.
+    IS_ELEMENT = (1 << 1),
   };
   uint8_t flags;
 
-  // Beginning of the key (MUST BE THE LAST FIELD IN THIS STRUCT!)
-  char key_data[1];
+  // The number of elements that hash to this slot or a lower one,
+  // but wind up in a higher slot.
+  uint32_t displacements;
 
-  Slice key() const { return Slice(key_data, key_length); }
+  std::array<char, kCacheKeySize> key_data;
+
+  LRUHandle() {
+    value = nullptr;
+    deleter = nullptr;
+    next = nullptr;
+    prev = nullptr;
+    total_charge = 0;
+    hash = 0;
+    refs = 0;
+    flags = 0;
+    displacements = 0;
+    key_data.fill(0);
+  }
+
+  Slice key() const { return Slice(key_data.data(), kCacheKeySize); }
 
   // Increase the reference count by 1.
   void Ref() { refs++; }
@@ -61,22 +154,31 @@ struct LRUHandle {
   // Return true if there are external refs, false otherwise.
   bool HasRefs() const { return refs > 0; }
 
-  bool InCache() const { return flags & IN_CACHE; }
+  bool IsVisible() const { return flags & IS_VISIBLE; }
 
-  void SetInCache(bool in_cache) {
-    if (in_cache) {
-      flags |= IN_CACHE;
+  void SetIsVisible(bool is_visible) {
+    if (is_visible) {
+      flags |= IS_VISIBLE;
     } else {
-      flags &= ~IN_CACHE;
+      flags &= ~IS_VISIBLE;
     }
   }
 
-  void Free() {
+  bool IsElement() const { return flags & IS_ELEMENT; }
+
+  void SetIsElement(bool is_element) {
+    if (is_element) {
+      flags |= IS_ELEMENT;
+    } else {
+      flags &= ~IS_ELEMENT;
+    }
+  }
+
+  void FreeData() {
     assert(refs == 0);
     if (deleter) {
       (*deleter)(key(), value);
     }
-    delete[] reinterpret_cast<char*>(this);
   }
 
   // Calculate the memory usage by metadata.
@@ -85,13 +187,22 @@ struct LRUHandle {
     if (metadata_charge_policy != kFullChargeCacheMetadata) {
       return 0;
     } else {
-#ifdef ROCKSDB_MALLOC_USABLE_SIZE
-      return malloc_usable_size(
-          const_cast<void*>(static_cast<const void*>(this)));
-#else
-      // This is the size that is used when a new handle is created.
-      return sizeof(LRUHandle) - 1 + key_length;
-#endif
+      // #ifdef ROCKSDB_MALLOC_USABLE_SIZE
+      //       return malloc_usable_size(
+      //           const_cast<void*>(static_cast<const void*>(this)));
+      // #else
+      // TODO(Guido) malloc_usable_size only works when we call it on
+      // a pointer allocated with malloc. Because our handles are all
+      // allocated in a single shot as an array, the user can't call
+      // CalcMetaCharge (or CalcTotalCharge or GetCharge) on a handle
+      // pointer returned by the cache. Moreover, malloc_usable_size
+      // expects a heap-allocated handle, but sometimes in our code we
+      // wish to pass a stack-allocated handle (this is only a performance
+      // concern).
+      // What is the right way to compute metadata charges with pre-allocated
+      // handles?
+      return sizeof(LRUHandle);
+      // #endif
     }
   }
 
@@ -106,54 +217,102 @@ struct LRUHandle {
     assert(total_charge >= meta_charge);
     return total_charge - meta_charge;
   }
+
+  inline bool IsEmpty() {
+    return !this->IsElement() && this->displacements == 0;
+  }
+
+  inline bool IsTombstone() {
+    return !this->IsElement() && this->displacements > 0;
+  }
+
+  inline bool Matches(const Slice& some_key, uint32_t some_hash) {
+    return this->IsElement() && this->hash == some_hash &&
+           this->key() == some_key;
+  }
 };
 
-// We provide our own simple hash table since it removes a whole bunch
-// of porting hacks and is also faster than some of the built-in hash
-// table implementations in some of the compiler/runtime combinations
-// we have tested.  E.g., readrandom speeds up by ~5% over the g++
-// 4.4.3's builtin hashtable.
+
 class LRUHandleTable {
  public:
   explicit LRUHandleTable(int hash_bits);
   ~LRUHandleTable();
 
+  // Returns a pointer to a visible element matching the key/hash, or
+  // nullptr if not present.
   LRUHandle* Lookup(const Slice& key, uint32_t hash);
-  LRUHandle* Insert(LRUHandle* h);
-  LRUHandle* Remove(const Slice& key, uint32_t hash);
+
+  // Inserts a copy of h into the hash table.
+  // Returns a pointer to the inserted handle, or nullptr if no slot
+  // available was found. If an existing visible element matching the
+  // key/hash is already present in the hash table, the argument old
+  // is set to pointe to it; otherwise, it's set to nullptr.
+  LRUHandle* Insert(LRUHandle* h, LRUHandle** old);
+
+  // Removes h from the hash table. The handle must already be off
+  // the LRU list.
+  void Remove(LRUHandle* h);
+
+  // Turns a visible element h into a ghost (i.e., not visible).
+  void Exclude(LRUHandle* h);
+
+  // Assigns a copy of h to the given slot.
+  void Assign(int slot, LRUHandle* h);
 
   template <typename T>
   void ApplyToEntriesRange(T func, uint32_t index_begin, uint32_t index_end) {
     for (uint32_t i = index_begin; i < index_end; i++) {
-      LRUHandle* h = list_[i];
-      while (h != nullptr) {
-        auto n = h->next_hash;
-        assert(h->InCache());
+      LRUHandle* h = &array_[i];
+      if (h->IsVisible()) {
         func(h);
-        h = n;
       }
     }
   }
 
+  uint32_t GetTableSize() const { return uint32_t{1} << length_bits_; }
+
   int GetLengthBits() const { return length_bits_; }
 
-  // Return the address of the head of the chain in the bucket given
-  // by the hash.
-  inline LRUHandle** Head(uint32_t hash);
+  uint32_t GetOccupancyLimit() const { return occupancy_limit_; }
+
+  uint32_t GetOccupancy() const { return occupancy_; }
+
+  // Returns x mod 2^{length_bits_}.
+  uint32_t ModTableSize(uint32_t x) { return x & length_bits_mask_; }
 
  private:
-  // Return a pointer to slot that points to a cache entry that
-  // matches key/hash.  If there is no such cache entry, return a
-  // pointer to the trailing slot in the corresponding linked list.
-  LRUHandle** FindPointer(const Slice& key, uint32_t hash);
+  int FindVisibleElement(const Slice& key, uint32_t hash, int& probe,
+                         int displacement);
 
-  // Number of hash bits (upper because lower bits used for sharding)
-  // used for table index. Length == 1 << length_bits_
+  int FindAvailableSlot(const Slice& key, int& probe, int displacement);
+
+  int FindVisibleElementOrAvailableSlot(const Slice& key, uint32_t hash,
+                                        int& probe, int displacement);
+
+  // Returns the index of the first slot probed (hashing with
+  // the given key) with a handle e such that cond(e) is true.
+  // Otherwise, if no match is found, returns -1.
+  // For every handle e probed except the final slot, updates
+  // e->displacements += displacement.
+  // The argument probe is modified such that consecutive calls
+  // to FindSlot continue probing right after where the previous
+  // call left.
+  int FindSlot(const Slice& key, std::function<bool(LRUHandle*)> cond,
+               int& probe, int displacement);
+
+  // Number of hash bits used for table index.
+  // The size of the table is 1 << length_bits_.
   int length_bits_;
 
-  // The table consists of an array of buckets where each bucket is
-  // a linked list of cache entries that hash into the bucket.
-  std::unique_ptr<LRUHandle*[]> list_;
+  const uint32_t length_bits_mask_;
+
+  // Number of elements in the table.
+  uint32_t occupancy_;
+
+  // Maximum number of elements the user can store in the table.
+  uint32_t occupancy_limit_;
+
+  std::unique_ptr<LRUHandle[]> array_;
 };
 
 // A single shard of sharded cache.
@@ -173,6 +332,10 @@ class ALIGN_AS(CACHE_LINE_SIZE) LRUCacheShard final : public CacheShard {
   void SetStrictCapacityLimit(bool strict_capacity_limit) override;
 
   // Like Cache methods, but with an extra "hash" parameter.
+  // Insert an item into the hash table and, if handle is null, insert into
+  // the LRU list. Older items are evicted as necessary. If the cache is full
+  // and free_handle_on_fail is true, the item is deleted and handle is set to
+  // nullptr.
   Status Insert(const Slice& key, uint32_t hash, void* value, size_t charge,
                 Cache::DeleterFn deleter, Cache::Handle** handle,
                 Cache::Priority priority) override;
@@ -217,26 +380,26 @@ class ALIGN_AS(CACHE_LINE_SIZE) LRUCacheShard final : public CacheShard {
 
  private:
   friend class LRUCache;
-  // Insert an item into the hash table and, if handle is null, insert into
-  // the LRU list. Older items are evicted as necessary. If the cache is full
-  // and free_handle_on_fail is true, the item is deleted and handle is set to
-  // nullptr.
-  Status InsertItem(LRUHandle* item, Cache::Handle** handle,
-                    bool free_handle_on_fail);
+  friend class FastLRUCacheTest;
 
   void LRU_Remove(LRUHandle* e);
   void LRU_Insert(LRUHandle* e);
 
   // Free some space following strict LRU policy until enough space
-  // to hold (usage_ + charge) is freed or the lru list is empty
+  // to hold (usage_ + charge) is freed or the LRU list is empty
   // This function is not thread safe - it needs to be executed while
   // holding the mutex_.
-  void EvictFromLRU(size_t charge, autovector<LRUHandle*>* deleted);
+  void EvictFromLRU(size_t charge, autovector<LRUHandle>* deleted);
 
-  // Returns the number of bits used to hash an element in the per-shard
+  // Returns the charge of a single handle.
+  static size_t CalcEstimatedHandleCharge(
+      size_t estimated_value_size,
+      CacheMetadataChargePolicy metadata_charge_policy);
+
+  // Returns the number of bits used to hash an element in the hash
   // table.
-  static int GetHashBits(size_t capacity, size_t estimated_value_size,
-                         CacheMetadataChargePolicy metadata_charge_policy);
+  static int CalcHashBits(size_t capacity, size_t estimated_value_size,
+                          CacheMetadataChargePolicy metadata_charge_policy);
 
   // Initialized before use.
   size_t capacity_;

cache/lru_cache.cc

@@ -111,14 +111,17 @@ void LRUHandleTable::Resize() {
 
 LRUCacheShard::LRUCacheShard(
     size_t capacity, bool strict_capacity_limit, double high_pri_pool_ratio,
-    bool use_adaptive_mutex, CacheMetadataChargePolicy metadata_charge_policy,
-    int max_upper_hash_bits,
+    double low_pri_pool_ratio, bool use_adaptive_mutex,
+    CacheMetadataChargePolicy metadata_charge_policy, int max_upper_hash_bits,
     const std::shared_ptr<SecondaryCache>& secondary_cache)
     : capacity_(0),
       high_pri_pool_usage_(0),
+      low_pri_pool_usage_(0),
       strict_capacity_limit_(strict_capacity_limit),
       high_pri_pool_ratio_(high_pri_pool_ratio),
       high_pri_pool_capacity_(0),
+      low_pri_pool_ratio_(low_pri_pool_ratio),
+      low_pri_pool_capacity_(0),
       table_(max_upper_hash_bits),
       usage_(0),
       lru_usage_(0),
@@ -129,6 +132,7 @@ LRUCacheShard::LRUCacheShard(
   lru_.next = &lru_;
   lru_.prev = &lru_;
   lru_low_pri_ = &lru_;
+  lru_bottom_pri_ = &lru_;
   SetCapacity(capacity);
 }
 
@@ -192,10 +196,12 @@ void LRUCacheShard::ApplyToSomeEntries(
       index_begin, index_end);
 }
 
-void LRUCacheShard::TEST_GetLRUList(LRUHandle** lru, LRUHandle** lru_low_pri) {
+void LRUCacheShard::TEST_GetLRUList(LRUHandle** lru, LRUHandle** lru_low_pri,
+                                    LRUHandle** lru_bottom_pri) {
   DMutexLock l(mutex_);
   *lru = &lru_;
   *lru_low_pri = lru_low_pri_;
+  *lru_bottom_pri = lru_bottom_pri_;
 }
 
 size_t LRUCacheShard::TEST_GetLRUSize() {
@@ -214,20 +220,32 @@ double LRUCacheShard::GetHighPriPoolRatio() {
   return high_pri_pool_ratio_;
 }
 
+double LRUCacheShard::GetLowPriPoolRatio() {
+  DMutexLock l(mutex_);
+  return low_pri_pool_ratio_;
+}
+
 void LRUCacheShard::LRU_Remove(LRUHandle* e) {
   assert(e->next != nullptr);
   assert(e->prev != nullptr);
   if (lru_low_pri_ == e) {
     lru_low_pri_ = e->prev;
   }
+  if (lru_bottom_pri_ == e) {
+    lru_bottom_pri_ = e->prev;
+  }
   e->next->prev = e->prev;
   e->prev->next = e->next;
   e->prev = e->next = nullptr;
   assert(lru_usage_ >= e->total_charge);
   lru_usage_ -= e->total_charge;
+  assert(!e->InHighPriPool() || !e->InLowPriPool());
   if (e->InHighPriPool()) {
     assert(high_pri_pool_usage_ >= e->total_charge);
     high_pri_pool_usage_ -= e->total_charge;
+  } else if (e->InLowPriPool()) {
+    assert(low_pri_pool_usage_ >= e->total_charge);
+    low_pri_pool_usage_ -= e->total_charge;
   }
 }
 
@@ -241,17 +259,34 @@ void LRUCacheShard::LRU_Insert(LRUHandle* e) {
     e->prev->next = e;
     e->next->prev = e;
     e->SetInHighPriPool(true);
+    e->SetInLowPriPool(false);
     high_pri_pool_usage_ += e->total_charge;
     MaintainPoolSize();
-  } else {
-    // Insert "e" to the head of low-pri pool. Note that when
-    // high_pri_pool_ratio is 0, head of low-pri pool is also head of LRU list.
+  } else if (low_pri_pool_ratio_ > 0 &&
+             (e->IsHighPri() || e->IsLowPri() || e->HasHit())) {
+    // Insert "e" to the head of low-pri pool.
     e->next = lru_low_pri_->next;
     e->prev = lru_low_pri_;
     e->prev->next = e;
     e->next->prev = e;
     e->SetInHighPriPool(false);
+    e->SetInLowPriPool(true);
+    low_pri_pool_usage_ += e->total_charge;
+    MaintainPoolSize();
     lru_low_pri_ = e;
+  } else {
+    // Insert "e" to the head of bottom-pri pool.
+    e->next = lru_bottom_pri_->next;
+    e->prev = lru_bottom_pri_;
+    e->prev->next = e;
+    e->next->prev = e;
+    e->SetInHighPriPool(false);
+    e->SetInLowPriPool(false);
+    // if the low-pri pool is empty, lru_low_pri_ also needs to be updated.
+    if (lru_bottom_pri_ == lru_low_pri_) {
+      lru_low_pri_ = e;
+    }
+    lru_bottom_pri_ = e;
   }
   lru_usage_ += e->total_charge;
 }
@@ -262,8 +297,20 @@ void LRUCacheShard::MaintainPoolSize() {
     lru_low_pri_ = lru_low_pri_->next;
     assert(lru_low_pri_ != &lru_);
     lru_low_pri_->SetInHighPriPool(false);
+    lru_low_pri_->SetInLowPriPool(true);
     assert(high_pri_pool_usage_ >= lru_low_pri_->total_charge);
     high_pri_pool_usage_ -= lru_low_pri_->total_charge;
+    low_pri_pool_usage_ += lru_low_pri_->total_charge;
+  }
+
+  while (low_pri_pool_usage_ > low_pri_pool_capacity_) {
+    // Overflow last entry in low-pri pool to bottom-pri pool.
+    lru_bottom_pri_ = lru_bottom_pri_->next;
+    assert(lru_bottom_pri_ != &lru_);
+    lru_bottom_pri_->SetInHighPriPool(false);
+    lru_bottom_pri_->SetInLowPriPool(false);
+    assert(low_pri_pool_usage_ >= lru_bottom_pri_->total_charge);
+    low_pri_pool_usage_ -= lru_bottom_pri_->total_charge;
   }
 }
 
@@ -288,6 +335,7 @@ void LRUCacheShard::SetCapacity(size_t capacity) {
     DMutexLock l(mutex_);
     capacity_ = capacity;
     high_pri_pool_capacity_ = capacity_ * high_pri_pool_ratio_;
+    low_pri_pool_capacity_ = capacity_ * low_pri_pool_ratio_;
     EvictFromLRU(0, &last_reference_list);
   }
 
@@ -332,7 +380,7 @@ Status LRUCacheShard::InsertItem(LRUHandle* e, Cache::Handle** handle,
           delete[] reinterpret_cast<char*>(e);
           *handle = nullptr;
         }
-        s = Status::Incomplete("Insert failed due to LRU cache being full.");
+        s = Status::MemoryLimit("Insert failed due to LRU cache being full.");
       }
     } else {
       // Insert into the cache. Note that the cache might get larger than its
@@ -458,11 +506,12 @@ Cache::Handle* LRUCacheShard::Lookup(
       memcpy(e->key_data, key.data(), key.size());
       e->value = nullptr;
       e->sec_handle = secondary_handle.release();
+      e->total_charge = 0;
       e->Ref();
+      e->SetIsInSecondaryCache(is_in_sec_cache);
 
       if (wait) {
         Promote(e);
-        e->SetIsInSecondaryCache(is_in_sec_cache);
         if (!e->value) {
           // The secondary cache returned a handle, but the lookup failed.
           e->Unref();
@@ -476,7 +525,6 @@ Cache::Handle* LRUCacheShard::Lookup(
         // If wait is false, we always return a handle and let the caller
         // release the handle after checking for success or failure.
         e->SetIncomplete(true);
-        e->SetIsInSecondaryCache(is_in_sec_cache);
         // This may be slightly inaccurate, if the lookup eventually fails.
         // But the probability is very low.
         PERF_COUNTER_ADD(secondary_cache_hit_count, 1);
@@ -503,6 +551,13 @@ void LRUCacheShard::SetHighPriorityPoolRatio(double high_pri_pool_ratio) {
   MaintainPoolSize();
 }
 
+void LRUCacheShard::SetLowPriorityPoolRatio(double low_pri_pool_ratio) {
+  DMutexLock l(mutex_);
+  low_pri_pool_ratio_ = low_pri_pool_ratio;
+  low_pri_pool_capacity_ = capacity_ * low_pri_pool_ratio_;
+  MaintainPoolSize();
+}
+
 bool LRUCacheShard::Release(Cache::Handle* handle, bool erase_if_last_ref) {
   if (handle == nullptr) {
     return false;
@@ -529,7 +584,7 @@ bool LRUCacheShard::Release(Cache::Handle* handle, bool erase_if_last_ref) {
     // If it was the last reference, and the entry is either not secondary
     // cache compatible (i.e a dummy entry for accounting), or is secondary
     // cache compatible and has a non-null value, then decrement the cache
-    // usage. If value is null in the latter case, taht means the lookup
+    // usage. If value is null in the latter case, that means the lookup
     // failed and we didn't charge the cache.
     if (last_reference && (!e->IsSecondaryCacheCompatible() || e->value)) {
       assert(usage_ >= e->total_charge);
@@ -634,12 +689,15 @@ std::string LRUCacheShard::GetPrintableOptions() const {
     DMutexLock l(mutex_);
     snprintf(buffer, kBufferSize, "    high_pri_pool_ratio: %.3lf\n",
              high_pri_pool_ratio_);
+    snprintf(buffer + strlen(buffer), kBufferSize - strlen(buffer),
+             "    low_pri_pool_ratio: %.3lf\n", low_pri_pool_ratio_);
   }
   return std::string(buffer);
 }
 
 LRUCache::LRUCache(size_t capacity, int num_shard_bits,
                    bool strict_capacity_limit, double high_pri_pool_ratio,
+                   double low_pri_pool_ratio,
                    std::shared_ptr<MemoryAllocator> allocator,
                    bool use_adaptive_mutex,
                    CacheMetadataChargePolicy metadata_charge_policy,
@@ -653,7 +711,7 @@ LRUCache::LRUCache(size_t capacity, int num_shard_bits,
   for (int i = 0; i < num_shards_; i++) {
     new (&shards_[i]) LRUCacheShard(
         per_shard, strict_capacity_limit, high_pri_pool_ratio,
-        use_adaptive_mutex, metadata_charge_policy,
+        low_pri_pool_ratio, use_adaptive_mutex, metadata_charge_policy,
         /* max_upper_hash_bits */ 32 - num_shard_bits, secondary_cache);
   }
   secondary_cache_ = secondary_cache;
@@ -757,6 +815,17 @@ void LRUCache::WaitAll(std::vector<Handle*>& handles) {
   }
 }
 
+std::string LRUCache::GetPrintableOptions() const {
+  std::string ret;
+  ret.reserve(20000);
+  ret.append(ShardedCache::GetPrintableOptions());
+  if (secondary_cache_) {
+    ret.append("  secondary_cache:\n");
+    ret.append(secondary_cache_->GetPrintableOptions());
+  }
+  return ret;
+}
+
 }  // namespace lru_cache
 
 std::shared_ptr<Cache> NewLRUCache(
@@ -764,7 +833,8 @@ std::shared_ptr<Cache> NewLRUCache(
     double high_pri_pool_ratio,
     std::shared_ptr<MemoryAllocator> memory_allocator, bool use_adaptive_mutex,
     CacheMetadataChargePolicy metadata_charge_policy,
-    const std::shared_ptr<SecondaryCache>& secondary_cache) {
+    const std::shared_ptr<SecondaryCache>& secondary_cache,
+    double low_pri_pool_ratio) {
   if (num_shard_bits >= 20) {
     return nullptr;  // The cache cannot be sharded into too many fine pieces.
   }
@@ -772,30 +842,40 @@ std::shared_ptr<Cache> NewLRUCache(
     // Invalid high_pri_pool_ratio
     return nullptr;
   }
+  if (low_pri_pool_ratio < 0.0 || low_pri_pool_ratio > 1.0) {
+    // Invalid high_pri_pool_ratio
+    return nullptr;
+  }
+  if (low_pri_pool_ratio + high_pri_pool_ratio > 1.0) {
+    // Invalid high_pri_pool_ratio and low_pri_pool_ratio combination
+    return nullptr;
+  }
   if (num_shard_bits < 0) {
     num_shard_bits = GetDefaultCacheShardBits(capacity);
   }
   return std::make_shared<LRUCache>(
       capacity, num_shard_bits, strict_capacity_limit, high_pri_pool_ratio,
-      std::move(memory_allocator), use_adaptive_mutex, metadata_charge_policy,
-      secondary_cache);
+      low_pri_pool_ratio, std::move(memory_allocator), use_adaptive_mutex,
+      metadata_charge_policy, secondary_cache);
 }
 
 std::shared_ptr<Cache> NewLRUCache(const LRUCacheOptions& cache_opts) {
-  return NewLRUCache(
-      cache_opts.capacity, cache_opts.num_shard_bits,
-      cache_opts.strict_capacity_limit, cache_opts.high_pri_pool_ratio,
-      cache_opts.memory_allocator, cache_opts.use_adaptive_mutex,
-      cache_opts.metadata_charge_policy, cache_opts.secondary_cache);
+  return NewLRUCache(cache_opts.capacity, cache_opts.num_shard_bits,
+                     cache_opts.strict_capacity_limit,
+                     cache_opts.high_pri_pool_ratio,
+                     cache_opts.memory_allocator, cache_opts.use_adaptive_mutex,
+                     cache_opts.metadata_charge_policy,
+                     cache_opts.secondary_cache, cache_opts.low_pri_pool_ratio);
 }
 
 std::shared_ptr<Cache> NewLRUCache(
     size_t capacity, int num_shard_bits, bool strict_capacity_limit,
     double high_pri_pool_ratio,
     std::shared_ptr<MemoryAllocator> memory_allocator, bool use_adaptive_mutex,
-    CacheMetadataChargePolicy metadata_charge_policy) {
+    CacheMetadataChargePolicy metadata_charge_policy,
+    double low_pri_pool_ratio) {
   return NewLRUCache(capacity, num_shard_bits, strict_capacity_limit,
                      high_pri_pool_ratio, memory_allocator, use_adaptive_mutex,
-                     metadata_charge_policy, nullptr);
+                     metadata_charge_policy, nullptr, low_pri_pool_ratio);
 }
 }  // namespace ROCKSDB_NAMESPACE

cache/lru_cache.h

@@ -74,7 +74,7 @@ struct LRUHandle {
   // The number of external refs to this entry. The cache itself is not counted.
   uint32_t refs;
 
-  enum Flags : uint8_t {
+  enum Flags : uint16_t {
     // Whether this entry is referenced by the hash table.
     IN_CACHE = (1 << 0),
     // Whether this entry is high priority entry.
@@ -89,9 +89,13 @@ struct LRUHandle {
     IS_PENDING = (1 << 5),
     // Whether this handle is still in a lower tier
     IS_IN_SECONDARY_CACHE = (1 << 6),
+    // Whether this entry is low priority entry.
+    IS_LOW_PRI = (1 << 7),
+    // Whether this entry is in low-pri pool.
+    IN_LOW_PRI_POOL = (1 << 8),
   };
 
-  uint8_t flags;
+  uint16_t flags;
 
 #ifdef __SANITIZE_THREAD__
   // TSAN can report a false data race on flags, where one thread is writing
@@ -122,6 +126,8 @@ struct LRUHandle {
   bool InCache() const { return flags & IN_CACHE; }
   bool IsHighPri() const { return flags & IS_HIGH_PRI; }
   bool InHighPriPool() const { return flags & IN_HIGH_PRI_POOL; }
+  bool IsLowPri() const { return flags & IS_LOW_PRI; }
+  bool InLowPriPool() const { return flags & IN_LOW_PRI_POOL; }
   bool HasHit() const { return flags & HAS_HIT; }
   bool IsSecondaryCacheCompatible() const {
 #ifdef __SANITIZE_THREAD__
@@ -144,8 +150,13 @@ struct LRUHandle {
   void SetPriority(Cache::Priority priority) {
     if (priority == Cache::Priority::HIGH) {
       flags |= IS_HIGH_PRI;
+      flags &= ~IS_LOW_PRI;
+    } else if (priority == Cache::Priority::LOW) {
+      flags &= ~IS_HIGH_PRI;
+      flags |= IS_LOW_PRI;
     } else {
       flags &= ~IS_HIGH_PRI;
+      flags &= ~IS_LOW_PRI;
     }
   }
 
@@ -157,6 +168,14 @@ struct LRUHandle {
     }
   }
 
+  void SetInLowPriPool(bool in_low_pri_pool) {
+    if (in_low_pri_pool) {
+      flags |= IN_LOW_PRI_POOL;
+    } else {
+      flags &= ~IN_LOW_PRI_POOL;
+    }
+  }
+
   void SetHit() { flags |= HAS_HIT; }
 
   void SetSecondaryCacheCompatible(bool compat) {
@@ -298,7 +317,8 @@ class LRUHandleTable {
 class ALIGN_AS(CACHE_LINE_SIZE) LRUCacheShard final : public CacheShard {
  public:
   LRUCacheShard(size_t capacity, bool strict_capacity_limit,
-                double high_pri_pool_ratio, bool use_adaptive_mutex,
+                double high_pri_pool_ratio, double low_pri_pool_ratio,
+                bool use_adaptive_mutex,
                 CacheMetadataChargePolicy metadata_charge_policy,
                 int max_upper_hash_bits,
                 const std::shared_ptr<SecondaryCache>& secondary_cache);
@@ -315,6 +335,9 @@ class ALIGN_AS(CACHE_LINE_SIZE) LRUCacheShard final : public CacheShard {
   // Set percentage of capacity reserved for high-pri cache entries.
   void SetHighPriorityPoolRatio(double high_pri_pool_ratio);
 
+  // Set percentage of capacity reserved for low-pri cache entries.
+  void SetLowPriorityPoolRatio(double low_pri_pool_ratio);
+
   // Like Cache methods, but with an extra "hash" parameter.
   virtual Status Insert(const Slice& key, uint32_t hash, void* value,
                         size_t charge, Cache::DeleterFn deleter,
@@ -366,15 +389,19 @@ class ALIGN_AS(CACHE_LINE_SIZE) LRUCacheShard final : public CacheShard {
 
   virtual std::string GetPrintableOptions() const override;
 
-  void TEST_GetLRUList(LRUHandle** lru, LRUHandle** lru_low_pri);
+  void TEST_GetLRUList(LRUHandle** lru, LRUHandle** lru_low_pri,
+                       LRUHandle** lru_bottom_pri);
 
-  //  Retrieves number of elements in LRU, for unit test purpose only.
-  //  Not threadsafe.
+  // Retrieves number of elements in LRU, for unit test purpose only.
+  // Not threadsafe.
   size_t TEST_GetLRUSize();
 
-  //  Retrieves high pri pool ratio
+  // Retrieves high pri pool ratio
   double GetHighPriPoolRatio();
 
+  // Retrieves low pri pool ratio
+  double GetLowPriPoolRatio();
+
  private:
   friend class LRUCache;
   // Insert an item into the hash table and, if handle is null, insert into
@@ -414,6 +441,9 @@ class ALIGN_AS(CACHE_LINE_SIZE) LRUCacheShard final : public CacheShard {
   // Memory size for entries in high-pri pool.
   size_t high_pri_pool_usage_;
 
+  // Memory size for entries in low-pri pool.
+  size_t low_pri_pool_usage_;
+
   // Whether to reject insertion if cache reaches its full capacity.
   bool strict_capacity_limit_;
 
@@ -424,6 +454,13 @@ class ALIGN_AS(CACHE_LINE_SIZE) LRUCacheShard final : public CacheShard {
   // Remember the value to avoid recomputing each time.
   double high_pri_pool_capacity_;
 
+  // Ratio of capacity reserved for low priority cache entries.
+  double low_pri_pool_ratio_;
+
+  // Low-pri pool size, equals to capacity * low_pri_pool_ratio.
+  // Remember the value to avoid recomputing each time.
+  double low_pri_pool_capacity_;
+
   // Dummy head of LRU list.
   // lru.prev is newest entry, lru.next is oldest entry.
   // LRU contains items which can be evicted, ie reference only by cache
@@ -432,6 +469,9 @@ class ALIGN_AS(CACHE_LINE_SIZE) LRUCacheShard final : public CacheShard {
   // Pointer to head of low-pri pool in LRU list.
   LRUHandle* lru_low_pri_;
 
+  // Pointer to head of bottom-pri pool in LRU list.
+  LRUHandle* lru_bottom_pri_;
+
   // ------------^^^^^^^^^^^^^-----------
   // Not frequently modified data members
   // ------------------------------------
@@ -466,7 +506,7 @@ class LRUCache
     : public ShardedCache {
  public:
   LRUCache(size_t capacity, int num_shard_bits, bool strict_capacity_limit,
-           double high_pri_pool_ratio,
+           double high_pri_pool_ratio, double low_pri_pool_ratio,
            std::shared_ptr<MemoryAllocator> memory_allocator = nullptr,
            bool use_adaptive_mutex = kDefaultToAdaptiveMutex,
            CacheMetadataChargePolicy metadata_charge_policy =
@@ -482,10 +522,11 @@ class LRUCache
   virtual DeleterFn GetDeleter(Handle* handle) const override;
   virtual void DisownData() override;
   virtual void WaitAll(std::vector<Handle*>& handles) override;
+  std::string GetPrintableOptions() const override;
 
-  //  Retrieves number of elements in LRU, for unit test purpose only.
+  // Retrieves number of elements in LRU, for unit test purpose only.
   size_t TEST_GetLRUSize();
-  //  Retrieves high pri pool ratio.
+  // Retrieves high pri pool ratio.
   double GetHighPriPoolRatio();
 
  private:

cache/sharded_cache.h

@@ -86,7 +86,7 @@ class ShardedCache : public Cache {
                         DeleterFn deleter, Handle** handle,
                         Priority priority) override;
   virtual Status Insert(const Slice& key, void* value,
-                        const CacheItemHelper* helper, size_t chargge,
+                        const CacheItemHelper* helper, size_t charge,
                         Handle** handle = nullptr,
                         Priority priority = Priority::LOW) override;
   virtual Handle* Lookup(const Slice& key, Statistics* stats) override;

crash_test.mk

@@ -18,7 +18,9 @@ CRASHTEST_PY=$(PYTHON) -u tools/db_crashtest.py --stress_cmd=$(DB_STRESS_CMD)
 	whitebox_crash_test whitebox_crash_test_with_atomic_flush \
 	whitebox_crash_test_with_txn whitebox_crash_test_with_ts \
 	blackbox_crash_test_with_multiops_wc_txn \
-	blackbox_crash_test_with_multiops_wp_txn
+	blackbox_crash_test_with_multiops_wp_txn \
+	crash_test_with_tiered_storage blackbox_crash_test_with_tiered_storage \
+	whitebox_crash_test_with_tiered_storage \
 
 crash_test: $(DB_STRESS_CMD)
 # Do not parallelize
@@ -42,6 +44,11 @@ crash_test_with_ts: $(DB_STRESS_CMD)
 	$(CRASHTEST_MAKE) whitebox_crash_test_with_ts
 	$(CRASHTEST_MAKE) blackbox_crash_test_with_ts
 
+crash_test_with_tiered_storage: $(DB_STRESS_CMD)
+# Do not parallelize
+	$(CRASHTEST_MAKE) whitebox_crash_test_with_tiered_storage
+	$(CRASHTEST_MAKE) blackbox_crash_test_with_tiered_storage
+
 crash_test_with_multiops_wc_txn: $(DB_STRESS_CMD)
 	$(CRASHTEST_MAKE) blackbox_crash_test_with_multiops_wc_txn
 
@@ -70,6 +77,9 @@ blackbox_crash_test_with_multiops_wc_txn: $(DB_STRESS_CMD)
 blackbox_crash_test_with_multiops_wp_txn: $(DB_STRESS_CMD)
 	$(CRASHTEST_PY) --test_multiops_txn --write_policy write_prepared blackbox $(CRASH_TEST_EXT_ARGS)
 
+blackbox_crash_test_with_tiered_storage: $(DB_STRESS_CMD)
+	$(CRASHTEST_PY) --enable_tiered_storage blackbox $(CRASH_TEST_EXT_ARGS)
+
 ifeq ($(CRASH_TEST_KILL_ODD),)
   CRASH_TEST_KILL_ODD=888887
 endif
@@ -91,3 +101,7 @@ whitebox_crash_test_with_txn: $(DB_STRESS_CMD)
 whitebox_crash_test_with_ts: $(DB_STRESS_CMD)
 	$(CRASHTEST_PY) --enable_ts whitebox --random_kill_odd \
       $(CRASH_TEST_KILL_ODD) $(CRASH_TEST_EXT_ARGS)
+
+whitebox_crash_test_with_tiered_storage: $(DB_STRESS_CMD)
+	$(CRASHTEST_PY) --enable_tiered_storage whitebox --random_kill_odd \
+      $(CRASH_TEST_KILL_ODD) $(CRASH_TEST_EXT_ARGS)

db/arena_wrapped_db_iter.cc

@@ -89,8 +89,8 @@ Status ArenaWrappedDBIter::Refresh() {
         ReadRangeDelAggregator* range_del_agg =
             db_iter_->GetRangeDelAggregator();
         std::unique_ptr<FragmentedRangeTombstoneIterator> range_del_iter;
-        range_del_iter.reset(
-            sv->mem->NewRangeTombstoneIterator(read_options_, latest_seq));
+        range_del_iter.reset(sv->mem->NewRangeTombstoneIterator(
+            read_options_, latest_seq, false /* immutable_memtable */));
         range_del_agg->AddTombstones(std::move(range_del_iter));
         cfd_->ReturnThreadLocalSuperVersion(sv);
       }

db/blob/blob_file_builder.cc

@@ -32,9 +32,9 @@ BlobFileBuilder::BlobFileBuilder(
     VersionSet* versions, FileSystem* fs,
     const ImmutableOptions* immutable_options,
     const MutableCFOptions* mutable_cf_options, const FileOptions* file_options,
-    int job_id, uint32_t column_family_id,
-    const std::string& column_family_name, Env::IOPriority io_priority,
-    Env::WriteLifeTimeHint write_hint,
+    std::string db_id, std::string db_session_id, int job_id,
+    uint32_t column_family_id, const std::string& column_family_name,
+    Env::IOPriority io_priority, Env::WriteLifeTimeHint write_hint,
     const std::shared_ptr<IOTracer>& io_tracer,
     BlobFileCompletionCallback* blob_callback,
     BlobFileCreationReason creation_reason,
@@ -42,17 +42,18 @@ BlobFileBuilder::BlobFileBuilder(
     std::vector<BlobFileAddition>* blob_file_additions)
     : BlobFileBuilder([versions]() { return versions->NewFileNumber(); }, fs,
                       immutable_options, mutable_cf_options, file_options,
-                      job_id, column_family_id, column_family_name, io_priority,
-                      write_hint, io_tracer, blob_callback, creation_reason,
-                      blob_file_paths, blob_file_additions) {}
+                      db_id, db_session_id, job_id, column_family_id,
+                      column_family_name, io_priority, write_hint, io_tracer,
+                      blob_callback, creation_reason, blob_file_paths,
+                      blob_file_additions) {}
 
 BlobFileBuilder::BlobFileBuilder(
     std::function<uint64_t()> file_number_generator, FileSystem* fs,
     const ImmutableOptions* immutable_options,
     const MutableCFOptions* mutable_cf_options, const FileOptions* file_options,
-    int job_id, uint32_t column_family_id,
-    const std::string& column_family_name, Env::IOPriority io_priority,
-    Env::WriteLifeTimeHint write_hint,
+    std::string db_id, std::string db_session_id, int job_id,
+    uint32_t column_family_id, const std::string& column_family_name,
+    Env::IOPriority io_priority, Env::WriteLifeTimeHint write_hint,
     const std::shared_ptr<IOTracer>& io_tracer,
     BlobFileCompletionCallback* blob_callback,
     BlobFileCreationReason creation_reason,
@@ -64,7 +65,10 @@ BlobFileBuilder::BlobFileBuilder(
       min_blob_size_(mutable_cf_options->min_blob_size),
       blob_file_size_(mutable_cf_options->blob_file_size),
       blob_compression_type_(mutable_cf_options->blob_compression_type),
+      prepopulate_blob_cache_(mutable_cf_options->prepopulate_blob_cache),
       file_options_(file_options),
+      db_id_(std::move(db_id)),
+      db_session_id_(std::move(db_session_id)),
       job_id_(job_id),
       column_family_id_(column_family_id),
       column_family_name_(column_family_name),
@@ -133,6 +137,16 @@ Status BlobFileBuilder::Add(const Slice& key, const Slice& value,
     }
   }
 
+  {
+    const Status s =
+        PutBlobIntoCacheIfNeeded(value, blob_file_number, blob_offset);
+    if (!s.ok()) {
+      ROCKS_LOG_WARN(immutable_options_->info_log,
+                     "Failed to pre-populate the blob into blob cache: %s",
+                     s.ToString().c_str());
+    }
+  }
+
   BlobIndex::EncodeBlob(blob_index, blob_file_number, blob_offset, blob.size(),
                         blob_compression_type_);
 
@@ -372,4 +386,48 @@ void BlobFileBuilder::Abandon(const Status& s) {
   blob_count_ = 0;
   blob_bytes_ = 0;
 }
+
+Status BlobFileBuilder::PutBlobIntoCacheIfNeeded(const Slice& blob,
+                                                 uint64_t blob_file_number,
+                                                 uint64_t blob_offset) const {
+  Status s = Status::OK();
+
+  auto blob_cache = immutable_options_->blob_cache;
+  auto statistics = immutable_options_->statistics.get();
+  bool warm_cache =
+      prepopulate_blob_cache_ == PrepopulateBlobCache::kFlushOnly &&
+      creation_reason_ == BlobFileCreationReason::kFlush;
+
+  if (blob_cache && warm_cache) {
+    const OffsetableCacheKey base_cache_key(db_id_, db_session_id_,
+                                            blob_file_number);
+    const CacheKey cache_key = base_cache_key.WithOffset(blob_offset);
+    const Slice key = cache_key.AsSlice();
+
+    const Cache::Priority priority = Cache::Priority::BOTTOM;
+
+    // Objects to be put into the cache have to be heap-allocated and
+    // self-contained, i.e. own their contents. The Cache has to be able to
+    // take unique ownership of them. Therefore, we copy the blob into a
+    // string directly, and insert that into the cache.
+    std::unique_ptr<std::string> buf = std::make_unique<std::string>();
+    buf->assign(blob.data(), blob.size());
+
+    // TODO: support custom allocators and provide a better estimated memory
+    // usage using malloc_usable_size.
+    s = blob_cache->Insert(key, buf.get(), buf->size(),
+                           &DeleteCacheEntry<std::string>,
+                           nullptr /* cache_handle */, priority);
+    if (s.ok()) {
+      RecordTick(statistics, BLOB_DB_CACHE_ADD);
+      RecordTick(statistics, BLOB_DB_CACHE_BYTES_WRITE, buf->size());
+      buf.release();
+    } else {
+      RecordTick(statistics, BLOB_DB_CACHE_ADD_FAILURES);
+    }
+  }
+
+  return s;
+}
+
 }  // namespace ROCKSDB_NAMESPACE

db/blob/blob_file_builder.h

@@ -10,6 +10,7 @@
 #include <string>
 #include <vector>
 
+#include "rocksdb/advanced_options.h"
 #include "rocksdb/compression_type.h"
 #include "rocksdb/env.h"
 #include "rocksdb/rocksdb_namespace.h"
@@ -35,7 +36,8 @@ class BlobFileBuilder {
   BlobFileBuilder(VersionSet* versions, FileSystem* fs,
                   const ImmutableOptions* immutable_options,
                   const MutableCFOptions* mutable_cf_options,
-                  const FileOptions* file_options, int job_id,
+                  const FileOptions* file_options, std::string db_id,
+                  std::string db_session_id, int job_id,
                   uint32_t column_family_id,
                   const std::string& column_family_name,
                   Env::IOPriority io_priority,
@@ -49,7 +51,8 @@ class BlobFileBuilder {
   BlobFileBuilder(std::function<uint64_t()> file_number_generator,
                   FileSystem* fs, const ImmutableOptions* immutable_options,
                   const MutableCFOptions* mutable_cf_options,
-                  const FileOptions* file_options, int job_id,
+                  const FileOptions* file_options, std::string db_id,
+                  std::string db_session_id, int job_id,
                   uint32_t column_family_id,
                   const std::string& column_family_name,
                   Env::IOPriority io_priority,
@@ -78,13 +81,19 @@ class BlobFileBuilder {
   Status CloseBlobFile();
   Status CloseBlobFileIfNeeded();
 
+  Status PutBlobIntoCacheIfNeeded(const Slice& blob, uint64_t blob_file_number,
+                                  uint64_t blob_offset) const;
+
   std::function<uint64_t()> file_number_generator_;
   FileSystem* fs_;
   const ImmutableOptions* immutable_options_;
   uint64_t min_blob_size_;
   uint64_t blob_file_size_;
   CompressionType blob_compression_type_;
+  PrepopulateBlobCache prepopulate_blob_cache_;
   const FileOptions* file_options_;
+  const std::string db_id_;
+  const std::string db_session_id_;
   int job_id_;
   uint32_t column_family_id_;
   std::string column_family_name_;

db/blob/blob_file_builder_test.cc

@@ -144,8 +144,9 @@ TEST_F(BlobFileBuilderTest, BuildAndCheckOneFile) {
 
   BlobFileBuilder builder(
       TestFileNumberGenerator(), fs_, &immutable_options, &mutable_cf_options,
-      &file_options_, job_id, column_family_id, column_family_name, io_priority,
-      write_hint, nullptr /*IOTracer*/, nullptr /*BlobFileCompletionCallback*/,
+      &file_options_, "" /*db_id*/, "" /*db_session_id*/, job_id,
+      column_family_id, column_family_name, io_priority, write_hint,
+      nullptr /*IOTracer*/, nullptr /*BlobFileCompletionCallback*/,
       BlobFileCreationReason::kFlush, &blob_file_paths, &blob_file_additions);
 
   std::vector<std::pair<std::string, std::string>> expected_key_value_pairs(
@@ -228,8 +229,9 @@ TEST_F(BlobFileBuilderTest, BuildAndCheckMultipleFiles) {
 
   BlobFileBuilder builder(
       TestFileNumberGenerator(), fs_, &immutable_options, &mutable_cf_options,
-      &file_options_, job_id, column_family_id, column_family_name, io_priority,
-      write_hint, nullptr /*IOTracer*/, nullptr /*BlobFileCompletionCallback*/,
+      &file_options_, "" /*db_id*/, "" /*db_session_id*/, job_id,
+      column_family_id, column_family_name, io_priority, write_hint,
+      nullptr /*IOTracer*/, nullptr /*BlobFileCompletionCallback*/,
       BlobFileCreationReason::kFlush, &blob_file_paths, &blob_file_additions);
 
   std::vector<std::pair<std::string, std::string>> expected_key_value_pairs(
@@ -315,8 +317,9 @@ TEST_F(BlobFileBuilderTest, InlinedValues) {
 
   BlobFileBuilder builder(
       TestFileNumberGenerator(), fs_, &immutable_options, &mutable_cf_options,
-      &file_options_, job_id, column_family_id, column_family_name, io_priority,
-      write_hint, nullptr /*IOTracer*/, nullptr /*BlobFileCompletionCallback*/,
+      &file_options_, "" /*db_id*/, "" /*db_session_id*/, job_id,
+      column_family_id, column_family_name, io_priority, write_hint,
+      nullptr /*IOTracer*/, nullptr /*BlobFileCompletionCallback*/,
       BlobFileCreationReason::kFlush, &blob_file_paths, &blob_file_additions);
 
   for (size_t i = 0; i < number_of_blobs; ++i) {
@@ -369,8 +372,9 @@ TEST_F(BlobFileBuilderTest, Compression) {
 
   BlobFileBuilder builder(
       TestFileNumberGenerator(), fs_, &immutable_options, &mutable_cf_options,
-      &file_options_, job_id, column_family_id, column_family_name, io_priority,
-      write_hint, nullptr /*IOTracer*/, nullptr /*BlobFileCompletionCallback*/,
+      &file_options_, "" /*db_id*/, "" /*db_session_id*/, job_id,
+      column_family_id, column_family_name, io_priority, write_hint,
+      nullptr /*IOTracer*/, nullptr /*BlobFileCompletionCallback*/,
       BlobFileCreationReason::kFlush, &blob_file_paths, &blob_file_additions);
 
   const std::string key("1");
@@ -452,8 +456,9 @@ TEST_F(BlobFileBuilderTest, CompressionError) {
 
   BlobFileBuilder builder(
       TestFileNumberGenerator(), fs_, &immutable_options, &mutable_cf_options,
-      &file_options_, job_id, column_family_id, column_family_name, io_priority,
-      write_hint, nullptr /*IOTracer*/, nullptr /*BlobFileCompletionCallback*/,
+      &file_options_, "" /*db_id*/, "" /*db_session_id*/, job_id,
+      column_family_id, column_family_name, io_priority, write_hint,
+      nullptr /*IOTracer*/, nullptr /*BlobFileCompletionCallback*/,
       BlobFileCreationReason::kFlush, &blob_file_paths, &blob_file_additions);
 
   SyncPoint::GetInstance()->SetCallBack("CompressData:TamperWithReturnValue",
@@ -531,8 +536,9 @@ TEST_F(BlobFileBuilderTest, Checksum) {
 
   BlobFileBuilder builder(
       TestFileNumberGenerator(), fs_, &immutable_options, &mutable_cf_options,
-      &file_options_, job_id, column_family_id, column_family_name, io_priority,
-      write_hint, nullptr /*IOTracer*/, nullptr /*BlobFileCompletionCallback*/,
+      &file_options_, "" /*db_id*/, "" /*db_session_id*/, job_id,
+      column_family_id, column_family_name, io_priority, write_hint,
+      nullptr /*IOTracer*/, nullptr /*BlobFileCompletionCallback*/,
       BlobFileCreationReason::kFlush, &blob_file_paths, &blob_file_additions);
 
   const std::string key("1");
@@ -628,8 +634,9 @@ TEST_P(BlobFileBuilderIOErrorTest, IOError) {
 
   BlobFileBuilder builder(
       TestFileNumberGenerator(), fs_, &immutable_options, &mutable_cf_options,
-      &file_options_, job_id, column_family_id, column_family_name, io_priority,
-      write_hint, nullptr /*IOTracer*/, nullptr /*BlobFileCompletionCallback*/,
+      &file_options_, "" /*db_id*/, "" /*db_session_id*/, job_id,
+      column_family_id, column_family_name, io_priority, write_hint,
+      nullptr /*IOTracer*/, nullptr /*BlobFileCompletionCallback*/,
       BlobFileCreationReason::kFlush, &blob_file_paths, &blob_file_additions);
 
   SyncPoint::GetInstance()->SetCallBack(sync_point_, [this](void* arg) {

db/blob/blob_file_cache_test.cc

@@ -254,7 +254,7 @@ TEST_F(BlobFileCacheTest, GetBlobFileReader_CacheFull) {
   CacheHandleGuard<BlobFileReader> reader;
 
   ASSERT_TRUE(blob_file_cache.GetBlobFileReader(blob_file_number, &reader)
-                  .IsIncomplete());
+                  .IsMemoryLimit());
   ASSERT_EQ(reader.GetValue(), nullptr);
   ASSERT_EQ(options.statistics->getTickerCount(NO_FILE_OPENS), 1);
   ASSERT_EQ(options.statistics->getTickerCount(NO_FILE_ERRORS), 1);

db/blob/blob_file_reader.cc

@@ -16,6 +16,7 @@
 #include "rocksdb/file_system.h"
 #include "rocksdb/slice.h"
 #include "rocksdb/status.h"
+#include "table/multiget_context.h"
 #include "test_util/sync_point.h"
 #include "util/compression.h"
 #include "util/crc32c.h"
@@ -335,7 +336,9 @@ Status BlobFileReader::GetBlob(const ReadOptions& read_options,
 
   if (!prefetched) {
     TEST_SYNC_POINT("BlobFileReader::GetBlob:ReadFromFile");
-
+    PERF_COUNTER_ADD(blob_read_count, 1);
+    PERF_COUNTER_ADD(blob_read_byte, record_size);
+    PERF_TIMER_GUARD(blob_read_time);
     const Status s = ReadFromFile(file_reader_.get(), record_offset,
                                   static_cast<size_t>(record_size), statistics_,
                                   &record_slice, &buf, &aligned_buf,
@@ -372,40 +375,50 @@ Status BlobFileReader::GetBlob(const ReadOptions& read_options,
   return Status::OK();
 }
 
-void BlobFileReader::MultiGetBlob(
-    const ReadOptions& read_options,
-    const autovector<std::reference_wrapper<const Slice>>& user_keys,
-    const autovector<uint64_t>& offsets,
-    const autovector<uint64_t>& value_sizes, autovector<Status*>& statuses,
-    autovector<PinnableSlice*>& values, uint64_t* bytes_read) const {
-  const size_t num_blobs = user_keys.size();
+void BlobFileReader::MultiGetBlob(const ReadOptions& read_options,
+                                  autovector<BlobReadRequest*>& blob_reqs,
+                                  uint64_t* bytes_read) const {
+  const size_t num_blobs = blob_reqs.size();
   assert(num_blobs > 0);
-  assert(num_blobs == offsets.size());
-  assert(num_blobs == value_sizes.size());
-  assert(num_blobs == statuses.size());
-  assert(num_blobs == values.size());
+  assert(num_blobs <= MultiGetContext::MAX_BATCH_SIZE);
 
 #ifndef NDEBUG
-  for (size_t i = 0; i < offsets.size() - 1; ++i) {
-    assert(offsets[i] <= offsets[i + 1]);
+  for (size_t i = 0; i < num_blobs - 1; ++i) {
+    assert(blob_reqs[i]->offset <= blob_reqs[i + 1]->offset);
   }
 #endif  // !NDEBUG
 
-  std::vector<FSReadRequest> read_reqs(num_blobs);
+  std::vector<FSReadRequest> read_reqs;
   autovector<uint64_t> adjustments;
   uint64_t total_len = 0;
+  read_reqs.reserve(num_blobs);
   for (size_t i = 0; i < num_blobs; ++i) {
-    const size_t key_size = user_keys[i].get().size();
-    assert(IsValidBlobOffset(offsets[i], key_size, value_sizes[i], file_size_));
+    const size_t key_size = blob_reqs[i]->user_key->size();
+    const uint64_t offset = blob_reqs[i]->offset;
+    const uint64_t value_size = blob_reqs[i]->len;
+
+    if (!IsValidBlobOffset(offset, key_size, value_size, file_size_)) {
+      *blob_reqs[i]->status = Status::Corruption("Invalid blob offset");
+      continue;
+    }
+    if (blob_reqs[i]->compression != compression_type_) {
+      *blob_reqs[i]->status =
+          Status::Corruption("Compression type mismatch when reading a blob");
+      continue;
+    }
+
     const uint64_t adjustment =
         read_options.verify_checksums
             ? BlobLogRecord::CalculateAdjustmentForRecordHeader(key_size)
             : 0;
-    assert(offsets[i] >= adjustment);
+    assert(blob_reqs[i]->offset >= adjustment);
     adjustments.push_back(adjustment);
-    read_reqs[i].offset = offsets[i] - adjustment;
-    read_reqs[i].len = value_sizes[i] + adjustment;
-    total_len += read_reqs[i].len;
+
+    FSReadRequest read_req = {};
+    read_req.offset = blob_reqs[i]->offset - adjustment;
+    read_req.len = blob_reqs[i]->len + adjustment;
+    read_reqs.emplace_back(read_req);
+    total_len += read_req.len;
   }
 
   RecordTick(statistics_, BLOB_DB_BLOB_FILE_BYTES_READ, total_len);
@@ -428,6 +441,8 @@ void BlobFileReader::MultiGetBlob(
     }
   }
   TEST_SYNC_POINT("BlobFileReader::MultiGetBlob:ReadFromFile");
+  PERF_COUNTER_ADD(blob_read_count, num_blobs);
+  PERF_COUNTER_ADD(blob_read_byte, total_len);
   s = file_reader_->MultiRead(IOOptions(), read_reqs.data(), read_reqs.size(),
                               direct_io ? &aligned_buf : nullptr,
                               read_options.rate_limiter_priority);
@@ -435,64 +450,65 @@ void BlobFileReader::MultiGetBlob(
     for (auto& req : read_reqs) {
       req.status.PermitUncheckedError();
     }
-    for (size_t i = 0; i < num_blobs; ++i) {
-      assert(statuses[i]);
-      *statuses[i] = s;
+    for (auto& req : blob_reqs) {
+      assert(req->status);
+      if (!req->status->IsCorruption()) {
+        // Avoid overwriting corruption status.
+        *req->status = s;
+      }
     }
     return;
   }
 
   assert(s.ok());
-  for (size_t i = 0; i < num_blobs; ++i) {
-    auto& req = read_reqs[i];
-    assert(statuses[i]);
-    if (req.status.ok() && req.result.size() != req.len) {
-      req.status = IOStatus::Corruption("Failed to read data from blob file");
-    }
-    *statuses[i] = req.status;
-  }
 
-  if (read_options.verify_checksums) {
-    for (size_t i = 0; i < num_blobs; ++i) {
-      assert(statuses[i]);
-      if (!statuses[i]->ok()) {
-        continue;
-      }
-      const Slice& record_slice = read_reqs[i].result;
-      s = VerifyBlob(record_slice, user_keys[i], value_sizes[i]);
-      if (!s.ok()) {
-        assert(statuses[i]);
-        *statuses[i] = s;
-      }
-    }
-  }
-
-  for (size_t i = 0; i < num_blobs; ++i) {
-    assert(statuses[i]);
-    if (!statuses[i]->ok()) {
+  uint64_t total_bytes = 0;
+  for (size_t i = 0, j = 0; i < num_blobs; ++i) {
+    assert(blob_reqs[i]->status);
+    if (!blob_reqs[i]->status->ok()) {
       continue;
     }
-    const Slice& record_slice = read_reqs[i].result;
-    const Slice value_slice(record_slice.data() + adjustments[i],
-                            value_sizes[i]);
-    s = UncompressBlobIfNeeded(value_slice, compression_type_, clock_,
-                               statistics_, values[i]);
-    if (!s.ok()) {
-      *statuses[i] = s;
+
+    assert(j < read_reqs.size());
+    auto& req = read_reqs[j++];
+    const auto& record_slice = req.result;
+    if (req.status.ok() && record_slice.size() != req.len) {
+      req.status = IOStatus::Corruption("Failed to read data from blob file");
+    }
+
+    *blob_reqs[i]->status = req.status;
+    if (!blob_reqs[i]->status->ok()) {
+      continue;
+    }
+
+    // Verify checksums if enabled
+    if (read_options.verify_checksums) {
+      *blob_reqs[i]->status =
+          VerifyBlob(record_slice, *blob_reqs[i]->user_key, blob_reqs[i]->len);
+      if (!blob_reqs[i]->status->ok()) {
+        continue;
+      }
+    }
+
+    // Uncompress blob if needed
+    Slice value_slice(record_slice.data() + adjustments[i], blob_reqs[i]->len);
+    *blob_reqs[i]->status =
+        UncompressBlobIfNeeded(value_slice, compression_type_, clock_,
+                               statistics_, blob_reqs[i]->result);
+    if (blob_reqs[i]->status->ok()) {
+      total_bytes += record_slice.size();
     }
   }
 
   if (bytes_read) {
-    uint64_t total_bytes = 0;
-    for (const auto& req : read_reqs) {
-      total_bytes += req.result.size();
-    }
     *bytes_read = total_bytes;
   }
 }
 
 Status BlobFileReader::VerifyBlob(const Slice& record_slice,
                                   const Slice& user_key, uint64_t value_size) {
+  PERF_TIMER_GUARD(blob_checksum_time);
+
   BlobLogRecord record;
 
   const Slice header_slice(record_slice.data(), BlobLogRecord::kHeaderSize);
@@ -557,6 +573,7 @@ Status BlobFileReader::UncompressBlobIfNeeded(const Slice& value_slice,
   CacheAllocationPtr output;
 
   {
+    PERF_TIMER_GUARD(blob_decompress_time);
     StopWatch stop_watch(clock, statistics, BLOB_DB_DECOMPRESSION_MICROS);
     output = UncompressData(info, value_slice.data(), value_slice.size(),
                             &uncompressed_size, compression_format_version,

db/blob/blob_file_reader.h

@@ -8,6 +8,7 @@
 #include <cinttypes>
 #include <memory>
 
+#include "db/blob/blob_read_request.h"
 #include "file/random_access_file_reader.h"
 #include "rocksdb/compression_type.h"
 #include "rocksdb/rocksdb_namespace.h"
@@ -47,12 +48,9 @@ class BlobFileReader {
                  uint64_t* bytes_read) const;
 
   // offsets must be sorted in ascending order by caller.
-  void MultiGetBlob(
-      const ReadOptions& read_options,
-      const autovector<std::reference_wrapper<const Slice>>& user_keys,
-      const autovector<uint64_t>& offsets,
-      const autovector<uint64_t>& value_sizes, autovector<Status*>& statuses,
-      autovector<PinnableSlice*>& values, uint64_t* bytes_read) const;
+  void MultiGetBlob(const ReadOptions& read_options,
+                    autovector<BlobReadRequest*>& blob_reqs,
+                    uint64_t* bytes_read) const;
 
   CompressionType GetCompressionType() const { return compression_type_; }
 

db/blob/blob_file_reader_test.cc

@@ -194,21 +194,21 @@ TEST_F(BlobFileReaderTest, CreateReaderAndGetBlob) {
     // MultiGetBlob
     bytes_read = 0;
     size_t total_size = 0;
-    autovector<std::reference_wrapper<const Slice>> key_refs;
-    for (const auto& key_ref : keys) {
-      key_refs.emplace_back(std::cref(key_ref));
-    }
-    autovector<uint64_t> offsets{blob_offsets[0], blob_offsets[1],
-                                 blob_offsets[2]};
-    autovector<uint64_t> sizes{blob_sizes[0], blob_sizes[1], blob_sizes[2]};
+
     std::array<Status, num_blobs> statuses_buf;
-    autovector<Status*> statuses{&statuses_buf[0], &statuses_buf[1],
-                                 &statuses_buf[2]};
     std::array<PinnableSlice, num_blobs> value_buf;
-    autovector<PinnableSlice*> values{&value_buf[0], &value_buf[1],
-                                      &value_buf[2]};
-    reader->MultiGetBlob(read_options, key_refs, offsets, sizes, statuses,
-                         values, &bytes_read);
+    std::array<BlobReadRequest, num_blobs> requests_buf;
+    autovector<BlobReadRequest*> blob_reqs;
+
+    for (size_t i = 0; i < num_blobs; ++i) {
+      requests_buf[i] =
+          BlobReadRequest(keys[i], blob_offsets[i], blob_sizes[i],
+                          kNoCompression, &value_buf[i], &statuses_buf[i]);
+      blob_reqs.push_back(&requests_buf[i]);
+    }
+
+    reader->MultiGetBlob(read_options, blob_reqs, &bytes_read);
+
     for (size_t i = 0; i < num_blobs; ++i) {
       ASSERT_OK(statuses_buf[i]);
       ASSERT_EQ(value_buf[i], blobs[i]);
@@ -300,15 +300,21 @@ TEST_F(BlobFileReaderTest, CreateReaderAndGetBlob) {
         blob_offsets[0],
         blob_offsets[1] - (keys[1].size() - key_refs[1].get().size()),
         blob_offsets[2]};
-    autovector<uint64_t> sizes{blob_sizes[0], blob_sizes[1], blob_sizes[2]};
+
     std::array<Status, num_blobs> statuses_buf;
-    autovector<Status*> statuses{&statuses_buf[0], &statuses_buf[1],
-                                 &statuses_buf[2]};
     std::array<PinnableSlice, num_blobs> value_buf;
-    autovector<PinnableSlice*> values{&value_buf[0], &value_buf[1],
-                                      &value_buf[2]};
-    reader->MultiGetBlob(read_options, key_refs, offsets, sizes, statuses,
-                         values, &bytes_read);
+    std::array<BlobReadRequest, num_blobs> requests_buf;
+    autovector<BlobReadRequest*> blob_reqs;
+
+    for (size_t i = 0; i < num_blobs; ++i) {
+      requests_buf[i] =
+          BlobReadRequest(key_refs[i], offsets[i], blob_sizes[i],
+                          kNoCompression, &value_buf[i], &statuses_buf[i]);
+      blob_reqs.push_back(&requests_buf[i]);
+    }
+
+    reader->MultiGetBlob(read_options, blob_reqs, &bytes_read);
+
     for (size_t i = 0; i < num_blobs; ++i) {
       if (i == 1) {
         ASSERT_TRUE(statuses_buf[i].IsCorruption());
@@ -339,17 +345,21 @@ TEST_F(BlobFileReaderTest, CreateReaderAndGetBlob) {
     Slice wrong_key_slice(incorrect_key, sizeof(incorrect_key) - 1);
     key_refs[2] = std::cref(wrong_key_slice);
 
-    autovector<uint64_t> offsets{blob_offsets[0], blob_offsets[1],
-                                 blob_offsets[2]};
-    autovector<uint64_t> sizes{blob_sizes[0], blob_sizes[1], blob_sizes[2]};
     std::array<Status, num_blobs> statuses_buf;
-    autovector<Status*> statuses{&statuses_buf[0], &statuses_buf[1],
-                                 &statuses_buf[2]};
     std::array<PinnableSlice, num_blobs> value_buf;
-    autovector<PinnableSlice*> values{&value_buf[0], &value_buf[1],
-                                      &value_buf[2]};
-    reader->MultiGetBlob(read_options, key_refs, offsets, sizes, statuses,
-                         values, &bytes_read);
+    std::array<BlobReadRequest, num_blobs> requests_buf;
+
+    for (size_t i = 0; i < num_blobs; ++i) {
+      requests_buf[i] =
+          BlobReadRequest(key_refs[i], blob_offsets[i], blob_sizes[i],
+                          kNoCompression, &value_buf[i], &statuses_buf[i]);
+    }
+
+    autovector<BlobReadRequest*> blob_reqs = {
+        &requests_buf[0], &requests_buf[1], &requests_buf[2]};
+
+    reader->MultiGetBlob(read_options, blob_reqs, &bytes_read);
+
     for (size_t i = 0; i < num_blobs; ++i) {
       if (i == num_blobs - 1) {
         ASSERT_TRUE(statuses_buf[i].IsCorruption());
@@ -376,17 +386,26 @@ TEST_F(BlobFileReaderTest, CreateReaderAndGetBlob) {
     for (const auto& key_ref : keys) {
       key_refs.emplace_back(std::cref(key_ref));
     }
-    autovector<uint64_t> offsets{blob_offsets[0], blob_offsets[1],
-                                 blob_offsets[2]};
-    autovector<uint64_t> sizes{blob_sizes[0], blob_sizes[1] + 1, blob_sizes[2]};
+
     std::array<Status, num_blobs> statuses_buf;
-    autovector<Status*> statuses{&statuses_buf[0], &statuses_buf[1],
-                                 &statuses_buf[2]};
     std::array<PinnableSlice, num_blobs> value_buf;
-    autovector<PinnableSlice*> values{&value_buf[0], &value_buf[1],
-                                      &value_buf[2]};
-    reader->MultiGetBlob(read_options, key_refs, offsets, sizes, statuses,
-                         values, &bytes_read);
+    std::array<BlobReadRequest, num_blobs> requests_buf;
+
+    requests_buf[0] =
+        BlobReadRequest(key_refs[0], blob_offsets[0], blob_sizes[0],
+                        kNoCompression, &value_buf[0], &statuses_buf[0]);
+    requests_buf[1] =
+        BlobReadRequest(key_refs[1], blob_offsets[1], blob_sizes[1] + 1,
+                        kNoCompression, &value_buf[1], &statuses_buf[1]);
+    requests_buf[2] =
+        BlobReadRequest(key_refs[2], blob_offsets[2], blob_sizes[2],
+                        kNoCompression, &value_buf[2], &statuses_buf[2]);
+
+    autovector<BlobReadRequest*> blob_reqs = {
+        &requests_buf[0], &requests_buf[1], &requests_buf[2]};
+
+    reader->MultiGetBlob(read_options, blob_reqs, &bytes_read);
+
     for (size_t i = 0; i < num_blobs; ++i) {
       if (i != 1) {
         ASSERT_OK(statuses_buf[i]);

db/blob/blob_index.h

@@ -92,7 +92,7 @@ class BlobIndex {
   }
 
   Status DecodeFrom(Slice slice) {
-    static const std::string kErrorMessage = "Error while decoding blob index";
+    const char* kErrorMessage = "Error while decoding blob index";
     assert(slice.size() > 0);
     type_ = static_cast<Type>(*slice.data());
     if (type_ >= Type::kUnknown) {

db/blob/blob_log_format.cc

@@ -26,8 +26,7 @@ void BlobLogHeader::EncodeTo(std::string* dst) {
 }
 
 Status BlobLogHeader::DecodeFrom(Slice src) {
-  static const std::string kErrorMessage =
-      "Error while decoding blob log header";
+  const char* kErrorMessage = "Error while decoding blob log header";
   if (src.size() != BlobLogHeader::kSize) {
     return Status::Corruption(kErrorMessage,
                               "Unexpected blob file header size");
@@ -71,8 +70,7 @@ void BlobLogFooter::EncodeTo(std::string* dst) {
 }
 
 Status BlobLogFooter::DecodeFrom(Slice src) {
-  static const std::string kErrorMessage =
-      "Error while decoding blob log footer";
+  const char* kErrorMessage = "Error while decoding blob log footer";
   if (src.size() != BlobLogFooter::kSize) {
     return Status::Corruption(kErrorMessage,
                               "Unexpected blob file footer size");
@@ -112,7 +110,7 @@ void BlobLogRecord::EncodeHeaderTo(std::string* dst) {
 }
 
 Status BlobLogRecord::DecodeHeaderFrom(Slice src) {
-  static const std::string kErrorMessage = "Error while decoding blob record";
+  const char* kErrorMessage = "Error while decoding blob record";
   if (src.size() != BlobLogRecord::kHeaderSize) {
     return Status::Corruption(kErrorMessage,
                               "Unexpected blob record header size");

db/blob/blob_log_writer.cc

@@ -70,32 +70,38 @@ Status BlobLogWriter::AppendFooter(BlobLogFooter& footer,
   std::string str;
   footer.EncodeTo(&str);
 
-  Status s = dest_->Append(Slice(str));
-  if (s.ok()) {
-    block_offset_ += str.size();
-
-    s = Sync();
-
+  Status s;
+  if (dest_->seen_error()) {
+    s.PermitUncheckedError();
+    return Status::IOError("Seen Error. Skip closing.");
+  } else {
+    s = dest_->Append(Slice(str));
     if (s.ok()) {
-      s = dest_->Close();
+      block_offset_ += str.size();
+
+      s = Sync();
 
       if (s.ok()) {
-        assert(!!checksum_method == !!checksum_value);
+        s = dest_->Close();
 
-        if (checksum_method) {
-          assert(checksum_method->empty());
+        if (s.ok()) {
+          assert(!!checksum_method == !!checksum_value);
 
-          std::string method = dest_->GetFileChecksumFuncName();
-          if (method != kUnknownFileChecksumFuncName) {
-            *checksum_method = std::move(method);
+          if (checksum_method) {
+            assert(checksum_method->empty());
+
+            std::string method = dest_->GetFileChecksumFuncName();
+            if (method != kUnknownFileChecksumFuncName) {
+              *checksum_method = std::move(method);
+            }
           }
-        }
-        if (checksum_value) {
-          assert(checksum_value->empty());
+          if (checksum_value) {
+            assert(checksum_value->empty());
 
-          std::string value = dest_->GetFileChecksum();
-          if (value != kUnknownFileChecksum) {
-            *checksum_value = std::move(value);
+            std::string value = dest_->GetFileChecksum();
+            if (value != kUnknownFileChecksum) {
+              *checksum_value = std::move(value);
+            }
           }
         }
       }

db/blob/blob_read_request.h

@@ -0,0 +1,58 @@
+//  Copyright (c) Meta Platforms, Inc. and affiliates.
+//  This source code is licensed under both the GPLv2 (found in the
+//  COPYING file in the root directory) and Apache 2.0 License
+//  (found in the LICENSE.Apache file in the root directory).
+
+#pragma once
+
+#include <cinttypes>
+
+#include "rocksdb/compression_type.h"
+#include "rocksdb/slice.h"
+#include "rocksdb/status.h"
+#include "util/autovector.h"
+
+namespace ROCKSDB_NAMESPACE {
+
+// A read Blob request structure for use in BlobSource::MultiGetBlob and
+// BlobFileReader::MultiGetBlob.
+struct BlobReadRequest {
+  // User key to lookup the paired blob
+  const Slice* user_key = nullptr;
+
+  // File offset in bytes
+  uint64_t offset = 0;
+
+  // Length to read in bytes
+  size_t len = 0;
+
+  // Blob compression type
+  CompressionType compression = kNoCompression;
+
+  // Output parameter set by MultiGetBlob() to point to the data buffer, and
+  // the number of valid bytes
+  PinnableSlice* result = nullptr;
+
+  // Status of read
+  Status* status = nullptr;
+
+  BlobReadRequest(const Slice& _user_key, uint64_t _offset, size_t _len,
+                  CompressionType _compression, PinnableSlice* _result,
+                  Status* _status)
+      : user_key(&_user_key),
+        offset(_offset),
+        len(_len),
+        compression(_compression),
+        result(_result),
+        status(_status) {}
+
+  BlobReadRequest() = default;
+  BlobReadRequest(const BlobReadRequest& other) = default;
+  BlobReadRequest& operator=(const BlobReadRequest& other) = default;
+};
+
+using BlobFileReadRequests =
+    std::tuple<uint64_t /* file_number */, uint64_t /* file_size */,
+               autovector<BlobReadRequest>>;
+
+}  // namespace ROCKSDB_NAMESPACE

db/blob/blob_source.cc

@@ -8,8 +8,14 @@
 #include <cassert>
 #include <string>
 
+#include "cache/cache_reservation_manager.h"
+#include "cache/charged_cache.h"
 #include "db/blob/blob_file_reader.h"
+#include "db/blob/blob_log_format.h"
+#include "monitoring/statistics.h"
 #include "options/cf_options.h"
+#include "table/get_context.h"
+#include "table/multiget_context.h"
 
 namespace ROCKSDB_NAMESPACE {
 
@@ -21,12 +27,24 @@ BlobSource::BlobSource(const ImmutableOptions* immutable_options,
       db_session_id_(db_session_id),
       statistics_(immutable_options->statistics.get()),
       blob_file_cache_(blob_file_cache),
-      blob_cache_(immutable_options->blob_cache) {}
+      blob_cache_(immutable_options->blob_cache),
+      lowest_used_cache_tier_(immutable_options->lowest_used_cache_tier) {
+#ifndef ROCKSDB_LITE
+  auto bbto =
+      immutable_options->table_factory->GetOptions<BlockBasedTableOptions>();
+  if (bbto &&
+      bbto->cache_usage_options.options_overrides.at(CacheEntryRole::kBlobCache)
+              .charged == CacheEntryRoleOptions::Decision::kEnabled) {
+    blob_cache_ = std::make_shared<ChargedCache>(immutable_options->blob_cache,
+                                                 bbto->block_cache);
+  }
+#endif  // ROCKSDB_LITE
+}
 
 BlobSource::~BlobSource() = default;
 
 Status BlobSource::GetBlobFromCache(const Slice& cache_key,
-                                    CachableEntry<std::string>* blob) const {
+                                    CacheHandleGuard<std::string>* blob) const {
   assert(blob);
   assert(blob->IsEmpty());
   assert(blob_cache_);
@@ -35,9 +53,7 @@ Status BlobSource::GetBlobFromCache(const Slice& cache_key,
   Cache::Handle* cache_handle = nullptr;
   cache_handle = GetEntryFromCache(cache_key);
   if (cache_handle != nullptr) {
-    blob->SetCachedValue(
-        static_cast<std::string*>(blob_cache_->Value(cache_handle)),
-        blob_cache_.get(), cache_handle);
+    *blob = CacheHandleGuard<std::string>(blob_cache_.get(), cache_handle);
     return Status::OK();
   }
 
@@ -47,30 +63,89 @@ Status BlobSource::GetBlobFromCache(const Slice& cache_key,
 }
 
 Status BlobSource::PutBlobIntoCache(const Slice& cache_key,
-                                    CachableEntry<std::string>* cached_blob,
+                                    CacheHandleGuard<std::string>* cached_blob,
                                     PinnableSlice* blob) const {
   assert(blob);
   assert(!cache_key.empty());
   assert(blob_cache_);
 
   Status s;
-  const Cache::Priority priority = Cache::Priority::LOW;
+  const Cache::Priority priority = Cache::Priority::BOTTOM;
 
   // Objects to be put into the cache have to be heap-allocated and
   // self-contained, i.e. own their contents. The Cache has to be able to take
   // unique ownership of them. Therefore, we copy the blob into a string
   // directly, and insert that into the cache.
-  std::string* buf = new std::string();
+  std::unique_ptr<std::string> buf = std::make_unique<std::string>();
   buf->assign(blob->data(), blob->size());
 
   // TODO: support custom allocators and provide a better estimated memory
   // usage using malloc_usable_size.
   Cache::Handle* cache_handle = nullptr;
-  s = InsertEntryIntoCache(cache_key, buf, buf->size(), &cache_handle,
+  s = InsertEntryIntoCache(cache_key, buf.get(), buf->size(), &cache_handle,
                            priority);
   if (s.ok()) {
+    buf.release();
     assert(cache_handle != nullptr);
-    cached_blob->SetCachedValue(buf, blob_cache_.get(), cache_handle);
+    *cached_blob =
+        CacheHandleGuard<std::string>(blob_cache_.get(), cache_handle);
+  }
+
+  return s;
+}
+
+Cache::Handle* BlobSource::GetEntryFromCache(const Slice& key) const {
+  Cache::Handle* cache_handle = nullptr;
+
+  if (lowest_used_cache_tier_ == CacheTier::kNonVolatileBlockTier) {
+    Cache::CreateCallback create_cb = [&](const void* buf, size_t size,
+                                          void** out_obj,
+                                          size_t* charge) -> Status {
+      std::string* blob = new std::string();
+      blob->assign(static_cast<const char*>(buf), size);
+      *out_obj = blob;
+      *charge = size;
+      return Status::OK();
+    };
+    cache_handle = blob_cache_->Lookup(key, GetCacheItemHelper(), create_cb,
+                                       Cache::Priority::BOTTOM,
+                                       true /* wait_for_cache */, statistics_);
+  } else {
+    cache_handle = blob_cache_->Lookup(key, statistics_);
+  }
+
+  if (cache_handle != nullptr) {
+    PERF_COUNTER_ADD(blob_cache_hit_count, 1);
+    RecordTick(statistics_, BLOB_DB_CACHE_HIT);
+    RecordTick(statistics_, BLOB_DB_CACHE_BYTES_READ,
+               blob_cache_->GetUsage(cache_handle));
+  } else {
+    RecordTick(statistics_, BLOB_DB_CACHE_MISS);
+  }
+  return cache_handle;
+}
+
+Status BlobSource::InsertEntryIntoCache(const Slice& key, std::string* value,
+                                        size_t charge,
+                                        Cache::Handle** cache_handle,
+                                        Cache::Priority priority) const {
+  Status s;
+
+  if (lowest_used_cache_tier_ == CacheTier::kNonVolatileBlockTier) {
+    s = blob_cache_->Insert(key, value, GetCacheItemHelper(), charge,
+                            cache_handle, priority);
+  } else {
+    s = blob_cache_->Insert(key, value, charge, &DeleteCacheEntry<std::string>,
+                            cache_handle, priority);
+  }
+
+  if (s.ok()) {
+    assert(*cache_handle != nullptr);
+    RecordTick(statistics_, BLOB_DB_CACHE_ADD);
+    RecordTick(statistics_, BLOB_DB_CACHE_BYTES_WRITE,
+               blob_cache_->GetUsage(*cache_handle));
+  } else {
+    RecordTick(statistics_, BLOB_DB_CACHE_ADD_FAILURES);
   }
 
   return s;
@@ -89,29 +164,56 @@ Status BlobSource::GetBlob(const ReadOptions& read_options,
 
   const CacheKey cache_key = GetCacheKey(file_number, file_size, offset);
 
-  CachableEntry<std::string> blob_entry;
+  CacheHandleGuard<std::string> blob_handle;
 
   // First, try to get the blob from the cache
   //
   // If blob cache is enabled, we'll try to read from it.
   if (blob_cache_) {
     Slice key = cache_key.AsSlice();
-    s = GetBlobFromCache(key, &blob_entry);
-    if (s.ok() && blob_entry.GetValue()) {
-      assert(blob_entry.GetValue()->size() == value_size);
-      if (bytes_read) {
-        *bytes_read = value_size;
+    s = GetBlobFromCache(key, &blob_handle);
+    if (s.ok() && blob_handle.GetValue()) {
+      {
+        value->Reset();
+        // To avoid copying the cached blob into the buffer provided by the
+        // application, we can simply transfer ownership of the cache handle to
+        // the target PinnableSlice. This has the potential to save a lot of
+        // CPU, especially with large blob values.
+        value->PinSlice(
+            *blob_handle.GetValue(),
+            [](void* arg1, void* arg2) {
+              Cache* const cache = static_cast<Cache*>(arg1);
+              Cache::Handle* const handle = static_cast<Cache::Handle*>(arg2);
+              cache->Release(handle);
+            },
+            blob_handle.GetCache(), blob_handle.GetCacheHandle());
+        // Make the CacheHandleGuard relinquish ownership of the handle.
+        blob_handle.TransferTo(nullptr);
+      }
+
+      // For consistency, the size of on-disk (possibly compressed) blob record
+      // is assigned to bytes_read.
+      uint64_t adjustment =
+          read_options.verify_checksums
+              ? BlobLogRecord::CalculateAdjustmentForRecordHeader(
+                    user_key.size())
+              : 0;
+      assert(offset >= adjustment);
+
+      uint64_t record_size = value_size + adjustment;
+      if (bytes_read) {
+        *bytes_read = record_size;
       }
-      value->PinSelf(*blob_entry.GetValue());
       return s;
     }
   }
 
-  assert(blob_entry.IsEmpty());
+  assert(blob_handle.IsEmpty());
 
   const bool no_io = read_options.read_tier == kBlockCacheTier;
   if (no_io) {
-    return Status::Incomplete("Cannot read blob(s): no disk I/O allowed");
+    s = Status::Incomplete("Cannot read blob(s): no disk I/O allowed");
+    return s;
   }
 
   // Can't find the blob from the cache. Since I/O is allowed, read from the
@@ -129,19 +231,23 @@ Status BlobSource::GetBlob(const ReadOptions& read_options,
       return Status::Corruption("Compression type mismatch when reading blob");
     }
 
+    uint64_t read_size = 0;
     s = blob_file_reader.GetValue()->GetBlob(
         read_options, user_key, offset, value_size, compression_type,
-        prefetch_buffer, value, bytes_read);
+        prefetch_buffer, value, &read_size);
     if (!s.ok()) {
       return s;
     }
+    if (bytes_read) {
+      *bytes_read = read_size;
+    }
   }
 
   if (blob_cache_ && read_options.fill_cache) {
     // If filling cache is allowed and a cache is configured, try to put the
     // blob to the cache.
     Slice key = cache_key.AsSlice();
-    s = PutBlobIntoCache(key, &blob_entry, value);
+    s = PutBlobIntoCache(key, &blob_handle, value);
     if (!s.ok()) {
       return s;
     }
@@ -151,19 +257,209 @@ Status BlobSource::GetBlob(const ReadOptions& read_options,
   return s;
 }
 
+void BlobSource::MultiGetBlob(const ReadOptions& read_options,
+                              autovector<BlobFileReadRequests>& blob_reqs,
+                              uint64_t* bytes_read) {
+  assert(blob_reqs.size() > 0);
+
+  uint64_t total_bytes_read = 0;
+  uint64_t bytes_read_in_file = 0;
+
+  for (auto& [file_number, file_size, blob_reqs_in_file] : blob_reqs) {
+    // sort blob_reqs_in_file by file offset.
+    std::sort(
+        blob_reqs_in_file.begin(), blob_reqs_in_file.end(),
+        [](const BlobReadRequest& lhs, const BlobReadRequest& rhs) -> bool {
+          return lhs.offset < rhs.offset;
+        });
+
+    MultiGetBlobFromOneFile(read_options, file_number, file_size,
+                            blob_reqs_in_file, &bytes_read_in_file);
+
+    total_bytes_read += bytes_read_in_file;
+  }
+
+  if (bytes_read) {
+    *bytes_read = total_bytes_read;
+  }
+}
+
+void BlobSource::MultiGetBlobFromOneFile(const ReadOptions& read_options,
+                                         uint64_t file_number,
+                                         uint64_t /*file_size*/,
+                                         autovector<BlobReadRequest>& blob_reqs,
+                                         uint64_t* bytes_read) {
+  const size_t num_blobs = blob_reqs.size();
+  assert(num_blobs > 0);
+  assert(num_blobs <= MultiGetContext::MAX_BATCH_SIZE);
+
+#ifndef NDEBUG
+  for (size_t i = 0; i < num_blobs - 1; ++i) {
+    assert(blob_reqs[i].offset <= blob_reqs[i + 1].offset);
+  }
+#endif  // !NDEBUG
+
+  using Mask = uint64_t;
+  Mask cache_hit_mask = 0;
+
+  uint64_t total_bytes = 0;
+  const OffsetableCacheKey base_cache_key(db_id_, db_session_id_, file_number);
+
+  if (blob_cache_) {
+    size_t cached_blob_count = 0;
+    for (size_t i = 0; i < num_blobs; ++i) {
+      auto& req = blob_reqs[i];
+
+      CacheHandleGuard<std::string> blob_handle;
+      const CacheKey cache_key = base_cache_key.WithOffset(req.offset);
+      const Slice key = cache_key.AsSlice();
+
+      const Status s = GetBlobFromCache(key, &blob_handle);
+
+      if (s.ok() && blob_handle.GetValue()) {
+        assert(req.status);
+        *req.status = s;
+
+        {
+          req.result->Reset();
+          // To avoid copying the cached blob into the buffer provided by the
+          // application, we can simply transfer ownership of the cache handle
+          // to the target PinnableSlice. This has the potential to save a lot
+          // of CPU, especially with large blob values.
+          req.result->PinSlice(
+              *blob_handle.GetValue(),
+              [](void* arg1, void* arg2) {
+                Cache* const cache = static_cast<Cache*>(arg1);
+                Cache::Handle* const handle = static_cast<Cache::Handle*>(arg2);
+                cache->Release(handle);
+              },
+              blob_handle.GetCache(), blob_handle.GetCacheHandle());
+          // Make the CacheHandleGuard relinquish ownership of the handle.
+          blob_handle.TransferTo(nullptr);
+        }
+
+        // Update the counter for the number of valid blobs read from the cache.
+        ++cached_blob_count;
+
+        // For consistency, the size of each on-disk (possibly compressed) blob
+        // record is accumulated to total_bytes.
+        uint64_t adjustment =
+            read_options.verify_checksums
+                ? BlobLogRecord::CalculateAdjustmentForRecordHeader(
+                      req.user_key->size())
+                : 0;
+        assert(req.offset >= adjustment);
+        total_bytes += req.len + adjustment;
+        cache_hit_mask |= (Mask{1} << i);  // cache hit
+      }
+    }
+
+    // All blobs were read from the cache.
+    if (cached_blob_count == num_blobs) {
+      if (bytes_read) {
+        *bytes_read = total_bytes;
+      }
+      return;
+    }
+  }
+
+  const bool no_io = read_options.read_tier == kBlockCacheTier;
+  if (no_io) {
+    for (size_t i = 0; i < num_blobs; ++i) {
+      if (!(cache_hit_mask & (Mask{1} << i))) {
+        assert(blob_reqs[i].status);
+        *blob_reqs[i].status =
+            Status::Incomplete("Cannot read blob(s): no disk I/O allowed");
+      }
+    }
+    return;
+  }
+
+  {
+    // Find the rest of blobs from the file since I/O is allowed.
+    autovector<BlobReadRequest*> _blob_reqs;
+    uint64_t _bytes_read = 0;
+
+    for (size_t i = 0; i < num_blobs; ++i) {
+      if (!(cache_hit_mask & (Mask{1} << i))) {
+        _blob_reqs.push_back(&blob_reqs[i]);
+      }
+    }
+
+    CacheHandleGuard<BlobFileReader> blob_file_reader;
+    Status s =
+        blob_file_cache_->GetBlobFileReader(file_number, &blob_file_reader);
+    if (!s.ok()) {
+      for (size_t i = 0; i < _blob_reqs.size(); ++i) {
+        assert(_blob_reqs[i]->status);
+        *_blob_reqs[i]->status = s;
+      }
+      return;
+    }
+
+    assert(blob_file_reader.GetValue());
+
+    blob_file_reader.GetValue()->MultiGetBlob(read_options, _blob_reqs,
+                                              &_bytes_read);
+
+    if (blob_cache_ && read_options.fill_cache) {
+      // If filling cache is allowed and a cache is configured, try to put
+      // the blob(s) to the cache.
+      for (size_t i = 0; i < _blob_reqs.size(); ++i) {
+        if (_blob_reqs[i]->status->ok()) {
+          CacheHandleGuard<std::string> blob_handle;
+          const CacheKey cache_key =
+              base_cache_key.WithOffset(_blob_reqs[i]->offset);
+          const Slice key = cache_key.AsSlice();
+          s = PutBlobIntoCache(key, &blob_handle, _blob_reqs[i]->result);
+          if (!s.ok()) {
+            *_blob_reqs[i]->status = s;
+          }
+        }
+      }
+    }
+
+    total_bytes += _bytes_read;
+    if (bytes_read) {
+      *bytes_read = total_bytes;
+    }
+  }
+}
+
 bool BlobSource::TEST_BlobInCache(uint64_t file_number, uint64_t file_size,
                                   uint64_t offset) const {
   const CacheKey cache_key = GetCacheKey(file_number, file_size, offset);
   const Slice key = cache_key.AsSlice();
 
-  CachableEntry<std::string> blob_entry;
-  const Status s = GetBlobFromCache(key, &blob_entry);
+  CacheHandleGuard<std::string> blob_handle;
+  const Status s = GetBlobFromCache(key, &blob_handle);
 
-  if (s.ok() && blob_entry.GetValue() != nullptr) {
+  if (s.ok() && blob_handle.GetValue() != nullptr) {
     return true;
   }
 
   return false;
 }
 
+// Callbacks for secondary blob cache
+size_t BlobSource::SizeCallback(void* obj) {
+  assert(obj != nullptr);
+  return static_cast<const std::string*>(obj)->size();
+}
+
+Status BlobSource::SaveToCallback(void* from_obj, size_t from_offset,
+                                  size_t length, void* out) {
+  assert(from_obj != nullptr);
+  const std::string* buf = static_cast<const std::string*>(from_obj);
+  assert(buf->size() >= from_offset + length);
+  memcpy(out, buf->data() + from_offset, length);
+  return Status::OK();
+}
+
+Cache::CacheItemHelper* BlobSource::GetCacheItemHelper() {
+  static Cache::CacheItemHelper cache_helper(SizeCallback, SaveToCallback,
+                                             &DeleteCacheEntry<std::string>);
+  return &cache_helper;
+}
+
 }  // namespace ROCKSDB_NAMESPACE

db/blob/blob_source.h

@@ -10,9 +10,11 @@
 #include "cache/cache_helpers.h"
 #include "cache/cache_key.h"
 #include "db/blob/blob_file_cache.h"
-#include "include/rocksdb/cache.h"
+#include "db/blob/blob_read_request.h"
+#include "rocksdb/cache.h"
 #include "rocksdb/rocksdb_namespace.h"
 #include "table/block_based/cachable_entry.h"
+#include "util/autovector.h"
 
 namespace ROCKSDB_NAMESPACE {
 
@@ -36,45 +38,102 @@ class BlobSource {
 
   ~BlobSource();
 
+  // Read a blob from the underlying cache or one blob file.
+  //
+  // If successful, returns ok and sets "*value" to the newly retrieved
+  // uncompressed blob. If there was an error while fetching the blob, sets
+  // "*value" to empty and returns a non-ok status.
+  //
+  // Note: For consistency, whether the blob is found in the cache or on disk,
+  // sets "*bytes_read" to the size of on-disk (possibly compressed) blob
+  // record.
   Status GetBlob(const ReadOptions& read_options, const Slice& user_key,
                  uint64_t file_number, uint64_t offset, uint64_t file_size,
                  uint64_t value_size, CompressionType compression_type,
                  FilePrefetchBuffer* prefetch_buffer, PinnableSlice* value,
                  uint64_t* bytes_read);
 
+  // Read multiple blobs from the underlying cache or blob file(s).
+  //
+  // If successful, returns ok and sets "result" in the elements of "blob_reqs"
+  // to the newly retrieved uncompressed blobs. If there was an error while
+  // fetching one of blobs, sets its "result" to empty and sets its
+  // corresponding "status" to a non-ok status.
+  //
+  // Note:
+  //  - The main difference between this function and MultiGetBlobFromOneFile is
+  //    that this function can read multiple blobs from multiple blob files.
+  //
+  //  - For consistency, whether the blob is found in the cache or on disk, sets
+  //  "*bytes_read" to the total size of on-disk (possibly compressed) blob
+  //  records.
+  void MultiGetBlob(const ReadOptions& read_options,
+                    autovector<BlobFileReadRequests>& blob_reqs,
+                    uint64_t* bytes_read);
+
+  // Read multiple blobs from the underlying cache or one blob file.
+  //
+  // If successful, returns ok and sets "result" in the elements of "blob_reqs"
+  // to the newly retrieved uncompressed blobs. If there was an error while
+  // fetching one of blobs, sets its "result" to empty and sets its
+  // corresponding "status" to a non-ok status.
+  //
+  // Note:
+  //  - The main difference between this function and MultiGetBlob is that this
+  //  function is only used for the case where the demanded blobs are stored in
+  //  one blob file. MultiGetBlob will call this function multiple times if the
+  //  demanded blobs are stored in multiple blob files.
+  //
+  //  - For consistency, whether the blob is found in the cache or on disk, sets
+  //  "*bytes_read" to the total size of on-disk (possibly compressed) blob
+  //  records.
+  void MultiGetBlobFromOneFile(const ReadOptions& read_options,
+                               uint64_t file_number, uint64_t file_size,
+                               autovector<BlobReadRequest>& blob_reqs,
+                               uint64_t* bytes_read);
+
+  inline Status GetBlobFileReader(
+      uint64_t blob_file_number,
+      CacheHandleGuard<BlobFileReader>* blob_file_reader) {
+    return blob_file_cache_->GetBlobFileReader(blob_file_number,
+                                               blob_file_reader);
+  }
+
+  inline Cache* GetBlobCache() const { return blob_cache_.get(); }
+
   bool TEST_BlobInCache(uint64_t file_number, uint64_t file_size,
                         uint64_t offset) const;
 
  private:
   Status GetBlobFromCache(const Slice& cache_key,
-                          CachableEntry<std::string>* blob) const;
+                          CacheHandleGuard<std::string>* blob) const;
 
   Status PutBlobIntoCache(const Slice& cache_key,
-                          CachableEntry<std::string>* cached_blob,
+                          CacheHandleGuard<std::string>* cached_blob,
                           PinnableSlice* blob) const;
 
-  inline CacheKey GetCacheKey(uint64_t file_number, uint64_t file_size,
+  Cache::Handle* GetEntryFromCache(const Slice& key) const;
+
+  Status InsertEntryIntoCache(const Slice& key, std::string* value,
+                              size_t charge, Cache::Handle** cache_handle,
+                              Cache::Priority priority) const;
+
+  inline CacheKey GetCacheKey(uint64_t file_number, uint64_t /*file_size*/,
                               uint64_t offset) const {
-    OffsetableCacheKey base_cache_key(db_id_, db_session_id_, file_number,
-                                      file_size);
+    OffsetableCacheKey base_cache_key(db_id_, db_session_id_, file_number);
     return base_cache_key.WithOffset(offset);
   }
 
-  inline Cache::Handle* GetEntryFromCache(const Slice& key) const {
-    return blob_cache_->Lookup(key, statistics_);
-  }
+  // Callbacks for secondary blob cache
+  static size_t SizeCallback(void* obj);
 
-  inline Status InsertEntryIntoCache(const Slice& key, std::string* value,
-                                     size_t charge,
-                                     Cache::Handle** cache_handle,
-                                     Cache::Priority priority) const {
-    return blob_cache_->Insert(key, value, charge,
-                               &DeleteCacheEntry<std::string>, cache_handle,
-                               priority);
-  }
+  static Status SaveToCallback(void* from_obj, size_t from_offset,
+                               size_t length, void* out);
 
-  const std::string db_id_;
-  const std::string db_session_id_;
+  static Cache::CacheItemHelper* GetCacheItemHelper();
+
+  const std::string& db_id_;
+  const std::string& db_session_id_;
 
   Statistics* statistics_;
 
@@ -83,6 +142,12 @@ class BlobSource {
 
   // A cache to store uncompressed blobs.
   std::shared_ptr<Cache> blob_cache_;
+
+  // The control option of how the cache tiers will be used. Currently rocksdb
+  // support block/blob cache (volatile tier) and secondary cache (this tier
+  // isn't strictly speaking a non-volatile tier since the compressed cache in
+  // this tier is in volatile memory).
+  const CacheTier lowest_used_cache_tier_;
 };
 
 }  // namespace ROCKSDB_NAMESPACE

db/blob/db_blob_basic_test.cc

@@ -5,6 +5,7 @@
 
 #include <array>
 #include <sstream>
+#include <string>
 
 #include "db/blob/blob_index.h"
 #include "db/blob/blob_log_format.h"
@@ -48,6 +49,326 @@ TEST_F(DBBlobBasicTest, GetBlob) {
                   .IsIncomplete());
 }
 
+TEST_F(DBBlobBasicTest, GetBlobFromCache) {
+  Options options = GetDefaultOptions();
+
+  LRUCacheOptions co;
+  co.capacity = 2048;
+  co.num_shard_bits = 2;
+  co.metadata_charge_policy = kDontChargeCacheMetadata;
+  auto backing_cache = NewLRUCache(co);
+
+  options.enable_blob_files = true;
+  options.blob_cache = backing_cache;
+
+  BlockBasedTableOptions block_based_options;
+  block_based_options.no_block_cache = false;
+  block_based_options.block_cache = backing_cache;
+  block_based_options.cache_index_and_filter_blocks = true;
+  options.table_factory.reset(NewBlockBasedTableFactory(block_based_options));
+
+  Reopen(options);
+
+  constexpr char key[] = "key";
+  constexpr char blob_value[] = "blob_value";
+
+  ASSERT_OK(Put(key, blob_value));
+
+  ASSERT_OK(Flush());
+
+  ReadOptions read_options;
+
+  read_options.fill_cache = false;
+
+  {
+    PinnableSlice result;
+
+    read_options.read_tier = kReadAllTier;
+    ASSERT_OK(db_->Get(read_options, db_->DefaultColumnFamily(), key, &result));
+    ASSERT_EQ(result, blob_value);
+
+    result.Reset();
+    read_options.read_tier = kBlockCacheTier;
+
+    // Try again with no I/O allowed. Since we didn't re-fill the cache, the
+    // blob itself can only be read from the blob file, so the read should
+    // return Incomplete.
+    ASSERT_TRUE(db_->Get(read_options, db_->DefaultColumnFamily(), key, &result)
+                    .IsIncomplete());
+    ASSERT_TRUE(result.empty());
+  }
+
+  read_options.fill_cache = true;
+
+  {
+    PinnableSlice result;
+
+    read_options.read_tier = kReadAllTier;
+    ASSERT_OK(db_->Get(read_options, db_->DefaultColumnFamily(), key, &result));
+    ASSERT_EQ(result, blob_value);
+
+    result.Reset();
+    read_options.read_tier = kBlockCacheTier;
+
+    // Try again with no I/O allowed. The table and the necessary blocks/blobs
+    // should already be in their respective caches.
+    ASSERT_OK(db_->Get(read_options, db_->DefaultColumnFamily(), key, &result));
+    ASSERT_EQ(result, blob_value);
+  }
+}
+
+TEST_F(DBBlobBasicTest, IterateBlobsFromCache) {
+  Options options = GetDefaultOptions();
+
+  LRUCacheOptions co;
+  co.capacity = 2048;
+  co.num_shard_bits = 2;
+  co.metadata_charge_policy = kDontChargeCacheMetadata;
+  auto backing_cache = NewLRUCache(co);
+
+  options.enable_blob_files = true;
+  options.blob_cache = backing_cache;
+
+  BlockBasedTableOptions block_based_options;
+  block_based_options.no_block_cache = false;
+  block_based_options.block_cache = backing_cache;
+  block_based_options.cache_index_and_filter_blocks = true;
+  options.table_factory.reset(NewBlockBasedTableFactory(block_based_options));
+
+  options.statistics = CreateDBStatistics();
+
+  Reopen(options);
+
+  int num_blobs = 5;
+  std::vector<std::string> keys;
+  std::vector<std::string> blobs;
+
+  for (int i = 0; i < num_blobs; ++i) {
+    keys.push_back("key" + std::to_string(i));
+    blobs.push_back("blob" + std::to_string(i));
+    ASSERT_OK(Put(keys[i], blobs[i]));
+  }
+  ASSERT_OK(Flush());
+
+  ReadOptions read_options;
+
+  {
+    read_options.fill_cache = false;
+    read_options.read_tier = kReadAllTier;
+
+    std::unique_ptr<Iterator> iter(db_->NewIterator(read_options));
+    ASSERT_OK(iter->status());
+
+    int i = 0;
+    for (iter->SeekToFirst(); iter->Valid(); iter->Next()) {
+      ASSERT_OK(iter->status());
+      ASSERT_EQ(iter->key().ToString(), keys[i]);
+      ASSERT_EQ(iter->value().ToString(), blobs[i]);
+      ++i;
+    }
+    ASSERT_EQ(i, num_blobs);
+    ASSERT_EQ(options.statistics->getAndResetTickerCount(BLOB_DB_CACHE_ADD), 0);
+  }
+
+  {
+    read_options.fill_cache = false;
+    read_options.read_tier = kBlockCacheTier;
+
+    std::unique_ptr<Iterator> iter(db_->NewIterator(read_options));
+    ASSERT_OK(iter->status());
+
+    // Try again with no I/O allowed. Since we didn't re-fill the cache,
+    // the blob itself can only be read from the blob file, so iter->Valid()
+    // should be false.
+    iter->SeekToFirst();
+    ASSERT_NOK(iter->status());
+    ASSERT_FALSE(iter->Valid());
+    ASSERT_EQ(options.statistics->getAndResetTickerCount(BLOB_DB_CACHE_ADD), 0);
+  }
+
+  {
+    read_options.fill_cache = true;
+    read_options.read_tier = kReadAllTier;
+
+    std::unique_ptr<Iterator> iter(db_->NewIterator(read_options));
+    ASSERT_OK(iter->status());
+
+    // Read blobs from the file and refill the cache.
+    int i = 0;
+    for (iter->SeekToFirst(); iter->Valid(); iter->Next()) {
+      ASSERT_OK(iter->status());
+      ASSERT_EQ(iter->key().ToString(), keys[i]);
+      ASSERT_EQ(iter->value().ToString(), blobs[i]);
+      ++i;
+    }
+    ASSERT_EQ(i, num_blobs);
+    ASSERT_EQ(options.statistics->getAndResetTickerCount(BLOB_DB_CACHE_ADD),
+              num_blobs);
+  }
+
+  {
+    read_options.fill_cache = false;
+    read_options.read_tier = kBlockCacheTier;
+
+    std::unique_ptr<Iterator> iter(db_->NewIterator(read_options));
+    ASSERT_OK(iter->status());
+
+    // Try again with no I/O allowed. The table and the necessary blocks/blobs
+    // should already be in their respective caches.
+    int i = 0;
+    for (iter->SeekToFirst(); iter->Valid(); iter->Next()) {
+      ASSERT_OK(iter->status());
+      ASSERT_EQ(iter->key().ToString(), keys[i]);
+      ASSERT_EQ(iter->value().ToString(), blobs[i]);
+      ++i;
+    }
+    ASSERT_EQ(i, num_blobs);
+    ASSERT_EQ(options.statistics->getAndResetTickerCount(BLOB_DB_CACHE_ADD), 0);
+  }
+}
+
+TEST_F(DBBlobBasicTest, IterateBlobsFromCachePinning) {
+  constexpr size_t min_blob_size = 6;
+
+  Options options = GetDefaultOptions();
+
+  LRUCacheOptions cache_options;
+  cache_options.capacity = 2048;
+  cache_options.num_shard_bits = 0;
+  cache_options.metadata_charge_policy = kDontChargeCacheMetadata;
+
+  options.blob_cache = NewLRUCache(cache_options);
+  options.enable_blob_files = true;
+  options.min_blob_size = min_blob_size;
+
+  Reopen(options);
+
+  // Put then iterate over three key-values. The second value is below the size
+  // limit and is thus stored inline; the other two are stored separately as
+  // blobs. We expect to have something pinned in the cache iff we are
+  // positioned on a blob.
+
+  constexpr char first_key[] = "first_key";
+  constexpr char first_value[] = "long_value";
+  static_assert(sizeof(first_value) - 1 >= min_blob_size,
+                "first_value too short to be stored as blob");
+
+  ASSERT_OK(Put(first_key, first_value));
+
+  constexpr char second_key[] = "second_key";
+  constexpr char second_value[] = "short";
+  static_assert(sizeof(second_value) - 1 < min_blob_size,
+                "second_value too long to be inlined");
+
+  ASSERT_OK(Put(second_key, second_value));
+
+  constexpr char third_key[] = "third_key";
+  constexpr char third_value[] = "other_long_value";
+  static_assert(sizeof(third_value) - 1 >= min_blob_size,
+                "third_value too short to be stored as blob");
+
+  ASSERT_OK(Put(third_key, third_value));
+
+  ASSERT_OK(Flush());
+
+  {
+    ReadOptions read_options;
+    read_options.fill_cache = true;
+
+    std::unique_ptr<Iterator> iter(db_->NewIterator(read_options));
+
+    iter->SeekToFirst();
+    ASSERT_TRUE(iter->Valid());
+    ASSERT_OK(iter->status());
+    ASSERT_EQ(iter->key(), first_key);
+    ASSERT_EQ(iter->value(), first_value);
+
+    iter->Next();
+    ASSERT_TRUE(iter->Valid());
+    ASSERT_OK(iter->status());
+    ASSERT_EQ(iter->key(), second_key);
+    ASSERT_EQ(iter->value(), second_value);
+
+    iter->Next();
+    ASSERT_TRUE(iter->Valid());
+    ASSERT_OK(iter->status());
+    ASSERT_EQ(iter->key(), third_key);
+    ASSERT_EQ(iter->value(), third_value);
+
+    iter->Next();
+    ASSERT_FALSE(iter->Valid());
+    ASSERT_OK(iter->status());
+  }
+
+  {
+    ReadOptions read_options;
+    read_options.fill_cache = false;
+    read_options.read_tier = kBlockCacheTier;
+
+    std::unique_ptr<Iterator> iter(db_->NewIterator(read_options));
+
+    iter->SeekToFirst();
+    ASSERT_TRUE(iter->Valid());
+    ASSERT_OK(iter->status());
+    ASSERT_EQ(iter->key(), first_key);
+    ASSERT_EQ(iter->value(), first_value);
+    ASSERT_GT(options.blob_cache->GetPinnedUsage(), 0);
+
+    iter->Next();
+    ASSERT_TRUE(iter->Valid());
+    ASSERT_OK(iter->status());
+    ASSERT_EQ(iter->key(), second_key);
+    ASSERT_EQ(iter->value(), second_value);
+    ASSERT_EQ(options.blob_cache->GetPinnedUsage(), 0);
+
+    iter->Next();
+    ASSERT_TRUE(iter->Valid());
+    ASSERT_OK(iter->status());
+    ASSERT_EQ(iter->key(), third_key);
+    ASSERT_EQ(iter->value(), third_value);
+    ASSERT_GT(options.blob_cache->GetPinnedUsage(), 0);
+
+    iter->Next();
+    ASSERT_FALSE(iter->Valid());
+    ASSERT_OK(iter->status());
+    ASSERT_EQ(options.blob_cache->GetPinnedUsage(), 0);
+  }
+
+  {
+    ReadOptions read_options;
+    read_options.fill_cache = false;
+    read_options.read_tier = kBlockCacheTier;
+
+    std::unique_ptr<Iterator> iter(db_->NewIterator(read_options));
+
+    iter->SeekToLast();
+    ASSERT_TRUE(iter->Valid());
+    ASSERT_OK(iter->status());
+    ASSERT_EQ(iter->key(), third_key);
+    ASSERT_EQ(iter->value(), third_value);
+    ASSERT_GT(options.blob_cache->GetPinnedUsage(), 0);
+
+    iter->Prev();
+    ASSERT_TRUE(iter->Valid());
+    ASSERT_OK(iter->status());
+    ASSERT_EQ(iter->key(), second_key);
+    ASSERT_EQ(iter->value(), second_value);
+    ASSERT_EQ(options.blob_cache->GetPinnedUsage(), 0);
+
+    iter->Prev();
+    ASSERT_TRUE(iter->Valid());
+    ASSERT_OK(iter->status());
+    ASSERT_EQ(iter->key(), first_key);
+    ASSERT_EQ(iter->value(), first_value);
+    ASSERT_GT(options.blob_cache->GetPinnedUsage(), 0);
+
+    iter->Prev();
+    ASSERT_FALSE(iter->Valid());
+    ASSERT_OK(iter->status());
+    ASSERT_EQ(options.blob_cache->GetPinnedUsage(), 0);
+  }
+}
+
 TEST_F(DBBlobBasicTest, MultiGetBlobs) {
   constexpr size_t min_blob_size = 6;
 
@@ -127,6 +448,141 @@ TEST_F(DBBlobBasicTest, MultiGetBlobs) {
   }
 }
 
+TEST_F(DBBlobBasicTest, MultiGetBlobsFromCache) {
+  Options options = GetDefaultOptions();
+
+  LRUCacheOptions co;
+  co.capacity = 2048;
+  co.num_shard_bits = 2;
+  co.metadata_charge_policy = kDontChargeCacheMetadata;
+  auto backing_cache = NewLRUCache(co);
+
+  constexpr size_t min_blob_size = 6;
+  options.min_blob_size = min_blob_size;
+  options.create_if_missing = true;
+  options.enable_blob_files = true;
+  options.blob_cache = backing_cache;
+
+  BlockBasedTableOptions block_based_options;
+  block_based_options.no_block_cache = false;
+  block_based_options.block_cache = backing_cache;
+  block_based_options.cache_index_and_filter_blocks = true;
+  options.table_factory.reset(NewBlockBasedTableFactory(block_based_options));
+
+  DestroyAndReopen(options);
+
+  // Put then retrieve three key-values. The first value is below the size limit
+  // and is thus stored inline; the other two are stored separately as blobs.
+  constexpr size_t num_keys = 3;
+
+  constexpr char first_key[] = "first_key";
+  constexpr char first_value[] = "short";
+  static_assert(sizeof(first_value) - 1 < min_blob_size,
+                "first_value too long to be inlined");
+
+  ASSERT_OK(Put(first_key, first_value));
+
+  constexpr char second_key[] = "second_key";
+  constexpr char second_value[] = "long_value";
+  static_assert(sizeof(second_value) - 1 >= min_blob_size,
+                "second_value too short to be stored as blob");
+
+  ASSERT_OK(Put(second_key, second_value));
+
+  constexpr char third_key[] = "third_key";
+  constexpr char third_value[] = "other_long_value";
+  static_assert(sizeof(third_value) - 1 >= min_blob_size,
+                "third_value too short to be stored as blob");
+
+  ASSERT_OK(Put(third_key, third_value));
+
+  ASSERT_OK(Flush());
+
+  ReadOptions read_options;
+  read_options.fill_cache = false;
+
+  std::array<Slice, num_keys> keys{{first_key, second_key, third_key}};
+
+  {
+    std::array<PinnableSlice, num_keys> values;
+    std::array<Status, num_keys> statuses;
+
+    db_->MultiGet(read_options, db_->DefaultColumnFamily(), num_keys, &keys[0],
+                  &values[0], &statuses[0]);
+
+    ASSERT_OK(statuses[0]);
+    ASSERT_EQ(values[0], first_value);
+
+    ASSERT_OK(statuses[1]);
+    ASSERT_EQ(values[1], second_value);
+
+    ASSERT_OK(statuses[2]);
+    ASSERT_EQ(values[2], third_value);
+  }
+
+  // Try again with no I/O allowed. The first (inlined) value should be
+  // successfully read; however, the two blob values could only be read from the
+  // blob file, so for those the read should return Incomplete.
+  read_options.read_tier = kBlockCacheTier;
+
+  {
+    std::array<PinnableSlice, num_keys> values;
+    std::array<Status, num_keys> statuses;
+
+    db_->MultiGet(read_options, db_->DefaultColumnFamily(), num_keys, &keys[0],
+                  &values[0], &statuses[0]);
+
+    ASSERT_OK(statuses[0]);
+    ASSERT_EQ(values[0], first_value);
+
+    ASSERT_TRUE(statuses[1].IsIncomplete());
+
+    ASSERT_TRUE(statuses[2].IsIncomplete());
+  }
+
+  // Fill the cache when reading blobs from the blob file.
+  read_options.read_tier = kReadAllTier;
+  read_options.fill_cache = true;
+
+  {
+    std::array<PinnableSlice, num_keys> values;
+    std::array<Status, num_keys> statuses;
+
+    db_->MultiGet(read_options, db_->DefaultColumnFamily(), num_keys, &keys[0],
+                  &values[0], &statuses[0]);
+
+    ASSERT_OK(statuses[0]);
+    ASSERT_EQ(values[0], first_value);
+
+    ASSERT_OK(statuses[1]);
+    ASSERT_EQ(values[1], second_value);
+
+    ASSERT_OK(statuses[2]);
+    ASSERT_EQ(values[2], third_value);
+  }
+
+  // Try again with no I/O allowed. All blobs should be successfully read from
+  // the cache.
+  read_options.read_tier = kBlockCacheTier;
+
+  {
+    std::array<PinnableSlice, num_keys> values;
+    std::array<Status, num_keys> statuses;
+
+    db_->MultiGet(read_options, db_->DefaultColumnFamily(), num_keys, &keys[0],
+                  &values[0], &statuses[0]);
+
+    ASSERT_OK(statuses[0]);
+    ASSERT_EQ(values[0], first_value);
+
+    ASSERT_OK(statuses[1]);
+    ASSERT_EQ(values[1], second_value);
+
+    ASSERT_OK(statuses[2]);
+    ASSERT_EQ(values[2], third_value);
+  }
+}
+
 #ifndef ROCKSDB_LITE
 TEST_F(DBBlobBasicTest, MultiGetWithDirectIO) {
   Options options = GetDefaultOptions();
@@ -320,8 +776,23 @@ TEST_F(DBBlobBasicTest, MultiGetWithDirectIO) {
 
 TEST_F(DBBlobBasicTest, MultiGetBlobsFromMultipleFiles) {
   Options options = GetDefaultOptions();
-  options.enable_blob_files = true;
+
+  LRUCacheOptions co;
+  co.capacity = 2 << 20; // 2MB
+  co.num_shard_bits = 2;
+  co.metadata_charge_policy = kDontChargeCacheMetadata;
+  auto backing_cache = NewLRUCache(co);
+
   options.min_blob_size = 0;
+  options.create_if_missing = true;
+  options.enable_blob_files = true;
+  options.blob_cache = backing_cache;
+
+  BlockBasedTableOptions block_based_options;
+  block_based_options.no_block_cache = false;
+  block_based_options.block_cache = backing_cache;
+  block_based_options.cache_index_and_filter_blocks = true;
+  options.table_factory.reset(NewBlockBasedTableFactory(block_based_options));
 
   Reopen(options);
 
@@ -347,14 +818,64 @@ TEST_F(DBBlobBasicTest, MultiGetBlobsFromMultipleFiles) {
   for (size_t i = 0; i < keys.size(); ++i) {
     keys[i] = key_strs[i];
   }
-  std::array<PinnableSlice, kNumKeys> values;
-  std::array<Status, kNumKeys> statuses;
-  db_->MultiGet(ReadOptions(), db_->DefaultColumnFamily(), kNumKeys, &keys[0],
-                &values[0], &statuses[0]);
 
-  for (size_t i = 0; i < kNumKeys; ++i) {
-    ASSERT_OK(statuses[i]);
-    ASSERT_EQ(value_strs[i], values[i]);
+  ReadOptions read_options;
+  read_options.read_tier = kReadAllTier;
+  read_options.fill_cache = false;
+
+  {
+    std::array<PinnableSlice, kNumKeys> values;
+    std::array<Status, kNumKeys> statuses;
+    db_->MultiGet(read_options, db_->DefaultColumnFamily(), kNumKeys, &keys[0],
+                  &values[0], &statuses[0]);
+
+    for (size_t i = 0; i < kNumKeys; ++i) {
+      ASSERT_OK(statuses[i]);
+      ASSERT_EQ(value_strs[i], values[i]);
+    }
+  }
+
+  read_options.read_tier = kBlockCacheTier;
+
+  {
+    std::array<PinnableSlice, kNumKeys> values;
+    std::array<Status, kNumKeys> statuses;
+    db_->MultiGet(read_options, db_->DefaultColumnFamily(), kNumKeys, &keys[0],
+                  &values[0], &statuses[0]);
+
+    for (size_t i = 0; i < kNumKeys; ++i) {
+      ASSERT_TRUE(statuses[i].IsIncomplete());
+      ASSERT_TRUE(values[i].empty());
+    }
+  }
+
+  read_options.read_tier = kReadAllTier;
+  read_options.fill_cache = true;
+
+  {
+    std::array<PinnableSlice, kNumKeys> values;
+    std::array<Status, kNumKeys> statuses;
+    db_->MultiGet(read_options, db_->DefaultColumnFamily(), kNumKeys, &keys[0],
+                  &values[0], &statuses[0]);
+
+    for (size_t i = 0; i < kNumKeys; ++i) {
+      ASSERT_OK(statuses[i]);
+      ASSERT_EQ(value_strs[i], values[i]);
+    }
+  }
+
+  read_options.read_tier = kBlockCacheTier;
+
+  {
+    std::array<PinnableSlice, kNumKeys> values;
+    std::array<Status, kNumKeys> statuses;
+    db_->MultiGet(read_options, db_->DefaultColumnFamily(), kNumKeys, &keys[0],
+                  &values[0], &statuses[0]);
+
+    for (size_t i = 0; i < kNumKeys; ++i) {
+      ASSERT_OK(statuses[i]);
+      ASSERT_EQ(value_strs[i], values[i]);
+    }
   }
 }
 
@@ -1060,6 +1581,126 @@ TEST_P(DBBlobBasicIOErrorTest, CompactionFilterReadBlob_IOError) {
   SyncPoint::GetInstance()->ClearAllCallBacks();
 }
 
+TEST_F(DBBlobBasicTest, WarmCacheWithBlobsDuringFlush) {
+  Options options = GetDefaultOptions();
+
+  LRUCacheOptions co;
+  co.capacity = 1 << 25;
+  co.num_shard_bits = 2;
+  co.metadata_charge_policy = kDontChargeCacheMetadata;
+  auto backing_cache = NewLRUCache(co);
+
+  options.blob_cache = backing_cache;
+
+  BlockBasedTableOptions block_based_options;
+  block_based_options.no_block_cache = false;
+  block_based_options.block_cache = backing_cache;
+  block_based_options.cache_index_and_filter_blocks = true;
+  options.table_factory.reset(NewBlockBasedTableFactory(block_based_options));
+
+  options.enable_blob_files = true;
+  options.create_if_missing = true;
+  options.disable_auto_compactions = true;
+  options.enable_blob_garbage_collection = true;
+  options.blob_garbage_collection_age_cutoff = 1.0;
+  options.prepopulate_blob_cache = PrepopulateBlobCache::kFlushOnly;
+  options.statistics = ROCKSDB_NAMESPACE::CreateDBStatistics();
+
+  DestroyAndReopen(options);
+
+  constexpr size_t kNumBlobs = 10;
+  constexpr size_t kValueSize = 100;
+
+  std::string value(kValueSize, 'a');
+
+  for (size_t i = 1; i <= kNumBlobs; i++) {
+    ASSERT_OK(Put(std::to_string(i), value));
+    ASSERT_OK(Put(std::to_string(i + kNumBlobs), value));  // Add some overlap
+    ASSERT_OK(Flush());
+    ASSERT_EQ(i * 2, options.statistics->getTickerCount(BLOB_DB_CACHE_ADD));
+    ASSERT_EQ(value, Get(std::to_string(i)));
+    ASSERT_EQ(value, Get(std::to_string(i + kNumBlobs)));
+    ASSERT_EQ(0, options.statistics->getTickerCount(BLOB_DB_CACHE_MISS));
+    ASSERT_EQ(i * 2, options.statistics->getTickerCount(BLOB_DB_CACHE_HIT));
+  }
+
+  // Verify compaction not counted
+  ASSERT_OK(db_->CompactRange(CompactRangeOptions(), /*begin=*/nullptr,
+                              /*end=*/nullptr));
+  EXPECT_EQ(kNumBlobs * 2,
+            options.statistics->getTickerCount(BLOB_DB_CACHE_ADD));
+}
+
+#ifndef ROCKSDB_LITE
+TEST_F(DBBlobBasicTest, DynamicallyWarmCacheDuringFlush) {
+  Options options = GetDefaultOptions();
+
+  LRUCacheOptions co;
+  co.capacity = 1 << 25;
+  co.num_shard_bits = 2;
+  co.metadata_charge_policy = kDontChargeCacheMetadata;
+  auto backing_cache = NewLRUCache(co);
+
+  options.blob_cache = backing_cache;
+
+  BlockBasedTableOptions block_based_options;
+  block_based_options.no_block_cache = false;
+  block_based_options.block_cache = backing_cache;
+  block_based_options.cache_index_and_filter_blocks = true;
+  options.table_factory.reset(NewBlockBasedTableFactory(block_based_options));
+
+  options.enable_blob_files = true;
+  options.create_if_missing = true;
+  options.disable_auto_compactions = true;
+  options.enable_blob_garbage_collection = true;
+  options.blob_garbage_collection_age_cutoff = 1.0;
+  options.prepopulate_blob_cache = PrepopulateBlobCache::kFlushOnly;
+  options.statistics = ROCKSDB_NAMESPACE::CreateDBStatistics();
+
+  DestroyAndReopen(options);
+
+  constexpr size_t kNumBlobs = 10;
+  constexpr size_t kValueSize = 100;
+
+  std::string value(kValueSize, 'a');
+
+  for (size_t i = 1; i <= 5; i++) {
+    ASSERT_OK(Put(std::to_string(i), value));
+    ASSERT_OK(Put(std::to_string(i + kNumBlobs), value));  // Add some overlap
+    ASSERT_OK(Flush());
+    ASSERT_EQ(2, options.statistics->getAndResetTickerCount(BLOB_DB_CACHE_ADD));
+
+    ASSERT_EQ(value, Get(std::to_string(i)));
+    ASSERT_EQ(value, Get(std::to_string(i + kNumBlobs)));
+    ASSERT_EQ(0, options.statistics->getAndResetTickerCount(BLOB_DB_CACHE_ADD));
+    ASSERT_EQ(0,
+              options.statistics->getAndResetTickerCount(BLOB_DB_CACHE_MISS));
+    ASSERT_EQ(2, options.statistics->getAndResetTickerCount(BLOB_DB_CACHE_HIT));
+  }
+
+  ASSERT_OK(dbfull()->SetOptions({{"prepopulate_blob_cache", "kDisable"}}));
+
+  for (size_t i = 6; i <= kNumBlobs; i++) {
+    ASSERT_OK(Put(std::to_string(i), value));
+    ASSERT_OK(Put(std::to_string(i + kNumBlobs), value));  // Add some overlap
+    ASSERT_OK(Flush());
+    ASSERT_EQ(0, options.statistics->getAndResetTickerCount(BLOB_DB_CACHE_ADD));
+
+    ASSERT_EQ(value, Get(std::to_string(i)));
+    ASSERT_EQ(value, Get(std::to_string(i + kNumBlobs)));
+    ASSERT_EQ(2, options.statistics->getAndResetTickerCount(BLOB_DB_CACHE_ADD));
+    ASSERT_EQ(2,
+              options.statistics->getAndResetTickerCount(BLOB_DB_CACHE_MISS));
+    ASSERT_EQ(0, options.statistics->getAndResetTickerCount(BLOB_DB_CACHE_HIT));
+  }
+
+  // Verify compaction not counted
+  ASSERT_OK(db_->CompactRange(CompactRangeOptions(), /*begin=*/nullptr,
+                              /*end=*/nullptr));
+  EXPECT_EQ(0, options.statistics->getTickerCount(BLOB_DB_CACHE_ADD));
+}
+#endif  // !ROCKSDB_LITE
+
 }  // namespace ROCKSDB_NAMESPACE
 
 int main(int argc, char** argv) {

db/blob/db_blob_compaction_test.cc

@@ -54,6 +54,26 @@ class FilterByKeyLength : public CompactionFilter {
   size_t length_threshold_;
 };
 
+class FilterByValueLength : public CompactionFilter {
+ public:
+  explicit FilterByValueLength(size_t len) : length_threshold_(len) {}
+  const char* Name() const override {
+    return "rocksdb.compaction.filter.by.value.length";
+  }
+  CompactionFilter::Decision FilterV2(
+      int /*level*/, const Slice& /*key*/, ValueType /*value_type*/,
+      const Slice& existing_value, std::string* /*new_value*/,
+      std::string* /*skip_until*/) const override {
+    if (existing_value.size() < length_threshold_) {
+      return CompactionFilter::Decision::kRemove;
+    }
+    return CompactionFilter::Decision::kKeep;
+  }
+
+ private:
+  size_t length_threshold_;
+};
+
 class BadBlobCompactionFilter : public CompactionFilter {
  public:
   explicit BadBlobCompactionFilter(std::string prefix,
@@ -243,6 +263,55 @@ TEST_F(DBBlobCompactionTest, FilterByKeyLength) {
   Close();
 }
 
+TEST_F(DBBlobCompactionTest, FilterByValueLength) {
+  Options options = GetDefaultOptions();
+  options.enable_blob_files = true;
+  options.min_blob_size = 5;
+  options.create_if_missing = true;
+  constexpr size_t kValueLength = 5;
+  std::unique_ptr<CompactionFilter> compaction_filter_guard(
+      new FilterByValueLength(kValueLength));
+  options.compaction_filter = compaction_filter_guard.get();
+
+  const std::vector<std::string> short_value_keys = {"a", "e", "j"};
+  constexpr char short_value[] = "val";
+  const std::vector<std::string> long_value_keys = {"b", "f", "k"};
+  constexpr char long_value[] = "valuevalue";
+
+  DestroyAndReopen(options);
+  for (size_t i = 0; i < short_value_keys.size(); ++i) {
+    ASSERT_OK(Put(short_value_keys[i], short_value));
+  }
+  for (size_t i = 0; i < short_value_keys.size(); ++i) {
+    ASSERT_OK(Put(long_value_keys[i], long_value));
+  }
+  ASSERT_OK(Flush());
+  CompactRangeOptions cro;
+  ASSERT_OK(db_->CompactRange(cro, /*begin=*/nullptr, /*end=*/nullptr));
+  std::string value;
+  for (size_t i = 0; i < short_value_keys.size(); ++i) {
+    ASSERT_TRUE(
+        db_->Get(ReadOptions(), short_value_keys[i], &value).IsNotFound());
+    value.clear();
+  }
+  for (size_t i = 0; i < long_value_keys.size(); ++i) {
+    ASSERT_OK(db_->Get(ReadOptions(), long_value_keys[i], &value));
+    ASSERT_EQ(long_value, value);
+  }
+
+#ifndef ROCKSDB_LITE
+  const auto& compaction_stats = GetCompactionStats();
+  ASSERT_GE(compaction_stats.size(), 2);
+
+  // Filter decides between kKeep and kRemove based on value;
+  // this involves reading but not writing blobs
+  ASSERT_GT(compaction_stats[1].bytes_read_blob, 0);
+  ASSERT_EQ(compaction_stats[1].bytes_written_blob, 0);
+#endif  // ROCKSDB_LITE
+
+  Close();
+}
+
 #ifndef ROCKSDB_LITE
 TEST_F(DBBlobCompactionTest, BlobCompactWithStartingLevel) {
   Options options = GetDefaultOptions();
@@ -798,6 +867,42 @@ TEST_F(DBBlobCompactionTest, CompactionReadaheadMerge) {
   Close();
 }
 
+TEST_F(DBBlobCompactionTest, CompactionDoNotFillCache) {
+  Options options = GetDefaultOptions();
+
+  options.enable_blob_files = true;
+  options.min_blob_size = 0;
+  options.enable_blob_garbage_collection = true;
+  options.blob_garbage_collection_age_cutoff = 1.0;
+  options.disable_auto_compactions = true;
+  options.statistics = CreateDBStatistics();
+
+  LRUCacheOptions cache_options;
+  cache_options.capacity = 1 << 20;
+  cache_options.metadata_charge_policy = kDontChargeCacheMetadata;
+
+  options.blob_cache = NewLRUCache(cache_options);
+
+  Reopen(options);
+
+  ASSERT_OK(Put("key", "lime"));
+  ASSERT_OK(Put("foo", "bar"));
+  ASSERT_OK(Flush());
+
+  ASSERT_OK(Put("key", "pie"));
+  ASSERT_OK(Put("foo", "baz"));
+  ASSERT_OK(Flush());
+
+  constexpr Slice* begin = nullptr;
+  constexpr Slice* end = nullptr;
+
+  ASSERT_OK(db_->CompactRange(CompactRangeOptions(), begin, end));
+
+  ASSERT_EQ(options.statistics->getTickerCount(BLOB_DB_CACHE_ADD), 0);
+
+  Close();
+}
+
 }  // namespace ROCKSDB_NAMESPACE
 
 int main(int argc, char** argv) {

db/builder.cc

@@ -66,7 +66,8 @@ Status BuildTable(
     SequenceNumber job_snapshot, SnapshotChecker* snapshot_checker,
     bool paranoid_file_checks, InternalStats* internal_stats,
     IOStatus* io_status, const std::shared_ptr<IOTracer>& io_tracer,
-    BlobFileCreationReason blob_creation_reason, EventLogger* event_logger,
+    BlobFileCreationReason blob_creation_reason,
+    const SeqnoToTimeMapping& seqno_to_time_mapping, EventLogger* event_logger,
     int job_id, const Env::IOPriority io_priority,
     TableProperties* table_properties, Env::WriteLifeTimeHint write_hint,
     const std::string* full_history_ts_low,
@@ -187,10 +188,10 @@ Status BuildTable(
          blob_file_additions)
             ? new BlobFileBuilder(
                   versions, fs, &ioptions, &mutable_cf_options, &file_options,
-                  job_id, tboptions.column_family_id,
-                  tboptions.column_family_name, io_priority, write_hint,
-                  io_tracer, blob_callback, blob_creation_reason,
-                  &blob_file_paths, blob_file_additions)
+                  tboptions.db_id, tboptions.db_session_id, job_id,
+                  tboptions.column_family_id, tboptions.column_family_name,
+                  io_priority, write_hint, io_tracer, blob_callback,
+                  blob_creation_reason, &blob_file_paths, blob_file_additions)
             : nullptr);
 
     const std::atomic<bool> kManualCompactionCanceledFalse{false};
@@ -260,6 +261,15 @@ Status BuildTable(
     if (!s.ok() || empty) {
       builder->Abandon();
     } else {
+      std::string seqno_time_mapping_str;
+      seqno_to_time_mapping.Encode(
+          seqno_time_mapping_str, meta->fd.smallest_seqno,
+          meta->fd.largest_seqno, meta->file_creation_time);
+      builder->SetSeqnoTimeTableProperties(
+          seqno_time_mapping_str,
+          ioptions.compaction_style == CompactionStyle::kCompactionStyleFIFO
+              ? meta->file_creation_time
+              : meta->oldest_ancester_time);
       s = builder->Finish();
     }
     if (io_status->ok()) {

db/builder.h

@@ -9,7 +9,9 @@
 #include <string>
 #include <utility>
 #include <vector>
+
 #include "db/range_tombstone_fragmenter.h"
+#include "db/seqno_to_time_mapping.h"
 #include "db/table_properties_collector.h"
 #include "logging/event_logger.h"
 #include "options/cf_options.h"
@@ -61,6 +63,7 @@ extern Status BuildTable(
     bool paranoid_file_checks, InternalStats* internal_stats,
     IOStatus* io_status, const std::shared_ptr<IOTracer>& io_tracer,
     BlobFileCreationReason blob_creation_reason,
+    const SeqnoToTimeMapping& seqno_to_time_mapping,
     EventLogger* event_logger = nullptr, int job_id = 0,
     const Env::IOPriority io_priority = Env::IO_HIGH,
     TableProperties* table_properties = nullptr,

db/c.cc

@@ -23,6 +23,7 @@
 #include "rocksdb/convenience.h"
 #include "rocksdb/db.h"
 #include "rocksdb/env.h"
+#include "rocksdb/experimental.h"
 #include "rocksdb/filter_policy.h"
 #include "rocksdb/iterator.h"
 #include "rocksdb/memtablerep.h"
@@ -40,6 +41,7 @@
 #include "rocksdb/utilities/db_ttl.h"
 #include "rocksdb/utilities/memory_util.h"
 #include "rocksdb/utilities/optimistic_transaction_db.h"
+#include "rocksdb/utilities/options_util.h"
 #include "rocksdb/utilities/table_properties_collectors.h"
 #include "rocksdb/utilities/transaction.h"
 #include "rocksdb/utilities/transaction_db.h"
@@ -59,6 +61,7 @@ using ROCKSDB_NAMESPACE::Cache;
 using ROCKSDB_NAMESPACE::Checkpoint;
 using ROCKSDB_NAMESPACE::ColumnFamilyDescriptor;
 using ROCKSDB_NAMESPACE::ColumnFamilyHandle;
+using ROCKSDB_NAMESPACE::ColumnFamilyMetaData;
 using ROCKSDB_NAMESPACE::ColumnFamilyOptions;
 using ROCKSDB_NAMESPACE::CompactionFilter;
 using ROCKSDB_NAMESPACE::CompactionFilterFactory;
@@ -78,6 +81,7 @@ using ROCKSDB_NAMESPACE::FlushOptions;
 using ROCKSDB_NAMESPACE::InfoLogLevel;
 using ROCKSDB_NAMESPACE::IngestExternalFileOptions;
 using ROCKSDB_NAMESPACE::Iterator;
+using ROCKSDB_NAMESPACE::LevelMetaData;
 using ROCKSDB_NAMESPACE::LiveFileMetaData;
 using ROCKSDB_NAMESPACE::Logger;
 using ROCKSDB_NAMESPACE::LRUCacheOptions;
@@ -95,6 +99,7 @@ using ROCKSDB_NAMESPACE::Options;
 using ROCKSDB_NAMESPACE::PerfContext;
 using ROCKSDB_NAMESPACE::PerfLevel;
 using ROCKSDB_NAMESPACE::PinnableSlice;
+using ROCKSDB_NAMESPACE::PrepopulateBlobCache;
 using ROCKSDB_NAMESPACE::RandomAccessFile;
 using ROCKSDB_NAMESPACE::Range;
 using ROCKSDB_NAMESPACE::RateLimiter;
@@ -105,6 +110,7 @@ using ROCKSDB_NAMESPACE::Slice;
 using ROCKSDB_NAMESPACE::SliceParts;
 using ROCKSDB_NAMESPACE::SliceTransform;
 using ROCKSDB_NAMESPACE::Snapshot;
+using ROCKSDB_NAMESPACE::SstFileMetaData;
 using ROCKSDB_NAMESPACE::SstFileWriter;
 using ROCKSDB_NAMESPACE::Status;
 using ROCKSDB_NAMESPACE::TablePropertiesCollectorFactory;
@@ -178,6 +184,15 @@ struct rocksdb_cache_t {
 };
 struct rocksdb_livefiles_t       { std::vector<LiveFileMetaData> rep; };
 struct rocksdb_column_family_handle_t  { ColumnFamilyHandle* rep; };
+struct rocksdb_column_family_metadata_t {
+  ColumnFamilyMetaData rep;
+};
+struct rocksdb_level_metadata_t {
+  const LevelMetaData* rep;
+};
+struct rocksdb_sst_file_metadata_t {
+  const SstFileMetaData* rep;
+};
 struct rocksdb_envoptions_t      { EnvOptions        rep; };
 struct rocksdb_ingestexternalfileoptions_t  { IngestExternalFileOptions rep; };
 struct rocksdb_sstfilewriter_t   { SstFileWriter*    rep; };
@@ -1737,6 +1752,29 @@ void rocksdb_compact_range_cf(
       (limit_key ? (b = Slice(limit_key, limit_key_len), &b) : nullptr));
 }
 
+void rocksdb_suggest_compact_range(rocksdb_t* db, const char* start_key,
+                                   size_t start_key_len, const char* limit_key,
+                                   size_t limit_key_len, char** errptr) {
+  Slice a, b;
+  Status s = ROCKSDB_NAMESPACE::experimental::SuggestCompactRange(
+      db->rep,
+      (start_key ? (a = Slice(start_key, start_key_len), &a) : nullptr),
+      (limit_key ? (b = Slice(limit_key, limit_key_len), &b) : nullptr));
+  SaveError(errptr, s);
+}
+
+void rocksdb_suggest_compact_range_cf(
+    rocksdb_t* db, rocksdb_column_family_handle_t* column_family,
+    const char* start_key, size_t start_key_len, const char* limit_key,
+    size_t limit_key_len, char** errptr) {
+  Slice a, b;
+  Status s = db->rep->SuggestCompactRange(
+      column_family->rep,
+      (start_key ? (a = Slice(start_key, start_key_len), &a) : nullptr),
+      (limit_key ? (b = Slice(limit_key, limit_key_len), &b) : nullptr));
+  SaveError(errptr, s);
+}
+
 void rocksdb_compact_range_opt(rocksdb_t* db, rocksdb_compactoptions_t* opt,
                                const char* start_key, size_t start_key_len,
                                const char* limit_key, size_t limit_key_len) {
@@ -2508,6 +2546,56 @@ void rocksdb_write_writebatch_wi(
   SaveError(errptr, db->rep->Write(options->rep, wb));
 }
 
+void rocksdb_load_latest_options(
+    const char* db_path, rocksdb_env_t* env, bool ignore_unknown_options,
+    rocksdb_cache_t* cache, rocksdb_options_t** db_options,
+    size_t* num_column_families, char*** list_column_family_names,
+    rocksdb_options_t*** list_column_family_options, char** errptr) {
+  DBOptions db_opt;
+  std::vector<ColumnFamilyDescriptor> cf_descs;
+  Status s = LoadLatestOptions(std::string(db_path), env->rep, &db_opt,
+                               &cf_descs, ignore_unknown_options, &cache->rep);
+  if (s.ok()) {
+    char** cf_names = (char**)malloc(cf_descs.size() * sizeof(char*));
+    rocksdb_options_t** cf_options = (rocksdb_options_t**)malloc(
+        cf_descs.size() * sizeof(rocksdb_options_t*));
+    for (size_t i = 0; i < cf_descs.size(); ++i) {
+      cf_names[i] = strdup(cf_descs[i].name.c_str());
+      cf_options[i] = new rocksdb_options_t{
+          Options(DBOptions(), std::move(cf_descs[i].options))};
+    }
+    *num_column_families = cf_descs.size();
+    *db_options = new rocksdb_options_t{
+        Options(std::move(db_opt), ColumnFamilyOptions())};
+    *list_column_family_names = cf_names;
+    *list_column_family_options = cf_options;
+  } else {
+    *num_column_families = 0;
+    *db_options = nullptr;
+    *list_column_family_names = nullptr;
+    *list_column_family_options = nullptr;
+    SaveError(errptr, s);
+  }
+}
+
+void rocksdb_load_latest_options_destroy(
+    rocksdb_options_t* db_options, char** list_column_family_names,
+    rocksdb_options_t** list_column_family_options, size_t len) {
+  rocksdb_options_destroy(db_options);
+  if (list_column_family_names) {
+    for (size_t i = 0; i < len; ++i) {
+      free(list_column_family_names[i]);
+    }
+    free(list_column_family_names);
+  }
+  if (list_column_family_options) {
+    for (size_t i = 0; i < len; ++i) {
+      rocksdb_options_destroy(list_column_family_options[i]);
+    }
+    free(list_column_family_options);
+  }
+}
+
 rocksdb_block_based_table_options_t*
 rocksdb_block_based_options_create() {
   return new rocksdb_block_based_table_options_t;
@@ -3053,6 +3141,14 @@ void rocksdb_options_set_blob_cache(rocksdb_options_t* opt,
   opt->rep.blob_cache = blob_cache->rep;
 }
 
+void rocksdb_options_set_prepopulate_blob_cache(rocksdb_options_t* opt, int t) {
+  opt->rep.prepopulate_blob_cache = static_cast<PrepopulateBlobCache>(t);
+}
+
+int rocksdb_options_get_prepopulate_blob_cache(rocksdb_options_t* opt) {
+  return static_cast<int>(opt->rep.prepopulate_blob_cache);
+}
+
 void rocksdb_options_set_num_levels(rocksdb_options_t* opt, int n) {
   opt->rep.num_levels = n;
 }
@@ -3338,11 +3434,6 @@ unsigned char rocksdb_options_get_advise_random_on_open(
   return opt->rep.advise_random_on_open;
 }
 
-void rocksdb_options_set_experimental_mempurge_threshold(rocksdb_options_t* opt,
-                                                         double v) {
-  opt->rep.experimental_mempurge_threshold = v;
-}
-
 void rocksdb_options_set_access_hint_on_compaction_start(
     rocksdb_options_t* opt, int v) {
   switch(v) {
@@ -3528,6 +3619,16 @@ int rocksdb_options_get_max_background_flushes(rocksdb_options_t* opt) {
   return opt->rep.max_background_flushes;
 }
 
+void rocksdb_options_set_experimental_mempurge_threshold(rocksdb_options_t* opt,
+                                                         double v) {
+  opt->rep.experimental_mempurge_threshold = v;
+}
+
+double rocksdb_options_get_experimental_mempurge_threshold(
+    rocksdb_options_t* opt) {
+  return opt->rep.experimental_mempurge_threshold;
+}
+
 void rocksdb_options_set_max_log_file_size(rocksdb_options_t* opt, size_t v) {
   opt->rep.max_log_file_size = v;
 }
@@ -3986,6 +4087,18 @@ uint64_t rocksdb_perfcontext_metric(rocksdb_perfcontext_t* context,
       return rep->env_new_logger_nanos;
     case rocksdb_number_async_seek:
       return rep->number_async_seek;
+    case rocksdb_blob_cache_hit_count:
+      return rep->blob_cache_hit_count;
+    case rocksdb_blob_read_count:
+      return rep->blob_read_count;
+    case rocksdb_blob_read_byte:
+      return rep->blob_read_byte;
+    case rocksdb_blob_read_time:
+      return rep->blob_read_time;
+    case rocksdb_blob_checksum_time:
+      return rep->blob_checksum_time;
+    case rocksdb_blob_decompress_time:
+      return rep->blob_decompress_time;
     default:
       break;
   }
@@ -4583,6 +4696,11 @@ void rocksdb_lru_cache_options_set_capacity(rocksdb_lru_cache_options_t* opt,
   opt->rep.capacity = capacity;
 }
 
+void rocksdb_lru_cache_options_set_num_shard_bits(
+    rocksdb_lru_cache_options_t* opt, int num_shard_bits) {
+  opt->rep.num_shard_bits = num_shard_bits;
+}
+
 void rocksdb_lru_cache_options_set_memory_allocator(
     rocksdb_lru_cache_options_t* opt, rocksdb_memory_allocator_t* allocator) {
   opt->rep.memory_allocator = allocator->rep;
@@ -4790,6 +4908,15 @@ void rocksdb_sstfilewriter_delete_with_ts(rocksdb_sstfilewriter_t* writer,
   SaveError(errptr, writer->rep->Delete(Slice(key, keylen), Slice(ts, tslen)));
 }
 
+void rocksdb_sstfilewriter_delete_range(rocksdb_sstfilewriter_t* writer,
+                                        const char* begin_key,
+                                        size_t begin_keylen,
+                                        const char* end_key, size_t end_keylen,
+                                        char** errptr) {
+  SaveError(errptr, writer->rep->DeleteRange(Slice(begin_key, begin_keylen),
+                                             Slice(end_key, end_keylen)));
+}
+
 void rocksdb_sstfilewriter_finish(rocksdb_sstfilewriter_t* writer,
                                   char** errptr) {
   SaveError(errptr, writer->rep->Finish(nullptr));
@@ -5131,6 +5258,119 @@ void rocksdb_delete_file_in_range_cf(
           (limit_key ? (b = Slice(limit_key, limit_key_len), &b) : nullptr)));
 }
 
+/* MetaData */
+
+rocksdb_column_family_metadata_t* rocksdb_get_column_family_metadata(
+    rocksdb_t* db) {
+  rocksdb_column_family_metadata_t* meta = new rocksdb_column_family_metadata_t;
+  db->rep->GetColumnFamilyMetaData(&meta->rep);
+  return meta;
+}
+
+rocksdb_column_family_metadata_t* rocksdb_get_column_family_metadata_cf(
+    rocksdb_t* db, rocksdb_column_family_handle_t* column_family) {
+  rocksdb_column_family_metadata_t* meta = new rocksdb_column_family_metadata_t;
+  db->rep->GetColumnFamilyMetaData(column_family->rep, &meta->rep);
+  return meta;
+}
+
+void rocksdb_column_family_metadata_destroy(
+    rocksdb_column_family_metadata_t* cf_meta) {
+  delete cf_meta;
+}
+
+uint64_t rocksdb_column_family_metadata_get_size(
+    rocksdb_column_family_metadata_t* cf_meta) {
+  return cf_meta->rep.size;
+}
+
+size_t rocksdb_column_family_metadata_get_file_count(
+    rocksdb_column_family_metadata_t* cf_meta) {
+  return cf_meta->rep.file_count;
+}
+
+char* rocksdb_column_family_metadata_get_name(
+    rocksdb_column_family_metadata_t* cf_meta) {
+  return strdup(cf_meta->rep.name.c_str());
+}
+
+size_t rocksdb_column_family_metadata_get_level_count(
+    rocksdb_column_family_metadata_t* cf_meta) {
+  return cf_meta->rep.levels.size();
+}
+
+rocksdb_level_metadata_t* rocksdb_column_family_metadata_get_level_metadata(
+    rocksdb_column_family_metadata_t* cf_meta, size_t i) {
+  if (i >= cf_meta->rep.levels.size()) {
+    return NULL;
+  }
+  rocksdb_level_metadata_t* level_meta =
+      (rocksdb_level_metadata_t*)malloc(sizeof(rocksdb_level_metadata_t));
+  level_meta->rep = &cf_meta->rep.levels[i];
+
+  return level_meta;
+}
+
+void rocksdb_level_metadata_destroy(rocksdb_level_metadata_t* level_meta) {
+  // Only free the base pointer as its parent rocksdb_column_family_metadata_t
+  // has the ownership of its rep.
+  free(level_meta);
+}
+
+int rocksdb_level_metadata_get_level(rocksdb_level_metadata_t* level_meta) {
+  return level_meta->rep->level;
+}
+
+uint64_t rocksdb_level_metadata_get_size(rocksdb_level_metadata_t* level_meta) {
+  return level_meta->rep->size;
+}
+
+size_t rocksdb_level_metadata_get_file_count(
+    rocksdb_level_metadata_t* level_meta) {
+  return level_meta->rep->files.size();
+}
+
+rocksdb_sst_file_metadata_t* rocksdb_level_metadata_get_sst_file_metadata(
+    rocksdb_level_metadata_t* level_meta, size_t i) {
+  if (i >= level_meta->rep->files.size()) {
+    return nullptr;
+  }
+  rocksdb_sst_file_metadata_t* file_meta =
+      (rocksdb_sst_file_metadata_t*)malloc(sizeof(rocksdb_sst_file_metadata_t));
+  file_meta->rep = &level_meta->rep->files[i];
+  return file_meta;
+}
+
+void rocksdb_sst_file_metadata_destroy(rocksdb_sst_file_metadata_t* file_meta) {
+  // Only free the base pointer as its parent rocksdb_level_metadata_t
+  // has the ownership of its rep.
+  free(file_meta);
+}
+
+char* rocksdb_sst_file_metadata_get_relative_filename(
+    rocksdb_sst_file_metadata_t* file_meta) {
+  return strdup(file_meta->rep->relative_filename.c_str());
+}
+
+uint64_t rocksdb_sst_file_metadata_get_size(
+    rocksdb_sst_file_metadata_t* file_meta) {
+  return file_meta->rep->size;
+}
+
+char* rocksdb_sst_file_metadata_get_smallestkey(
+    rocksdb_sst_file_metadata_t* file_meta, size_t* key_len) {
+  *key_len = file_meta->rep->smallestkey.size();
+  return CopyString(file_meta->rep->smallestkey);
+}
+
+char* rocksdb_sst_file_metadata_get_largestkey(
+    rocksdb_sst_file_metadata_t* file_meta, size_t* key_len) {
+  *key_len = file_meta->rep->largestkey.size();
+  return CopyString(file_meta->rep->largestkey);
+}
+
+/* Transactions */
+
 rocksdb_transactiondb_options_t* rocksdb_transactiondb_options_create() {
   return new rocksdb_transactiondb_options_t;
 }

db/c_test.c

@@ -272,6 +272,92 @@ static rocksdb_compactionfilter_t* CFilterCreate(
                                          CFilterName);
 }
 
+void CheckMetaData(rocksdb_column_family_metadata_t* cf_meta,
+                   const char* expected_cf_name) {
+  char* cf_name = rocksdb_column_family_metadata_get_name(cf_meta);
+  assert(strcmp(cf_name, expected_cf_name) == 0);
+  rocksdb_free(cf_name);
+
+  size_t cf_size = rocksdb_column_family_metadata_get_size(cf_meta);
+  assert(cf_size > 0);
+  size_t cf_file_count = rocksdb_column_family_metadata_get_size(cf_meta);
+  assert(cf_file_count > 0);
+
+  uint64_t total_level_size = 0;
+  size_t total_file_count = 0;
+  size_t level_count = rocksdb_column_family_metadata_get_level_count(cf_meta);
+  assert(level_count > 0);
+  for (size_t l = 0; l < level_count; ++l) {
+    rocksdb_level_metadata_t* level_meta =
+        rocksdb_column_family_metadata_get_level_metadata(cf_meta, l);
+    assert(level_meta);
+    assert(rocksdb_level_metadata_get_level(level_meta) >= (int)l);
+    uint64_t level_size = rocksdb_level_metadata_get_size(level_meta);
+    uint64_t file_size_in_level = 0;
+
+    size_t file_count = rocksdb_level_metadata_get_file_count(level_meta);
+    total_file_count += file_count;
+    for (size_t f = 0; f < file_count; ++f) {
+      rocksdb_sst_file_metadata_t* file_meta =
+          rocksdb_level_metadata_get_sst_file_metadata(level_meta, f);
+      assert(file_meta);
+
+      uint64_t file_size = rocksdb_sst_file_metadata_get_size(file_meta);
+      assert(file_size > 0);
+      file_size_in_level += file_size;
+
+      char* file_name =
+          rocksdb_sst_file_metadata_get_relative_filename(file_meta);
+      assert(file_name);
+      assert(strlen(file_name) > 0);
+      rocksdb_free(file_name);
+
+      size_t smallest_key_len;
+      char* smallest_key = rocksdb_sst_file_metadata_get_smallestkey(
+          file_meta, &smallest_key_len);
+      assert(smallest_key);
+      assert(smallest_key_len > 0);
+      size_t largest_key_len;
+      char* largest_key =
+          rocksdb_sst_file_metadata_get_largestkey(file_meta, &largest_key_len);
+      assert(largest_key);
+      assert(largest_key_len > 0);
+      rocksdb_free(smallest_key);
+      rocksdb_free(largest_key);
+
+      rocksdb_sst_file_metadata_destroy(file_meta);
+    }
+    assert(level_size == file_size_in_level);
+    total_level_size += level_size;
+    rocksdb_level_metadata_destroy(level_meta);
+  }
+  assert(total_file_count > 0);
+  assert(cf_size == total_level_size);
+}
+
+void GetAndCheckMetaData(rocksdb_t* db) {
+  rocksdb_column_family_metadata_t* cf_meta =
+      rocksdb_get_column_family_metadata(db);
+
+  CheckMetaData(cf_meta, "default");
+
+  rocksdb_column_family_metadata_destroy(cf_meta);
+}
+
+void GetAndCheckMetaDataCf(rocksdb_t* db,
+                           rocksdb_column_family_handle_t* handle,
+                           const char* cf_name) {
+  // Compact to make sure we have at least one sst file to obtain datadata.
+  rocksdb_compact_range_cf(db, handle, NULL, 0, NULL, 0);
+
+  rocksdb_column_family_metadata_t* cf_meta =
+      rocksdb_get_column_family_metadata_cf(db, handle);
+
+  CheckMetaData(cf_meta, cf_name);
+
+  rocksdb_column_family_metadata_destroy(cf_meta);
+}
+
 static rocksdb_t* CheckCompaction(rocksdb_t* db, rocksdb_options_t* options,
                                   rocksdb_readoptions_t* roptions,
                                   rocksdb_writeoptions_t* woptions) {
@@ -304,6 +390,11 @@ static rocksdb_t* CheckCompaction(rocksdb_t* db, rocksdb_options_t* options,
   CheckGet(db, roptions, "foo", "foovalue");
   CheckGet(db, roptions, "bar", NULL);
   CheckGet(db, roptions, "baz", "newbazvalue");
+
+  rocksdb_suggest_compact_range(db, "bar", 3, "foo", 3, &err);
+  GetAndCheckMetaData(db);
+  CheckNoError(err);
+
   return db;
 }
 
@@ -470,6 +561,71 @@ static void CheckTxnDBPinGetCF(rocksdb_transactiondb_t* txn_db,
   rocksdb_pinnableslice_destroy(p);
 }
 
+static void LoadAndCheckLatestOptions(const char* db_name, rocksdb_env_t* env,
+                                      bool ignore_unknown_options,
+                                      rocksdb_cache_t* cache,
+                                      rocksdb_comparator_t* cmp,
+                                      const size_t expected_num_column_families,
+                                      const char** expected_cf_names,
+                                      const char* expected_open_err) {
+  rocksdb_options_t* db_options;
+  size_t num_column_families;
+  char** list_column_family_names;
+  rocksdb_options_t** list_column_family_options;
+  char* err = 0;
+
+  // load the latest rocksdb option
+  rocksdb_load_latest_options(db_name, env, ignore_unknown_options, cache,
+                              &db_options, &num_column_families,
+                              &list_column_family_names,
+                              &list_column_family_options, &err);
+  assert(num_column_families == expected_num_column_families);
+  CheckNoError(err);
+
+  // verify the loaded options by opening the db.
+  rocksdb_options_set_error_if_exists(db_options, 0);
+
+  char** list_const_cf_names =
+      (char**)malloc(num_column_families * sizeof(char*));
+  rocksdb_options_t** list_const_cf_options = (rocksdb_options_t**)malloc(
+      num_column_families * sizeof(rocksdb_options_t*));
+  for (size_t i = 0; i < num_column_families; ++i) {
+    assert(strcmp(list_column_family_names[i], expected_cf_names[i]) == 0);
+    list_const_cf_names[i] = list_column_family_names[i];
+    if (cmp) {
+      rocksdb_options_set_comparator(list_column_family_options[i], cmp);
+    }
+    list_const_cf_options[i] = list_column_family_options[i];
+  }
+  rocksdb_column_family_handle_t** handles =
+      (rocksdb_column_family_handle_t**)malloc(
+          num_column_families * sizeof(rocksdb_column_family_handle_t*));
+
+  rocksdb_t* db = rocksdb_open_column_families(
+      db_options, db_name, (int)num_column_families,
+      (const char* const*)list_const_cf_names,
+      (const rocksdb_options_t* const*)list_const_cf_options, handles, &err);
+  if (expected_open_err == NULL) {
+    CheckNoError(err);
+    for (size_t i = 0; i < num_column_families; ++i) {
+      rocksdb_column_family_handle_destroy(handles[i]);
+    }
+    free(handles);
+    rocksdb_close(db);
+  } else {
+    assert(err != NULL);
+    assert(strcmp(err, expected_open_err) == 0);
+    free(handles);
+    free(err);
+  }
+
+  free(list_const_cf_names);
+  free(list_const_cf_options);
+  rocksdb_load_latest_options_destroy(db_options, list_column_family_names,
+                                      list_column_family_options,
+                                      num_column_families);
+}
+
 int main(int argc, char** argv) {
   (void)argc;
   (void)argv;
@@ -749,6 +905,21 @@ int main(int argc, char** argv) {
     CheckGet(db, roptions, "sstk22", "v5");
     CheckGet(db, roptions, "sstk3", "v6");
 
+    rocksdb_sstfilewriter_open(writer, sstfilename, &err);
+    CheckNoError(err);
+    rocksdb_sstfilewriter_put(writer, "abc1", 4, "v7", 2, &err);
+    CheckNoError(err);
+    rocksdb_sstfilewriter_put(writer, "abc2", 4, "v8", 2, &err);
+    CheckNoError(err);
+    rocksdb_sstfilewriter_put(writer, "abc3", 4, "v9", 2, &err);
+    CheckNoError(err);
+    rocksdb_sstfilewriter_put(writer, "abc4", 4, "v10", 3, &err);
+    CheckNoError(err);
+    rocksdb_sstfilewriter_delete_range(writer, "abc1", 4, "abc4", 4, &err);
+    CheckNoError(err);
+    rocksdb_sstfilewriter_finish(writer, &err);
+    CheckNoError(err);
+
     rocksdb_ingestexternalfileoptions_destroy(ing_opt);
     rocksdb_sstfilewriter_destroy(writer);
     rocksdb_options_destroy(io_options);
@@ -1250,7 +1421,6 @@ int main(int argc, char** argv) {
     rocksdb_merge(db, woptions, "bar", 3, "barvalue", 8, &err);
     CheckNoError(err);
     CheckGet(db, roptions, "bar", "fake");
-
   }
 
   StartPhase("columnfamilies");
@@ -1262,7 +1432,16 @@ int main(int argc, char** argv) {
     rocksdb_options_t* db_options = rocksdb_options_create();
     rocksdb_options_set_create_if_missing(db_options, 1);
     db = rocksdb_open(db_options, dbname, &err);
-    CheckNoError(err)
+    CheckNoError(err);
+    rocksdb_close(db);
+    {
+      const char* expected_cf_names[1] = {"default"};
+      LoadAndCheckLatestOptions(dbname, env, false, cache, NULL, 1,
+                                expected_cf_names, NULL);
+    }
+
+    rocksdb_options_set_create_if_missing(db_options, 0);
+    db = rocksdb_open(db_options, dbname, &err);
     rocksdb_column_family_handle_t* cfh;
     cfh = rocksdb_create_column_family(db, db_options, "cf1", &err);
     rocksdb_column_family_handle_destroy(cfh);
@@ -1282,6 +1461,10 @@ int main(int argc, char** argv) {
     const char* cf_names[2] = {"default", "cf1"};
     const rocksdb_options_t* cf_opts[2] = {cf_options, cf_options};
     rocksdb_column_family_handle_t* handles[2];
+
+    LoadAndCheckLatestOptions(dbname, env, false, cache, NULL, 2, cf_names,
+                              NULL);
+
     db = rocksdb_open_column_families(db_options, dbname, 2, cf_names, cf_opts, handles, &err);
     CheckNoError(err);
 
@@ -1296,6 +1479,9 @@ int main(int argc, char** argv) {
     CheckNoError(err);
     rocksdb_put_cf(db, woptions, handles[1], "foobar4", 7, "hello4", 6, &err);
     CheckNoError(err);
+    rocksdb_suggest_compact_range_cf(db, handles[1], "foo", 3, "foobar9", 7,
+                                     &err);
+    CheckNoError(err);
 
     rocksdb_flushoptions_t *flush_options = rocksdb_flushoptions_create();
     rocksdb_flushoptions_set_wait(flush_options, 1);
@@ -1443,12 +1629,20 @@ int main(int argc, char** argv) {
     CheckNoError(err);
     rocksdb_iter_destroy(iter);
 
+    GetAndCheckMetaDataCf(db, handles[1], cf_names[1]);
+
     rocksdb_drop_column_family(db, handles[1], &err);
     CheckNoError(err);
     for (i = 0; i < 2; i++) {
       rocksdb_column_family_handle_destroy(handles[i]);
     }
     rocksdb_close(db);
+    {
+      // As column family has been dropped, we expect only one column family.
+      const char* expected_cf_names[1] = {"default"};
+      LoadAndCheckLatestOptions(dbname, env, false, cache, NULL, 1,
+                                expected_cf_names, NULL);
+    }
     rocksdb_destroy_db(options, dbname, &err);
     rocksdb_options_destroy(db_options);
     rocksdb_options_destroy(cf_options);
@@ -1510,6 +1704,16 @@ int main(int argc, char** argv) {
     rocksdb_readoptions_set_total_order_seek(roptions, 0);
 
     rocksdb_close(db);
+
+    {
+      const char* expected_cf_names[1] = {"default"};
+      LoadAndCheckLatestOptions(dbname, env, false, cache, NULL, 1,
+                                expected_cf_names,
+                                "Invalid argument: leveldb.BytewiseComparator: "
+                                "does not match existing comparator foo");
+      LoadAndCheckLatestOptions(dbname, env, false, cache, cmp, 1,
+                                expected_cf_names, NULL);
+    }
     rocksdb_destroy_db(options, dbname, &err);
   }
 
@@ -1831,6 +2035,10 @@ int main(int argc, char** argv) {
     rocksdb_options_set_wal_compression(o, 1);
     CheckCondition(1 == rocksdb_options_get_wal_compression(o));
 
+    rocksdb_options_set_experimental_mempurge_threshold(o, 29.0);
+    CheckCondition(29.0 ==
+                   rocksdb_options_get_experimental_mempurge_threshold(o));
+
     /* Blob Options */
     rocksdb_options_set_enable_blob_files(o, 1);
     CheckCondition(1 == rocksdb_options_get_enable_blob_files(o));
@@ -1860,6 +2068,9 @@ int main(int argc, char** argv) {
     rocksdb_options_set_blob_file_starting_level(o, 5);
     CheckCondition(5 == rocksdb_options_get_blob_file_starting_level(o));
 
+    rocksdb_options_set_prepopulate_blob_cache(o, 1 /* flush only */);
+    CheckCondition(1 == rocksdb_options_get_prepopulate_blob_cache(o));
+
     // Create a copy that should be equal to the original.
     rocksdb_options_t* copy;
     copy = rocksdb_options_create_copy(o);
@@ -1961,6 +2172,8 @@ int main(int argc, char** argv) {
     CheckCondition(4 == rocksdb_options_get_bottommost_compression(copy));
     CheckCondition(2 == rocksdb_options_get_compaction_style(copy));
     CheckCondition(1 == rocksdb_options_get_atomic_flush(copy));
+    CheckCondition(29.0 ==
+                   rocksdb_options_get_experimental_mempurge_threshold(copy));
 
     // Copies should be independent.
     rocksdb_options_set_allow_ingest_behind(copy, 0);
@@ -2309,6 +2522,12 @@ int main(int argc, char** argv) {
     CheckCondition(0 == rocksdb_options_get_atomic_flush(copy));
     CheckCondition(1 == rocksdb_options_get_atomic_flush(o));
 
+    rocksdb_options_set_experimental_mempurge_threshold(copy, 229.0);
+    CheckCondition(229.0 ==
+                   rocksdb_options_get_experimental_mempurge_threshold(copy));
+    CheckCondition(29.0 ==
+                   rocksdb_options_get_experimental_mempurge_threshold(o));
+
     rocksdb_options_destroy(copy);
     rocksdb_options_destroy(o);
   }

db/column_family.cc

@@ -17,6 +17,7 @@
 #include <vector>
 
 #include "db/blob/blob_file_cache.h"
+#include "db/blob/blob_source.h"
 #include "db/compaction/compaction_picker.h"
 #include "db/compaction/compaction_picker_fifo.h"
 #include "db/compaction/compaction_picker_level.h"
@@ -516,7 +517,7 @@ ColumnFamilyData::ColumnFamilyData(
     const ColumnFamilyOptions& cf_options, const ImmutableDBOptions& db_options,
     const FileOptions* file_options, ColumnFamilySet* column_family_set,
     BlockCacheTracer* const block_cache_tracer,
-    const std::shared_ptr<IOTracer>& io_tracer,
+    const std::shared_ptr<IOTracer>& io_tracer, const std::string& db_id,
     const std::string& db_session_id)
     : id_(id),
       name_(name),
@@ -549,7 +550,8 @@ ColumnFamilyData::ColumnFamilyData(
       prev_compaction_needed_bytes_(0),
       allow_2pc_(db_options.allow_2pc),
       last_memtable_id_(0),
-      db_paths_registered_(false) {
+      db_paths_registered_(false),
+      mempurge_used_(false) {
   if (id_ != kDummyColumnFamilyDataId) {
     // TODO(cc): RegisterDbPaths can be expensive, considering moving it
     // outside of this constructor which might be called with db mutex held.
@@ -580,6 +582,8 @@ ColumnFamilyData::ColumnFamilyData(
     blob_file_cache_.reset(
         new BlobFileCache(_table_cache, ioptions(), soptions(), id_,
                           internal_stats_->GetBlobFileReadHist(), io_tracer));
+    blob_source_.reset(new BlobSource(ioptions(), db_id, db_session_id,
+                                      blob_file_cache_.get()));
 
     if (ioptions_.compaction_style == kCompactionStyleLevel) {
       compaction_picker_.reset(
@@ -695,19 +699,6 @@ ColumnFamilyData::~ColumnFamilyData() {
           id_, name_.c_str());
     }
   }
-
-  if (data_dirs_.size()) {  // Explicitly close data directories
-    Status s = Status::OK();
-    for (auto& data_dir_ptr : data_dirs_) {
-      if (data_dir_ptr) {
-        s = data_dir_ptr->Close(IOOptions(), nullptr);
-        if (!s.ok()) {
-          // TODO(zichen): add `Status Close()` and `CloseDirectories()
-          s.PermitUncheckedError();
-        }
-      }
-    }
-  }
 }
 
 bool ColumnFamilyData::UnrefAndTryDelete() {
@@ -782,13 +773,13 @@ namespace {
 std::unique_ptr<WriteControllerToken> SetupDelay(
     WriteController* write_controller, uint64_t compaction_needed_bytes,
     uint64_t prev_compaction_need_bytes, bool penalize_stop,
-    bool auto_comapctions_disabled) {
+    bool auto_compactions_disabled) {
   const uint64_t kMinWriteRate = 16 * 1024u;  // Minimum write rate 16KB/s.
 
   uint64_t max_write_rate = write_controller->max_delayed_write_rate();
   uint64_t write_rate = write_controller->delayed_write_rate();
 
-  if (auto_comapctions_disabled) {
+  if (auto_compactions_disabled) {
     // When auto compaction is disabled, always use the value user gave.
     write_rate = max_write_rate;
   } else if (write_controller->NeedsDelay() && max_write_rate > kMinWriteRate) {
@@ -1158,8 +1149,8 @@ Status ColumnFamilyData::RangesOverlapWithMemtables(
 
   auto read_seq = super_version->current->version_set()->LastSequence();
   ReadRangeDelAggregator range_del_agg(&internal_comparator_, read_seq);
-  auto* active_range_del_iter =
-      super_version->mem->NewRangeTombstoneIterator(read_opts, read_seq);
+  auto* active_range_del_iter = super_version->mem->NewRangeTombstoneIterator(
+      read_opts, read_seq, false /* immutable_memtable */);
   range_del_agg.AddTombstones(
       std::unique_ptr<FragmentedRangeTombstoneIterator>(active_range_del_iter));
   Status status;
@@ -1312,9 +1303,18 @@ void ColumnFamilyData::InstallSuperVersion(
   super_version_ = new_superversion;
   ++super_version_number_;
   super_version_->version_number = super_version_number_;
-  super_version_->write_stall_condition =
-      RecalculateWriteStallConditions(mutable_cf_options);
-
+  if (old_superversion == nullptr || old_superversion->current != current() ||
+      old_superversion->mem != mem_ ||
+      old_superversion->imm != imm_.current()) {
+    // Should not recalculate slow down condition if nothing has changed, since
+    // currently RecalculateWriteStallConditions() treats it as further slowing
+    // down is needed.
+    super_version_->write_stall_condition =
+        RecalculateWriteStallConditions(mutable_cf_options);
+  } else {
+    super_version_->write_stall_condition =
+        old_superversion->write_stall_condition;
+  }
   if (old_superversion != nullptr) {
     // Reset SuperVersions cached in thread local storage.
     // This should be done before old_superversion->Unref(). That's to ensure
@@ -1504,13 +1504,14 @@ ColumnFamilySet::ColumnFamilySet(const std::string& dbname,
                                  WriteController* _write_controller,
                                  BlockCacheTracer* const block_cache_tracer,
                                  const std::shared_ptr<IOTracer>& io_tracer,
+                                 const std::string& db_id,
                                  const std::string& db_session_id)
     : max_column_family_(0),
       file_options_(file_options),
       dummy_cfd_(new ColumnFamilyData(
           ColumnFamilyData::kDummyColumnFamilyDataId, "", nullptr, nullptr,
           nullptr, ColumnFamilyOptions(), *db_options, &file_options_, nullptr,
-          block_cache_tracer, io_tracer, db_session_id)),
+          block_cache_tracer, io_tracer, db_id, db_session_id)),
       default_cfd_cache_(nullptr),
       db_name_(dbname),
       db_options_(db_options),
@@ -1519,6 +1520,7 @@ ColumnFamilySet::ColumnFamilySet(const std::string& dbname,
       write_controller_(_write_controller),
       block_cache_tracer_(block_cache_tracer),
       io_tracer_(io_tracer),
+      db_id_(db_id),
       db_session_id_(db_session_id) {
   // initialize linked list
   dummy_cfd_->prev_ = dummy_cfd_;
@@ -1586,7 +1588,7 @@ ColumnFamilyData* ColumnFamilySet::CreateColumnFamily(
   ColumnFamilyData* new_cfd = new ColumnFamilyData(
       id, name, dummy_versions, table_cache_, write_buffer_manager_, options,
       *db_options_, &file_options_, this, block_cache_tracer_, io_tracer_,
-      db_session_id_);
+      db_id_, db_session_id_);
   column_families_.insert({name, id});
   column_family_data_.insert({id, new_cfd});
   max_column_family_ = std::max(max_column_family_, id);

db/column_family.h

@@ -47,6 +47,7 @@ class InstrumentedMutex;
 class InstrumentedMutexLock;
 struct SuperVersionContext;
 class BlobFileCache;
+class BlobSource;
 
 extern const double kIncSlowdownRatio;
 // This file contains a list of data structures for managing column family
@@ -376,7 +377,7 @@ class ColumnFamilyData {
                          SequenceNumber earliest_seq);
 
   TableCache* table_cache() const { return table_cache_.get(); }
-  BlobFileCache* blob_file_cache() const { return blob_file_cache_.get(); }
+  BlobSource* blob_source() const { return blob_source_.get(); }
 
   // See documentation in compaction_picker.h
   // REQUIRES: DB mutex held
@@ -479,11 +480,8 @@ class ColumnFamilyData {
       const MutableCFOptions& mutable_cf_options,
       const ImmutableCFOptions& immutable_cf_options);
 
-  // Recalculate some small conditions, which are changed only during
-  // compaction, adding new memtable and/or
-  // recalculation of compaction score. These values are used in
-  // DBImpl::MakeRoomForWrite function to decide, if it need to make
-  // a write stall
+  // Recalculate some stall conditions, which are changed only during
+  // compaction, adding new memtable and/or recalculation of compaction score.
   WriteStallCondition RecalculateWriteStallConditions(
       const MutableCFOptions& mutable_cf_options);
 
@@ -526,8 +524,14 @@ class ColumnFamilyData {
     return file_metadata_cache_res_mgr_;
   }
 
+  SequenceNumber GetFirstMemtableSequenceNumber() const;
+
   static const uint32_t kDummyColumnFamilyDataId;
 
+  // Keep track of whether the mempurge feature was ever used.
+  void SetMempurgeUsed() { mempurge_used_ = true; }
+  bool GetMempurgeUsed() { return mempurge_used_; }
+
  private:
   friend class ColumnFamilySet;
   ColumnFamilyData(uint32_t id, const std::string& name,
@@ -539,7 +543,7 @@ class ColumnFamilyData {
                    ColumnFamilySet* column_family_set,
                    BlockCacheTracer* const block_cache_tracer,
                    const std::shared_ptr<IOTracer>& io_tracer,
-                   const std::string& db_session_id);
+                   const std::string& db_id, const std::string& db_session_id);
 
   std::vector<std::string> GetDbPaths() const;
 
@@ -563,6 +567,7 @@ class ColumnFamilyData {
 
   std::unique_ptr<TableCache> table_cache_;
   std::unique_ptr<BlobFileCache> blob_file_cache_;
+  std::unique_ptr<BlobSource> blob_source_;
 
   std::unique_ptr<InternalStats> internal_stats_;
 
@@ -627,6 +632,7 @@ class ColumnFamilyData {
   // For charging memory usage of file metadata created for newly added files to
   // a Version associated with this CFD
   std::shared_ptr<CacheReservationManager> file_metadata_cache_res_mgr_;
+  bool mempurge_used_;
 };
 
 // ColumnFamilySet has interesting thread-safety requirements
@@ -673,7 +679,7 @@ class ColumnFamilySet {
                   WriteController* _write_controller,
                   BlockCacheTracer* const block_cache_tracer,
                   const std::shared_ptr<IOTracer>& io_tracer,
-                  const std::string& db_session_id);
+                  const std::string& db_id, const std::string& db_session_id);
   ~ColumnFamilySet();
 
   ColumnFamilyData* GetDefault() const;
@@ -735,6 +741,7 @@ class ColumnFamilySet {
   WriteController* write_controller_;
   BlockCacheTracer* const block_cache_tracer_;
   std::shared_ptr<IOTracer> io_tracer_;
+  const std::string& db_id_;
   std::string db_session_id_;
 };
 

db/column_family_test.cc

@@ -1116,7 +1116,7 @@ TEST_P(ColumnFamilyTest, DifferentWriteBufferSizes) {
   CreateColumnFamilies({"one", "two", "three"});
   ColumnFamilyOptions default_cf, one, two, three;
   // setup options. all column families have max_write_buffer_number setup to 10
-  // "default" -> 100KB memtable, start flushing immediatelly
+  // "default" -> 100KB memtable, start flushing immediately
   // "one" -> 200KB memtable, start flushing with two immutable memtables
   // "two" -> 1MB memtable, start flushing with three immutable memtables
   // "three" -> 90KB memtable, start flushing with four immutable memtables
@@ -2207,9 +2207,22 @@ TEST_P(ColumnFamilyTest, FlushStaleColumnFamilies) {
   PutRandomData(0, 100, 1000);  // flush
   WaitForFlush(0);
   WaitForFlush(2);
-  // 3 files for default column families, 1 file for column family [two], zero
-  // files for column family [one], because it's empty
-  AssertCountLiveFiles(4);
+  // at least 3 files for default column families, 1 file for column family
+  // [two], zero files for column family [one], because it's empty
+  std::vector<LiveFileMetaData> metadata;
+  db_->GetLiveFilesMetaData(&metadata);
+  ASSERT_GE(metadata.size(), 4);
+  bool has_cf1_sst = false;
+  bool has_cf2_sst = false;
+  for (const auto& file : metadata) {
+    if (file.column_family_name == "one") {
+      has_cf1_sst = true;
+    } else if (file.column_family_name == "two") {
+      has_cf2_sst = true;
+    }
+  }
+  ASSERT_FALSE(has_cf1_sst);
+  ASSERT_TRUE(has_cf2_sst);
 
   ASSERT_OK(Flush(0));
   ASSERT_EQ(0, dbfull()->TEST_total_log_size());
@@ -2926,7 +2939,7 @@ TEST_P(ColumnFamilyTest, CompactionSpeedupTwoColumnFamilies) {
   ASSERT_EQ(1, dbfull()->TEST_BGCompactionsAllowed());
 }
 
-TEST_P(ColumnFamilyTest, CreateAndDestoryOptions) {
+TEST_P(ColumnFamilyTest, CreateAndDestroyOptions) {
   std::unique_ptr<ColumnFamilyOptions> cfo(new ColumnFamilyOptions());
   ColumnFamilyHandle* cfh;
   Open();

db/compact_files_test.cc

@@ -77,7 +77,7 @@ TEST_F(CompactFilesTest, L0ConflictsFiles) {
   options.compression = kNoCompression;
 
   DB* db = nullptr;
-  DestroyDB(db_name_, options);
+  ASSERT_OK(DestroyDB(db_name_, options));
   Status s = DB::Open(options, db_name_, &db);
   assert(s.ok());
   assert(db);
@@ -128,7 +128,7 @@ TEST_F(CompactFilesTest, MultipleLevel) {
   options.listeners.emplace_back(collector);
 
   DB* db = nullptr;
-  DestroyDB(db_name_, options);
+  ASSERT_OK(DestroyDB(db_name_, options));
   Status s = DB::Open(options, db_name_, &db);
   ASSERT_OK(s);
   ASSERT_NE(db, nullptr);
@@ -211,7 +211,7 @@ TEST_F(CompactFilesTest, ObsoleteFiles) {
   options.listeners.emplace_back(collector);
 
   DB* db = nullptr;
-  DestroyDB(db_name_, options);
+  ASSERT_OK(DestroyDB(db_name_, options));
   Status s = DB::Open(options, db_name_, &db);
   ASSERT_OK(s);
   ASSERT_NE(db, nullptr);
@@ -250,7 +250,7 @@ TEST_F(CompactFilesTest, NotCutOutputOnLevel0) {
   options.listeners.emplace_back(collector);
 
   DB* db = nullptr;
-  DestroyDB(db_name_, options);
+  ASSERT_OK(DestroyDB(db_name_, options));
   Status s = DB::Open(options, db_name_, &db);
   assert(s.ok());
   assert(db);
@@ -288,7 +288,7 @@ TEST_F(CompactFilesTest, CapturingPendingFiles) {
   options.listeners.emplace_back(collector);
 
   DB* db = nullptr;
-  DestroyDB(db_name_, options);
+  ASSERT_OK(DestroyDB(db_name_, options));
   Status s = DB::Open(options, db_name_, &db);
   ASSERT_OK(s);
   assert(db);
@@ -366,7 +366,7 @@ TEST_F(CompactFilesTest, CompactionFilterWithGetSv) {
   options.compaction_filter = cf.get();
 
   DB* db = nullptr;
-  DestroyDB(db_name_, options);
+  ASSERT_OK(DestroyDB(db_name_, options));
   Status s = DB::Open(options, db_name_, &db);
   ASSERT_OK(s);
 
@@ -404,7 +404,7 @@ TEST_F(CompactFilesTest, SentinelCompressionType) {
        {CompactionStyle::kCompactionStyleLevel,
         CompactionStyle::kCompactionStyleUniversal,
         CompactionStyle::kCompactionStyleNone}) {
-    DestroyDB(db_name_, Options());
+    ASSERT_OK(DestroyDB(db_name_, Options()));
     Options options;
     options.compaction_style = compaction_style;
     // L0: Snappy, L1: ZSTD, L2: Snappy
@@ -458,7 +458,7 @@ TEST_F(CompactFilesTest, GetCompactionJobInfo) {
   options.listeners.emplace_back(collector);
 
   DB* db = nullptr;
-  DestroyDB(db_name_, options);
+  ASSERT_OK(DestroyDB(db_name_, options));
   Status s = DB::Open(options, db_name_, &db);
   ASSERT_OK(s);
   assert(db);

db/compaction/clipping_iterator.h

@@ -7,6 +7,7 @@
 
 #include <cassert>
 
+#include "rocksdb/comparator.h"
 #include "table/internal_iterator.h"
 
 namespace ROCKSDB_NAMESPACE {
@@ -19,7 +20,7 @@ namespace ROCKSDB_NAMESPACE {
 class ClippingIterator : public InternalIterator {
  public:
   ClippingIterator(InternalIterator* iter, const Slice* start, const Slice* end,
-                   const Comparator* cmp)
+                   const CompareInterface* cmp)
       : iter_(iter), start_(start), end_(end), cmp_(cmp), valid_(false) {
     assert(iter_);
     assert(cmp_);
@@ -268,7 +269,7 @@ class ClippingIterator : public InternalIterator {
   InternalIterator* iter_;
   const Slice* start_;
   const Slice* end_;
-  const Comparator* cmp_;
+  const CompareInterface* cmp_;
   bool valid_;
 };
 

db/compaction/compaction.cc

@@ -77,11 +77,11 @@ void Compaction::SetInputVersion(Version* _input_version) {
 void Compaction::GetBoundaryKeys(
     VersionStorageInfo* vstorage,
     const std::vector<CompactionInputFiles>& inputs, Slice* smallest_user_key,
-    Slice* largest_user_key) {
+    Slice* largest_user_key, int exclude_level) {
   bool initialized = false;
   const Comparator* ucmp = vstorage->InternalComparator()->user_comparator();
   for (size_t i = 0; i < inputs.size(); ++i) {
-    if (inputs[i].files.empty()) {
+    if (inputs[i].files.empty() || inputs[i].level == exclude_level) {
       continue;
     }
     if (inputs[i].level == 0) {
@@ -214,7 +214,8 @@ Compaction::Compaction(
     CompressionOptions _compression_opts, Temperature _output_temperature,
     uint32_t _max_subcompactions, std::vector<FileMetaData*> _grandparents,
     bool _manual_compaction, const std::string& _trim_ts, double _score,
-    bool _deletion_compaction, CompactionReason _compaction_reason,
+    bool _deletion_compaction, bool l0_files_might_overlap,
+    CompactionReason _compaction_reason,
     BlobGarbageCollectionPolicy _blob_garbage_collection_policy,
     double _blob_garbage_collection_age_cutoff)
     : input_vstorage_(vstorage),
@@ -233,6 +234,7 @@ Compaction::Compaction(
       output_compression_opts_(_compression_opts),
       output_temperature_(_output_temperature),
       deletion_compaction_(_deletion_compaction),
+      l0_files_might_overlap_(l0_files_might_overlap),
       inputs_(PopulateWithAtomicBoundaries(vstorage, std::move(_inputs))),
       grandparents_(std::move(_grandparents)),
       score_(_score),
@@ -241,6 +243,7 @@ Compaction::Compaction(
       is_manual_compaction_(_manual_compaction),
       trim_ts_(_trim_ts),
       is_trivial_move_(false),
+
       compaction_reason_(_compaction_reason),
       notify_on_compaction_completion_(false),
       enable_blob_garbage_collection_(
@@ -254,7 +257,9 @@ Compaction::Compaction(
           _blob_garbage_collection_age_cutoff < 0 ||
                   _blob_garbage_collection_age_cutoff > 1
               ? mutable_cf_options()->blob_garbage_collection_age_cutoff
-              : _blob_garbage_collection_age_cutoff) {
+              : _blob_garbage_collection_age_cutoff),
+      penultimate_level_(EvaluatePenultimateLevel(
+          immutable_options_, start_level_, output_level_)) {
   MarkFilesBeingCompacted(true);
   if (is_manual_compaction_) {
     compaction_reason_ = CompactionReason::kManualCompaction;
@@ -279,6 +284,39 @@ Compaction::Compaction(
   }
 
   GetBoundaryKeys(vstorage, inputs_, &smallest_user_key_, &largest_user_key_);
+
+  // Every compaction regardless of any compaction reason may respect the
+  // existing compact cursor in the output level to split output files
+  output_split_key_ = nullptr;
+  if (immutable_options_.compaction_style == kCompactionStyleLevel &&
+      immutable_options_.compaction_pri == kRoundRobin) {
+    const InternalKey* cursor =
+        &input_vstorage_->GetCompactCursors()[output_level_];
+    if (cursor->size() != 0) {
+      const Slice& cursor_user_key = ExtractUserKey(cursor->Encode());
+      auto ucmp = vstorage->InternalComparator()->user_comparator();
+      // May split output files according to the cursor if it in the user-key
+      // range
+      if (ucmp->CompareWithoutTimestamp(cursor_user_key, smallest_user_key_) >
+              0 &&
+          ucmp->CompareWithoutTimestamp(cursor_user_key, largest_user_key_) <=
+              0) {
+        output_split_key_ = cursor;
+      }
+    }
+  }
+
+  PopulatePenultimateLevelOutputRange();
+}
+
+void Compaction::PopulatePenultimateLevelOutputRange() {
+  if (!SupportsPerKeyPlacement()) {
+    return;
+  }
+
+  GetBoundaryKeys(input_vstorage_, inputs_,
+                  &penultimate_level_smallest_user_key_,
+                  &penultimate_level_largest_user_key_, number_levels_ - 1);
 }
 
 Compaction::~Compaction() {
@@ -290,6 +328,37 @@ Compaction::~Compaction() {
   }
 }
 
+bool Compaction::SupportsPerKeyPlacement() const {
+  return penultimate_level_ != kInvalidLevel;
+}
+
+int Compaction::GetPenultimateLevel() const { return penultimate_level_; }
+
+bool Compaction::OverlapPenultimateLevelOutputRange(
+    const Slice& smallest_key, const Slice& largest_key) const {
+  if (!SupportsPerKeyPlacement()) {
+    return false;
+  }
+  const Comparator* ucmp =
+      input_vstorage_->InternalComparator()->user_comparator();
+
+  return ucmp->Compare(smallest_key, penultimate_level_largest_user_key_) <=
+             0 &&
+         ucmp->Compare(largest_key, penultimate_level_smallest_user_key_) >= 0;
+}
+
+bool Compaction::WithinPenultimateLevelOutputRange(const Slice& key) const {
+  if (!SupportsPerKeyPlacement()) {
+    return false;
+  }
+
+  const Comparator* ucmp =
+      input_vstorage_->InternalComparator()->user_comparator();
+
+  return ucmp->Compare(key, penultimate_level_smallest_user_key_) >= 0 &&
+         ucmp->Compare(key, penultimate_level_largest_user_key_) <= 0;
+}
+
 bool Compaction::InputCompressionMatchesOutput() const {
   int base_level = input_vstorage_->base_level();
   bool matches =
@@ -311,8 +380,10 @@ bool Compaction::IsTrivialMove() const {
   // filter to be applied to that level, and thus cannot be a trivial move.
 
   // Check if start level have files with overlapping ranges
-  if (start_level_ == 0 && input_vstorage_->level0_non_overlapping() == false) {
-    // We cannot move files from L0 to L1 if the files are overlapping
+  if (start_level_ == 0 && input_vstorage_->level0_non_overlapping() == false &&
+      l0_files_might_overlap_) {
+    // We cannot move files from L0 to L1 if the L0 files in the LSM-tree are
+    // overlapping, unless we are sure that files picked in L0 don't overlap.
     return false;
   }
 
@@ -369,6 +440,11 @@ bool Compaction::IsTrivialMove() const {
     }
   }
 
+  // PerKeyPlacement compaction should never be trivial move.
+  if (SupportsPerKeyPlacement()) {
+    return false;
+  }
+
   return true;
 }
 
@@ -584,20 +660,23 @@ bool Compaction::IsOutputLevelEmpty() const {
 }
 
 bool Compaction::ShouldFormSubcompactions() const {
-  if (max_subcompactions_ <= 1 || cfd_ == nullptr) {
+  if (cfd_ == nullptr) {
     return false;
   }
 
-  // Note: the subcompaction boundary picking logic does not currently guarantee
-  // that all user keys that differ only by timestamp get processed by the same
-  // subcompaction.
-  if (cfd_->user_comparator()->timestamp_size() > 0) {
+  // Round-Robin pri under leveled compaction allows subcompactions by default
+  // and the number of subcompactions can be larger than max_subcompactions_
+  if (cfd_->ioptions()->compaction_pri == kRoundRobin &&
+      cfd_->ioptions()->compaction_style == kCompactionStyleLevel) {
+    return output_level_ > 0;
+  }
+
+  if (max_subcompactions_ <= 1) {
     return false;
   }
 
   if (cfd_->ioptions()->compaction_style == kCompactionStyleLevel) {
-    return (start_level_ == 0 || is_manual_compaction_) && output_level_ > 0 &&
-           !IsOutputLevelEmpty();
+    return (start_level_ == 0 || is_manual_compaction_) && output_level_ > 0;
   } else if (cfd_->ioptions()->compaction_style == kCompactionStyleUniversal) {
     return number_levels_ > 1 && output_level_ > 0;
   } else {
@@ -651,8 +730,36 @@ uint64_t Compaction::MinInputFileOldestAncesterTime(
   return min_oldest_ancester_time;
 }
 
-int Compaction::GetInputBaseLevel() const {
-  return input_vstorage_->base_level();
+int Compaction::EvaluatePenultimateLevel(
+    const ImmutableOptions& immutable_options, const int start_level,
+    const int output_level) {
+  // TODO: currently per_key_placement feature only support level and universal
+  //  compaction
+  if (immutable_options.compaction_style != kCompactionStyleLevel &&
+      immutable_options.compaction_style != kCompactionStyleUniversal) {
+    return kInvalidLevel;
+  }
+  if (output_level != immutable_options.num_levels - 1) {
+    return kInvalidLevel;
+  }
+
+  int penultimate_level = output_level - 1;
+  assert(penultimate_level < immutable_options.num_levels);
+  if (penultimate_level <= 0 || penultimate_level < start_level) {
+    return kInvalidLevel;
+  }
+
+  bool supports_per_key_placement =
+      immutable_options.preclude_last_level_data_seconds > 0;
+
+  // it could be overridden by unittest
+  TEST_SYNC_POINT_CALLBACK("Compaction::SupportsPerKeyPlacement:Enabled",
+                           &supports_per_key_placement);
+  if (!supports_per_key_placement) {
+    return kInvalidLevel;
+  }
+
+  return penultimate_level;
 }
 
 }  // namespace ROCKSDB_NAMESPACE

db/compaction/compaction.h

@@ -81,6 +81,7 @@ class Compaction {
              std::vector<FileMetaData*> grandparents,
              bool manual_compaction = false, const std::string& trim_ts = "",
              double score = -1, bool deletion_compaction = false,
+             bool l0_files_might_overlap = true,
              CompactionReason compaction_reason = CompactionReason::kUnknown,
              BlobGarbageCollectionPolicy blob_garbage_collection_policy =
                  BlobGarbageCollectionPolicy::kUseDefault,
@@ -177,6 +178,12 @@ class Compaction {
   // moving a single input file to the next level (no merging or splitting)
   bool IsTrivialMove() const;
 
+  // The split user key in the output level if this compaction is required to
+  // split the output files according to the existing cursor in the output
+  // level under round-robin compaction policy. Empty indicates no required
+  // splitting key
+  const InternalKey* GetOutputSplitKey() const { return output_split_key_; }
+
   // If true, then the compaction can be done by simply deleting input files.
   bool deletion_compaction() const { return deletion_compaction_; }
 
@@ -205,6 +212,11 @@ class Compaction {
   // Is this compaction creating a file in the bottom most level?
   bool bottommost_level() const { return bottommost_level_; }
 
+  // Is the compaction compact to the last level
+  bool is_last_level() const {
+    return output_level_ == immutable_options_.num_levels - 1;
+  }
+
   // Does this compaction include all sst files?
   bool is_full_compaction() const { return is_full_compaction_; }
 
@@ -295,7 +307,25 @@ class Compaction {
 
   Slice GetLargestUserKey() const { return largest_user_key_; }
 
-  int GetInputBaseLevel() const;
+  // Return true if the compaction supports per_key_placement
+  bool SupportsPerKeyPlacement() const;
+
+  // Get per_key_placement penultimate output level, which is `last_level - 1`
+  // if per_key_placement feature is supported. Otherwise, return -1.
+  int GetPenultimateLevel() const;
+
+  // Return true if the given range is overlap with penultimate level output
+  // range.
+  bool OverlapPenultimateLevelOutputRange(const Slice& smallest_key,
+                                          const Slice& largest_key) const;
+
+  // Return true if the key is within penultimate level output range for
+  // per_key_placement feature, which is safe to place the key to the
+  // penultimate level. different compaction strategy has different rules.
+  // If per_key_placement is not supported, always return false.
+  // TODO: currently it doesn't support moving data from the last level to the
+  //  penultimate level
+  bool WithinPenultimateLevelOutputRange(const Slice& key) const;
 
   CompactionReason compaction_reason() const { return compaction_reason_; }
 
@@ -332,6 +362,15 @@ class Compaction {
     return notify_on_compaction_completion_;
   }
 
+  static constexpr int kInvalidLevel = -1;
+  // Evaluate penultimate output level. If the compaction supports
+  // per_key_placement feature, it returns the penultimate level number.
+  // Otherwise, it's set to kInvalidLevel (-1), which means
+  // output_to_penultimate_level is not supported.
+  static int EvaluatePenultimateLevel(const ImmutableOptions& immutable_options,
+                                      const int start_level,
+                                      const int output_level);
+
  private:
   // mark (or clear) all files that are being compacted
   void MarkFilesBeingCompacted(bool mark_as_compacted);
@@ -339,7 +378,18 @@ class Compaction {
   // get the smallest and largest key present in files to be compacted
   static void GetBoundaryKeys(VersionStorageInfo* vstorage,
                               const std::vector<CompactionInputFiles>& inputs,
-                              Slice* smallest_key, Slice* largest_key);
+                              Slice* smallest_key, Slice* largest_key,
+                              int exclude_level = -1);
+
+  // populate penultimate level output range, which will be used to determine if
+  // a key is safe to output to the penultimate level (details see
+  // `Compaction::WithinPenultimateLevelOutputRange()`.
+  // TODO: Currently the penultimate level output range is the min/max keys of
+  //  non-last-level input files. Which is only good if there's no key moved
+  //  from the last level to the penultimate level. For a more complicated per
+  //  key placement which may move data from the last level to the penultimate
+  //  level, it needs extra check.
+  void PopulatePenultimateLevelOutputRange();
 
   // Get the atomic file boundaries for all files in the compaction. Necessary
   // in order to avoid the scenario described in
@@ -379,6 +429,13 @@ class Compaction {
   Temperature output_temperature_;
   // If true, then the compaction can be done by simply deleting input files.
   const bool deletion_compaction_;
+  // should it split the output file using the compact cursor?
+  const InternalKey* output_split_key_;
+
+  // L0 files in LSM-tree might be overlapping. But the compaction picking
+  // logic might pick a subset of the files that aren't overlapping. if
+  // that is the case, set the value to false. Otherwise, set it true.
+  bool l0_files_might_overlap_;
 
   // Compaction input files organized by level. Constant after construction
   const std::vector<CompactionInputFiles> inputs_;
@@ -430,8 +487,36 @@ class Compaction {
 
   // Blob garbage collection age cutoff.
   double blob_garbage_collection_age_cutoff_;
+
+  // only set when per_key_placement feature is enabled, -1 (kInvalidLevel)
+  // means not supported.
+  const int penultimate_level_;
+
+  // Key range for penultimate level output
+  Slice penultimate_level_smallest_user_key_;
+  Slice penultimate_level_largest_user_key_;
 };
 
+#ifndef NDEBUG
+// Helper struct only for tests, which contains the data to decide if a key
+// should be output to the penultimate level.
+// TODO: remove this when the public feature knob is available
+struct PerKeyPlacementContext {
+  const int level;
+  const Slice key;
+  const Slice value;
+  const SequenceNumber seq_num;
+
+  bool output_to_penultimate_level;
+
+  PerKeyPlacementContext(int _level, Slice _key, Slice _value,
+                         SequenceNumber _seq_num)
+      : level(_level), key(_key), value(_value), seq_num(_seq_num) {
+    output_to_penultimate_level = false;
+  }
+};
+#endif /* !NDEBUG */
+
 // Return sum of sizes of all files in `files`.
 extern uint64_t TotalFileSize(const std::vector<FileMetaData*>& files);
 

db/compaction/compaction_iterator.cc

@@ -33,7 +33,8 @@ CompactionIterator::CompactionIterator(
     const Compaction* compaction, const CompactionFilter* compaction_filter,
     const std::atomic<bool>* shutting_down,
     const std::shared_ptr<Logger> info_log,
-    const std::string* full_history_ts_low)
+    const std::string* full_history_ts_low,
+    const SequenceNumber penultimate_level_cutoff_seqno)
     : CompactionIterator(
           input, cmp, merge_helper, last_sequence, snapshots,
           earliest_write_conflict_snapshot, job_snapshot, snapshot_checker, env,
@@ -42,7 +43,8 @@ CompactionIterator::CompactionIterator(
           manual_compaction_canceled,
           std::unique_ptr<CompactionProxy>(
               compaction ? new RealCompaction(compaction) : nullptr),
-          compaction_filter, shutting_down, info_log, full_history_ts_low) {}
+          compaction_filter, shutting_down, info_log, full_history_ts_low,
+          penultimate_level_cutoff_seqno) {}
 
 CompactionIterator::CompactionIterator(
     InternalIterator* input, const Comparator* cmp, MergeHelper* merge_helper,
@@ -58,7 +60,8 @@ CompactionIterator::CompactionIterator(
     const CompactionFilter* compaction_filter,
     const std::atomic<bool>* shutting_down,
     const std::shared_ptr<Logger> info_log,
-    const std::string* full_history_ts_low)
+    const std::string* full_history_ts_low,
+    const SequenceNumber penultimate_level_cutoff_seqno)
     : input_(input, cmp,
              !compaction || compaction->DoesInputReferenceBlobFiles()),
       cmp_(cmp),
@@ -77,6 +80,15 @@ CompactionIterator::CompactionIterator(
       compaction_filter_(compaction_filter),
       shutting_down_(shutting_down),
       manual_compaction_canceled_(manual_compaction_canceled),
+      bottommost_level_(!compaction_ ? false
+                                     : compaction_->bottommost_level() &&
+                                           !compaction_->allow_ingest_behind()),
+      // snapshots_ cannot be nullptr, but we will assert later in the body of
+      // the constructor.
+      visible_at_tip_(snapshots_ ? snapshots_->empty() : false),
+      earliest_snapshot_(!snapshots_ || snapshots_->empty()
+                             ? kMaxSequenceNumber
+                             : snapshots_->at(0)),
       info_log_(info_log),
       allow_data_in_errors_(allow_data_in_errors),
       enforce_single_del_contracts_(enforce_single_del_contracts),
@@ -92,27 +104,13 @@ CompactionIterator::CompactionIterator(
           CreatePrefetchBufferCollectionIfNeeded(compaction_.get())),
       current_key_committed_(false),
       cmp_with_history_ts_low_(0),
-      level_(compaction_ == nullptr ? 0 : compaction_->level()) {
+      level_(compaction_ == nullptr ? 0 : compaction_->level()),
+      penultimate_level_cutoff_seqno_(penultimate_level_cutoff_seqno) {
   assert(snapshots_ != nullptr);
-  bottommost_level_ = compaction_ == nullptr
-                          ? false
-                          : compaction_->bottommost_level() &&
-                                !compaction_->allow_ingest_behind();
+
   if (compaction_ != nullptr) {
     level_ptrs_ = std::vector<size_t>(compaction_->number_levels(), 0);
   }
-  if (snapshots_->size() == 0) {
-    // optimize for fast path if there are no snapshots
-    visible_at_tip_ = true;
-    earliest_snapshot_iter_ = snapshots_->end();
-    earliest_snapshot_ = kMaxSequenceNumber;
-    latest_snapshot_ = 0;
-  } else {
-    visible_at_tip_ = false;
-    earliest_snapshot_iter_ = snapshots_->begin();
-    earliest_snapshot_ = snapshots_->at(0);
-    latest_snapshot_ = snapshots_->back();
-  }
 #ifndef NDEBUG
   // findEarliestVisibleSnapshot assumes this ordering.
   for (size_t i = 1; i < snapshots_->size(); ++i) {
@@ -169,7 +167,7 @@ void CompactionIterator::Next() {
       current_key_.UpdateInternalKey(ikey_.sequence, ikey_.type);
       key_ = current_key_.GetInternalKey();
       ikey_.user_key = current_key_.GetUserKey();
-      valid_ = true;
+      validity_info_.SetValid(ValidContext::kMerge1);
     } else {
       // We consumed all pinned merge operands, release pinned iterators
       pinned_iters_mgr_.ReleasePinnedData();
@@ -187,7 +185,7 @@ void CompactionIterator::Next() {
     NextFromInput();
   }
 
-  if (valid_) {
+  if (Valid()) {
     // Record that we've outputted a record for the current key.
     has_outputted_key_ = true;
   }
@@ -197,6 +195,7 @@ void CompactionIterator::Next() {
 
 bool CompactionIterator::InvokeFilterIfNeeded(bool* need_skip,
                                               Slice* skip_until) {
+  // TODO: support compaction filter for wide-column entities
   if (!compaction_filter_ ||
       (ikey_.type != kTypeValue && ikey_.type != kTypeBlobIndex)) {
     return true;
@@ -223,7 +222,6 @@ bool CompactionIterator::InvokeFilterIfNeeded(bool* need_skip,
   {
     StopWatchNano timer(clock_, report_detailed_time_);
     if (kTypeBlobIndex == ikey_.type) {
-      blob_value_.Reset();
       filter = compaction_filter_->FilterBlobByKey(
           level_, filter_key, &compaction_filter_value_,
           compaction_filter_skip_until_.rep());
@@ -232,7 +230,7 @@ bool CompactionIterator::InvokeFilterIfNeeded(bool* need_skip,
         if (compaction_ == nullptr) {
           status_ =
               Status::Corruption("Unexpected blob index outside of compaction");
-          valid_ = false;
+          validity_info_.Invalidate();
           return false;
         }
 
@@ -247,7 +245,7 @@ bool CompactionIterator::InvokeFilterIfNeeded(bool* need_skip,
         Status s = blob_index.DecodeFrom(value_);
         if (!s.ok()) {
           status_ = s;
-          valid_ = false;
+          validity_info_.Invalidate();
           return false;
         }
 
@@ -265,7 +263,7 @@ bool CompactionIterator::InvokeFilterIfNeeded(bool* need_skip,
                                      &bytes_read);
         if (!s.ok()) {
           status_ = s;
-          valid_ = false;
+          validity_info_.Invalidate();
           return false;
         }
 
@@ -289,7 +287,7 @@ bool CompactionIterator::InvokeFilterIfNeeded(bool* need_skip,
     // Should not reach here, since FilterV2 should never return kUndetermined.
     status_ =
         Status::NotSupported("FilterV2() should never return kUndetermined");
-    valid_ = false;
+    validity_info_.Invalidate();
     return false;
   }
 
@@ -338,7 +336,7 @@ bool CompactionIterator::InvokeFilterIfNeeded(bool* need_skip,
       status_ = Status::NotSupported(
           "Only stacked BlobDB's internal compaction filter can return "
           "kChangeBlobIndex.");
-      valid_ = false;
+      validity_info_.Invalidate();
       return false;
     }
     if (ikey_.type == kTypeValue) {
@@ -351,7 +349,7 @@ bool CompactionIterator::InvokeFilterIfNeeded(bool* need_skip,
     if (!compaction_filter_->IsStackedBlobDbInternalCompactionFilter()) {
       status_ = Status::NotSupported(
           "CompactionFilter for integrated BlobDB should not return kIOError");
-      valid_ = false;
+      validity_info_.Invalidate();
       return false;
     }
     status_ = Status::IOError("Failed to access blob during compaction filter");
@@ -362,12 +360,13 @@ bool CompactionIterator::InvokeFilterIfNeeded(bool* need_skip,
 
 void CompactionIterator::NextFromInput() {
   at_next_ = false;
-  valid_ = false;
+  validity_info_.Invalidate();
 
-  while (!valid_ && input_.Valid() && !IsPausingManualCompaction() &&
+  while (!Valid() && input_.Valid() && !IsPausingManualCompaction() &&
          !IsShuttingDown()) {
     key_ = input_.key();
     value_ = input_.value();
+    blob_value_.Reset();
     iter_stats_.num_input_records++;
 
     Status pik_status = ParseInternalKey(key_, &ikey_, allow_data_in_errors_);
@@ -384,7 +383,7 @@ void CompactionIterator::NextFromInput() {
       has_current_user_key_ = false;
       current_user_key_sequence_ = kMaxSequenceNumber;
       current_user_key_snapshot_ = 0;
-      valid_ = true;
+      validity_info_.SetValid(ValidContext::kParseKeyError);
       break;
     }
     TEST_SYNC_POINT_CALLBACK("CompactionIterator:ProcessKV", &ikey_);
@@ -497,7 +496,7 @@ void CompactionIterator::NextFromInput() {
 
     if (UNLIKELY(!current_key_committed_)) {
       assert(snapshot_checker_ != nullptr);
-      valid_ = true;
+      validity_info_.SetValid(ValidContext::kCurrentKeyUncommitted);
       break;
     }
 
@@ -519,7 +518,8 @@ void CompactionIterator::NextFromInput() {
       // In the previous iteration we encountered a single delete that we could
       // not compact out.  We will keep this Put, but can drop it's data.
       // (See Optimization 3, below.)
-      if (ikey_.type != kTypeValue && ikey_.type != kTypeBlobIndex) {
+      if (ikey_.type != kTypeValue && ikey_.type != kTypeBlobIndex &&
+          ikey_.type != kTypeWideColumnEntity) {
         ROCKS_LOG_FATAL(info_log_, "Unexpected key %s for compaction output",
                         ikey_.DebugString(allow_data_in_errors_, true).c_str());
         assert(false);
@@ -533,13 +533,13 @@ void CompactionIterator::NextFromInput() {
         assert(false);
       }
 
-      if (ikey_.type == kTypeBlobIndex) {
+      if (ikey_.type == kTypeBlobIndex || ikey_.type == kTypeWideColumnEntity) {
         ikey_.type = kTypeValue;
         current_key_.UpdateInternalKey(ikey_.sequence, ikey_.type);
       }
 
       value_.clear();
-      valid_ = true;
+      validity_info_.SetValid(ValidContext::kKeepSDAndClearPut);
       clear_and_output_next_key_ = false;
     } else if (ikey_.type == kTypeSingleDeletion) {
       // We can compact out a SingleDelete if:
@@ -663,7 +663,7 @@ void CompactionIterator::NextFromInput() {
             ++iter_stats_.num_single_del_mismatch;
             if (enforce_single_del_contracts_) {
               ROCKS_LOG_ERROR(info_log_, "%s", oss.str().c_str());
-              valid_ = false;
+              validity_info_.Invalidate();
               status_ = Status::Corruption(oss.str());
               return;
             }
@@ -672,7 +672,7 @@ void CompactionIterator::NextFromInput() {
             // We cannot drop the SingleDelete as timestamp is enabled, and
             // timestamp of this key is greater than or equal to
             // *full_history_ts_low_. We will output the SingleDelete.
-            valid_ = true;
+            validity_info_.SetValid(ValidContext::kKeepTsHistory);
           } else if (has_outputted_key_ ||
                      DefinitelyInSnapshot(ikey_.sequence,
                                           earliest_write_conflict_snapshot_) ||
@@ -689,7 +689,8 @@ void CompactionIterator::NextFromInput() {
             // either way. We will maintain counts of how many mismatches
             // happened
             if (next_ikey.type != kTypeValue &&
-                next_ikey.type != kTypeBlobIndex) {
+                next_ikey.type != kTypeBlobIndex &&
+                next_ikey.type != kTypeWideColumnEntity) {
               ++iter_stats_.num_single_del_mismatch;
             }
 
@@ -706,7 +707,7 @@ void CompactionIterator::NextFromInput() {
             // outputted on the next iteration.)
 
             // Setting valid_ to true will output the current SingleDelete
-            valid_ = true;
+            validity_info_.SetValid(ValidContext::kKeepSDForConflictCheck);
 
             // Set up the Put to be outputted in the next iteration.
             // (Optimization 3).
@@ -718,7 +719,7 @@ void CompactionIterator::NextFromInput() {
         } else {
           // We hit the next snapshot without hitting a put, so the iterator
           // returns the single delete.
-          valid_ = true;
+          validity_info_.SetValid(ValidContext::kKeepSDForSnapshot);
           TEST_SYNC_POINT_CALLBACK(
               "CompactionIterator::NextFromInput:SingleDelete:3",
               const_cast<Compaction*>(c));
@@ -751,11 +752,11 @@ void CompactionIterator::NextFromInput() {
           assert(bottommost_level_);
         } else {
           // Output SingleDelete
-          valid_ = true;
+          validity_info_.SetValid(ValidContext::kKeepSD);
         }
       }
 
-      if (valid_) {
+      if (Valid()) {
         at_next_ = true;
       }
     } else if (last_snapshot == current_user_key_snapshot_ ||
@@ -854,7 +855,7 @@ void CompactionIterator::NextFromInput() {
           (ParseInternalKey(input_.key(), &next_ikey, allow_data_in_errors_)
                .ok()) &&
           cmp_->EqualWithoutTimestamp(ikey_.user_key, next_ikey.user_key)) {
-        valid_ = true;
+        validity_info_.SetValid(ValidContext::kKeepDel);
         at_next_ = true;
       }
     } else if (ikey_.type == kTypeMerge) {
@@ -898,7 +899,7 @@ void CompactionIterator::NextFromInput() {
         current_key_.UpdateInternalKey(ikey_.sequence, ikey_.type);
         key_ = current_key_.GetInternalKey();
         ikey_.user_key = current_key_.GetUserKey();
-        valid_ = true;
+        validity_info_.SetValid(ValidContext::kMerge2);
       } else {
         // all merge operands were filtered out. reset the user key, since the
         // batch consumed by the merge operator should not shadow any keys
@@ -920,7 +921,7 @@ void CompactionIterator::NextFromInput() {
         ++iter_stats_.num_record_drop_range_del;
         AdvanceInputIter();
       } else {
-        valid_ = true;
+        validity_info_.SetValid(ValidContext::kNewUserKey);
       }
     }
 
@@ -929,13 +930,18 @@ void CompactionIterator::NextFromInput() {
     }
   }
 
-  if (!valid_ && IsShuttingDown()) {
+  if (!Valid() && IsShuttingDown()) {
     status_ = Status::ShutdownInProgress();
   }
 
   if (IsPausingManualCompaction()) {
     status_ = Status::Incomplete(Status::SubCode::kManualCompactionPaused);
   }
+
+  // Propagate corruption status from memtable itereator
+  if (!input_.Valid() && input_.status().IsCorruption()) {
+    status_ = input_.status();
+  }
 }
 
 bool CompactionIterator::ExtractLargeValueIfNeededImpl() {
@@ -948,7 +954,7 @@ bool CompactionIterator::ExtractLargeValueIfNeededImpl() {
 
   if (!s.ok()) {
     status_ = s;
-    valid_ = false;
+    validity_info_.Invalidate();
 
     return false;
   }
@@ -993,7 +999,7 @@ void CompactionIterator::GarbageCollectBlobIfNeeded() {
 
       if (!s.ok()) {
         status_ = s;
-        valid_ = false;
+        validity_info_.Invalidate();
 
         return;
       }
@@ -1019,7 +1025,7 @@ void CompactionIterator::GarbageCollectBlobIfNeeded() {
 
       if (!s.ok()) {
         status_ = s;
-        valid_ = false;
+        validity_info_.Invalidate();
 
         return;
       }
@@ -1052,14 +1058,14 @@ void CompactionIterator::GarbageCollectBlobIfNeeded() {
     if (blob_decision == CompactionFilter::BlobDecision::kCorruption) {
       status_ =
           Status::Corruption("Corrupted blob reference encountered during GC");
-      valid_ = false;
+      validity_info_.Invalidate();
 
       return;
     }
 
     if (blob_decision == CompactionFilter::BlobDecision::kIOError) {
       status_ = Status::IOError("Could not relocate blob during GC");
-      valid_ = false;
+      validity_info_.Invalidate();
 
       return;
     }
@@ -1072,14 +1078,64 @@ void CompactionIterator::GarbageCollectBlobIfNeeded() {
   }
 }
 
+void CompactionIterator::DecideOutputLevel() {
+#ifndef NDEBUG
+  // Could be overridden by unittest
+  PerKeyPlacementContext context(level_, ikey_.user_key, value_,
+                                 ikey_.sequence);
+  TEST_SYNC_POINT_CALLBACK("CompactionIterator::PrepareOutput.context",
+                           &context);
+  output_to_penultimate_level_ = context.output_to_penultimate_level;
+#endif /* !NDEBUG */
+
+  // if the key is newer than the cutoff sequence or within the earliest
+  // snapshot, it should output to the penultimate level.
+  if (ikey_.sequence > penultimate_level_cutoff_seqno_ ||
+      ikey_.sequence > earliest_snapshot_) {
+    output_to_penultimate_level_ = true;
+  }
+
+  if (output_to_penultimate_level_) {
+    // If it's decided to output to the penultimate level, but unsafe to do so,
+    // still output to the last level. For example, moving the data from a lower
+    // level to a higher level outside of the higher-level input key range is
+    // considered unsafe, because the key may conflict with higher-level SSTs
+    // not from this compaction.
+    // TODO: add statistic for declined output_to_penultimate_level
+    bool safe_to_penultimate_level =
+        compaction_->WithinPenultimateLevelOutputRange(ikey_.user_key);
+    if (!safe_to_penultimate_level) {
+      output_to_penultimate_level_ = false;
+      // It could happen when disable/enable `last_level_temperature` while
+      // holding a snapshot. When `last_level_temperature` is not set
+      // (==kUnknown), the data newer than any snapshot is pushed to the last
+      // level, but when the per_key_placement feature is enabled on the fly,
+      // the data later than the snapshot has to be moved to the penultimate
+      // level, which may or may not be safe. So the user needs to make sure all
+      // snapshot is released before enabling `last_level_temperature` feature
+      // We will migrate the feature to `last_level_temperature` and maybe make
+      // it not dynamically changeable.
+      if (ikey_.sequence > earliest_snapshot_) {
+        status_ = Status::Corruption(
+            "Unsafe to store Seq later than snapshot in the last level if "
+            "per_key_placement is enabled");
+      }
+    }
+  }
+}
+
 void CompactionIterator::PrepareOutput() {
-  if (valid_) {
+  if (Valid()) {
     if (ikey_.type == kTypeValue) {
       ExtractLargeValueIfNeeded();
     } else if (ikey_.type == kTypeBlobIndex) {
       GarbageCollectBlobIfNeeded();
     }
 
+    if (compaction_ != nullptr && compaction_->SupportsPerKeyPlacement()) {
+      DecideOutputLevel();
+    }
+
     // Zeroing out the sequence number leads to better compression.
     // If this is the bottommost level (no files in lower levels)
     // and the earliest snapshot is larger than this seqno
@@ -1091,10 +1147,12 @@ void CompactionIterator::PrepareOutput() {
     //
     // Can we do the same for levels above bottom level as long as
     // KeyNotExistsBeyondOutputLevel() return true?
-    if (valid_ && compaction_ != nullptr &&
+    if (Valid() && compaction_ != nullptr &&
         !compaction_->allow_ingest_behind() && bottommost_level_ &&
         DefinitelyInSnapshot(ikey_.sequence, earliest_snapshot_) &&
-        ikey_.type != kTypeMerge && current_key_committed_) {
+        ikey_.type != kTypeMerge && current_key_committed_ &&
+        !output_to_penultimate_level_ &&
+        ikey_.sequence < penultimate_level_cutoff_seqno_) {
       if (ikey_.type == kTypeDeletion ||
           (ikey_.type == kTypeSingleDeletion && timestamp_size_ == 0)) {
         ROCKS_LOG_FATAL(
@@ -1103,13 +1161,14 @@ void CompactionIterator::PrepareOutput() {
             "earliest_snapshot %" PRIu64
             ", earliest_write_conflict_snapshot %" PRIu64
             " job_snapshot %" PRIu64
-            ". timestamp_size: %d full_history_ts_low_ %s",
+            ". timestamp_size: %d full_history_ts_low_ %s. validity %x",
             ikey_.DebugString(allow_data_in_errors_, true).c_str(),
             earliest_snapshot_, earliest_write_conflict_snapshot_,
             job_snapshot_, static_cast<int>(timestamp_size_),
             full_history_ts_low_ != nullptr
                 ? Slice(*full_history_ts_low_).ToString(true).c_str()
-                : "null");
+                : "null",
+            validity_info_.rep);
         assert(false);
       }
       ikey_.sequence = 0;
@@ -1225,7 +1284,10 @@ std::unique_ptr<BlobFetcher> CompactionIterator::CreateBlobFetcherIfNeeded(
     return nullptr;
   }
 
-  return std::unique_ptr<BlobFetcher>(new BlobFetcher(version, ReadOptions()));
+  ReadOptions read_options;
+  read_options.fill_cache = false;
+
+  return std::unique_ptr<BlobFetcher>(new BlobFetcher(version, read_options));
 }
 
 std::unique_ptr<PrefetchBufferCollection>

db/compaction/compaction_iterator.h

@@ -32,7 +32,7 @@ class SequenceIterWrapper : public InternalIterator {
  public:
   SequenceIterWrapper(InternalIterator* iter, const Comparator* cmp,
                       bool need_count_entries)
-      : icmp_(cmp, /*named=*/false),
+      : icmp_(cmp),
         inner_iter_(iter),
         need_count_entries_(need_count_entries) {}
   bool Valid() const override { return inner_iter_->Valid(); }
@@ -105,6 +105,10 @@ class CompactionIterator {
     virtual bool DoesInputReferenceBlobFiles() const = 0;
 
     virtual const Compaction* real_compaction() const = 0;
+
+    virtual bool SupportsPerKeyPlacement() const = 0;
+
+    virtual bool WithinPenultimateLevelOutputRange(const Slice& key) const = 0;
   };
 
   class RealCompaction : public CompactionProxy {
@@ -163,46 +167,54 @@ class CompactionIterator {
 
     const Compaction* real_compaction() const override { return compaction_; }
 
+    bool SupportsPerKeyPlacement() const override {
+      return compaction_->SupportsPerKeyPlacement();
+    }
+
+    // Check if key is within penultimate level output range, to see if it's
+    // safe to output to the penultimate level for per_key_placement feature.
+    bool WithinPenultimateLevelOutputRange(const Slice& key) const override {
+      return compaction_->WithinPenultimateLevelOutputRange(key);
+    }
+
    private:
     const Compaction* compaction_;
   };
 
-  CompactionIterator(InternalIterator* input, const Comparator* cmp,
-                     MergeHelper* merge_helper, SequenceNumber last_sequence,
-                     std::vector<SequenceNumber>* snapshots,
-                     SequenceNumber earliest_write_conflict_snapshot,
-                     SequenceNumber job_snapshot,
-                     const SnapshotChecker* snapshot_checker, Env* env,
-                     bool report_detailed_time, bool expect_valid_internal_key,
-                     CompactionRangeDelAggregator* range_del_agg,
-                     BlobFileBuilder* blob_file_builder,
-                     bool allow_data_in_errors,
-                     bool enforce_single_del_contracts,
-                     const std::atomic<bool>& manual_compaction_canceled,
-                     const Compaction* compaction = nullptr,
-                     const CompactionFilter* compaction_filter = nullptr,
-                     const std::atomic<bool>* shutting_down = nullptr,
-                     const std::shared_ptr<Logger> info_log = nullptr,
-                     const std::string* full_history_ts_low = nullptr);
+  CompactionIterator(
+      InternalIterator* input, const Comparator* cmp, MergeHelper* merge_helper,
+      SequenceNumber last_sequence, std::vector<SequenceNumber>* snapshots,
+      SequenceNumber earliest_write_conflict_snapshot,
+      SequenceNumber job_snapshot, const SnapshotChecker* snapshot_checker,
+      Env* env, bool report_detailed_time, bool expect_valid_internal_key,
+      CompactionRangeDelAggregator* range_del_agg,
+      BlobFileBuilder* blob_file_builder, bool allow_data_in_errors,
+      bool enforce_single_del_contracts,
+      const std::atomic<bool>& manual_compaction_canceled,
+      const Compaction* compaction = nullptr,
+      const CompactionFilter* compaction_filter = nullptr,
+      const std::atomic<bool>* shutting_down = nullptr,
+      const std::shared_ptr<Logger> info_log = nullptr,
+      const std::string* full_history_ts_low = nullptr,
+      const SequenceNumber penultimate_level_cutoff_seqno = kMaxSequenceNumber);
 
   // Constructor with custom CompactionProxy, used for tests.
-  CompactionIterator(InternalIterator* input, const Comparator* cmp,
-                     MergeHelper* merge_helper, SequenceNumber last_sequence,
-                     std::vector<SequenceNumber>* snapshots,
-                     SequenceNumber earliest_write_conflict_snapshot,
-                     SequenceNumber job_snapshot,
-                     const SnapshotChecker* snapshot_checker, Env* env,
-                     bool report_detailed_time, bool expect_valid_internal_key,
-                     CompactionRangeDelAggregator* range_del_agg,
-                     BlobFileBuilder* blob_file_builder,
-                     bool allow_data_in_errors,
-                     bool enforce_single_del_contracts,
-                     const std::atomic<bool>& manual_compaction_canceled,
-                     std::unique_ptr<CompactionProxy> compaction,
-                     const CompactionFilter* compaction_filter = nullptr,
-                     const std::atomic<bool>* shutting_down = nullptr,
-                     const std::shared_ptr<Logger> info_log = nullptr,
-                     const std::string* full_history_ts_low = nullptr);
+  CompactionIterator(
+      InternalIterator* input, const Comparator* cmp, MergeHelper* merge_helper,
+      SequenceNumber last_sequence, std::vector<SequenceNumber>* snapshots,
+      SequenceNumber earliest_write_conflict_snapshot,
+      SequenceNumber job_snapshot, const SnapshotChecker* snapshot_checker,
+      Env* env, bool report_detailed_time, bool expect_valid_internal_key,
+      CompactionRangeDelAggregator* range_del_agg,
+      BlobFileBuilder* blob_file_builder, bool allow_data_in_errors,
+      bool enforce_single_del_contracts,
+      const std::atomic<bool>& manual_compaction_canceled,
+      std::unique_ptr<CompactionProxy> compaction,
+      const CompactionFilter* compaction_filter = nullptr,
+      const std::atomic<bool>* shutting_down = nullptr,
+      const std::shared_ptr<Logger> info_log = nullptr,
+      const std::string* full_history_ts_low = nullptr,
+      const SequenceNumber penultimate_level_cutoff_seqno = kMaxSequenceNumber);
 
   ~CompactionIterator();
 
@@ -223,10 +235,16 @@ class CompactionIterator {
   const Slice& value() const { return value_; }
   const Status& status() const { return status_; }
   const ParsedInternalKey& ikey() const { return ikey_; }
-  bool Valid() const { return valid_; }
+  inline bool Valid() const { return validity_info_.IsValid(); }
   const Slice& user_key() const { return current_user_key_; }
   const CompactionIterationStats& iter_stats() const { return iter_stats_; }
   uint64_t num_input_entry_scanned() const { return input_.num_itered(); }
+  // If the current key should be placed on penultimate level, only valid if
+  // per_key_placement is supported
+  bool output_to_penultimate_level() const {
+    return output_to_penultimate_level_;
+  }
+  Status InputStatus() const { return input_.status(); }
 
  private:
   // Processes the input stream to find the next output
@@ -235,6 +253,10 @@ class CompactionIterator {
   // Do final preparations before presenting the output to the callee.
   void PrepareOutput();
 
+  // Decide the current key should be output to the last level or penultimate
+  // level, only call for compaction supports per key placement
+  void DecideOutputLevel();
+
   // Passes the output value to the blob file builder (if any), and replaces it
   // with the corresponding blob reference if it has been actually written to a
   // blob file (i.e. if it passed the value size check). Returns true if the
@@ -310,29 +332,26 @@ class CompactionIterator {
   // earliest visible snapshot of an older value.
   // See WritePreparedTransactionTest::ReleaseSnapshotDuringCompaction3.
   std::unordered_set<SequenceNumber> released_snapshots_;
-  std::vector<SequenceNumber>::const_iterator earliest_snapshot_iter_;
   const SequenceNumber earliest_write_conflict_snapshot_;
   const SequenceNumber job_snapshot_;
   const SnapshotChecker* const snapshot_checker_;
   Env* env_;
   SystemClock* clock_;
-  bool report_detailed_time_;
-  bool expect_valid_internal_key_;
+  const bool report_detailed_time_;
+  const bool expect_valid_internal_key_;
   CompactionRangeDelAggregator* range_del_agg_;
   BlobFileBuilder* blob_file_builder_;
   std::unique_ptr<CompactionProxy> compaction_;
   const CompactionFilter* compaction_filter_;
   const std::atomic<bool>* shutting_down_;
   const std::atomic<bool>& manual_compaction_canceled_;
-  bool bottommost_level_;
-  bool valid_ = false;
-  bool visible_at_tip_;
-  SequenceNumber earliest_snapshot_;
-  SequenceNumber latest_snapshot_;
+  const bool bottommost_level_;
+  const bool visible_at_tip_;
+  const SequenceNumber earliest_snapshot_;
 
   std::shared_ptr<Logger> info_log_;
 
-  bool allow_data_in_errors_;
+  const bool allow_data_in_errors_;
 
   const bool enforce_single_del_contracts_;
 
@@ -348,8 +367,33 @@ class CompactionIterator {
 
   // State
   //
+  enum ValidContext : uint8_t {
+    kMerge1 = 0,
+    kMerge2 = 1,
+    kParseKeyError = 2,
+    kCurrentKeyUncommitted = 3,
+    kKeepSDAndClearPut = 4,
+    kKeepTsHistory = 5,
+    kKeepSDForConflictCheck = 6,
+    kKeepSDForSnapshot = 7,
+    kKeepSD = 8,
+    kKeepDel = 9,
+    kNewUserKey = 10,
+  };
+
+  struct ValidityInfo {
+    inline bool IsValid() const { return rep & 1; }
+    ValidContext GetContext() const {
+      return static_cast<ValidContext>(rep >> 1);
+    }
+    inline void SetValid(uint8_t ctx) { rep = (ctx << 1) | 1; }
+    inline void Invalidate() { rep = 0; }
+
+    uint8_t rep{0};
+  } validity_info_;
+
   // Points to a copy of the current compaction iterator output (current_key_)
-  // if valid_.
+  // if valid.
   Slice key_;
   // Points to the value in the underlying iterator that corresponds to the
   // current output.
@@ -417,6 +461,15 @@ class CompactionIterator {
   // just been zeroed out during bottommost compaction.
   bool last_key_seq_zeroed_{false};
 
+  // True if the current key should be output to the penultimate level if
+  // possible, compaction logic makes the final decision on which level to
+  // output to.
+  bool output_to_penultimate_level_{false};
+
+  // any key later than this sequence number should have
+  // output_to_penultimate_level_ set to true
+  const SequenceNumber penultimate_level_cutoff_seqno_ = kMaxSequenceNumber;
+
   void AdvanceInputIter() { input_.Next(); }
 
   void SkipUntil(const Slice& skip_until) { input_.Seek(skip_until); }

db/compaction/compaction_iterator_test.cc

@@ -180,11 +180,21 @@ class FakeCompaction : public CompactionIterator::CompactionProxy {
 
   const Compaction* real_compaction() const override { return nullptr; }
 
+  bool SupportsPerKeyPlacement() const override {
+    return supports_per_key_placement;
+  }
+
+  bool WithinPenultimateLevelOutputRange(const Slice& key) const override {
+    return (!key.starts_with("unsafe_pb"));
+  }
+
   bool key_not_exists_beyond_output_level = false;
 
   bool is_bottommost_level = false;
 
   bool is_allow_ingest_behind = false;
+
+  bool supports_per_key_placement = false;
 };
 
 // A simplified snapshot checker which assumes each snapshot has a global
@@ -254,6 +264,7 @@ class CompactionIteratorTest : public testing::TestWithParam<bool> {
       compaction_proxy_->is_allow_ingest_behind = AllowIngestBehind();
       compaction_proxy_->key_not_exists_beyond_output_level =
           key_not_exists_beyond_output_level;
+      compaction_proxy_->supports_per_key_placement = SupportsPerKeyPlacement();
       compaction.reset(compaction_proxy_);
     }
     bool use_snapshot_checker = UseSnapshotChecker() || GetParam();
@@ -295,6 +306,8 @@ class CompactionIteratorTest : public testing::TestWithParam<bool> {
 
   virtual bool AllowIngestBehind() const { return false; }
 
+  virtual bool SupportsPerKeyPlacement() const { return false; }
+
   void RunTest(
       const std::vector<std::string>& input_keys,
       const std::vector<std::string>& input_values,
@@ -756,6 +769,119 @@ TEST_P(CompactionIteratorTest, ConvertToPutAtBottom) {
 INSTANTIATE_TEST_CASE_P(CompactionIteratorTestInstance, CompactionIteratorTest,
                         testing::Values(true, false));
 
+class PerKeyPlacementCompIteratorTest : public CompactionIteratorTest {
+ public:
+  bool SupportsPerKeyPlacement() const override { return true; }
+};
+
+TEST_P(PerKeyPlacementCompIteratorTest, SplitLastLevelData) {
+  std::atomic_uint64_t latest_cold_seq = 0;
+
+  SyncPoint::GetInstance()->SetCallBack(
+      "CompactionIterator::PrepareOutput.context", [&](void* arg) {
+        auto context = static_cast<PerKeyPlacementContext*>(arg);
+        context->output_to_penultimate_level =
+            context->seq_num > latest_cold_seq;
+      });
+  SyncPoint::GetInstance()->EnableProcessing();
+
+  latest_cold_seq = 5;
+
+  InitIterators(
+      {test::KeyStr("a", 7, kTypeValue), test::KeyStr("b", 6, kTypeValue),
+       test::KeyStr("c", 5, kTypeValue)},
+      {"vala", "valb", "valc"}, {}, {}, kMaxSequenceNumber, kMaxSequenceNumber,
+      nullptr, nullptr, true);
+  c_iter_->SeekToFirst();
+  ASSERT_TRUE(c_iter_->Valid());
+
+  // the first 2 keys are hot, which should has
+  // `output_to_penultimate_level()==true` and seq num not zeroed out
+  ASSERT_EQ(test::KeyStr("a", 7, kTypeValue), c_iter_->key().ToString());
+  ASSERT_TRUE(c_iter_->output_to_penultimate_level());
+  c_iter_->Next();
+  ASSERT_TRUE(c_iter_->Valid());
+  ASSERT_EQ(test::KeyStr("b", 6, kTypeValue), c_iter_->key().ToString());
+  ASSERT_TRUE(c_iter_->output_to_penultimate_level());
+  c_iter_->Next();
+  ASSERT_TRUE(c_iter_->Valid());
+  // `a` is cold data, which should be output to bottommost
+  ASSERT_EQ(test::KeyStr("c", 0, kTypeValue), c_iter_->key().ToString());
+  ASSERT_FALSE(c_iter_->output_to_penultimate_level());
+  c_iter_->Next();
+  ASSERT_OK(c_iter_->status());
+  ASSERT_FALSE(c_iter_->Valid());
+}
+
+TEST_P(PerKeyPlacementCompIteratorTest, SnapshotData) {
+  AddSnapshot(5);
+
+  InitIterators(
+      {test::KeyStr("a", 7, kTypeValue), test::KeyStr("b", 6, kTypeDeletion),
+       test::KeyStr("b", 5, kTypeValue)},
+      {"vala", "", "valb"}, {}, {}, kMaxSequenceNumber, kMaxSequenceNumber,
+      nullptr, nullptr, true);
+  c_iter_->SeekToFirst();
+  ASSERT_TRUE(c_iter_->Valid());
+
+  // The first key and the tombstone are within snapshot, which should output
+  // to the penultimate level (and seq num cannot be zeroed out).
+  ASSERT_EQ(test::KeyStr("a", 7, kTypeValue), c_iter_->key().ToString());
+  ASSERT_TRUE(c_iter_->output_to_penultimate_level());
+  c_iter_->Next();
+  ASSERT_TRUE(c_iter_->Valid());
+  ASSERT_EQ(test::KeyStr("b", 6, kTypeDeletion), c_iter_->key().ToString());
+  ASSERT_TRUE(c_iter_->output_to_penultimate_level());
+  c_iter_->Next();
+  ASSERT_TRUE(c_iter_->Valid());
+  // `a` is not protected by the snapshot, the sequence number is zero out and
+  // should output bottommost
+  ASSERT_EQ(test::KeyStr("b", 0, kTypeValue), c_iter_->key().ToString());
+  ASSERT_FALSE(c_iter_->output_to_penultimate_level());
+  c_iter_->Next();
+  ASSERT_OK(c_iter_->status());
+  ASSERT_FALSE(c_iter_->Valid());
+}
+
+TEST_P(PerKeyPlacementCompIteratorTest, ConflictWithSnapshot) {
+  std::atomic_uint64_t latest_cold_seq = 0;
+
+  SyncPoint::GetInstance()->SetCallBack(
+      "CompactionIterator::PrepareOutput.context", [&](void* arg) {
+        auto context = static_cast<PerKeyPlacementContext*>(arg);
+        context->output_to_penultimate_level =
+            context->seq_num > latest_cold_seq;
+      });
+  SyncPoint::GetInstance()->EnableProcessing();
+
+  latest_cold_seq = 6;
+
+  AddSnapshot(5);
+
+  InitIterators({test::KeyStr("a", 7, kTypeValue),
+                 test::KeyStr("unsafe_pb", 6, kTypeValue),
+                 test::KeyStr("c", 5, kTypeValue)},
+                {"vala", "valb", "valc"}, {}, {}, kMaxSequenceNumber,
+                kMaxSequenceNumber, nullptr, nullptr, true);
+  c_iter_->SeekToFirst();
+  ASSERT_TRUE(c_iter_->Valid());
+
+  ASSERT_EQ(test::KeyStr("a", 7, kTypeValue), c_iter_->key().ToString());
+  ASSERT_TRUE(c_iter_->output_to_penultimate_level());
+  // the 2nd key is unsafe to output_to_penultimate_level, but it's within
+  // snapshot so for per_key_placement feature it has to be outputted to the
+  // penultimate level. which is a corruption. We should never see
+  // such case as the data with seq num (within snapshot) should always come
+  // from higher compaction input level, which makes it safe to
+  // output_to_penultimate_level.
+  c_iter_->Next();
+  ASSERT_TRUE(c_iter_->status().IsCorruption());
+}
+
+INSTANTIATE_TEST_CASE_P(PerKeyPlacementCompIteratorTest,
+                        PerKeyPlacementCompIteratorTest,
+                        testing::Values(true, false));
+
 // Tests how CompactionIterator work together with SnapshotChecker.
 class CompactionIteratorWithSnapshotCheckerTest
     : public CompactionIteratorTest {
@@ -981,6 +1107,21 @@ TEST_F(CompactionIteratorWithSnapshotCheckerTest,
           2 /*earliest_write_conflict_snapshot*/);
 }
 
+// Same as above but with a wide-column entity. In addition to the value getting
+// trimmed, the type of the KV is changed to kTypeValue.
+TEST_F(CompactionIteratorWithSnapshotCheckerTest,
+       KeepSingleDeletionForWriteConflictChecking_WideColumnEntity) {
+  AddSnapshot(2, 0);
+  RunTest({test::KeyStr("a", 2, kTypeSingleDeletion),
+           test::KeyStr("a", 1, kTypeWideColumnEntity)},
+          {"", "fake_entity"},
+          {test::KeyStr("a", 2, kTypeSingleDeletion),
+           test::KeyStr("a", 1, kTypeValue)},
+          {"", ""}, 2 /* last_committed_seq */, nullptr /* merge_operator */,
+          nullptr /* compaction_filter */, false /* bottommost_level */,
+          2 /* earliest_write_conflict_snapshot */);
+}
+
 // Compaction filter should keep uncommitted key as-is, and
 //   * Convert the latest value to deletion, and/or
 //   * if latest value is a merge, apply filter to all subsequent merges.

db/compaction/compaction_job.h

@@ -20,12 +20,14 @@
 #include "db/blob/blob_file_completion_callback.h"
 #include "db/column_family.h"
 #include "db/compaction/compaction_iterator.h"
+#include "db/compaction/compaction_outputs.h"
 #include "db/flush_scheduler.h"
 #include "db/internal_stats.h"
 #include "db/job_context.h"
 #include "db/log_writer.h"
 #include "db/memtable_list.h"
 #include "db/range_del_aggregator.h"
+#include "db/seqno_to_time_mapping.h"
 #include "db/version_edit.h"
 #include "db/write_controller.h"
 #include "db/write_thread.h"
@@ -47,6 +49,7 @@
 namespace ROCKSDB_NAMESPACE {
 
 class Arena;
+class CompactionState;
 class ErrorHandler;
 class MemTable;
 class SnapshotChecker;
@@ -56,11 +59,91 @@ class Version;
 class VersionEdit;
 class VersionSet;
 
+class SubcompactionState;
+
 // CompactionJob is responsible for executing the compaction. Each (manual or
 // automated) compaction corresponds to a CompactionJob object, and usually
 // goes through the stages of `Prepare()`->`Run()`->`Install()`. CompactionJob
 // will divide the compaction into subcompactions and execute them in parallel
 // if needed.
+//
+// CompactionJob has 2 main stats:
+// 1. CompactionJobStats compaction_job_stats_
+//    CompactionJobStats is a public data structure which is part of Compaction
+//    event listener that rocksdb share the job stats with the user.
+//    Internally it's an aggregation of all the compaction_job_stats from each
+//    `SubcompactionState`:
+//                                           +------------------------+
+//                                           | SubcompactionState     |
+//                                           |                        |
+//                                +--------->|   compaction_job_stats |
+//                                |          |                        |
+//                                |          +------------------------+
+// +------------------------+     |
+// | CompactionJob          |     |          +------------------------+
+// |                        |     |          | SubcompactionState     |
+// |   compaction_job_stats +-----+          |                        |
+// |                        |     +--------->|   compaction_job_stats |
+// |                        |     |          |                        |
+// +------------------------+     |          +------------------------+
+//                                |
+//                                |          +------------------------+
+//                                |          | SubcompactionState     |
+//                                |          |                        |
+//                                +--------->+   compaction_job_stats |
+//                                |          |                        |
+//                                |          +------------------------+
+//                                |
+//                                |          +------------------------+
+//                                |          |       ...              |
+//                                +--------->+                        |
+//                                           +------------------------+
+//
+// 2. CompactionStatsFull compaction_stats_
+//    `CompactionStatsFull` is an internal stats about the compaction, which
+//    is eventually sent to `ColumnFamilyData::internal_stats_` and used for
+//    logging and public metrics.
+//    Internally, it's an aggregation of stats_ from each `SubcompactionState`.
+//    It has 2 parts, normal stats about the main compaction information and
+//    the penultimate level output stats.
+//    `SubcompactionState` maintains the CompactionOutputs for normal output and
+//    the penultimate level output if exists, the per_level stats is
+//    stored with the outputs.
+//                                                +---------------------------+
+//                                                | SubcompactionState        |
+//                                                |                           |
+//                                                | +----------------------+  |
+//                                                | | CompactionOutputs    |  |
+//                                                | | (normal output)      |  |
+//                                            +---->|   stats_             |  |
+//                                            |   | +----------------------+  |
+//                                            |   |                           |
+//                                            |   | +----------------------+  |
+// +--------------------------------+         |   | | CompactionOutputs    |  |
+// | CompactionJob                  |         |   | | (penultimate_level)  |  |
+// |                                |    +--------->|   stats_             |  |
+// |   compaction_stats_            |    |    |   | +----------------------+  |
+// |    +-------------------------+ |    |    |   |                           |
+// |    |stats (normal)           |------|----+   +---------------------------+
+// |    +-------------------------+ |    |    |
+// |                                |    |    |
+// |    +-------------------------+ |    |    |   +---------------------------+
+// |    |penultimate_level_stats  +------+    |   | SubcompactionState        |
+// |    +-------------------------+ |    |    |   |                           |
+// |                                |    |    |   | +----------------------+  |
+// |                                |    |    |   | | CompactionOutputs    |  |
+// +--------------------------------+    |    |   | | (normal output)      |  |
+//                                       |    +---->|   stats_             |  |
+//                                       |        | +----------------------+  |
+//                                       |        |                           |
+//                                       |        | +----------------------+  |
+//                                       |        | | CompactionOutputs    |  |
+//                                       |        | | (penultimate_level)  |  |
+//                                       +--------->|   stats_             |  |
+//                                                | +----------------------+  |
+//                                                |                           |
+//                                                +---------------------------+
+
 class CompactionJob {
  public:
   CompactionJob(
@@ -81,7 +164,9 @@ class CompactionJob {
       const std::atomic<bool>& manual_compaction_canceled,
       const std::string& db_id = "", const std::string& db_session_id = "",
       std::string full_history_ts_low = "", std::string trim_ts = "",
-      BlobFileCompletionCallback* blob_callback = nullptr);
+      BlobFileCompletionCallback* blob_callback = nullptr,
+      int* bg_compaction_scheduled = nullptr,
+      int* bg_bottom_compaction_scheduled = nullptr);
 
   virtual ~CompactionJob();
 
@@ -107,11 +192,6 @@ class CompactionJob {
   IOStatus io_status() const { return io_status_; }
 
  protected:
-  struct SubcompactionState;
-  // CompactionJob state
-  struct CompactionState;
-
-  void AggregateStatistics();
   void UpdateCompactionStats();
   void LogCompaction();
   virtual void RecordCompactionIOStats();
@@ -122,7 +202,7 @@ class CompactionJob {
   void ProcessKeyValueCompaction(SubcompactionState* sub_compact);
 
   CompactionState* compact_;
-  InternalStats::CompactionStats compaction_stats_;
+  InternalStats::CompactionStatsFull compaction_stats_;
   const ImmutableDBOptions& db_options_;
   const MutableDBOptions mutable_db_options_copy_;
   LogBuffer* log_buffer_;
@@ -135,6 +215,8 @@ class CompactionJob {
 
   IOStatus io_status_;
 
+  CompactionJobStats* compaction_job_stats_;
+
  private:
   friend class CompactionJobTestBase;
 
@@ -145,20 +227,39 @@ class CompactionJob {
   // consecutive groups such that each group has a similar size.
   void GenSubcompactionBoundaries();
 
+  // Get the number of planned subcompactions based on max_subcompactions and
+  // extra reserved resources
+  uint64_t GetSubcompactionsLimit();
+
+  // Additional reserved threads are reserved and the number is stored in
+  // extra_num_subcompaction_threads_reserved__. For now, this happens only if
+  // the compaction priority is round-robin and max_subcompactions is not
+  // sufficient (extra resources may be needed)
+  void AcquireSubcompactionResources(int num_extra_required_subcompactions);
+
+  // Additional threads may be reserved during IncreaseSubcompactionResources()
+  // if num_actual_subcompactions is less than num_planned_subcompactions.
+  // Additional threads will be released and the bg_compaction_scheduled_ or
+  // bg_bottom_compaction_scheduled_ will be updated if they are used.
+  // DB Mutex lock is required.
+  void ShrinkSubcompactionResources(uint64_t num_extra_resources);
+
+  // Release all reserved threads and update the compaction limits.
+  void ReleaseSubcompactionResources();
+
   CompactionServiceJobStatus ProcessKeyValueCompactionWithCompactionService(
       SubcompactionState* sub_compact);
 
   // update the thread status for starting a compaction.
   void ReportStartedCompaction(Compaction* compaction);
-  void AllocateCompactionOutputFileNumbers();
 
-  Status FinishCompactionOutputFile(
-      const Status& input_status, SubcompactionState* sub_compact,
-      CompactionRangeDelAggregator* range_del_agg,
-      CompactionIterationStats* range_del_out_stats,
-      const Slice* next_table_min_key = nullptr);
+  Status FinishCompactionOutputFile(const Status& input_status,
+                                    SubcompactionState* sub_compact,
+                                    CompactionOutputs& outputs,
+                                    const Slice& next_table_min_key);
   Status InstallCompactionResults(const MutableCFOptions& mutable_cf_options);
-  Status OpenCompactionOutputFile(SubcompactionState* sub_compact);
+  Status OpenCompactionOutputFile(SubcompactionState* sub_compact,
+                                  CompactionOutputs& outputs);
   void UpdateCompactionJobStats(
     const InternalStats::CompactionStats& stats) const;
   void RecordDroppedKeys(const CompactionIterationStats& c_iter_stats,
@@ -167,20 +268,12 @@ class CompactionJob {
   void UpdateCompactionInputStatsHelper(
       int* num_files, uint64_t* bytes_read, int input_level);
 
-#ifndef ROCKSDB_LITE
-  void BuildSubcompactionJobInfo(
-      SubcompactionState* sub_compact,
-      SubcompactionJobInfo* subcompaction_job_info) const;
-#endif  // ROCKSDB_LITE
-
   void NotifyOnSubcompactionBegin(SubcompactionState* sub_compact);
 
   void NotifyOnSubcompactionCompleted(SubcompactionState* sub_compact);
 
   uint32_t job_id_;
 
-  CompactionJobStats* compaction_job_stats_;
-
   // DBImpl state
   const std::string& dbname_;
   const std::string db_id_;
@@ -221,15 +314,33 @@ class CompactionJob {
   bool paranoid_file_checks_;
   bool measure_io_stats_;
   // Stores the Slices that designate the boundaries for each subcompaction
-  std::vector<Slice> boundaries_;
-  // Stores the approx size of keys covered in the range of each subcompaction
-  std::vector<uint64_t> sizes_;
+  std::vector<std::string> boundaries_;
   Env::Priority thread_pri_;
   std::string full_history_ts_low_;
   std::string trim_ts_;
   BlobFileCompletionCallback* blob_callback_;
 
-  uint64_t GetCompactionId(SubcompactionState* sub_compact);
+  uint64_t GetCompactionId(SubcompactionState* sub_compact) const;
+  // Stores the number of reserved threads in shared env_ for the number of
+  // extra subcompaction in kRoundRobin compaction priority
+  int extra_num_subcompaction_threads_reserved_;
+
+  // Stores the pointer to bg_compaction_scheduled_,
+  // bg_bottom_compaction_scheduled_ in DBImpl. Mutex is required when accessing
+  // or updating it.
+  int* bg_compaction_scheduled_;
+  int* bg_bottom_compaction_scheduled_;
+
+  // Stores the sequence number to time mapping gathered from all input files
+  // it also collects the smallest_seqno -> oldest_ancester_time from the SST.
+  SeqnoToTimeMapping seqno_time_mapping_;
+
+  // cutoff sequence number for penultimate level, only set when
+  // per_key_placement feature is enabled.
+  // If a key with sequence number larger than penultimate_level_cutoff_seqno_,
+  // it will be placed on the penultimate_level and seqnuence number won't be
+  // zeroed out.
+  SequenceNumber penultimate_level_cutoff_seqno_ = kMaxSequenceNumber;
 
   // Get table file name in where it's outputting to, which should also be in
   // `output_directory_`.
@@ -265,7 +376,6 @@ struct CompactionServiceInput {
   std::string begin;
   bool has_end = false;
   std::string end;
-  uint64_t approx_size = 0;
 
   // serialization interface to read and write the object
   static Status Read(const std::string& data_str, CompactionServiceInput* obj);
@@ -357,7 +467,7 @@ class CompactionServiceCompactionJob : private CompactionJob {
       const std::string& dbname, const std::shared_ptr<IOTracer>& io_tracer,
       const std::atomic<bool>& manual_compaction_canceled,
       const std::string& db_id, const std::string& db_session_id,
-      const std::string& output_path,
+      std::string output_path,
       const CompactionServiceInput& compaction_service_input,
       CompactionServiceResult* compaction_service_result);
 

db/compaction/compaction_job_test.cc

@@ -208,11 +208,11 @@ class CompactionJobTestBase : public testing::Test {
         mutable_db_options_(),
         table_cache_(NewLRUCache(50000, 16)),
         write_buffer_manager_(db_options_.db_write_buffer_size),
-        versions_(new VersionSet(dbname_, &db_options_, env_options_,
-                                 table_cache_.get(), &write_buffer_manager_,
-                                 &write_controller_,
-                                 /*block_cache_tracer=*/nullptr,
-                                 /*io_tracer=*/nullptr, /*db_session_id*/ "")),
+        versions_(new VersionSet(
+            dbname_, &db_options_, env_options_, table_cache_.get(),
+            &write_buffer_manager_, &write_controller_,
+            /*block_cache_tracer=*/nullptr,
+            /*io_tracer=*/nullptr, /*db_id*/ "", /*db_session_id*/ "")),
         shutting_down_(false),
         mock_table_factory_(new mock::MockTableFactory()),
         error_handler_(nullptr, db_options_, &mutex_),
@@ -372,8 +372,7 @@ class CompactionJobTestBase : public testing::Test {
                  smallest_seqno, largest_seqno, false, Temperature::kUnknown,
                  oldest_blob_file_number, kUnknownOldestAncesterTime,
                  kUnknownFileCreationTime, kUnknownFileChecksum,
-                 kUnknownFileChecksumFuncName, kDisableUserTimestamp,
-                 kDisableUserTimestamp, kNullUniqueId64x2);
+                 kUnknownFileChecksumFuncName, kNullUniqueId64x2);
 
     mutex_.Lock();
     EXPECT_OK(
@@ -444,7 +443,7 @@ class CompactionJobTestBase : public testing::Test {
         new VersionSet(dbname_, &db_options_, env_options_, table_cache_.get(),
                        &write_buffer_manager_, &write_controller_,
                        /*block_cache_tracer=*/nullptr, /*io_tracer=*/nullptr,
-                       /*db_session_id*/ ""));
+                       /*db_id*/ "", /*db_session_id*/ ""));
     compaction_job_stats_.Reset();
     ASSERT_OK(SetIdentityFile(env_, dbname_));
 
@@ -482,6 +481,17 @@ class CompactionJobTestBase : public testing::Test {
     cfd_ = versions_->GetColumnFamilySet()->GetDefault();
   }
 
+  void RunLastLevelCompaction(
+      const std::vector<std::vector<FileMetaData*>>& input_files,
+      std::function<void(Compaction& comp)>&& verify_func,
+      const std::vector<SequenceNumber>& snapshots = {}) {
+    const int kLastLevel = cf_options_.num_levels - 1;
+    verify_per_key_placement_ = std::move(verify_func);
+    mock::KVVector empty_map;
+    RunCompaction(input_files, empty_map, snapshots, kMaxSequenceNumber,
+                  kLastLevel, false);
+  }
+
   void RunCompaction(
       const std::vector<std::vector<FileMetaData*>>& input_files,
       const mock::KVVector& expected_results,
@@ -571,6 +581,12 @@ class CompactionJobTestBase : public testing::Test {
     if (check_get_priority) {
       CheckGetRateLimiterPriority(compaction_job);
     }
+
+    if (verify_per_key_placement_) {
+      // Verify per_key_placement compaction
+      assert(compaction.SupportsPerKeyPlacement());
+      verify_per_key_placement_(compaction);
+    }
   }
 
   void CheckGetRateLimiterPriority(CompactionJob& compaction_job) {
@@ -620,6 +636,7 @@ class CompactionJobTestBase : public testing::Test {
   std::string full_history_ts_low_;
   const std::function<std::string(uint64_t)> encode_u64_ts_;
   bool test_io_priority_;
+  std::function<void(Compaction& comp)> verify_per_key_placement_;
 };
 
 // TODO(icanadi) Make it simpler once we mock out VersionSet
@@ -1311,6 +1328,75 @@ TEST_F(CompactionJobTest, OldestBlobFileNumber) {
                 /* expected_oldest_blob_file_number */ 19);
 }
 
+TEST_F(CompactionJobTest, VerifyPenultimateLevelOutput) {
+  cf_options_.bottommost_temperature = Temperature::kCold;
+  SyncPoint::GetInstance()->SetCallBack(
+      "Compaction::SupportsPerKeyPlacement:Enabled", [&](void* arg) {
+        auto supports_per_key_placement = static_cast<bool*>(arg);
+        *supports_per_key_placement = true;
+      });
+
+  std::atomic_uint64_t latest_cold_seq = 0;
+
+  SyncPoint::GetInstance()->SetCallBack(
+      "CompactionIterator::PrepareOutput.context", [&](void* arg) {
+        auto context = static_cast<PerKeyPlacementContext*>(arg);
+        context->output_to_penultimate_level =
+            context->seq_num > latest_cold_seq;
+      });
+  SyncPoint::GetInstance()->EnableProcessing();
+
+  NewDB();
+
+  // Add files on different levels that may overlap
+  auto file0_1 = mock::MakeMockFile({{KeyStr("z", 12U, kTypeValue), "val"}});
+  AddMockFile(file0_1);
+
+  auto file1_1 = mock::MakeMockFile({{KeyStr("b", 10U, kTypeValue), "val"},
+                                     {KeyStr("f", 11U, kTypeValue), "val"}});
+  AddMockFile(file1_1, 1);
+  auto file1_2 = mock::MakeMockFile({{KeyStr("j", 12U, kTypeValue), "val"},
+                                     {KeyStr("k", 13U, kTypeValue), "val"}});
+  AddMockFile(file1_2, 1);
+  auto file1_3 = mock::MakeMockFile({{KeyStr("p", 14U, kTypeValue), "val"},
+                                     {KeyStr("u", 15U, kTypeValue), "val"}});
+  AddMockFile(file1_3, 1);
+
+  auto file2_1 = mock::MakeMockFile({{KeyStr("f", 8U, kTypeValue), "val"},
+                                     {KeyStr("h", 9U, kTypeValue), "val"}});
+  AddMockFile(file2_1, 2);
+  auto file2_2 = mock::MakeMockFile({{KeyStr("m", 6U, kTypeValue), "val"},
+                                     {KeyStr("p", 7U, kTypeValue), "val"}});
+  AddMockFile(file2_2, 2);
+
+  auto file3_1 = mock::MakeMockFile({{KeyStr("g", 2U, kTypeValue), "val"},
+                                     {KeyStr("k", 3U, kTypeValue), "val"}});
+  AddMockFile(file3_1, 3);
+  auto file3_2 = mock::MakeMockFile({{KeyStr("v", 4U, kTypeValue), "val"},
+                                     {KeyStr("x", 5U, kTypeValue), "val"}});
+  AddMockFile(file3_2, 3);
+
+  auto cfd = versions_->GetColumnFamilySet()->GetDefault();
+  auto files0 = cfd->current()->storage_info()->LevelFiles(0);
+  auto files1 = cfd->current()->storage_info()->LevelFiles(1);
+  auto files2 = cfd->current()->storage_info()->LevelFiles(2);
+  auto files3 = cfd->current()->storage_info()->LevelFiles(3);
+
+  RunLastLevelCompaction(
+      {files0, files1, files2, files3}, /*verify_func=*/[&](Compaction& comp) {
+        for (char c = 'a'; c <= 'z'; c++) {
+          std::string c_str;
+          c_str = c;
+          const Slice key(c_str);
+          if (c == 'a') {
+            ASSERT_FALSE(comp.WithinPenultimateLevelOutputRange(key));
+          } else {
+            ASSERT_TRUE(comp.WithinPenultimateLevelOutputRange(key));
+          }
+        }
+      });
+}
+
 TEST_F(CompactionJobTest, NoEnforceSingleDeleteContract) {
   db_options_.enforce_single_del_contracts = false;
   NewDB();
@@ -1360,7 +1446,6 @@ TEST_F(CompactionJobTest, InputSerialization) {
   if (input.has_end) {
     input.end = rnd.RandomBinaryString(rnd.Uniform(kStrMaxLen));
   }
-  input.approx_size = rnd64.Uniform(UINT64_MAX);
 
   std::string output;
   ASSERT_OK(input.Write(&output));

db/compaction/compaction_outputs.cc

@@ -0,0 +1,321 @@
+//  Copyright (c) Meta Platforms, Inc. and affiliates.
+//
+//  This source code is licensed under both the GPLv2 (found in the
+//  COPYING file in the root directory) and Apache 2.0 License
+//  (found in the LICENSE.Apache file in the root directory).
+//
+// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file. See the AUTHORS file for names of contributors.
+
+#include "db/compaction/compaction_outputs.h"
+
+#include "db/builder.h"
+
+namespace ROCKSDB_NAMESPACE {
+
+void CompactionOutputs::NewBuilder(const TableBuilderOptions& tboptions) {
+  builder_.reset(NewTableBuilder(tboptions, file_writer_.get()));
+}
+
+Status CompactionOutputs::Finish(const Status& intput_status,
+                                 const SeqnoToTimeMapping& seqno_time_mapping) {
+  FileMetaData* meta = GetMetaData();
+  assert(meta != nullptr);
+  Status s = intput_status;
+  if (s.ok()) {
+    std::string seqno_time_mapping_str;
+    seqno_time_mapping.Encode(seqno_time_mapping_str, meta->fd.smallest_seqno,
+                              meta->fd.largest_seqno, meta->file_creation_time);
+    builder_->SetSeqnoTimeTableProperties(seqno_time_mapping_str,
+                                          meta->oldest_ancester_time);
+    s = builder_->Finish();
+
+  } else {
+    builder_->Abandon();
+  }
+  Status io_s = builder_->io_status();
+  if (s.ok()) {
+    s = io_s;
+  } else {
+    io_s.PermitUncheckedError();
+  }
+  const uint64_t current_bytes = builder_->FileSize();
+  if (s.ok()) {
+    meta->fd.file_size = current_bytes;
+    meta->marked_for_compaction = builder_->NeedCompact();
+  }
+  current_output().finished = true;
+  stats_.bytes_written += current_bytes;
+  stats_.num_output_files = outputs_.size();
+
+  return s;
+}
+
+IOStatus CompactionOutputs::WriterSyncClose(const Status& input_status,
+                                            SystemClock* clock,
+                                            Statistics* statistics,
+                                            bool use_fsync) {
+  IOStatus io_s;
+  if (input_status.ok()) {
+    StopWatch sw(clock, statistics, COMPACTION_OUTFILE_SYNC_MICROS);
+    io_s = file_writer_->Sync(use_fsync);
+  }
+  if (input_status.ok() && io_s.ok()) {
+    io_s = file_writer_->Close();
+  }
+
+  if (input_status.ok() && io_s.ok()) {
+    FileMetaData* meta = GetMetaData();
+    meta->file_checksum = file_writer_->GetFileChecksum();
+    meta->file_checksum_func_name = file_writer_->GetFileChecksumFuncName();
+  }
+
+  file_writer_.reset();
+
+  return io_s;
+}
+
+Status CompactionOutputs::AddToOutput(
+    const CompactionIterator& c_iter,
+    const CompactionFileOpenFunc& open_file_func,
+    const CompactionFileCloseFunc& close_file_func) {
+  Status s;
+  const Slice& key = c_iter.key();
+
+  if (!pending_close_ && c_iter.Valid() && partitioner_ && HasBuilder() &&
+      partitioner_->ShouldPartition(
+          PartitionerRequest(last_key_for_partitioner_, c_iter.user_key(),
+                             current_output_file_size_)) == kRequired) {
+    pending_close_ = true;
+  }
+
+  if (pending_close_) {
+    s = close_file_func(*this, c_iter.InputStatus(), key);
+    pending_close_ = false;
+  }
+  if (!s.ok()) {
+    return s;
+  }
+
+  // Open output file if necessary
+  if (!HasBuilder()) {
+    s = open_file_func(*this);
+  }
+  if (!s.ok()) {
+    return s;
+  }
+
+  Output& curr = current_output();
+  assert(builder_ != nullptr);
+  const Slice& value = c_iter.value();
+  s = curr.validator.Add(key, value);
+  if (!s.ok()) {
+    return s;
+  }
+  builder_->Add(key, value);
+
+  stats_.num_output_records++;
+  current_output_file_size_ = builder_->EstimatedFileSize();
+
+  if (blob_garbage_meter_) {
+    s = blob_garbage_meter_->ProcessOutFlow(key, value);
+  }
+
+  if (!s.ok()) {
+    return s;
+  }
+
+  const ParsedInternalKey& ikey = c_iter.ikey();
+  s = current_output().meta.UpdateBoundaries(key, value, ikey.sequence,
+                                             ikey.type);
+
+  // Close output file if it is big enough. Two possibilities determine it's
+  // time to close it: (1) the current key should be this file's last key, (2)
+  // the next key should not be in this file.
+  //
+  // TODO(aekmekji): determine if file should be closed earlier than this
+  // during subcompactions (i.e. if output size, estimated by input size, is
+  // going to be 1.2MB and max_output_file_size = 1MB, prefer to have 0.6MB
+  // and 0.6MB instead of 1MB and 0.2MB)
+  if (compaction_->output_level() != 0 &&
+      current_output_file_size_ >= compaction_->max_output_file_size()) {
+    pending_close_ = true;
+  }
+
+  if (partitioner_) {
+    last_key_for_partitioner_.assign(c_iter.user_key().data_,
+                                     c_iter.user_key().size_);
+  }
+
+  return s;
+}
+
+Status CompactionOutputs::AddRangeDels(
+    const Slice* comp_start, const Slice* comp_end,
+    CompactionIterationStats& range_del_out_stats, bool bottommost_level,
+    const InternalKeyComparator& icmp, SequenceNumber earliest_snapshot,
+    const Slice& next_table_min_key) {
+  assert(HasRangeDel());
+  FileMetaData& meta = current_output().meta;
+  const Comparator* ucmp = icmp.user_comparator();
+
+  Slice lower_bound_guard, upper_bound_guard;
+  std::string smallest_user_key;
+  const Slice *lower_bound, *upper_bound;
+  bool lower_bound_from_sub_compact = false;
+
+  size_t output_size = outputs_.size();
+  if (output_size == 1) {
+    // For the first output table, include range tombstones before the min
+    // key but after the subcompaction boundary.
+    lower_bound = comp_start;
+    lower_bound_from_sub_compact = true;
+  } else if (meta.smallest.size() > 0) {
+    // For subsequent output tables, only include range tombstones from min
+    // key onwards since the previous file was extended to contain range
+    // tombstones falling before min key.
+    smallest_user_key = meta.smallest.user_key().ToString(false /*hex*/);
+    lower_bound_guard = Slice(smallest_user_key);
+    lower_bound = &lower_bound_guard;
+  } else {
+    lower_bound = nullptr;
+  }
+  if (!next_table_min_key.empty()) {
+    // This may be the last file in the subcompaction in some cases, so we
+    // need to compare the end key of subcompaction with the next file start
+    // key. When the end key is chosen by the subcompaction, we know that
+    // it must be the biggest key in output file. Therefore, it is safe to
+    // use the smaller key as the upper bound of the output file, to ensure
+    // that there is no overlapping between different output files.
+    upper_bound_guard = ExtractUserKey(next_table_min_key);
+    if (comp_end != nullptr &&
+        ucmp->Compare(upper_bound_guard, *comp_end) >= 0) {
+      upper_bound = comp_end;
+    } else {
+      upper_bound = &upper_bound_guard;
+    }
+  } else {
+    // This is the last file in the subcompaction, so extend until the
+    // subcompaction ends.
+    upper_bound = comp_end;
+  }
+  bool has_overlapping_endpoints;
+  if (upper_bound != nullptr && meta.largest.size() > 0) {
+    has_overlapping_endpoints =
+        ucmp->Compare(meta.largest.user_key(), *upper_bound) == 0;
+  } else {
+    has_overlapping_endpoints = false;
+  }
+
+  // The end key of the subcompaction must be bigger or equal to the upper
+  // bound. If the end of subcompaction is null or the upper bound is null,
+  // it means that this file is the last file in the compaction. So there
+  // will be no overlapping between this file and others.
+  assert(comp_end == nullptr || upper_bound == nullptr ||
+         ucmp->Compare(*upper_bound, *comp_end) <= 0);
+  auto it = range_del_agg_->NewIterator(lower_bound, upper_bound,
+                                        has_overlapping_endpoints);
+  // Position the range tombstone output iterator. There may be tombstone
+  // fragments that are entirely out of range, so make sure that we do not
+  // include those.
+  if (lower_bound != nullptr) {
+    it->Seek(*lower_bound);
+  } else {
+    it->SeekToFirst();
+  }
+  for (; it->Valid(); it->Next()) {
+    auto tombstone = it->Tombstone();
+    if (upper_bound != nullptr) {
+      int cmp = ucmp->Compare(*upper_bound, tombstone.start_key_);
+      if ((has_overlapping_endpoints && cmp < 0) ||
+          (!has_overlapping_endpoints && cmp <= 0)) {
+        // Tombstones starting after upper_bound only need to be included in
+        // the next table. If the current SST ends before upper_bound, i.e.,
+        // `has_overlapping_endpoints == false`, we can also skip over range
+        // tombstones that start exactly at upper_bound. Such range
+        // tombstones will be included in the next file and are not relevant
+        // to the point keys or endpoints of the current file.
+        break;
+      }
+    }
+
+    if (bottommost_level && tombstone.seq_ <= earliest_snapshot) {
+      // TODO(andrewkr): tombstones that span multiple output files are
+      // counted for each compaction output file, so lots of double
+      // counting.
+      range_del_out_stats.num_range_del_drop_obsolete++;
+      range_del_out_stats.num_record_drop_obsolete++;
+      continue;
+    }
+
+    auto kv = tombstone.Serialize();
+    assert(lower_bound == nullptr ||
+           ucmp->Compare(*lower_bound, kv.second) < 0);
+    // Range tombstone is not supported by output validator yet.
+    builder_->Add(kv.first.Encode(), kv.second);
+    InternalKey smallest_candidate = std::move(kv.first);
+    if (lower_bound != nullptr &&
+        ucmp->Compare(smallest_candidate.user_key(), *lower_bound) <= 0) {
+      // Pretend the smallest key has the same user key as lower_bound
+      // (the max key in the previous table or subcompaction) in order for
+      // files to appear key-space partitioned.
+      //
+      // When lower_bound is chosen by a subcompaction, we know that
+      // subcompactions over smaller keys cannot contain any keys at
+      // lower_bound. We also know that smaller subcompactions exist,
+      // because otherwise the subcompaction woud be unbounded on the left.
+      // As a result, we know that no other files on the output level will
+      // contain actual keys at lower_bound (an output file may have a
+      // largest key of lower_bound@kMaxSequenceNumber, but this only
+      // indicates a large range tombstone was truncated). Therefore, it is
+      // safe to use the tombstone's sequence number, to ensure that keys at
+      // lower_bound at lower levels are covered by truncated tombstones.
+      //
+      // If lower_bound was chosen by the smallest data key in the file,
+      // choose lowest seqnum so this file's smallest internal key comes
+      // after the previous file's largest. The fake seqnum is OK because
+      // the read path's file-picking code only considers user key.
+      smallest_candidate = InternalKey(
+          *lower_bound, lower_bound_from_sub_compact ? tombstone.seq_ : 0,
+          kTypeRangeDeletion);
+    }
+    InternalKey largest_candidate = tombstone.SerializeEndKey();
+    if (upper_bound != nullptr &&
+        ucmp->Compare(*upper_bound, largest_candidate.user_key()) <= 0) {
+      // Pretend the largest key has the same user key as upper_bound (the
+      // min key in the following table or subcompaction) in order for files
+      // to appear key-space partitioned.
+      //
+      // Choose highest seqnum so this file's largest internal key comes
+      // before the next file's/subcompaction's smallest. The fake seqnum is
+      // OK because the read path's file-picking code only considers the
+      // user key portion.
+      //
+      // Note Seek() also creates InternalKey with (user_key,
+      // kMaxSequenceNumber), but with kTypeDeletion (0x7) instead of
+      // kTypeRangeDeletion (0xF), so the range tombstone comes before the
+      // Seek() key in InternalKey's ordering. So Seek() will look in the
+      // next file for the user key.
+      largest_candidate =
+          InternalKey(*upper_bound, kMaxSequenceNumber, kTypeRangeDeletion);
+    }
+#ifndef NDEBUG
+    SequenceNumber smallest_ikey_seqnum = kMaxSequenceNumber;
+    if (meta.smallest.size() > 0) {
+      smallest_ikey_seqnum = GetInternalKeySeqno(meta.smallest.Encode());
+    }
+#endif
+    meta.UpdateBoundariesForRange(smallest_candidate, largest_candidate,
+                                  tombstone.seq_, icmp);
+    // The smallest key in a file is used for range tombstone truncation, so
+    // it cannot have a seqnum of 0 (unless the smallest data key in a file
+    // has a seqnum of 0). Otherwise, the truncated tombstone may expose
+    // deleted keys at lower levels.
+    assert(smallest_ikey_seqnum == 0 ||
+           ExtractInternalKeyFooter(meta.smallest.Encode()) !=
+               PackSequenceAndType(0, kTypeRangeDeletion));
+  }
+  return Status::OK();
+}
+}  // namespace ROCKSDB_NAMESPACE

db/compaction/compaction_outputs.h

@@ -0,0 +1,329 @@
+//  Copyright (c) Meta Platforms, Inc. and affiliates.
+//
+//  This source code is licensed under both the GPLv2 (found in the
+//  COPYING file in the root directory) and Apache 2.0 License
+//  (found in the LICENSE.Apache file in the root directory).
+//
+// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file. See the AUTHORS file for names of contributors.
+
+#pragma once
+
+#include "db/blob/blob_garbage_meter.h"
+#include "db/compaction/compaction.h"
+#include "db/compaction/compaction_iterator.h"
+#include "db/internal_stats.h"
+#include "db/output_validator.h"
+
+namespace ROCKSDB_NAMESPACE {
+
+class CompactionOutputs;
+using CompactionFileOpenFunc = std::function<Status(CompactionOutputs&)>;
+using CompactionFileCloseFunc =
+    std::function<Status(CompactionOutputs&, const Status&, const Slice&)>;
+
+// Files produced by subcompaction, most of the functions are used by
+// compaction_job Open/Close compaction file functions.
+class CompactionOutputs {
+ public:
+  // compaction output file
+  struct Output {
+    Output(FileMetaData&& _meta, const InternalKeyComparator& _icmp,
+           bool _enable_order_check, bool _enable_hash, bool _finished,
+           uint64_t precalculated_hash)
+        : meta(std::move(_meta)),
+          validator(_icmp, _enable_order_check, _enable_hash,
+                    precalculated_hash),
+          finished(_finished) {}
+    FileMetaData meta;
+    OutputValidator validator;
+    bool finished;
+    std::shared_ptr<const TableProperties> table_properties;
+  };
+
+  CompactionOutputs() = delete;
+
+  explicit CompactionOutputs(const Compaction* compaction,
+                             const bool is_penultimate_level)
+      : compaction_(compaction), is_penultimate_level_(is_penultimate_level) {
+    partitioner_ = compaction->output_level() == 0
+                       ? nullptr
+                       : compaction->CreateSstPartitioner();
+  }
+
+  // Add generated output to the list
+  void AddOutput(FileMetaData&& meta, const InternalKeyComparator& icmp,
+                 bool enable_order_check, bool enable_hash,
+                 bool finished = false, uint64_t precalculated_hash = 0) {
+    outputs_.emplace_back(std::move(meta), icmp, enable_order_check,
+                          enable_hash, finished, precalculated_hash);
+  }
+
+  // Set new table builder for the current output
+  void NewBuilder(const TableBuilderOptions& tboptions);
+
+  // Assign a new WritableFileWriter to the current output
+  void AssignFileWriter(WritableFileWriter* writer) {
+    file_writer_.reset(writer);
+  }
+
+  // TODO: Remove it when remote compaction support tiered compaction
+  void SetTotalBytes(uint64_t bytes) { stats_.bytes_written += bytes; }
+  void SetNumOutputRecords(uint64_t num) { stats_.num_output_records = num; }
+
+  // TODO: Move the BlobDB builder into CompactionOutputs
+  const std::vector<BlobFileAddition>& GetBlobFileAdditions() const {
+    if (is_penultimate_level_) {
+      assert(blob_file_additions_.empty());
+    }
+    return blob_file_additions_;
+  }
+
+  std::vector<BlobFileAddition>* GetBlobFileAdditionsPtr() {
+    assert(!is_penultimate_level_);
+    return &blob_file_additions_;
+  }
+
+  bool HasBlobFileAdditions() const { return !blob_file_additions_.empty(); }
+
+  BlobGarbageMeter* CreateBlobGarbageMeter() {
+    assert(!is_penultimate_level_);
+    blob_garbage_meter_ = std::make_unique<BlobGarbageMeter>();
+    return blob_garbage_meter_.get();
+  }
+
+  BlobGarbageMeter* GetBlobGarbageMeter() const {
+    if (is_penultimate_level_) {
+      // blobdb doesn't support per_key_placement yet
+      assert(blob_garbage_meter_ == nullptr);
+      return nullptr;
+    }
+    return blob_garbage_meter_.get();
+  }
+
+  void UpdateBlobStats() {
+    assert(!is_penultimate_level_);
+    stats_.num_output_files_blob = blob_file_additions_.size();
+    for (const auto& blob : blob_file_additions_) {
+      stats_.bytes_written_blob += blob.GetTotalBlobBytes();
+    }
+  }
+
+  // Finish the current output file
+  Status Finish(const Status& intput_status,
+                const SeqnoToTimeMapping& seqno_time_mapping);
+
+  // Update output table properties from table builder
+  void UpdateTableProperties() {
+    current_output().table_properties =
+        std::make_shared<TableProperties>(GetTableProperties());
+  }
+
+  IOStatus WriterSyncClose(const Status& intput_status, SystemClock* clock,
+                           Statistics* statistics, bool use_fsync);
+
+  TableProperties GetTableProperties() {
+    return builder_->GetTableProperties();
+  }
+
+  Slice SmallestUserKey() const {
+    if (!outputs_.empty() && outputs_[0].finished) {
+      return outputs_[0].meta.smallest.user_key();
+    } else {
+      return Slice{nullptr, 0};
+    }
+  }
+
+  Slice LargestUserKey() const {
+    if (!outputs_.empty() && outputs_.back().finished) {
+      return outputs_.back().meta.largest.user_key();
+    } else {
+      return Slice{nullptr, 0};
+    }
+  }
+
+  // In case the last output file is empty, which doesn't need to keep.
+  void RemoveLastEmptyOutput() {
+    if (!outputs_.empty() && !outputs_.back().meta.fd.file_size) {
+      // An error occurred, so ignore the last output.
+      outputs_.pop_back();
+    }
+  }
+
+  // Remove the last output, for example the last output doesn't have data (no
+  // entry and no range-dels), but file_size might not be 0, as it has SST
+  // metadata.
+  void RemoveLastOutput() {
+    assert(!outputs_.empty());
+    outputs_.pop_back();
+  }
+
+  bool HasBuilder() const { return builder_ != nullptr; }
+
+  FileMetaData* GetMetaData() { return &current_output().meta; }
+
+  bool HasOutput() const { return !outputs_.empty(); }
+
+  uint64_t NumEntries() const { return builder_->NumEntries(); }
+
+  void ResetBuilder() {
+    builder_.reset();
+    current_output_file_size_ = 0;
+  }
+
+  // Add range-dels from the aggregator to the current output file
+  Status AddRangeDels(const Slice* comp_start, const Slice* comp_end,
+                      CompactionIterationStats& range_del_out_stats,
+                      bool bottommost_level, const InternalKeyComparator& icmp,
+                      SequenceNumber earliest_snapshot,
+                      const Slice& next_table_min_key);
+
+  // Is the current file is already pending for close
+  bool IsPendingClose() const { return pending_close_; }
+
+  // Current file should close before adding a new key
+  void SetPendingClose() { pending_close_ = true; }
+
+  // if the outputs have range delete, range delete is also data
+  bool HasRangeDel() const {
+    return range_del_agg_ && !range_del_agg_->IsEmpty();
+  }
+
+ private:
+  friend class SubcompactionState;
+
+  void Cleanup() {
+    if (builder_ != nullptr) {
+      // May happen if we get a shutdown call in the middle of compaction
+      builder_->Abandon();
+      builder_.reset();
+    }
+  }
+
+  uint64_t GetCurrentOutputFileSize() const {
+    return current_output_file_size_;
+  }
+
+  // Add curent key from compaction_iterator to the output file. If needed
+  // close and open new compaction output with the functions provided.
+  Status AddToOutput(const CompactionIterator& c_iter,
+                     const CompactionFileOpenFunc& open_file_func,
+                     const CompactionFileCloseFunc& close_file_func);
+
+  // Close the current output. `open_file_func` is needed for creating new file
+  // for range-dels only output file.
+  Status CloseOutput(const Status& curr_status,
+                     const CompactionFileOpenFunc& open_file_func,
+                     const CompactionFileCloseFunc& close_file_func) {
+    Status status = curr_status;
+    // handle subcompaction containing only range deletions
+    if (status.ok() && !HasBuilder() && !HasOutput() && HasRangeDel()) {
+      status = open_file_func(*this);
+    }
+    if (HasBuilder()) {
+      const Slice empty_key{};
+      Status s = close_file_func(*this, status, empty_key);
+      if (!s.ok() && status.ok()) {
+        status = s;
+      }
+    }
+
+    return status;
+  }
+
+  // This subcompaction's output could be empty if compaction was aborted before
+  // this subcompaction had a chance to generate any output files. When
+  // subcompactions are executed sequentially this is more likely and will be
+  // particularly likely for the later subcompactions to be empty. Once they are
+  // run in parallel however it should be much rarer.
+  // It's caller's responsibility to make sure it's not empty.
+  Output& current_output() {
+    assert(!outputs_.empty());
+    return outputs_.back();
+  }
+
+  // Assign the range_del_agg to the target output level. There's only one
+  // range-del-aggregator per compaction outputs, for
+  // output_to_penultimate_level compaction it is only assigned to the
+  // penultimate level.
+  void AssignRangeDelAggregator(
+      std::unique_ptr<CompactionRangeDelAggregator>&& range_del_agg) {
+    assert(range_del_agg_ == nullptr);
+    range_del_agg_ = std::move(range_del_agg);
+  }
+
+  const Compaction* compaction_;
+
+  // The current file is pending close, which needs to run `close_file_func()`
+  // first to add a new key.
+  bool pending_close_ = false;
+
+  // current output builder and writer
+  std::unique_ptr<TableBuilder> builder_;
+  std::unique_ptr<WritableFileWriter> file_writer_;
+  uint64_t current_output_file_size_ = 0;
+
+  // all the compaction outputs so far
+  std::vector<Output> outputs_;
+
+  // BlobDB info
+  std::vector<BlobFileAddition> blob_file_additions_;
+  std::unique_ptr<BlobGarbageMeter> blob_garbage_meter_;
+
+  // Basic compaction output stats for this level's outputs
+  InternalStats::CompactionOutputsStats stats_;
+
+  // indicate if this CompactionOutputs obj for penultimate_level, should always
+  // be false if per_key_placement feature is not enabled.
+  const bool is_penultimate_level_;
+  std::unique_ptr<CompactionRangeDelAggregator> range_del_agg_ = nullptr;
+
+  // partitioner information
+  std::string last_key_for_partitioner_;
+  std::unique_ptr<SstPartitioner> partitioner_;
+};
+
+// helper struct to concatenate the last level and penultimate level outputs
+// which could be replaced by std::ranges::join_view() in c++20
+struct OutputIterator {
+ public:
+  explicit OutputIterator(const std::vector<CompactionOutputs::Output>& a,
+                          const std::vector<CompactionOutputs::Output>& b)
+      : a_(a), b_(b) {
+    within_a = !a_.empty();
+    idx_ = 0;
+  }
+
+  OutputIterator begin() { return *this; }
+
+  OutputIterator end() { return *this; }
+
+  size_t size() { return a_.size() + b_.size(); }
+
+  const CompactionOutputs::Output& operator*() const {
+    return within_a ? a_[idx_] : b_[idx_];
+  }
+
+  OutputIterator& operator++() {
+    idx_++;
+    if (within_a && idx_ >= a_.size()) {
+      within_a = false;
+      idx_ = 0;
+    }
+    assert(within_a || idx_ <= b_.size());
+    return *this;
+  }
+
+  bool operator!=(const OutputIterator& /*rhs*/) const {
+    return within_a || idx_ < b_.size();
+  }
+
+ private:
+  const std::vector<CompactionOutputs::Output>& a_;
+  const std::vector<CompactionOutputs::Output>& b_;
+  bool within_a;
+  size_t idx_;
+};
+
+}  // namespace ROCKSDB_NAMESPACE

db/compaction/compaction_picker.cc

@@ -214,13 +214,13 @@ void CompactionPicker::GetRange(const CompactionInputFiles& inputs1,
 }
 
 void CompactionPicker::GetRange(const std::vector<CompactionInputFiles>& inputs,
-                                InternalKey* smallest,
-                                InternalKey* largest) const {
+                                InternalKey* smallest, InternalKey* largest,
+                                int exclude_level) const {
   InternalKey current_smallest;
   InternalKey current_largest;
   bool initialized = false;
   for (const auto& in : inputs) {
-    if (in.empty()) {
+    if (in.empty() || in.level == exclude_level) {
       continue;
     }
     GetRange(in, &current_smallest, &current_largest);
@@ -293,6 +293,12 @@ bool CompactionPicker::RangeOverlapWithCompaction(
       // Overlap
       return true;
     }
+    if (c->SupportsPerKeyPlacement()) {
+      if (c->OverlapPenultimateLevelOutputRange(smallest_user_key,
+                                                largest_user_key)) {
+        return true;
+      }
+    }
   }
   // Did not overlap with any running compaction in level `level`
   return false;
@@ -301,9 +307,11 @@ bool CompactionPicker::RangeOverlapWithCompaction(
 bool CompactionPicker::FilesRangeOverlapWithCompaction(
     const std::vector<CompactionInputFiles>& inputs, int level) const {
   bool is_empty = true;
+  int start_level = -1;
   for (auto& in : inputs) {
     if (!in.empty()) {
       is_empty = false;
+      start_level = in.level;  // inputs are sorted by level
       break;
     }
   }
@@ -313,7 +321,19 @@ bool CompactionPicker::FilesRangeOverlapWithCompaction(
   }
 
   InternalKey smallest, largest;
-  GetRange(inputs, &smallest, &largest);
+  GetRange(inputs, &smallest, &largest, Compaction::kInvalidLevel);
+  int penultimate_level =
+      Compaction::EvaluatePenultimateLevel(ioptions_, start_level, level);
+  if (penultimate_level != Compaction::kInvalidLevel) {
+    InternalKey penultimate_smallest, penultimate_largest;
+    GetRange(inputs, &penultimate_smallest, &penultimate_largest, level);
+    if (RangeOverlapWithCompaction(penultimate_smallest.user_key(),
+                                   penultimate_largest.user_key(),
+                                   penultimate_level)) {
+      return true;
+    }
+  }
+
   return RangeOverlapWithCompaction(smallest.user_key(), largest.user_key(),
                                     level);
 }
@@ -442,7 +462,7 @@ bool CompactionPicker::SetupOtherInputs(
     const std::string& cf_name, const MutableCFOptions& mutable_cf_options,
     VersionStorageInfo* vstorage, CompactionInputFiles* inputs,
     CompactionInputFiles* output_level_inputs, int* parent_index,
-    int base_index) {
+    int base_index, bool only_expand_towards_right) {
   assert(!inputs->empty());
   assert(output_level_inputs->empty());
   const int input_level = inputs->level;
@@ -495,8 +515,16 @@ bool CompactionPicker::SetupOtherInputs(
     InternalKey all_start, all_limit;
     GetRange(*inputs, *output_level_inputs, &all_start, &all_limit);
     bool try_overlapping_inputs = true;
-    vstorage->GetOverlappingInputs(input_level, &all_start, &all_limit,
-                                   &expanded_inputs.files, base_index, nullptr);
+    if (only_expand_towards_right) {
+      // Round-robin compaction only allows expansion towards the larger side.
+      vstorage->GetOverlappingInputs(input_level, &smallest, &all_limit,
+                                     &expanded_inputs.files, base_index,
+                                     nullptr);
+    } else {
+      vstorage->GetOverlappingInputs(input_level, &all_start, &all_limit,
+                                     &expanded_inputs.files, base_index,
+                                     nullptr);
+    }
     uint64_t expanded_inputs_size =
         TotalCompensatedFileSize(expanded_inputs.files);
     if (!ExpandInputsToCleanCut(cf_name, vstorage, &expanded_inputs)) {
@@ -543,6 +571,10 @@ bool CompactionPicker::SetupOtherInputs(
                      output_level_inputs_size);
       inputs->files = expanded_inputs.files;
     }
+  } else {
+    // Likely to be trivial move. Expand files if they are still trivial moves,
+    // but limit to mutable_cf_options.max_compaction_bytes or 8 files so that
+    // we don't create too much compaction pressure for the next level.
   }
   return true;
 }
@@ -641,7 +673,8 @@ Compaction* CompactionPicker::CompactRange(
         GetCompressionOptions(mutable_cf_options, vstorage, output_level),
         Temperature::kUnknown, compact_range_options.max_subcompactions,
         /* grandparents */ {}, /* is manual */ true, trim_ts, /* score */ -1,
-        /* deletion_compaction */ false, CompactionReason::kUnknown,
+        /* deletion_compaction */ false, /* l0_files_might_overlap */ true,
+        CompactionReason::kUnknown,
         compact_range_options.blob_garbage_collection_policy,
         compact_range_options.blob_garbage_collection_age_cutoff);
 
@@ -823,7 +856,8 @@ Compaction* CompactionPicker::CompactRange(
       GetCompressionOptions(mutable_cf_options, vstorage, output_level),
       Temperature::kUnknown, compact_range_options.max_subcompactions,
       std::move(grandparents), /* is manual */ true, trim_ts, /* score */ -1,
-      /* deletion_compaction */ false, CompactionReason::kUnknown,
+      /* deletion_compaction */ false, /* l0_files_might_overlap */ true,
+      CompactionReason::kUnknown,
       compact_range_options.blob_garbage_collection_policy,
       compact_range_options.blob_garbage_collection_age_cutoff);
 

db/compaction/compaction_picker.h

@@ -154,7 +154,8 @@ class CompactionPicker {
   // in *smallest, *largest.
   // REQUIRES: inputs is not empty (at least on entry have one file)
   void GetRange(const std::vector<CompactionInputFiles>& inputs,
-                InternalKey* smallest, InternalKey* largest) const;
+                InternalKey* smallest, InternalKey* largest,
+                int exclude_level) const;
 
   int NumberLevels() const { return ioptions_.num_levels; }
 
@@ -188,7 +189,8 @@ class CompactionPicker {
                         VersionStorageInfo* vstorage,
                         CompactionInputFiles* inputs,
                         CompactionInputFiles* output_level_inputs,
-                        int* parent_index, int base_index);
+                        int* parent_index, int base_index,
+                        bool only_expand_towards_right = false);
 
   void GetGrandparents(VersionStorageInfo* vstorage,
                        const CompactionInputFiles& inputs,
@@ -217,6 +219,8 @@ class CompactionPicker {
     return &compactions_in_progress_;
   }
 
+  const InternalKeyComparator* icmp() const { return icmp_; }
+
  protected:
   const ImmutableOptions& ioptions_;
 

db/compaction/compaction_picker_fifo.cc

@@ -83,7 +83,7 @@ Compaction* FIFOCompactionPicker::PickTTLCompaction(
           break;
         }
       }
-      total_size -= f->compensated_file_size;
+      total_size -= f->fd.file_size;
       inputs[0].files.push_back(f);
     }
   }
@@ -116,7 +116,8 @@ Compaction* FIFOCompactionPicker::PickTTLCompaction(
       mutable_cf_options.compression_opts, Temperature::kUnknown,
       /* max_subcompactions */ 0, {}, /* is manual */ false,
       /* trim_ts */ "", vstorage->CompactionScore(0),
-      /* is deletion compaction */ true, CompactionReason::kFIFOTtl);
+      /* is deletion compaction */ true, /* l0_files_might_overlap */ true,
+      CompactionReason::kFIFOTtl);
   return c;
 }
 
@@ -160,6 +161,7 @@ Compaction* FIFOCompactionPicker::PickSizeCompaction(
             0 /* max_subcompactions */, {}, /* is manual */ false,
             /* trim_ts */ "", vstorage->CompactionScore(0),
             /* is deletion compaction */ false,
+            /* l0_files_might_overlap */ true,
             CompactionReason::kFIFOReduceNumFiles);
         return c;
       }
@@ -189,7 +191,7 @@ Compaction* FIFOCompactionPicker::PickSizeCompaction(
 
   for (auto ritr = level_files.rbegin(); ritr != level_files.rend(); ++ritr) {
     auto f = *ritr;
-    total_size -= f->compensated_file_size;
+    total_size -= f->fd.file_size;
     inputs[0].files.push_back(f);
     char tmp_fsize[16];
     AppendHumanBytes(f->fd.GetFileSize(), tmp_fsize, sizeof(tmp_fsize));
@@ -209,7 +211,8 @@ Compaction* FIFOCompactionPicker::PickSizeCompaction(
       mutable_cf_options.compression_opts, Temperature::kUnknown,
       /* max_subcompactions */ 0, {}, /* is manual */ false,
       /* trim_ts */ "", vstorage->CompactionScore(0),
-      /* is deletion compaction */ true, CompactionReason::kFIFOMaxSize);
+      /* is deletion compaction */ true,
+      /* l0_files_might_overlap */ true, CompactionReason::kFIFOMaxSize);
   return c;
 }
 
@@ -315,7 +318,8 @@ Compaction* FIFOCompactionPicker::PickCompactionToWarm(
       Temperature::kWarm,
       /* max_subcompactions */ 0, {}, /* is manual */ false, /* trim_ts */ "",
       vstorage->CompactionScore(0),
-      /* is deletion compaction */ false, CompactionReason::kChangeTemperature);
+      /* is deletion compaction */ false, /* l0_files_might_overlap */ true,
+      CompactionReason::kChangeTemperature);
   return c;
 }
 

db/compaction/compaction_picker_level.cc

@@ -7,11 +7,13 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file. See the AUTHORS file for names of contributors.
 
+#include "db/compaction/compaction_picker_level.h"
+
 #include <string>
 #include <utility>
 #include <vector>
 
-#include "db/compaction/compaction_picker_level.h"
+#include "db/version_edit.h"
 #include "logging/log_buffer.h"
 #include "test_util/sync_point.h"
 
@@ -74,6 +76,9 @@ class LevelCompactionBuilder {
   // files if needed.
   bool SetupOtherL0FilesIfNeeded();
 
+  // Compaction with round-robin compaction priority allows more files to be
+  // picked to form a large compaction
+  void SetupOtherFilesWithRoundRobinExpansion();
   // Based on initial files, setup other files need to be compacted
   // in this compaction, accordingly.
   bool SetupOtherInputsIfNeeded();
@@ -82,11 +87,16 @@ class LevelCompactionBuilder {
 
   // For the specfied level, pick a file that we want to compact.
   // Returns false if there is no file to compact.
-  // If it returns true, inputs->files.size() will be exactly one.
+  // If it returns true, inputs->files.size() will be exactly one for
+  // all compaction priorities except round-robin. For round-robin,
+  // multiple consecutive files may be put into inputs->files.
   // If level is 0 and there is already a compaction on that level, this
   // function will return false.
   bool PickFileToCompact();
 
+  // Return true if a L0 trivial move is picked up.
+  bool TryPickL0TrivialMove();
+
   // For L0->L0, picks the longest span of files that aren't currently
   // undergoing compaction for which work-per-deleted-file decreases. The span
   // always starts from the newest L0 file.
@@ -98,6 +108,10 @@ class LevelCompactionBuilder {
   // otherwise, returns false.
   bool PickIntraL0Compaction();
 
+  // Return true if TrivialMove is extended. `start_index` is the index of
+  // the intiial file picked, which should already be in `start_level_inputs_`.
+  bool TryExtendNonL0TrivialMove(int start_index);
+
   // Picks a file from level_files to compact.
   // level_files is a vector of (level, file metadata) in ascending order of
   // level. If compact_to_next_level is true, compact the file to the next
@@ -117,6 +131,7 @@ class LevelCompactionBuilder {
   int base_index_ = -1;
   double start_level_score_ = 0;
   bool is_manual_ = false;
+  bool is_l0_trivial_move_ = false;
   CompactionInputFiles start_level_inputs_;
   std::vector<CompactionInputFiles> compaction_inputs_;
   CompactionInputFiles output_level_inputs_;
@@ -261,22 +276,148 @@ void LevelCompactionBuilder::SetupInitialFiles() {
 }
 
 bool LevelCompactionBuilder::SetupOtherL0FilesIfNeeded() {
-  if (start_level_ == 0 && output_level_ != 0) {
+  if (start_level_ == 0 && output_level_ != 0 && !is_l0_trivial_move_) {
     return compaction_picker_->GetOverlappingL0Files(
         vstorage_, &start_level_inputs_, output_level_, &parent_index_);
   }
   return true;
 }
 
+void LevelCompactionBuilder::SetupOtherFilesWithRoundRobinExpansion() {
+  // We only expand when the start level is not L0 under round robin
+  assert(start_level_ >= 1);
+
+  // For round-robin compaction priority, we have 3 constraints when picking
+  // multiple files.
+  // Constraint 1: We can only pick consecutive files
+  //  -> Constraint 1a: When a file is being compacted (or some input files
+  //                    are being compacted after expanding, we cannot
+  //                    choose it and have to stop choosing more files
+  //  -> Constraint 1b: When we reach the last file (with largest keys), we
+  //                    cannot choose more files (the next file will be the
+  //                    first one)
+  // Constraint 2: We should ensure the total compaction bytes (including the
+  //               overlapped files from the next level) is no more than
+  //               mutable_cf_options_.max_compaction_bytes
+  // Constraint 3: We try our best to pick as many files as possible so that
+  //               the post-compaction level size is less than
+  //               MaxBytesForLevel(start_level_)
+  // Constraint 4: We do not expand if it is possible to apply a trivial move
+  // Constraint 5 (TODO): Try to pick minimal files to split into the target
+  //               number of subcompactions
+  TEST_SYNC_POINT("LevelCompactionPicker::RoundRobin");
+
+  // Only expand the inputs when we have selected a file in start_level_inputs_
+  if (start_level_inputs_.size() == 0) return;
+
+  uint64_t start_lvl_bytes_no_compacting = 0;
+  uint64_t curr_bytes_to_compact = 0;
+  uint64_t start_lvl_max_bytes_to_compact = 0;
+  const std::vector<FileMetaData*>& level_files =
+      vstorage_->LevelFiles(start_level_);
+  // Constraint 3 (pre-calculate the ideal max bytes to compact)
+  for (auto f : level_files) {
+    if (!f->being_compacted) {
+      start_lvl_bytes_no_compacting += f->compensated_file_size;
+    }
+  }
+  if (start_lvl_bytes_no_compacting >
+      vstorage_->MaxBytesForLevel(start_level_)) {
+    start_lvl_max_bytes_to_compact = start_lvl_bytes_no_compacting -
+                                     vstorage_->MaxBytesForLevel(start_level_);
+  }
+
+  size_t start_index = vstorage_->FilesByCompactionPri(start_level_)[0];
+  InternalKey smallest, largest;
+  // Constraint 4 (No need to check again later)
+  compaction_picker_->GetRange(start_level_inputs_, &smallest, &largest);
+  CompactionInputFiles output_level_inputs;
+  output_level_inputs.level = output_level_;
+  vstorage_->GetOverlappingInputs(output_level_, &smallest, &largest,
+                                  &output_level_inputs.files);
+  if (output_level_inputs.empty()) {
+    if (TryExtendNonL0TrivialMove((int)start_index)) {
+      return;
+    }
+  }
+  // Constraint 3
+  if (start_level_inputs_[0]->compensated_file_size >=
+      start_lvl_max_bytes_to_compact) {
+    return;
+  }
+  CompactionInputFiles tmp_start_level_inputs;
+  tmp_start_level_inputs = start_level_inputs_;
+  // TODO (zichen): Future parallel round-robin may also need to update this
+  // Constraint 1b (only expand till the end)
+  for (size_t i = start_index + 1; i < level_files.size(); i++) {
+    auto* f = level_files[i];
+    if (f->being_compacted) {
+      // Constraint 1a
+      return;
+    }
+
+    tmp_start_level_inputs.files.push_back(f);
+    if (!compaction_picker_->ExpandInputsToCleanCut(cf_name_, vstorage_,
+                                                    &tmp_start_level_inputs) ||
+        compaction_picker_->FilesRangeOverlapWithCompaction(
+            {tmp_start_level_inputs}, output_level_)) {
+      // Constraint 1a
+      tmp_start_level_inputs.clear();
+      return;
+    }
+
+    curr_bytes_to_compact = 0;
+    for (auto start_lvl_f : tmp_start_level_inputs.files) {
+      curr_bytes_to_compact += start_lvl_f->compensated_file_size;
+    }
+
+    // Check whether any output level files are locked
+    compaction_picker_->GetRange(tmp_start_level_inputs, &smallest, &largest);
+    vstorage_->GetOverlappingInputs(output_level_, &smallest, &largest,
+                                    &output_level_inputs.files);
+    if (!output_level_inputs.empty() &&
+        !compaction_picker_->ExpandInputsToCleanCut(cf_name_, vstorage_,
+                                                    &output_level_inputs)) {
+      // Constraint 1a
+      tmp_start_level_inputs.clear();
+      return;
+    }
+
+    uint64_t start_lvl_curr_bytes_to_compact = curr_bytes_to_compact;
+    for (auto output_lvl_f : output_level_inputs.files) {
+      curr_bytes_to_compact += output_lvl_f->compensated_file_size;
+    }
+    if (curr_bytes_to_compact > mutable_cf_options_.max_compaction_bytes) {
+      // Constraint 2
+      tmp_start_level_inputs.clear();
+      return;
+    }
+
+    start_level_inputs_.files = tmp_start_level_inputs.files;
+    // Constraint 3
+    if (start_lvl_curr_bytes_to_compact > start_lvl_max_bytes_to_compact) {
+      return;
+    }
+  }
+}
+
 bool LevelCompactionBuilder::SetupOtherInputsIfNeeded() {
   // Setup input files from output level. For output to L0, we only compact
   // spans of files that do not interact with any pending compactions, so don't
   // need to consider other levels.
   if (output_level_ != 0) {
     output_level_inputs_.level = output_level_;
-    if (!compaction_picker_->SetupOtherInputs(
+    bool round_robin_expanding =
+        ioptions_.compaction_pri == kRoundRobin &&
+        compaction_reason_ == CompactionReason::kLevelMaxLevelSize;
+    if (round_robin_expanding) {
+      SetupOtherFilesWithRoundRobinExpansion();
+    }
+    if (!is_l0_trivial_move_ &&
+        !compaction_picker_->SetupOtherInputs(
             cf_name_, mutable_cf_options_, vstorage_, &start_level_inputs_,
-            &output_level_inputs_, &parent_index_, base_index_)) {
+            &output_level_inputs_, &parent_index_, base_index_,
+            round_robin_expanding)) {
       return false;
     }
 
@@ -285,20 +426,22 @@ bool LevelCompactionBuilder::SetupOtherInputsIfNeeded() {
       compaction_inputs_.push_back(output_level_inputs_);
     }
 
-    // In some edge cases we could pick a compaction that will be compacting
-    // a key range that overlap with another running compaction, and both
-    // of them have the same output level. This could happen if
-    // (1) we are running a non-exclusive manual compaction
-    // (2) AddFile ingest a new file into the LSM tree
-    // We need to disallow this from happening.
-    if (compaction_picker_->FilesRangeOverlapWithCompaction(compaction_inputs_,
-                                                            output_level_)) {
-      // This compaction output could potentially conflict with the output
-      // of a currently running compaction, we cannot run it.
-      return false;
+    if (!is_l0_trivial_move_) {
+      // In some edge cases we could pick a compaction that will be compacting
+      // a key range that overlap with another running compaction, and both
+      // of them have the same output level. This could happen if
+      // (1) we are running a non-exclusive manual compaction
+      // (2) AddFile ingest a new file into the LSM tree
+      // We need to disallow this from happening.
+      if (compaction_picker_->FilesRangeOverlapWithCompaction(
+              compaction_inputs_, output_level_)) {
+        // This compaction output could potentially conflict with the output
+        // of a currently running compaction, we cannot run it.
+        return false;
+      }
+      compaction_picker_->GetGrandparents(vstorage_, start_level_inputs_,
+                                          output_level_inputs_, &grandparents_);
     }
-    compaction_picker_->GetGrandparents(vstorage_, start_level_inputs_,
-                                        output_level_inputs_, &grandparents_);
   } else {
     compaction_inputs_.push_back(start_level_inputs_);
   }
@@ -349,6 +492,7 @@ Compaction* LevelCompactionBuilder::GetCompaction() {
       Temperature::kUnknown,
       /* max_subcompactions */ 0, std::move(grandparents_), is_manual_,
       /* trim_ts */ "", start_level_score_, false /* deletion_compaction */,
+      /* l0_files_might_overlap */ start_level_ == 0 && !is_l0_trivial_move_,
       compaction_reason_);
 
   // If it's level 0 compaction, make sure we don't execute any other level 0
@@ -417,6 +561,124 @@ uint32_t LevelCompactionBuilder::GetPathId(
   return p;
 }
 
+bool LevelCompactionBuilder::TryPickL0TrivialMove() {
+  if (vstorage_->base_level() <= 0) {
+    return false;
+  }
+  if (start_level_ == 0 && mutable_cf_options_.compression_per_level.empty() &&
+      !vstorage_->LevelFiles(output_level_).empty() &&
+      ioptions_.db_paths.size() <= 1) {
+    // Try to pick trivial move from L0 to L1. We start from the oldest
+    // file. We keep expanding to newer files if it would form a
+    // trivial move.
+    // For now we don't support it with
+    // mutable_cf_options_.compression_per_level to prevent the logic
+    // of determining whether L0 can be trivial moved to the next level.
+    // We skip the case where output level is empty, since in this case, at
+    // least the oldest file would qualify for trivial move, and this would
+    // be a surprising behavior with few benefits.
+
+    // We search from the oldest file from the newest. In theory, there are
+    // files in the middle can form trivial move too, but it is probably
+    // uncommon and we ignore these cases for simplicity.
+    const std::vector<FileMetaData*>& level_files =
+        vstorage_->LevelFiles(start_level_);
+
+    InternalKey my_smallest, my_largest;
+    for (auto it = level_files.rbegin(); it != level_files.rend(); ++it) {
+      CompactionInputFiles output_level_inputs;
+      output_level_inputs.level = output_level_;
+      FileMetaData* file = *it;
+      if (it == level_files.rbegin()) {
+        my_smallest = file->smallest;
+        my_largest = file->largest;
+      } else {
+        if (compaction_picker_->icmp()->Compare(file->largest, my_smallest) <
+            0) {
+          my_smallest = file->smallest;
+        } else if (compaction_picker_->icmp()->Compare(file->smallest,
+                                                       my_largest) > 0) {
+          my_largest = file->largest;
+        } else {
+          break;
+        }
+      }
+      vstorage_->GetOverlappingInputs(output_level_, &my_smallest, &my_largest,
+                                      &output_level_inputs.files);
+      if (output_level_inputs.empty()) {
+        assert(!file->being_compacted);
+        start_level_inputs_.files.push_back(file);
+      } else {
+        break;
+      }
+    }
+  }
+
+  if (!start_level_inputs_.empty()) {
+    // Sort files by key range. Not sure it's 100% necessary but it's cleaner
+    // to always keep files sorted by key the key ranges don't overlap.
+    std::sort(start_level_inputs_.files.begin(),
+              start_level_inputs_.files.end(),
+              [icmp = compaction_picker_->icmp()](FileMetaData* f1,
+                                                  FileMetaData* f2) -> bool {
+                return (icmp->Compare(f1->smallest, f2->smallest) < 0);
+              });
+
+    is_l0_trivial_move_ = true;
+    return true;
+  }
+  return false;
+}
+
+bool LevelCompactionBuilder::TryExtendNonL0TrivialMove(int start_index) {
+  if (start_level_inputs_.size() == 1 &&
+      (ioptions_.db_paths.empty() || ioptions_.db_paths.size() == 1) &&
+      (mutable_cf_options_.compression_per_level.empty())) {
+    // Only file of `index`, and it is likely a trivial move. Try to
+    // expand if it is still a trivial move, but not beyond
+    // max_compaction_bytes or 4 files, so that we don't create too
+    // much compaction pressure for the next level.
+    // Ignore if there are more than one DB path, as it would be hard
+    // to predict whether it is a trivial move.
+    const std::vector<FileMetaData*>& level_files =
+        vstorage_->LevelFiles(start_level_);
+    const size_t kMaxMultiTrivialMove = 4;
+    FileMetaData* initial_file = start_level_inputs_.files[0];
+    size_t total_size = initial_file->fd.GetFileSize();
+    CompactionInputFiles output_level_inputs;
+    output_level_inputs.level = output_level_;
+    for (int i = start_index + 1;
+         i < static_cast<int>(level_files.size()) &&
+         start_level_inputs_.size() < kMaxMultiTrivialMove;
+         i++) {
+      FileMetaData* next_file = level_files[i];
+      if (next_file->being_compacted) {
+        break;
+      }
+      vstorage_->GetOverlappingInputs(output_level_, &(initial_file->smallest),
+                                      &(next_file->largest),
+                                      &output_level_inputs.files);
+      if (!output_level_inputs.empty()) {
+        break;
+      }
+      if (i < static_cast<int>(level_files.size()) - 1 &&
+          compaction_picker_->icmp()->user_comparator()->Compare(
+              next_file->largest.user_key(),
+              level_files[i + 1]->smallest.user_key()) == 0) {
+        // Not a clean up after adding the next file. Skip.
+        break;
+      }
+      total_size += next_file->fd.GetFileSize();
+      if (total_size > mutable_cf_options_.max_compaction_bytes) {
+        break;
+      }
+      start_level_inputs_.files.push_back(next_file);
+    }
+    return start_level_inputs_.size() > 1;
+  }
+  return false;
+}
+
 bool LevelCompactionBuilder::PickFileToCompact() {
   // level 0 files are overlapping. So we cannot pick more
   // than one concurrent compactions at this level. This
@@ -429,30 +691,43 @@ bool LevelCompactionBuilder::PickFileToCompact() {
   }
 
   start_level_inputs_.clear();
+  start_level_inputs_.level = start_level_;
 
   assert(start_level_ >= 0);
 
-  // Pick the largest file in this level that is not already
-  // being compacted
-  const std::vector<int>& file_size =
-      vstorage_->FilesByCompactionPri(start_level_);
+  if (TryPickL0TrivialMove()) {
+    return true;
+  }
+
   const std::vector<FileMetaData*>& level_files =
       vstorage_->LevelFiles(start_level_);
 
+  // Pick the file with the highest score in this level that is not already
+  // being compacted.
+  const std::vector<int>& file_scores =
+      vstorage_->FilesByCompactionPri(start_level_);
+
   unsigned int cmp_idx;
   for (cmp_idx = vstorage_->NextCompactionIndex(start_level_);
-       cmp_idx < file_size.size(); cmp_idx++) {
-    int index = file_size[cmp_idx];
+       cmp_idx < file_scores.size(); cmp_idx++) {
+    int index = file_scores[cmp_idx];
     auto* f = level_files[index];
 
     // do not pick a file to compact if it is being compacted
     // from n-1 level.
     if (f->being_compacted) {
+      if (ioptions_.compaction_pri == kRoundRobin) {
+        // TODO(zichen): this file may be involved in one compaction from
+        // an upper level, cannot advance the cursor for round-robin policy.
+        // Currently, we do not pick any file to compact in this case. We
+        // should fix this later to ensure a compaction is picked but the
+        // cursor shall not be advanced.
+        return false;
+      }
       continue;
     }
 
     start_level_inputs_.files.push_back(f);
-    start_level_inputs_.level = start_level_;
     if (!compaction_picker_->ExpandInputsToCleanCut(cf_name_, vstorage_,
                                                     &start_level_inputs_) ||
         compaction_picker_->FilesRangeOverlapWithCompaction(
@@ -460,11 +735,15 @@ bool LevelCompactionBuilder::PickFileToCompact() {
       // A locked (pending compaction) input-level file was pulled in due to
       // user-key overlap.
       start_level_inputs_.clear();
+
+      if (ioptions_.compaction_pri == kRoundRobin) {
+        return false;
+      }
       continue;
     }
 
-    // Now that input level is fully expanded, we check whether any output files
-    // are locked due to pending compaction.
+    // Now that input level is fully expanded, we check whether any output
+    // files are locked due to pending compaction.
     //
     // Note we rely on ExpandInputsToCleanCut() to tell us whether any output-
     // level files are locked, not just the extra ones pulled in for user-key
@@ -475,19 +754,29 @@ bool LevelCompactionBuilder::PickFileToCompact() {
     output_level_inputs.level = output_level_;
     vstorage_->GetOverlappingInputs(output_level_, &smallest, &largest,
                                     &output_level_inputs.files);
-    if (!output_level_inputs.empty() &&
-        !compaction_picker_->ExpandInputsToCleanCut(cf_name_, vstorage_,
-                                                    &output_level_inputs)) {
-      start_level_inputs_.clear();
-      continue;
+    if (output_level_inputs.empty()) {
+      if (TryExtendNonL0TrivialMove(index)) {
+        break;
+      }
+    } else {
+      if (!compaction_picker_->ExpandInputsToCleanCut(cf_name_, vstorage_,
+                                                      &output_level_inputs)) {
+        start_level_inputs_.clear();
+        if (ioptions_.compaction_pri == kRoundRobin) {
+          return false;
+        }
+        continue;
+      }
     }
+
     base_index_ = index;
     break;
   }
 
   // store where to start the iteration in the next call to PickCompaction
-  vstorage_->SetNextCompactionIndex(start_level_, cmp_idx);
-
+  if (ioptions_.compaction_pri != kRoundRobin) {
+    vstorage_->SetNextCompactionIndex(start_level_, cmp_idx);
+  }
   return start_level_inputs_.size() > 0;
 }
 

db/compaction/compaction_picker_test.cc

@@ -12,6 +12,7 @@
 #include "db/compaction/compaction_picker_level.h"
 #include "db/compaction/compaction_picker_universal.h"
 #include "db/compaction/file_pri.h"
+#include "rocksdb/advanced_options.h"
 #include "table/unique_id_impl.h"
 #include "test_util/testharness.h"
 #include "test_util/testutil.h"
@@ -115,8 +116,7 @@ class CompactionPickerTest : public testing::Test {
         InternalKey(largest, largest_seq, kTypeValue), smallest_seq,
         largest_seq, marked_for_compact, temperature, kInvalidBlobFileNumber,
         kUnknownOldestAncesterTime, kUnknownFileCreationTime,
-        kUnknownFileChecksum, kUnknownFileChecksumFuncName,
-        kDisableUserTimestamp, kDisableUserTimestamp, kNullUniqueId64x2);
+        kUnknownFileChecksum, kUnknownFileChecksumFuncName, kNullUniqueId64x2);
     f->compensated_file_size =
         (compensated_file_size != 0) ? compensated_file_size : file_size;
     f->oldest_ancester_time = oldest_ancestor_time;
@@ -429,8 +429,7 @@ TEST_F(CompactionPickerTest, LevelTriggerDynamic4) {
 #ifndef ROCKSDB_LITE
 TEST_F(CompactionPickerTest, NeedsCompactionUniversal) {
   NewVersionStorage(1, kCompactionStyleUniversal);
-  UniversalCompactionPicker universal_compaction_picker(
-      ioptions_, &icmp_);
+  UniversalCompactionPicker universal_compaction_picker(ioptions_, &icmp_);
   UpdateVersionStorageInfo();
   // must return false when there's no files.
   ASSERT_EQ(universal_compaction_picker.NeedsCompaction(vstorage_.get()),
@@ -1311,6 +1310,228 @@ TEST_F(CompactionPickerTest, CompactionPriMinOverlapping4) {
   ASSERT_EQ(6U, compaction->input(0, 0)->fd.GetNumber());
 }
 
+TEST_F(CompactionPickerTest, CompactionPriRoundRobin) {
+  std::vector<InternalKey> test_cursors = {InternalKey("249", 100, kTypeValue),
+                                           InternalKey("600", 100, kTypeValue),
+                                           InternalKey()};
+  std::vector<uint32_t> selected_files = {8U, 6U, 6U};
+
+  ioptions_.compaction_pri = kRoundRobin;
+  mutable_cf_options_.max_bytes_for_level_base = 12000000;
+  mutable_cf_options_.max_bytes_for_level_multiplier = 10;
+  for (size_t i = 0; i < test_cursors.size(); i++) {
+    // start a brand new version in each test.
+    NewVersionStorage(6, kCompactionStyleLevel);
+    vstorage_->ResizeCompactCursors(6);
+    // Set the cursor
+    vstorage_->AddCursorForOneLevel(2, test_cursors[i]);
+    Add(2, 6U, "150", "199", 50000000U);  // Overlap with 26U, 27U
+    Add(2, 7U, "200", "249", 50000000U);  // File not overlapping
+    Add(2, 8U, "300", "600", 50000000U);  // Overlap with 28U, 29U
+
+    Add(3, 26U, "130", "165", 60000000U);
+    Add(3, 27U, "166", "170", 60000000U);
+    Add(3, 28U, "270", "340", 60000000U);
+    Add(3, 29U, "401", "500", 60000000U);
+    UpdateVersionStorageInfo();
+    LevelCompactionPicker local_level_compaction_picker =
+        LevelCompactionPicker(ioptions_, &icmp_);
+    std::unique_ptr<Compaction> compaction(
+        local_level_compaction_picker.PickCompaction(
+            cf_name_, mutable_cf_options_, mutable_db_options_, vstorage_.get(),
+            &log_buffer_));
+    ASSERT_TRUE(compaction.get() != nullptr);
+    // Since the max bytes for level 2 is 120M, picking one file to compact
+    // makes the post-compaction level size less than 120M, there is exactly one
+    // file picked for round-robin compaction
+    ASSERT_EQ(1U, compaction->num_input_files(0));
+    ASSERT_EQ(selected_files[i], compaction->input(0, 0)->fd.GetNumber());
+    // release the version storage
+    DeleteVersionStorage();
+  }
+}
+
+TEST_F(CompactionPickerTest, CompactionPriMultipleFilesRoundRobin1) {
+  ioptions_.compaction_pri = kRoundRobin;
+  mutable_cf_options_.max_compaction_bytes = 100000000u;
+  mutable_cf_options_.max_bytes_for_level_base = 120;
+  mutable_cf_options_.max_bytes_for_level_multiplier = 10;
+  // start a brand new version in each test.
+  NewVersionStorage(6, kCompactionStyleLevel);
+  vstorage_->ResizeCompactCursors(6);
+  // Set the cursor (file picking should start with 7U)
+  vstorage_->AddCursorForOneLevel(2, InternalKey("199", 100, kTypeValue));
+  Add(2, 6U, "150", "199", 500U);
+  Add(2, 7U, "200", "249", 500U);
+  Add(2, 8U, "300", "600", 500U);
+  Add(2, 9U, "700", "800", 500U);
+  Add(2, 10U, "850", "950", 500U);
+
+  Add(3, 26U, "130", "165", 600U);
+  Add(3, 27U, "166", "170", 600U);
+  Add(3, 28U, "270", "340", 600U);
+  Add(3, 29U, "401", "500", 600U);
+  Add(3, 30U, "601", "800", 600U);
+  Add(3, 31U, "830", "890", 600U);
+  UpdateVersionStorageInfo();
+  LevelCompactionPicker local_level_compaction_picker =
+      LevelCompactionPicker(ioptions_, &icmp_);
+  std::unique_ptr<Compaction> compaction(
+      local_level_compaction_picker.PickCompaction(
+          cf_name_, mutable_cf_options_, mutable_db_options_, vstorage_.get(),
+          &log_buffer_));
+  ASSERT_TRUE(compaction.get() != nullptr);
+
+  // The maximum compaction bytes is very large in this case so we can igore its
+  // constraint in this test case. The maximum bytes for level 2 is 1200
+  // bytes, and thus at least 3 files should be picked so that the bytes in
+  // level 2 is less than the maximum
+  ASSERT_EQ(3U, compaction->num_input_files(0));
+  ASSERT_EQ(7U, compaction->input(0, 0)->fd.GetNumber());
+  ASSERT_EQ(8U, compaction->input(0, 1)->fd.GetNumber());
+  ASSERT_EQ(9U, compaction->input(0, 2)->fd.GetNumber());
+  // release the version storage
+  DeleteVersionStorage();
+}
+
+TEST_F(CompactionPickerTest, CompactionPriMultipleFilesRoundRobin2) {
+  ioptions_.compaction_pri = kRoundRobin;
+  mutable_cf_options_.max_compaction_bytes = 2500u;
+  mutable_cf_options_.max_bytes_for_level_base = 120;
+  mutable_cf_options_.max_bytes_for_level_multiplier = 10;
+  // start a brand new version in each test.
+  NewVersionStorage(6, kCompactionStyleLevel);
+  vstorage_->ResizeCompactCursors(6);
+  // Set the cursor (file picking should start with 6U)
+  vstorage_->AddCursorForOneLevel(2, InternalKey("1000", 100, kTypeValue));
+  Add(2, 6U, "150", "199", 500U);  // Overlap with 26U, 27U
+  Add(2, 7U, "200", "249", 500U);  // Overlap with 27U
+  Add(2, 8U, "300", "600", 500U);  // Overlap with 28U, 29U
+  Add(2, 9U, "700", "800", 500U);
+  Add(2, 10U, "850", "950", 500U);
+
+  Add(3, 26U, "130", "165", 600U);
+  Add(3, 27U, "166", "230", 600U);
+  Add(3, 28U, "270", "340", 600U);
+  Add(3, 29U, "401", "500", 600U);
+  Add(3, 30U, "601", "800", 600U);
+  Add(3, 31U, "830", "890", 600U);
+  UpdateVersionStorageInfo();
+  LevelCompactionPicker local_level_compaction_picker =
+      LevelCompactionPicker(ioptions_, &icmp_);
+  std::unique_ptr<Compaction> compaction(
+      local_level_compaction_picker.PickCompaction(
+          cf_name_, mutable_cf_options_, mutable_db_options_, vstorage_.get(),
+          &log_buffer_));
+  ASSERT_TRUE(compaction.get() != nullptr);
+
+  // The maximum compaction bytes is only 2500 bytes now. Even though we are
+  // required to choose 3 files so that the post-compaction level size is less
+  // than 1200 bytes. We cannot pick 3 files to compact since the maximum
+  // compaction size is 2500. After picking files 6U and 7U, the number of
+  // compaction bytes has reached 2200, and thus no more space to add another
+  // input file with 50M bytes.
+  ASSERT_EQ(2U, compaction->num_input_files(0));
+  ASSERT_EQ(6U, compaction->input(0, 0)->fd.GetNumber());
+  ASSERT_EQ(7U, compaction->input(0, 1)->fd.GetNumber());
+  // release the version storage
+  DeleteVersionStorage();
+}
+
+TEST_F(CompactionPickerTest, CompactionPriMultipleFilesRoundRobin3) {
+  ioptions_.compaction_pri = kRoundRobin;
+  mutable_cf_options_.max_compaction_bytes = 1000000u;
+  mutable_cf_options_.max_bytes_for_level_base = 120;
+  mutable_cf_options_.max_bytes_for_level_multiplier = 10;
+  // start a brand new version in each test.
+  NewVersionStorage(6, kCompactionStyleLevel);
+  vstorage_->ResizeCompactCursors(6);
+  // Set the cursor (file picking should start with 9U)
+  vstorage_->AddCursorForOneLevel(2, InternalKey("700", 100, kTypeValue));
+  Add(2, 6U, "150", "199", 500U);
+  Add(2, 7U, "200", "249", 500U);
+  Add(2, 8U, "300", "600", 500U);
+  Add(2, 9U, "700", "800", 500U);
+  Add(2, 10U, "850", "950", 500U);
+
+  Add(3, 26U, "130", "165", 600U);
+  Add(3, 27U, "166", "170", 600U);
+  Add(3, 28U, "270", "340", 600U);
+  Add(3, 29U, "401", "500", 600U);
+  Add(3, 30U, "601", "800", 600U);
+  Add(3, 31U, "830", "890", 600U);
+  UpdateVersionStorageInfo();
+  LevelCompactionPicker local_level_compaction_picker =
+      LevelCompactionPicker(ioptions_, &icmp_);
+  std::unique_ptr<Compaction> compaction(
+      local_level_compaction_picker.PickCompaction(
+          cf_name_, mutable_cf_options_, mutable_db_options_, vstorage_.get(),
+          &log_buffer_));
+  ASSERT_TRUE(compaction.get() != nullptr);
+
+  // Cannot pick more files since we reach the last file in level 2
+  ASSERT_EQ(2U, compaction->num_input_files(0));
+  ASSERT_EQ(9U, compaction->input(0, 0)->fd.GetNumber());
+  ASSERT_EQ(10U, compaction->input(0, 1)->fd.GetNumber());
+  // release the version storage
+  DeleteVersionStorage();
+}
+
+TEST_F(CompactionPickerTest, CompactionPriMinOverlappingManyFiles) {
+  NewVersionStorage(6, kCompactionStyleLevel);
+  ioptions_.compaction_pri = kMinOverlappingRatio;
+  mutable_cf_options_.max_bytes_for_level_base = 15000000;
+  mutable_cf_options_.max_bytes_for_level_multiplier = 10;
+
+  // file 7 and 8 over lap with the same file, but file 8 is smaller so
+  // it will be picked.
+  Add(2, 13U, "010", "011",
+      6100U);  // Overlaps with a large file. Not picked
+  Add(2, 14U, "020", "021",
+      6100U);  // Overlaps with a large file. Not picked
+  Add(2, 15U, "030", "031",
+      6100U);  // Overlaps with a large file. Not picked
+  Add(2, 16U, "040", "041",
+      6100U);  // Overlaps with a large file. Not picked
+  Add(2, 17U, "050", "051",
+      6100U);  // Overlaps with a large file. Not picked
+  Add(2, 18U, "060", "061",
+      6100U);  // Overlaps with a large file. Not picked
+  Add(2, 19U, "070", "071",
+      6100U);  // Overlaps with a large file. Not picked
+  Add(2, 20U, "080", "081",
+      6100U);  // Overlaps with a large file. Not picked
+
+  Add(2, 6U, "150", "167", 60000000U);  // Overlaps with file 26, 27
+  Add(2, 7U, "168", "169", 60000000U);  // Overlaps with file 27
+  Add(2, 8U, "201", "300", 61000000U);  // Overlaps with file 28, but the file
+                                        // itself is larger. Should be picked.
+  Add(2, 9U, "610", "611",
+      6100U);  // Overlaps with a large file. Not picked
+  Add(2, 10U, "620", "621",
+      6100U);  // Overlaps with a large file. Not picked
+  Add(2, 11U, "630", "631",
+      6100U);  // Overlaps with a large file. Not picked
+  Add(2, 12U, "640", "641",
+      6100U);  // Overlaps with a large file. Not picked
+
+  Add(3, 31U, "001", "100", 260000000U);
+  Add(3, 26U, "160", "165", 260000000U);
+  Add(3, 27U, "166", "170", 260000000U);
+  Add(3, 28U, "180", "400", 260000000U);
+  Add(3, 29U, "401", "500", 260000000U);
+  Add(3, 30U, "601", "700", 260000000U);
+  UpdateVersionStorageInfo();
+
+  std::unique_ptr<Compaction> compaction(level_compaction_picker.PickCompaction(
+      cf_name_, mutable_cf_options_, mutable_db_options_, vstorage_.get(),
+      &log_buffer_));
+  ASSERT_TRUE(compaction.get() != nullptr);
+  ASSERT_EQ(1U, compaction->num_input_files(0));
+  // Picking file 8 because overlapping ratio is the biggest.
+  ASSERT_EQ(8U, compaction->input(0, 0)->fd.GetNumber());
+}
+
 // This test exhibits the bug where we don't properly reset parent_index in
 // PickCompaction()
 TEST_F(CompactionPickerTest, ParentIndexResetBug) {
@@ -2156,6 +2377,92 @@ TEST_F(CompactionPickerTest, IsTrivialMoveOn) {
   ASSERT_TRUE(compaction->IsTrivialMove());
 }
 
+TEST_F(CompactionPickerTest, L0TrivialMove1) {
+  mutable_cf_options_.max_bytes_for_level_base = 10000000u;
+  mutable_cf_options_.level0_file_num_compaction_trigger = 4;
+  mutable_cf_options_.max_compaction_bytes = 10000000u;
+  ioptions_.level_compaction_dynamic_level_bytes = false;
+  NewVersionStorage(6, kCompactionStyleLevel);
+
+  Add(0, 1U, "100", "150", 3000U, 0, 710, 800);
+  Add(0, 2U, "151", "200", 3001U, 0, 610, 700);
+  Add(0, 3U, "301", "350", 3000U, 0, 510, 600);
+  Add(0, 4U, "451", "400", 3000U, 0, 410, 500);
+
+  Add(1, 5U, "120", "130", 7000U);
+  Add(1, 6U, "170", "180", 7000U);
+  Add(1, 7U, "220", "230", 7000U);
+  Add(1, 8U, "270", "280", 7000U);
+  UpdateVersionStorageInfo();
+
+  std::unique_ptr<Compaction> compaction(level_compaction_picker.PickCompaction(
+      cf_name_, mutable_cf_options_, mutable_db_options_, vstorage_.get(),
+      &log_buffer_));
+  ASSERT_TRUE(compaction.get() != nullptr);
+  ASSERT_EQ(1, compaction->num_input_levels());
+  ASSERT_EQ(2, compaction->num_input_files(0));
+  ASSERT_EQ(3, compaction->input(0, 0)->fd.GetNumber());
+  ASSERT_EQ(4, compaction->input(0, 1)->fd.GetNumber());
+  ASSERT_TRUE(compaction->IsTrivialMove());
+}
+
+TEST_F(CompactionPickerTest, L0TrivialMoveOneFile) {
+  mutable_cf_options_.max_bytes_for_level_base = 10000000u;
+  mutable_cf_options_.level0_file_num_compaction_trigger = 4;
+  mutable_cf_options_.max_compaction_bytes = 10000000u;
+  ioptions_.level_compaction_dynamic_level_bytes = false;
+  NewVersionStorage(6, kCompactionStyleLevel);
+
+  Add(0, 1U, "100", "150", 3000U, 0, 710, 800);
+  Add(0, 2U, "551", "600", 3001U, 0, 610, 700);
+  Add(0, 3U, "101", "150", 3000U, 0, 510, 600);
+  Add(0, 4U, "451", "400", 3000U, 0, 410, 500);
+
+  Add(1, 5U, "120", "130", 7000U);
+  Add(1, 6U, "170", "180", 7000U);
+  Add(1, 7U, "220", "230", 7000U);
+  Add(1, 8U, "270", "280", 7000U);
+  UpdateVersionStorageInfo();
+
+  std::unique_ptr<Compaction> compaction(level_compaction_picker.PickCompaction(
+      cf_name_, mutable_cf_options_, mutable_db_options_, vstorage_.get(),
+      &log_buffer_));
+  ASSERT_TRUE(compaction.get() != nullptr);
+  ASSERT_EQ(1, compaction->num_input_levels());
+  ASSERT_EQ(1, compaction->num_input_files(0));
+  ASSERT_EQ(4, compaction->input(0, 0)->fd.GetNumber());
+  ASSERT_TRUE(compaction->IsTrivialMove());
+}
+
+TEST_F(CompactionPickerTest, L0TrivialMoveWholeL0) {
+  mutable_cf_options_.max_bytes_for_level_base = 10000000u;
+  mutable_cf_options_.level0_file_num_compaction_trigger = 4;
+  mutable_cf_options_.max_compaction_bytes = 10000000u;
+  ioptions_.level_compaction_dynamic_level_bytes = false;
+  NewVersionStorage(6, kCompactionStyleLevel);
+
+  Add(0, 1U, "300", "350", 3000U, 0, 710, 800);
+  Add(0, 2U, "651", "600", 3001U, 0, 610, 700);
+  Add(0, 3U, "501", "550", 3000U, 0, 510, 600);
+  Add(0, 4U, "451", "400", 3000U, 0, 410, 500);
+
+  Add(1, 5U, "120", "130", 7000U);
+  Add(1, 6U, "970", "980", 7000U);
+  UpdateVersionStorageInfo();
+
+  std::unique_ptr<Compaction> compaction(level_compaction_picker.PickCompaction(
+      cf_name_, mutable_cf_options_, mutable_db_options_, vstorage_.get(),
+      &log_buffer_));
+  ASSERT_TRUE(compaction.get() != nullptr);
+  ASSERT_EQ(1, compaction->num_input_levels());
+  ASSERT_EQ(4, compaction->num_input_files(0));
+  ASSERT_EQ(1, compaction->input(0, 0)->fd.GetNumber());
+  ASSERT_EQ(4, compaction->input(0, 1)->fd.GetNumber());
+  ASSERT_EQ(3, compaction->input(0, 2)->fd.GetNumber());
+  ASSERT_EQ(2, compaction->input(0, 3)->fd.GetNumber());
+  ASSERT_TRUE(compaction->IsTrivialMove());
+}
+
 TEST_F(CompactionPickerTest, IsTrivialMoveOffSstPartitioned) {
   mutable_cf_options_.max_bytes_for_level_base = 10000u;
   mutable_cf_options_.max_compaction_bytes = 10001u;
@@ -2204,6 +2511,197 @@ TEST_F(CompactionPickerTest, IsTrivialMoveOff) {
   ASSERT_FALSE(compaction->IsTrivialMove());
 }
 
+TEST_F(CompactionPickerTest, TrivialMoveMultipleFiles1) {
+  mutable_cf_options_.max_bytes_for_level_base = 1000u;
+  mutable_cf_options_.max_compaction_bytes = 10000001u;
+  ioptions_.level_compaction_dynamic_level_bytes = false;
+  ioptions_.compaction_pri = kMinOverlappingRatio;
+  NewVersionStorage(6, kCompactionStyleLevel);
+
+  Add(2, 1U, "100", "150", 3000U);
+  Add(2, 2U, "151", "200", 3001U);
+  Add(2, 3U, "301", "350", 3000U);
+  Add(2, 4U, "451", "400", 3000U);
+  Add(2, 5U, "551", "500", 3000U);
+  Add(2, 6U, "651", "600", 3000U);
+  Add(2, 7U, "751", "700", 3000U);
+  Add(2, 8U, "851", "900", 3000U);
+
+  Add(3, 15U, "120", "130", 700U);
+  Add(3, 16U, "170", "180", 700U);
+  Add(3, 17U, "220", "230", 700U);
+  Add(3, 18U, "870", "880", 700U);
+  UpdateVersionStorageInfo();
+
+  std::unique_ptr<Compaction> compaction(level_compaction_picker.PickCompaction(
+      cf_name_, mutable_cf_options_, mutable_db_options_, vstorage_.get(),
+      &log_buffer_));
+  ASSERT_TRUE(compaction.get() != nullptr);
+  ASSERT_TRUE(compaction->IsTrivialMove());
+  ASSERT_EQ(1, compaction->num_input_levels());
+  ASSERT_EQ(4, compaction->num_input_files(0));
+  ASSERT_EQ(3, compaction->input(0, 0)->fd.GetNumber());
+  ASSERT_EQ(4, compaction->input(0, 1)->fd.GetNumber());
+  ASSERT_EQ(5, compaction->input(0, 2)->fd.GetNumber());
+  ASSERT_EQ(6, compaction->input(0, 3)->fd.GetNumber());
+}
+
+TEST_F(CompactionPickerTest, TrivialMoveMultipleFiles2) {
+  mutable_cf_options_.max_bytes_for_level_base = 1000u;
+  mutable_cf_options_.max_compaction_bytes = 10000001u;
+  ioptions_.level_compaction_dynamic_level_bytes = false;
+  ioptions_.compaction_pri = kMinOverlappingRatio;
+  NewVersionStorage(6, kCompactionStyleLevel);
+
+  Add(2, 1U, "100", "150", 3000U);
+  Add(2, 2U, "151", "160", 3001U);
+  Add(2, 3U, "161", "179", 3000U);
+  Add(2, 4U, "220", "400", 3000U);
+  Add(2, 5U, "551", "500", 3000U);
+  Add(2, 6U, "651", "600", 3000U);
+  Add(2, 7U, "751", "700", 3000U);
+  Add(2, 8U, "851", "900", 3000U);
+
+  Add(3, 15U, "120", "130", 700U);
+  Add(3, 17U, "220", "230", 700U);
+  Add(3, 18U, "870", "880", 700U);
+  UpdateVersionStorageInfo();
+
+  std::unique_ptr<Compaction> compaction(level_compaction_picker.PickCompaction(
+      cf_name_, mutable_cf_options_, mutable_db_options_, vstorage_.get(),
+      &log_buffer_));
+  ASSERT_TRUE(compaction.get() != nullptr);
+  ASSERT_TRUE(compaction->IsTrivialMove());
+  ASSERT_EQ(1, compaction->num_input_levels());
+  ASSERT_EQ(2, compaction->num_input_files(0));
+  ASSERT_EQ(2, compaction->input(0, 0)->fd.GetNumber());
+  ASSERT_EQ(3, compaction->input(0, 1)->fd.GetNumber());
+}
+
+TEST_F(CompactionPickerTest, TrivialMoveMultipleFiles3) {
+  mutable_cf_options_.max_bytes_for_level_base = 1000u;
+  mutable_cf_options_.max_compaction_bytes = 10000001u;
+  ioptions_.level_compaction_dynamic_level_bytes = false;
+  ioptions_.compaction_pri = kMinOverlappingRatio;
+  NewVersionStorage(6, kCompactionStyleLevel);
+
+  // Even if consecutive files can be trivial moved, we don't pick them
+  // since in case trivial move can't be issued for a reason, we cannot
+  // fall back to normal compactions.
+  Add(2, 1U, "100", "150", 3000U);
+  Add(2, 2U, "151", "160", 3001U);
+  Add(2, 5U, "551", "500", 3000U);
+  Add(2, 6U, "651", "600", 3000U);
+  Add(2, 7U, "751", "700", 3000U);
+  Add(2, 8U, "851", "900", 3000U);
+
+  Add(3, 15U, "120", "130", 700U);
+  Add(3, 17U, "220", "230", 700U);
+  Add(3, 18U, "870", "880", 700U);
+  UpdateVersionStorageInfo();
+
+  std::unique_ptr<Compaction> compaction(level_compaction_picker.PickCompaction(
+      cf_name_, mutable_cf_options_, mutable_db_options_, vstorage_.get(),
+      &log_buffer_));
+  ASSERT_TRUE(compaction.get() != nullptr);
+  ASSERT_TRUE(compaction->IsTrivialMove());
+  ASSERT_EQ(1, compaction->num_input_levels());
+  ASSERT_EQ(1, compaction->num_input_files(0));
+  ASSERT_EQ(2, compaction->input(0, 0)->fd.GetNumber());
+}
+
+TEST_F(CompactionPickerTest, TrivialMoveMultipleFiles4) {
+  mutable_cf_options_.max_bytes_for_level_base = 1000u;
+  mutable_cf_options_.max_compaction_bytes = 10000001u;
+  ioptions_.level_compaction_dynamic_level_bytes = false;
+  ioptions_.compaction_pri = kMinOverlappingRatio;
+  NewVersionStorage(6, kCompactionStyleLevel);
+
+  Add(2, 1U, "100", "150", 4000U);
+  Add(2, 2U, "151", "160", 4001U);
+  Add(2, 3U, "161", "179", 4000U);
+
+  Add(3, 15U, "120", "130", 700U);
+  Add(3, 17U, "220", "230", 700U);
+  Add(3, 18U, "870", "880", 700U);
+  UpdateVersionStorageInfo();
+
+  std::unique_ptr<Compaction> compaction(level_compaction_picker.PickCompaction(
+      cf_name_, mutable_cf_options_, mutable_db_options_, vstorage_.get(),
+      &log_buffer_));
+  ASSERT_TRUE(compaction.get() != nullptr);
+  ASSERT_TRUE(compaction->IsTrivialMove());
+  ASSERT_EQ(1, compaction->num_input_levels());
+  ASSERT_EQ(2, compaction->num_input_files(0));
+  ASSERT_EQ(2, compaction->input(0, 0)->fd.GetNumber());
+  ASSERT_EQ(3, compaction->input(0, 1)->fd.GetNumber());
+}
+
+TEST_F(CompactionPickerTest, TrivialMoveMultipleFiles5) {
+  mutable_cf_options_.max_bytes_for_level_base = 1000u;
+  mutable_cf_options_.max_compaction_bytes = 10000001u;
+  ioptions_.level_compaction_dynamic_level_bytes = false;
+  ioptions_.compaction_pri = kMinOverlappingRatio;
+  NewVersionStorage(6, kCompactionStyleLevel);
+
+  // File 4 and 5 aren't clean cut, so only 2 and 3 are picked.
+  Add(2, 1U, "100", "150", 4000U);
+  Add(2, 2U, "151", "160", 4001U);
+  Add(2, 3U, "161", "179", 4000U);
+  Add(2, 4U, "180", "185", 4000U);
+  Add(2, 5U, "185", "190", 4000U);
+
+  Add(3, 15U, "120", "130", 700U);
+  Add(3, 17U, "220", "230", 700U);
+  Add(3, 18U, "870", "880", 700U);
+  UpdateVersionStorageInfo();
+
+  std::unique_ptr<Compaction> compaction(level_compaction_picker.PickCompaction(
+      cf_name_, mutable_cf_options_, mutable_db_options_, vstorage_.get(),
+      &log_buffer_));
+  ASSERT_TRUE(compaction.get() != nullptr);
+  ASSERT_TRUE(compaction->IsTrivialMove());
+  ASSERT_EQ(1, compaction->num_input_levels());
+  ASSERT_EQ(2, compaction->num_input_files(0));
+  ASSERT_EQ(2, compaction->input(0, 0)->fd.GetNumber());
+  ASSERT_EQ(3, compaction->input(0, 1)->fd.GetNumber());
+}
+
+TEST_F(CompactionPickerTest, TrivialMoveMultipleFiles6) {
+  mutable_cf_options_.max_bytes_for_level_base = 1000u;
+  mutable_cf_options_.max_compaction_bytes = 10000001u;
+  ioptions_.level_compaction_dynamic_level_bytes = false;
+  ioptions_.compaction_pri = kMinOverlappingRatio;
+  NewVersionStorage(6, kCompactionStyleLevel);
+
+  Add(2, 1U, "100", "150", 3000U);
+  Add(2, 2U, "151", "200", 3001U);
+  Add(2, 3U, "301", "350", 3000U);
+  Add(2, 4U, "451", "400", 3000U);
+  Add(2, 5U, "551", "500", 3000U);
+  file_map_[5U].first->being_compacted = true;
+  Add(2, 6U, "651", "600", 3000U);
+  Add(2, 7U, "751", "700", 3000U);
+  Add(2, 8U, "851", "900", 3000U);
+
+  Add(3, 15U, "120", "130", 700U);
+  Add(3, 16U, "170", "180", 700U);
+  Add(3, 17U, "220", "230", 700U);
+  Add(3, 18U, "870", "880", 700U);
+  UpdateVersionStorageInfo();
+
+  std::unique_ptr<Compaction> compaction(level_compaction_picker.PickCompaction(
+      cf_name_, mutable_cf_options_, mutable_db_options_, vstorage_.get(),
+      &log_buffer_));
+  ASSERT_TRUE(compaction.get() != nullptr);
+  ASSERT_TRUE(compaction->IsTrivialMove());
+  ASSERT_EQ(1, compaction->num_input_levels());
+  // Since the next file is being compacted. Stopping at 3 and 4.
+  ASSERT_EQ(2, compaction->num_input_files(0));
+  ASSERT_EQ(3, compaction->input(0, 0)->fd.GetNumber());
+  ASSERT_EQ(4, compaction->input(0, 1)->fd.GetNumber());
+}
+
 TEST_F(CompactionPickerTest, CacheNextCompactionIndex) {
   NewVersionStorage(6, kCompactionStyleLevel);
   mutable_cf_options_.max_compaction_bytes = 100000000000u;
@@ -2218,7 +2716,11 @@ TEST_F(CompactionPickerTest, CacheNextCompactionIndex) {
   Add(1 /* level */, 4U /* file_number */, "250" /* smallest */,
       "299" /* largest */, 700000000U /* file_size */);
   Add(2 /* level */, 5U /* file_number */, "150" /* smallest */,
-      "199" /* largest */, 1U /* file_size */);
+      "199" /* largest */, 100U /* file_size */);
+  Add(2 /* level */, 6U /* file_number */, "200" /* smallest */,
+      "240" /* largest */, 1U /* file_size */);
+  Add(2 /* level */, 7U /* file_number */, "260" /* smallest */,
+      "270" /* largest */, 1U /* file_size */);
   file_map_[5U].first->being_compacted = true;
 
   UpdateVersionStorageInfo();
@@ -2227,9 +2729,9 @@ TEST_F(CompactionPickerTest, CacheNextCompactionIndex) {
       cf_name_, mutable_cf_options_, mutable_db_options_, vstorage_.get(),
       &log_buffer_));
   ASSERT_TRUE(compaction.get() != nullptr);
-  ASSERT_EQ(1U, compaction->num_input_levels());
+  ASSERT_EQ(2U, compaction->num_input_levels());
   ASSERT_EQ(1U, compaction->num_input_files(0));
-  ASSERT_EQ(0U, compaction->num_input_files(1));
+  ASSERT_EQ(1U, compaction->num_input_files(1));
   ASSERT_EQ(3U, compaction->input(0, 0)->fd.GetNumber());
   ASSERT_EQ(2, vstorage_->NextCompactionIndex(1 /* level */));
 
@@ -2237,9 +2739,9 @@ TEST_F(CompactionPickerTest, CacheNextCompactionIndex) {
       cf_name_, mutable_cf_options_, mutable_db_options_, vstorage_.get(),
       &log_buffer_));
   ASSERT_TRUE(compaction.get() != nullptr);
-  ASSERT_EQ(1U, compaction->num_input_levels());
+  ASSERT_EQ(2U, compaction->num_input_levels());
   ASSERT_EQ(1U, compaction->num_input_files(0));
-  ASSERT_EQ(0U, compaction->num_input_files(1));
+  ASSERT_EQ(1U, compaction->num_input_files(1));
   ASSERT_EQ(4U, compaction->input(0, 0)->fd.GetNumber());
   ASSERT_EQ(3, vstorage_->NextCompactionIndex(1 /* level */));
 
@@ -2673,6 +3175,334 @@ TEST_F(CompactionPickerTest, UniversalMarkedManualCompaction) {
   ASSERT_EQ(0U, vstorage_->FilesMarkedForCompaction().size());
 }
 
+TEST_F(CompactionPickerTest, UniversalSizeAmpTierCompactionNonLastLevel) {
+  // This test make sure size amplification compaction could still be triggered
+  // if the last sorted run is not the last level.
+  const uint64_t kFileSize = 100000;
+  const int kNumLevels = 7;
+  const int kLastLevel = kNumLevels - 1;
+
+  ioptions_.compaction_style = kCompactionStyleUniversal;
+  ioptions_.preclude_last_level_data_seconds = 1000;
+  mutable_cf_options_.compaction_options_universal
+      .max_size_amplification_percent = 200;
+  UniversalCompactionPicker universal_compaction_picker(ioptions_, &icmp_);
+
+  NewVersionStorage(kNumLevels, kCompactionStyleUniversal);
+  Add(0, 100U, "100", "300", 1 * kFileSize);
+  Add(0, 101U, "200", "400", 1 * kFileSize);
+  Add(4, 90U, "100", "600", 4 * kFileSize);
+  Add(5, 80U, "200", "300", 2 * kFileSize);
+  UpdateVersionStorageInfo();
+
+  std::unique_ptr<Compaction> compaction(
+      universal_compaction_picker.PickCompaction(
+          cf_name_, mutable_cf_options_, mutable_db_options_, vstorage_.get(),
+          &log_buffer_));
+
+  // Make sure it's a size amp compaction and includes all files
+  ASSERT_EQ(compaction->compaction_reason(),
+            CompactionReason::kUniversalSizeAmplification);
+  ASSERT_EQ(compaction->output_level(), kLastLevel);
+  ASSERT_EQ(compaction->input_levels(0)->num_files, 2);
+  ASSERT_EQ(compaction->input_levels(4)->num_files, 1);
+  ASSERT_EQ(compaction->input_levels(5)->num_files, 1);
+}
+
+TEST_F(CompactionPickerTest, UniversalSizeRatioTierCompactionLastLevel) {
+  // This test makes sure the size amp calculation skips the last level (L6), so
+  // size amp compaction is not triggered, instead a size ratio compaction is
+  // triggered.
+  const uint64_t kFileSize = 100000;
+  const int kNumLevels = 7;
+  const int kLastLevel = kNumLevels - 1;
+  const int kPenultimateLevel = kLastLevel - 1;
+
+  ioptions_.compaction_style = kCompactionStyleUniversal;
+  ioptions_.preclude_last_level_data_seconds = 1000;
+  mutable_cf_options_.compaction_options_universal
+      .max_size_amplification_percent = 200;
+  UniversalCompactionPicker universal_compaction_picker(ioptions_, &icmp_);
+
+  NewVersionStorage(kNumLevels, kCompactionStyleUniversal);
+  Add(0, 100U, "100", "300", 1 * kFileSize);
+  Add(0, 101U, "200", "400", 1 * kFileSize);
+  Add(5, 90U, "100", "600", 4 * kFileSize);
+  Add(6, 80U, "200", "300", 2 * kFileSize);
+  UpdateVersionStorageInfo();
+
+  std::unique_ptr<Compaction> compaction(
+      universal_compaction_picker.PickCompaction(
+          cf_name_, mutable_cf_options_, mutable_db_options_, vstorage_.get(),
+          &log_buffer_));
+
+  // Internally, size amp compaction is evaluated before size ratio compaction.
+  // Here to make sure it's size ratio compaction instead of size amp
+  ASSERT_EQ(compaction->compaction_reason(),
+            CompactionReason::kUniversalSizeRatio);
+  ASSERT_EQ(compaction->output_level(), kPenultimateLevel - 1);
+  ASSERT_EQ(compaction->input_levels(0)->num_files, 2);
+  ASSERT_EQ(compaction->input_levels(5)->num_files, 0);
+  ASSERT_EQ(compaction->input_levels(6)->num_files, 0);
+}
+
+TEST_F(CompactionPickerTest, UniversalSizeAmpTierCompactionNotSuport) {
+  // Tiered compaction only support level_num > 2 (otherwise the penultimate
+  // level is going to be level 0, which may make thing more complicated), so
+  // when there's only 2 level, still treating level 1 as the last level for
+  // size amp compaction
+  const uint64_t kFileSize = 100000;
+  const int kNumLevels = 2;
+  const int kLastLevel = kNumLevels - 1;
+
+  ioptions_.compaction_style = kCompactionStyleUniversal;
+  ioptions_.preclude_last_level_data_seconds = 1000;
+  mutable_cf_options_.compaction_options_universal
+      .max_size_amplification_percent = 200;
+  UniversalCompactionPicker universal_compaction_picker(ioptions_, &icmp_);
+
+  NewVersionStorage(kNumLevels, kCompactionStyleUniversal);
+  Add(0, 100U, "100", "300", 1 * kFileSize);
+  Add(0, 101U, "200", "400", 1 * kFileSize);
+  Add(0, 90U, "100", "600", 4 * kFileSize);
+  Add(1, 80U, "200", "300", 2 * kFileSize);
+  UpdateVersionStorageInfo();
+
+  std::unique_ptr<Compaction> compaction(
+      universal_compaction_picker.PickCompaction(
+          cf_name_, mutable_cf_options_, mutable_db_options_, vstorage_.get(),
+          &log_buffer_));
+
+  // size amp compaction is still triggered even preclude_last_level is set
+  ASSERT_EQ(compaction->compaction_reason(),
+            CompactionReason::kUniversalSizeAmplification);
+  ASSERT_EQ(compaction->output_level(), kLastLevel);
+  ASSERT_EQ(compaction->input_levels(0)->num_files, 3);
+  ASSERT_EQ(compaction->input_levels(1)->num_files, 1);
+}
+
+TEST_F(CompactionPickerTest, UniversalSizeAmpTierCompactionLastLevel) {
+  // This test makes sure the size amp compaction for tiered storage could still
+  // be triggered, but only for non-last-level files
+  const uint64_t kFileSize = 100000;
+  const int kNumLevels = 7;
+  const int kLastLevel = kNumLevels - 1;
+  const int kPenultimateLevel = kLastLevel - 1;
+
+  ioptions_.compaction_style = kCompactionStyleUniversal;
+  ioptions_.preclude_last_level_data_seconds = 1000;
+  mutable_cf_options_.compaction_options_universal
+      .max_size_amplification_percent = 200;
+  UniversalCompactionPicker universal_compaction_picker(ioptions_, &icmp_);
+
+  NewVersionStorage(kNumLevels, kCompactionStyleUniversal);
+  Add(0, 100U, "100", "300", 3 * kFileSize);
+  Add(0, 101U, "200", "400", 2 * kFileSize);
+  Add(5, 90U, "100", "600", 2 * kFileSize);
+  Add(6, 80U, "200", "300", 2 * kFileSize);
+  UpdateVersionStorageInfo();
+
+  std::unique_ptr<Compaction> compaction(
+      universal_compaction_picker.PickCompaction(
+          cf_name_, mutable_cf_options_, mutable_db_options_, vstorage_.get(),
+          &log_buffer_));
+
+  // It's a Size Amp compaction, but doesn't include the last level file and
+  // output to the penultimate level.
+  ASSERT_EQ(compaction->compaction_reason(),
+            CompactionReason::kUniversalSizeAmplification);
+  ASSERT_EQ(compaction->output_level(), kPenultimateLevel);
+  ASSERT_EQ(compaction->input_levels(0)->num_files, 2);
+  ASSERT_EQ(compaction->input_levels(5)->num_files, 1);
+  ASSERT_EQ(compaction->input_levels(6)->num_files, 0);
+}
+
+class PerKeyPlacementCompactionPickerTest
+    : public CompactionPickerTest,
+      public testing::WithParamInterface<bool> {
+ public:
+  PerKeyPlacementCompactionPickerTest() : CompactionPickerTest() {}
+
+  void SetUp() override { enable_per_key_placement_ = GetParam(); }
+
+ protected:
+  bool enable_per_key_placement_ = false;
+};
+
+TEST_P(PerKeyPlacementCompactionPickerTest, OverlapWithNormalCompaction) {
+  SyncPoint::GetInstance()->SetCallBack(
+      "Compaction::SupportsPerKeyPlacement:Enabled", [&](void* arg) {
+        auto supports_per_key_placement = static_cast<bool*>(arg);
+        *supports_per_key_placement = enable_per_key_placement_;
+      });
+  SyncPoint::GetInstance()->EnableProcessing();
+
+  int num_levels = ioptions_.num_levels;
+  NewVersionStorage(num_levels, kCompactionStyleLevel);
+
+  Add(0, 21U, "100", "150", 60000000U);
+  Add(0, 22U, "300", "350", 60000000U);
+  Add(5, 40U, "200", "250", 60000000U);
+  Add(6, 50U, "101", "351", 60000000U);
+  UpdateVersionStorageInfo();
+
+  CompactionOptions comp_options;
+  std::unordered_set<uint64_t> input_set;
+  input_set.insert(40);
+  std::vector<CompactionInputFiles> input_files;
+  ASSERT_OK(level_compaction_picker.GetCompactionInputsFromFileNumbers(
+      &input_files, &input_set, vstorage_.get(), comp_options));
+
+  std::unique_ptr<Compaction> comp1(level_compaction_picker.CompactFiles(
+      comp_options, input_files, 5, vstorage_.get(), mutable_cf_options_,
+      mutable_db_options_, 0));
+
+  input_set.clear();
+  input_files.clear();
+  input_set.insert(21);
+  input_set.insert(22);
+  input_set.insert(50);
+  ASSERT_OK(level_compaction_picker.GetCompactionInputsFromFileNumbers(
+      &input_files, &input_set, vstorage_.get(), comp_options));
+
+  ASSERT_EQ(
+      enable_per_key_placement_,
+      level_compaction_picker.FilesRangeOverlapWithCompaction(input_files, 6));
+}
+
+TEST_P(PerKeyPlacementCompactionPickerTest, NormalCompactionOverlap) {
+  SyncPoint::GetInstance()->SetCallBack(
+      "Compaction::SupportsPerKeyPlacement:Enabled", [&](void* arg) {
+        auto supports_per_key_placement = static_cast<bool*>(arg);
+        *supports_per_key_placement = enable_per_key_placement_;
+      });
+  SyncPoint::GetInstance()->EnableProcessing();
+
+  int num_levels = ioptions_.num_levels;
+  NewVersionStorage(num_levels, kCompactionStyleLevel);
+
+  Add(0, 21U, "100", "150", 60000000U);
+  Add(0, 22U, "300", "350", 60000000U);
+  Add(4, 40U, "200", "220", 60000000U);
+  Add(4, 41U, "230", "250", 60000000U);
+  Add(6, 50U, "101", "351", 60000000U);
+  UpdateVersionStorageInfo();
+
+  CompactionOptions comp_options;
+  std::unordered_set<uint64_t> input_set;
+  input_set.insert(21);
+  input_set.insert(22);
+  input_set.insert(50);
+  std::vector<CompactionInputFiles> input_files;
+  ASSERT_OK(level_compaction_picker.GetCompactionInputsFromFileNumbers(
+      &input_files, &input_set, vstorage_.get(), comp_options));
+
+  std::unique_ptr<Compaction> comp1(level_compaction_picker.CompactFiles(
+      comp_options, input_files, 6, vstorage_.get(), mutable_cf_options_,
+      mutable_db_options_, 0));
+
+  input_set.clear();
+  input_files.clear();
+  input_set.insert(40);
+  input_set.insert(41);
+  ASSERT_OK(level_compaction_picker.GetCompactionInputsFromFileNumbers(
+      &input_files, &input_set, vstorage_.get(), comp_options));
+
+  ASSERT_EQ(
+      enable_per_key_placement_,
+      level_compaction_picker.FilesRangeOverlapWithCompaction(input_files, 5));
+}
+
+TEST_P(PerKeyPlacementCompactionPickerTest,
+       OverlapWithNormalCompactionUniveral) {
+  SyncPoint::GetInstance()->SetCallBack(
+      "Compaction::SupportsPerKeyPlacement:Enabled", [&](void* arg) {
+        auto supports_per_key_placement = static_cast<bool*>(arg);
+        *supports_per_key_placement = enable_per_key_placement_;
+      });
+  SyncPoint::GetInstance()->EnableProcessing();
+
+  int num_levels = ioptions_.num_levels;
+  UniversalCompactionPicker universal_compaction_picker(ioptions_, &icmp_);
+  NewVersionStorage(num_levels, kCompactionStyleUniversal);
+
+  Add(0, 21U, "100", "150", 60000000U);
+  Add(0, 22U, "300", "350", 60000000U);
+  Add(5, 40U, "200", "250", 60000000U);
+  Add(6, 50U, "101", "351", 60000000U);
+  UpdateVersionStorageInfo();
+
+  CompactionOptions comp_options;
+  std::unordered_set<uint64_t> input_set;
+  input_set.insert(40);
+  std::vector<CompactionInputFiles> input_files;
+  ASSERT_OK(universal_compaction_picker.GetCompactionInputsFromFileNumbers(
+      &input_files, &input_set, vstorage_.get(), comp_options));
+
+  std::unique_ptr<Compaction> comp1(universal_compaction_picker.CompactFiles(
+      comp_options, input_files, 5, vstorage_.get(), mutable_cf_options_,
+      mutable_db_options_, 0));
+
+  input_set.clear();
+  input_files.clear();
+  input_set.insert(21);
+  input_set.insert(22);
+  input_set.insert(50);
+  ASSERT_OK(universal_compaction_picker.GetCompactionInputsFromFileNumbers(
+      &input_files, &input_set, vstorage_.get(), comp_options));
+
+  ASSERT_EQ(enable_per_key_placement_,
+            universal_compaction_picker.FilesRangeOverlapWithCompaction(
+                input_files, 6));
+}
+
+TEST_P(PerKeyPlacementCompactionPickerTest, NormalCompactionOverlapUniversal) {
+  SyncPoint::GetInstance()->SetCallBack(
+      "Compaction::SupportsPerKeyPlacement:Enabled", [&](void* arg) {
+        auto supports_per_key_placement = static_cast<bool*>(arg);
+        *supports_per_key_placement = enable_per_key_placement_;
+      });
+  SyncPoint::GetInstance()->EnableProcessing();
+
+  int num_levels = ioptions_.num_levels;
+  UniversalCompactionPicker universal_compaction_picker(ioptions_, &icmp_);
+  NewVersionStorage(num_levels, kCompactionStyleUniversal);
+
+  Add(0, 21U, "100", "150", 60000000U);
+  Add(0, 22U, "300", "350", 60000000U);
+  Add(4, 40U, "200", "220", 60000000U);
+  Add(4, 41U, "230", "250", 60000000U);
+  Add(6, 50U, "101", "351", 60000000U);
+  UpdateVersionStorageInfo();
+
+  CompactionOptions comp_options;
+  std::unordered_set<uint64_t> input_set;
+  input_set.insert(21);
+  input_set.insert(22);
+  input_set.insert(50);
+  std::vector<CompactionInputFiles> input_files;
+  ASSERT_OK(universal_compaction_picker.GetCompactionInputsFromFileNumbers(
+      &input_files, &input_set, vstorage_.get(), comp_options));
+
+  std::unique_ptr<Compaction> comp1(universal_compaction_picker.CompactFiles(
+      comp_options, input_files, 6, vstorage_.get(), mutable_cf_options_,
+      mutable_db_options_, 0));
+
+  input_set.clear();
+  input_files.clear();
+  input_set.insert(40);
+  input_set.insert(41);
+  ASSERT_OK(universal_compaction_picker.GetCompactionInputsFromFileNumbers(
+      &input_files, &input_set, vstorage_.get(), comp_options));
+
+  ASSERT_EQ(enable_per_key_placement_,
+            universal_compaction_picker.FilesRangeOverlapWithCompaction(
+                input_files, 5));
+}
+
+INSTANTIATE_TEST_CASE_P(PerKeyPlacementCompactionPickerTest,
+                        PerKeyPlacementCompactionPickerTest, ::testing::Bool());
+
 #endif  // ROCKSDB_LITE
 
 }  // namespace ROCKSDB_NAMESPACE

db/compaction/compaction_picker_universal.cc

@@ -106,6 +106,9 @@ class UniversalCompactionBuilder {
   Compaction* PickCompactionToOldest(size_t start_index,
                                      CompactionReason compaction_reason);
 
+  Compaction* PickCompactionWithSortedRunRange(
+      size_t start_index, size_t end_index, CompactionReason compaction_reason);
+
   // Try to pick periodic compaction. The caller should only call it
   // if there is at least one file marked for periodic compaction.
   // null will be returned if no such a compaction can be formed
@@ -758,7 +761,8 @@ Compaction* UniversalCompactionBuilder::PickCompactionToReduceSortedRuns(
                         Temperature::kUnknown,
                         /* max_subcompactions */ 0, grandparents,
                         /* is manual */ false, /* trim_ts */ "", score_,
-                        false /* deletion_compaction */, compaction_reason);
+                        false /* deletion_compaction */,
+                        /* l0_files_might_overlap */ true, compaction_reason);
 }
 
 // Look at overall size amplification. If size amplification
@@ -810,8 +814,20 @@ Compaction* UniversalCompactionBuilder::PickCompactionToReduceSizeAmp() {
         cf_name_.c_str(), file_num_buf, start_index, " to reduce size amp.\n");
   }
 
+  // size of the base sorted run for size amp calculation
+  uint64_t base_sr_size = sorted_runs_.back().size;
+  size_t sr_end_idx = sorted_runs_.size() - 1;
+  // If tiered compaction is enabled and the last sorted run is the last level
+  if (ioptions_.preclude_last_level_data_seconds > 0 &&
+      ioptions_.num_levels > 2 &&
+      sorted_runs_.back().level == ioptions_.num_levels - 1 &&
+      sorted_runs_.size() > 1) {
+    sr_end_idx = sorted_runs_.size() - 2;
+    base_sr_size = sorted_runs_[sr_end_idx].size;
+  }
+
   // keep adding up all the remaining files
-  for (size_t loop = start_index; loop + 1 < sorted_runs_.size(); loop++) {
+  for (size_t loop = start_index; loop < sr_end_idx; loop++) {
     sr = &sorted_runs_[loop];
     if (sr->being_compacted) {
       // TODO with incremental compaction is supported, we might want to
@@ -831,23 +847,20 @@ Compaction* UniversalCompactionBuilder::PickCompactionToReduceSizeAmp() {
     return nullptr;
   }
 
-  // size of earliest file
-  uint64_t earliest_file_size = sorted_runs_.back().size;
-
   // size amplification = percentage of additional size
-  if (candidate_size * 100 < ratio * earliest_file_size) {
+  if (candidate_size * 100 < ratio * base_sr_size) {
     ROCKS_LOG_BUFFER(
         log_buffer_,
         "[%s] Universal: size amp not needed. newer-files-total-size %" PRIu64
         " earliest-file-size %" PRIu64,
-        cf_name_.c_str(), candidate_size, earliest_file_size);
+        cf_name_.c_str(), candidate_size, base_sr_size);
     return nullptr;
   } else {
     ROCKS_LOG_BUFFER(
         log_buffer_,
         "[%s] Universal: size amp needed. newer-files-total-size %" PRIu64
         " earliest-file-size %" PRIu64,
-        cf_name_.c_str(), candidate_size, earliest_file_size);
+        cf_name_.c_str(), candidate_size, base_sr_size);
   }
   // Since incremental compaction can't include more than second last
   // level, it can introduce penalty, compared to full compaction. We
@@ -859,7 +872,7 @@ Compaction* UniversalCompactionBuilder::PickCompactionToReduceSizeAmp() {
   // This also prevent the case when compaction falls behind and we
   // need to compact more levels for compactions to catch up.
   if (mutable_cf_options_.compaction_options_universal.incremental) {
-    double fanout_threshold = static_cast<double>(earliest_file_size) /
+    double fanout_threshold = static_cast<double>(base_sr_size) /
                               static_cast<double>(candidate_size) * 1.8;
     Compaction* picked = PickIncrementalForReduceSizeAmp(fanout_threshold);
     if (picked != nullptr) {
@@ -868,8 +881,8 @@ Compaction* UniversalCompactionBuilder::PickCompactionToReduceSizeAmp() {
       return picked;
     }
   }
-  return PickCompactionToOldest(start_index,
-                                CompactionReason::kUniversalSizeAmplification);
+  return PickCompactionWithSortedRunRange(
+      start_index, sr_end_idx, CompactionReason::kUniversalSizeAmplification);
 }
 
 Compaction* UniversalCompactionBuilder::PickIncrementalForReduceSizeAmp(
@@ -1083,6 +1096,7 @@ Compaction* UniversalCompactionBuilder::PickIncrementalForReduceSizeAmp(
       Temperature::kUnknown,
       /* max_subcompactions */ 0, /* grandparents */ {}, /* is manual */ false,
       /* trim_ts */ "", score_, false /* deletion_compaction */,
+      /* l0_files_might_overlap */ true,
       CompactionReason::kUniversalSizeAmplification);
 }
 
@@ -1225,16 +1239,23 @@ Compaction* UniversalCompactionBuilder::PickDeleteTriggeredCompaction() {
       Temperature::kUnknown,
       /* max_subcompactions */ 0, grandparents, /* is manual */ false,
       /* trim_ts */ "", score_, false /* deletion_compaction */,
+      /* l0_files_might_overlap */ true,
       CompactionReason::kFilesMarkedForCompaction);
 }
 
 Compaction* UniversalCompactionBuilder::PickCompactionToOldest(
     size_t start_index, CompactionReason compaction_reason) {
+  return PickCompactionWithSortedRunRange(start_index, sorted_runs_.size() - 1,
+                                          compaction_reason);
+}
+
+Compaction* UniversalCompactionBuilder::PickCompactionWithSortedRunRange(
+    size_t start_index, size_t end_index, CompactionReason compaction_reason) {
   assert(start_index < sorted_runs_.size());
 
   // Estimate total file size
   uint64_t estimated_total_size = 0;
-  for (size_t loop = start_index; loop < sorted_runs_.size(); loop++) {
+  for (size_t loop = start_index; loop <= end_index; loop++) {
     estimated_total_size += sorted_runs_[loop].size;
   }
   uint32_t path_id =
@@ -1245,7 +1266,7 @@ Compaction* UniversalCompactionBuilder::PickCompactionToOldest(
   for (size_t i = 0; i < inputs.size(); ++i) {
     inputs[i].level = start_level + static_cast<int>(i);
   }
-  for (size_t loop = start_index; loop < sorted_runs_.size(); loop++) {
+  for (size_t loop = start_index; loop <= end_index; loop++) {
     auto& picking_sr = sorted_runs_[loop];
     if (picking_sr.level == 0) {
       FileMetaData* f = picking_sr.file;
@@ -1276,12 +1297,19 @@ Compaction* UniversalCompactionBuilder::PickCompactionToOldest(
                      file_num_buf);
   }
 
-  // output files at the bottom most level, unless it's reserved
-  int output_level = vstorage_->num_levels() - 1;
-  // last level is reserved for the files ingested behind
-  if (ioptions_.allow_ingest_behind) {
-    assert(output_level > 1);
-    output_level--;
+  int output_level;
+  if (end_index == sorted_runs_.size() - 1) {
+    // output files at the last level, unless it's reserved
+    output_level = vstorage_->num_levels() - 1;
+    // last level is reserved for the files ingested behind
+    if (ioptions_.allow_ingest_behind) {
+      assert(output_level > 1);
+      output_level--;
+    }
+  } else {
+    // if it's not including all sorted_runs, it can only output to the level
+    // above the `end_index + 1` sorted_run.
+    output_level = sorted_runs_[end_index + 1].level - 1;
   }
 
   // We never check size for
@@ -1300,7 +1328,7 @@ Compaction* UniversalCompactionBuilder::PickCompactionToOldest(
       Temperature::kUnknown,
       /* max_subcompactions */ 0, /* grandparents */ {}, /* is manual */ false,
       /* trim_ts */ "", score_, false /* deletion_compaction */,
-      compaction_reason);
+      /* l0_files_might_overlap */ true, compaction_reason);
 }
 
 Compaction* UniversalCompactionBuilder::PickPeriodicCompaction() {

db/compaction/compaction_service_job.cc

@@ -0,0 +1,829 @@
+//  Copyright (c) Meta Platforms, Inc. and affiliates.
+//
+//  This source code is licensed under both the GPLv2 (found in the
+//  COPYING file in the root directory) and Apache 2.0 License
+//  (found in the LICENSE.Apache file in the root directory).
+//
+// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file. See the AUTHORS file for names of contributors.
+
+#include "db/compaction/compaction_job.h"
+#include "db/compaction/compaction_state.h"
+#include "logging/logging.h"
+#include "monitoring/iostats_context_imp.h"
+#include "monitoring/thread_status_util.h"
+#include "options/options_helper.h"
+#include "rocksdb/utilities/options_type.h"
+
+#ifndef ROCKSDB_LITE
+namespace ROCKSDB_NAMESPACE {
+class SubcompactionState;
+
+CompactionServiceJobStatus
+CompactionJob::ProcessKeyValueCompactionWithCompactionService(
+    SubcompactionState* sub_compact) {
+  assert(sub_compact);
+  assert(sub_compact->compaction);
+  assert(db_options_.compaction_service);
+
+  const Compaction* compaction = sub_compact->compaction;
+  CompactionServiceInput compaction_input;
+  compaction_input.output_level = compaction->output_level();
+  compaction_input.db_id = db_id_;
+
+  const std::vector<CompactionInputFiles>& inputs =
+      *(compact_->compaction->inputs());
+  for (const auto& files_per_level : inputs) {
+    for (const auto& file : files_per_level.files) {
+      compaction_input.input_files.emplace_back(
+          MakeTableFileName(file->fd.GetNumber()));
+    }
+  }
+  compaction_input.column_family.name =
+      compaction->column_family_data()->GetName();
+  compaction_input.column_family.options =
+      compaction->column_family_data()->GetLatestCFOptions();
+  compaction_input.db_options =
+      BuildDBOptions(db_options_, mutable_db_options_copy_);
+  compaction_input.snapshots = existing_snapshots_;
+  compaction_input.has_begin = sub_compact->start.has_value();
+  compaction_input.begin =
+      compaction_input.has_begin ? sub_compact->start->ToString() : "";
+  compaction_input.has_end = sub_compact->end.has_value();
+  compaction_input.end =
+      compaction_input.has_end ? sub_compact->end->ToString() : "";
+
+  std::string compaction_input_binary;
+  Status s = compaction_input.Write(&compaction_input_binary);
+  if (!s.ok()) {
+    sub_compact->status = s;
+    return CompactionServiceJobStatus::kFailure;
+  }
+
+  std::ostringstream input_files_oss;
+  bool is_first_one = true;
+  for (const auto& file : compaction_input.input_files) {
+    input_files_oss << (is_first_one ? "" : ", ") << file;
+    is_first_one = false;
+  }
+
+  ROCKS_LOG_INFO(
+      db_options_.info_log,
+      "[%s] [JOB %d] Starting remote compaction (output level: %d): %s",
+      compaction_input.column_family.name.c_str(), job_id_,
+      compaction_input.output_level, input_files_oss.str().c_str());
+  CompactionServiceJobInfo info(dbname_, db_id_, db_session_id_,
+                                GetCompactionId(sub_compact), thread_pri_);
+  CompactionServiceJobStatus compaction_status =
+      db_options_.compaction_service->StartV2(info, compaction_input_binary);
+  switch (compaction_status) {
+    case CompactionServiceJobStatus::kSuccess:
+      break;
+    case CompactionServiceJobStatus::kFailure:
+      sub_compact->status = Status::Incomplete(
+          "CompactionService failed to start compaction job.");
+      ROCKS_LOG_WARN(db_options_.info_log,
+                     "[%s] [JOB %d] Remote compaction failed to start.",
+                     compaction_input.column_family.name.c_str(), job_id_);
+      return compaction_status;
+    case CompactionServiceJobStatus::kUseLocal:
+      ROCKS_LOG_INFO(
+          db_options_.info_log,
+          "[%s] [JOB %d] Remote compaction fallback to local by API Start.",
+          compaction_input.column_family.name.c_str(), job_id_);
+      return compaction_status;
+    default:
+      assert(false);  // unknown status
+      break;
+  }
+
+  ROCKS_LOG_INFO(db_options_.info_log,
+                 "[%s] [JOB %d] Waiting for remote compaction...",
+                 compaction_input.column_family.name.c_str(), job_id_);
+  std::string compaction_result_binary;
+  compaction_status = db_options_.compaction_service->WaitForCompleteV2(
+      info, &compaction_result_binary);
+
+  if (compaction_status == CompactionServiceJobStatus::kUseLocal) {
+    ROCKS_LOG_INFO(db_options_.info_log,
+                   "[%s] [JOB %d] Remote compaction fallback to local by API "
+                   "WaitForComplete.",
+                   compaction_input.column_family.name.c_str(), job_id_);
+    return compaction_status;
+  }
+
+  CompactionServiceResult compaction_result;
+  s = CompactionServiceResult::Read(compaction_result_binary,
+                                    &compaction_result);
+
+  if (compaction_status == CompactionServiceJobStatus::kFailure) {
+    if (s.ok()) {
+      if (compaction_result.status.ok()) {
+        sub_compact->status = Status::Incomplete(
+            "CompactionService failed to run the compaction job (even though "
+            "the internal status is okay).");
+      } else {
+        // set the current sub compaction status with the status returned from
+        // remote
+        sub_compact->status = compaction_result.status;
+      }
+    } else {
+      sub_compact->status = Status::Incomplete(
+          "CompactionService failed to run the compaction job (and no valid "
+          "result is returned).");
+      compaction_result.status.PermitUncheckedError();
+    }
+    ROCKS_LOG_WARN(db_options_.info_log,
+                   "[%s] [JOB %d] Remote compaction failed.",
+                   compaction_input.column_family.name.c_str(), job_id_);
+    return compaction_status;
+  }
+
+  if (!s.ok()) {
+    sub_compact->status = s;
+    compaction_result.status.PermitUncheckedError();
+    return CompactionServiceJobStatus::kFailure;
+  }
+  sub_compact->status = compaction_result.status;
+
+  std::ostringstream output_files_oss;
+  is_first_one = true;
+  for (const auto& file : compaction_result.output_files) {
+    output_files_oss << (is_first_one ? "" : ", ") << file.file_name;
+    is_first_one = false;
+  }
+
+  ROCKS_LOG_INFO(db_options_.info_log,
+                 "[%s] [JOB %d] Receive remote compaction result, output path: "
+                 "%s, files: %s",
+                 compaction_input.column_family.name.c_str(), job_id_,
+                 compaction_result.output_path.c_str(),
+                 output_files_oss.str().c_str());
+
+  if (!s.ok()) {
+    sub_compact->status = s;
+    return CompactionServiceJobStatus::kFailure;
+  }
+
+  for (const auto& file : compaction_result.output_files) {
+    uint64_t file_num = versions_->NewFileNumber();
+    auto src_file = compaction_result.output_path + "/" + file.file_name;
+    auto tgt_file = TableFileName(compaction->immutable_options()->cf_paths,
+                                  file_num, compaction->output_path_id());
+    s = fs_->RenameFile(src_file, tgt_file, IOOptions(), nullptr);
+    if (!s.ok()) {
+      sub_compact->status = s;
+      return CompactionServiceJobStatus::kFailure;
+    }
+
+    FileMetaData meta;
+    uint64_t file_size;
+    s = fs_->GetFileSize(tgt_file, IOOptions(), &file_size, nullptr);
+    if (!s.ok()) {
+      sub_compact->status = s;
+      return CompactionServiceJobStatus::kFailure;
+    }
+    meta.fd = FileDescriptor(file_num, compaction->output_path_id(), file_size,
+                             file.smallest_seqno, file.largest_seqno);
+    meta.smallest.DecodeFrom(file.smallest_internal_key);
+    meta.largest.DecodeFrom(file.largest_internal_key);
+    meta.oldest_ancester_time = file.oldest_ancester_time;
+    meta.file_creation_time = file.file_creation_time;
+    meta.marked_for_compaction = file.marked_for_compaction;
+    meta.unique_id = file.unique_id;
+
+    auto cfd = compaction->column_family_data();
+    sub_compact->Current().AddOutput(std::move(meta),
+                                     cfd->internal_comparator(), false, false,
+                                     true, file.paranoid_hash);
+  }
+  sub_compact->compaction_job_stats = compaction_result.stats;
+  sub_compact->Current().SetNumOutputRecords(
+      compaction_result.num_output_records);
+  sub_compact->Current().SetTotalBytes(compaction_result.total_bytes);
+  RecordTick(stats_, REMOTE_COMPACT_READ_BYTES, compaction_result.bytes_read);
+  RecordTick(stats_, REMOTE_COMPACT_WRITE_BYTES,
+             compaction_result.bytes_written);
+  return CompactionServiceJobStatus::kSuccess;
+}
+
+std::string CompactionServiceCompactionJob::GetTableFileName(
+    uint64_t file_number) {
+  return MakeTableFileName(output_path_, file_number);
+}
+
+void CompactionServiceCompactionJob::RecordCompactionIOStats() {
+  compaction_result_->bytes_read += IOSTATS(bytes_read);
+  compaction_result_->bytes_written += IOSTATS(bytes_written);
+  CompactionJob::RecordCompactionIOStats();
+}
+
+CompactionServiceCompactionJob::CompactionServiceCompactionJob(
+    int job_id, Compaction* compaction, const ImmutableDBOptions& db_options,
+    const MutableDBOptions& mutable_db_options, const FileOptions& file_options,
+    VersionSet* versions, const std::atomic<bool>* shutting_down,
+    LogBuffer* log_buffer, FSDirectory* output_directory, Statistics* stats,
+    InstrumentedMutex* db_mutex, ErrorHandler* db_error_handler,
+    std::vector<SequenceNumber> existing_snapshots,
+    std::shared_ptr<Cache> table_cache, EventLogger* event_logger,
+    const std::string& dbname, const std::shared_ptr<IOTracer>& io_tracer,
+    const std::atomic<bool>& manual_compaction_canceled,
+    const std::string& db_id, const std::string& db_session_id,
+    std::string output_path,
+    const CompactionServiceInput& compaction_service_input,
+    CompactionServiceResult* compaction_service_result)
+    : CompactionJob(
+          job_id, compaction, db_options, mutable_db_options, file_options,
+          versions, shutting_down, log_buffer, nullptr, output_directory,
+          nullptr, stats, db_mutex, db_error_handler,
+          std::move(existing_snapshots), kMaxSequenceNumber, nullptr, nullptr,
+          std::move(table_cache), event_logger,
+          compaction->mutable_cf_options()->paranoid_file_checks,
+          compaction->mutable_cf_options()->report_bg_io_stats, dbname,
+          &(compaction_service_result->stats), Env::Priority::USER, io_tracer,
+          manual_compaction_canceled, db_id, db_session_id,
+          compaction->column_family_data()->GetFullHistoryTsLow()),
+      output_path_(std::move(output_path)),
+      compaction_input_(compaction_service_input),
+      compaction_result_(compaction_service_result) {}
+
+Status CompactionServiceCompactionJob::Run() {
+  AutoThreadOperationStageUpdater stage_updater(
+      ThreadStatus::STAGE_COMPACTION_RUN);
+
+  auto* c = compact_->compaction;
+  assert(c->column_family_data() != nullptr);
+  assert(c->column_family_data()->current()->storage_info()->NumLevelFiles(
+             compact_->compaction->level()) > 0);
+
+  write_hint_ =
+      c->column_family_data()->CalculateSSTWriteHint(c->output_level());
+  bottommost_level_ = c->bottommost_level();
+
+  Slice begin = compaction_input_.begin;
+  Slice end = compaction_input_.end;
+  compact_->sub_compact_states.emplace_back(
+      c,
+      compaction_input_.has_begin ? std::optional<Slice>(begin)
+                                  : std::optional<Slice>(),
+      compaction_input_.has_end ? std::optional<Slice>(end)
+                                : std::optional<Slice>(),
+      /*sub_job_id*/ 0);
+
+  log_buffer_->FlushBufferToLog();
+  LogCompaction();
+  const uint64_t start_micros = db_options_.clock->NowMicros();
+  // Pick the only sub-compaction we should have
+  assert(compact_->sub_compact_states.size() == 1);
+  SubcompactionState* sub_compact = compact_->sub_compact_states.data();
+
+  ProcessKeyValueCompaction(sub_compact);
+
+  compaction_stats_.stats.micros =
+      db_options_.clock->NowMicros() - start_micros;
+  compaction_stats_.stats.cpu_micros =
+      sub_compact->compaction_job_stats.cpu_micros;
+
+  RecordTimeToHistogram(stats_, COMPACTION_TIME,
+                        compaction_stats_.stats.micros);
+  RecordTimeToHistogram(stats_, COMPACTION_CPU_TIME,
+                        compaction_stats_.stats.cpu_micros);
+
+  Status status = sub_compact->status;
+  IOStatus io_s = sub_compact->io_status;
+
+  if (io_status_.ok()) {
+    io_status_ = io_s;
+  }
+
+  if (status.ok()) {
+    constexpr IODebugContext* dbg = nullptr;
+
+    if (output_directory_) {
+      io_s = output_directory_->FsyncWithDirOptions(IOOptions(), dbg,
+                                                    DirFsyncOptions());
+    }
+  }
+  if (io_status_.ok()) {
+    io_status_ = io_s;
+  }
+  if (status.ok()) {
+    status = io_s;
+  }
+  if (status.ok()) {
+    // TODO: Add verify_table()
+  }
+
+  // Finish up all book-keeping to unify the subcompaction results
+  compact_->AggregateCompactionStats(compaction_stats_, *compaction_job_stats_);
+  UpdateCompactionStats();
+  RecordCompactionIOStats();
+
+  LogFlush(db_options_.info_log);
+  compact_->status = status;
+  compact_->status.PermitUncheckedError();
+
+  // Build compaction result
+  compaction_result_->output_level = compact_->compaction->output_level();
+  compaction_result_->output_path = output_path_;
+  for (const auto& output_file : sub_compact->GetOutputs()) {
+    auto& meta = output_file.meta;
+    compaction_result_->output_files.emplace_back(
+        MakeTableFileName(meta.fd.GetNumber()), meta.fd.smallest_seqno,
+        meta.fd.largest_seqno, meta.smallest.Encode().ToString(),
+        meta.largest.Encode().ToString(), meta.oldest_ancester_time,
+        meta.file_creation_time, output_file.validator.GetHash(),
+        meta.marked_for_compaction, meta.unique_id);
+  }
+  InternalStats::CompactionStatsFull compaction_stats;
+  sub_compact->AggregateCompactionStats(compaction_stats);
+  compaction_result_->num_output_records =
+      compaction_stats.stats.num_output_records;
+  compaction_result_->total_bytes = compaction_stats.TotalBytesWritten();
+
+  return status;
+}
+
+void CompactionServiceCompactionJob::CleanupCompaction() {
+  CompactionJob::CleanupCompaction();
+}
+
+// Internal binary format for the input and result data
+enum BinaryFormatVersion : uint32_t {
+  kOptionsString = 1,  // Use string format similar to Option string format
+};
+
+static std::unordered_map<std::string, OptionTypeInfo> cfd_type_info = {
+    {"name",
+     {offsetof(struct ColumnFamilyDescriptor, name), OptionType::kEncodedString,
+      OptionVerificationType::kNormal, OptionTypeFlags::kNone}},
+    {"options",
+     {offsetof(struct ColumnFamilyDescriptor, options),
+      OptionType::kConfigurable, OptionVerificationType::kNormal,
+      OptionTypeFlags::kNone,
+      [](const ConfigOptions& opts, const std::string& /*name*/,
+         const std::string& value, void* addr) {
+        auto cf_options = static_cast<ColumnFamilyOptions*>(addr);
+        return GetColumnFamilyOptionsFromString(opts, ColumnFamilyOptions(),
+                                                value, cf_options);
+      },
+      [](const ConfigOptions& opts, const std::string& /*name*/,
+         const void* addr, std::string* value) {
+        const auto cf_options = static_cast<const ColumnFamilyOptions*>(addr);
+        std::string result;
+        auto status =
+            GetStringFromColumnFamilyOptions(opts, *cf_options, &result);
+        *value = "{" + result + "}";
+        return status;
+      },
+      [](const ConfigOptions& opts, const std::string& name, const void* addr1,
+         const void* addr2, std::string* mismatch) {
+        const auto this_one = static_cast<const ColumnFamilyOptions*>(addr1);
+        const auto that_one = static_cast<const ColumnFamilyOptions*>(addr2);
+        auto this_conf = CFOptionsAsConfigurable(*this_one);
+        auto that_conf = CFOptionsAsConfigurable(*that_one);
+        std::string mismatch_opt;
+        bool result =
+            this_conf->AreEquivalent(opts, that_conf.get(), &mismatch_opt);
+        if (!result) {
+          *mismatch = name + "." + mismatch_opt;
+        }
+        return result;
+      }}},
+};
+
+static std::unordered_map<std::string, OptionTypeInfo> cs_input_type_info = {
+    {"column_family",
+     OptionTypeInfo::Struct(
+         "column_family", &cfd_type_info,
+         offsetof(struct CompactionServiceInput, column_family),
+         OptionVerificationType::kNormal, OptionTypeFlags::kNone)},
+    {"db_options",
+     {offsetof(struct CompactionServiceInput, db_options),
+      OptionType::kConfigurable, OptionVerificationType::kNormal,
+      OptionTypeFlags::kNone,
+      [](const ConfigOptions& opts, const std::string& /*name*/,
+         const std::string& value, void* addr) {
+        auto options = static_cast<DBOptions*>(addr);
+        return GetDBOptionsFromString(opts, DBOptions(), value, options);
+      },
+      [](const ConfigOptions& opts, const std::string& /*name*/,
+         const void* addr, std::string* value) {
+        const auto options = static_cast<const DBOptions*>(addr);
+        std::string result;
+        auto status = GetStringFromDBOptions(opts, *options, &result);
+        *value = "{" + result + "}";
+        return status;
+      },
+      [](const ConfigOptions& opts, const std::string& name, const void* addr1,
+         const void* addr2, std::string* mismatch) {
+        const auto this_one = static_cast<const DBOptions*>(addr1);
+        const auto that_one = static_cast<const DBOptions*>(addr2);
+        auto this_conf = DBOptionsAsConfigurable(*this_one);
+        auto that_conf = DBOptionsAsConfigurable(*that_one);
+        std::string mismatch_opt;
+        bool result =
+            this_conf->AreEquivalent(opts, that_conf.get(), &mismatch_opt);
+        if (!result) {
+          *mismatch = name + "." + mismatch_opt;
+        }
+        return result;
+      }}},
+    {"snapshots", OptionTypeInfo::Vector<uint64_t>(
+                      offsetof(struct CompactionServiceInput, snapshots),
+                      OptionVerificationType::kNormal, OptionTypeFlags::kNone,
+                      {0, OptionType::kUInt64T})},
+    {"input_files", OptionTypeInfo::Vector<std::string>(
+                        offsetof(struct CompactionServiceInput, input_files),
+                        OptionVerificationType::kNormal, OptionTypeFlags::kNone,
+                        {0, OptionType::kEncodedString})},
+    {"output_level",
+     {offsetof(struct CompactionServiceInput, output_level), OptionType::kInt,
+      OptionVerificationType::kNormal, OptionTypeFlags::kNone}},
+    {"db_id",
+     {offsetof(struct CompactionServiceInput, db_id),
+      OptionType::kEncodedString}},
+    {"has_begin",
+     {offsetof(struct CompactionServiceInput, has_begin), OptionType::kBoolean,
+      OptionVerificationType::kNormal, OptionTypeFlags::kNone}},
+    {"begin",
+     {offsetof(struct CompactionServiceInput, begin),
+      OptionType::kEncodedString, OptionVerificationType::kNormal,
+      OptionTypeFlags::kNone}},
+    {"has_end",
+     {offsetof(struct CompactionServiceInput, has_end), OptionType::kBoolean,
+      OptionVerificationType::kNormal, OptionTypeFlags::kNone}},
+    {"end",
+     {offsetof(struct CompactionServiceInput, end), OptionType::kEncodedString,
+      OptionVerificationType::kNormal, OptionTypeFlags::kNone}},
+};
+
+static std::unordered_map<std::string, OptionTypeInfo>
+    cs_output_file_type_info = {
+        {"file_name",
+         {offsetof(struct CompactionServiceOutputFile, file_name),
+          OptionType::kEncodedString, OptionVerificationType::kNormal,
+          OptionTypeFlags::kNone}},
+        {"smallest_seqno",
+         {offsetof(struct CompactionServiceOutputFile, smallest_seqno),
+          OptionType::kUInt64T, OptionVerificationType::kNormal,
+          OptionTypeFlags::kNone}},
+        {"largest_seqno",
+         {offsetof(struct CompactionServiceOutputFile, largest_seqno),
+          OptionType::kUInt64T, OptionVerificationType::kNormal,
+          OptionTypeFlags::kNone}},
+        {"smallest_internal_key",
+         {offsetof(struct CompactionServiceOutputFile, smallest_internal_key),
+          OptionType::kEncodedString, OptionVerificationType::kNormal,
+          OptionTypeFlags::kNone}},
+        {"largest_internal_key",
+         {offsetof(struct CompactionServiceOutputFile, largest_internal_key),
+          OptionType::kEncodedString, OptionVerificationType::kNormal,
+          OptionTypeFlags::kNone}},
+        {"oldest_ancester_time",
+         {offsetof(struct CompactionServiceOutputFile, oldest_ancester_time),
+          OptionType::kUInt64T, OptionVerificationType::kNormal,
+          OptionTypeFlags::kNone}},
+        {"file_creation_time",
+         {offsetof(struct CompactionServiceOutputFile, file_creation_time),
+          OptionType::kUInt64T, OptionVerificationType::kNormal,
+          OptionTypeFlags::kNone}},
+        {"paranoid_hash",
+         {offsetof(struct CompactionServiceOutputFile, paranoid_hash),
+          OptionType::kUInt64T, OptionVerificationType::kNormal,
+          OptionTypeFlags::kNone}},
+        {"marked_for_compaction",
+         {offsetof(struct CompactionServiceOutputFile, marked_for_compaction),
+          OptionType::kBoolean, OptionVerificationType::kNormal,
+          OptionTypeFlags::kNone}},
+        {"unique_id",
+         OptionTypeInfo::Array<uint64_t, 2>(
+             offsetof(struct CompactionServiceOutputFile, unique_id),
+             OptionVerificationType::kNormal, OptionTypeFlags::kNone,
+             {0, OptionType::kUInt64T})},
+};
+
+static std::unordered_map<std::string, OptionTypeInfo>
+    compaction_job_stats_type_info = {
+        {"elapsed_micros",
+         {offsetof(struct CompactionJobStats, elapsed_micros),
+          OptionType::kUInt64T, OptionVerificationType::kNormal,
+          OptionTypeFlags::kNone}},
+        {"cpu_micros",
+         {offsetof(struct CompactionJobStats, cpu_micros), OptionType::kUInt64T,
+          OptionVerificationType::kNormal, OptionTypeFlags::kNone}},
+        {"num_input_records",
+         {offsetof(struct CompactionJobStats, num_input_records),
+          OptionType::kUInt64T, OptionVerificationType::kNormal,
+          OptionTypeFlags::kNone}},
+        {"num_blobs_read",
+         {offsetof(struct CompactionJobStats, num_blobs_read),
+          OptionType::kUInt64T, OptionVerificationType::kNormal,
+          OptionTypeFlags::kNone}},
+        {"num_input_files",
+         {offsetof(struct CompactionJobStats, num_input_files),
+          OptionType::kSizeT, OptionVerificationType::kNormal,
+          OptionTypeFlags::kNone}},
+        {"num_input_files_at_output_level",
+         {offsetof(struct CompactionJobStats, num_input_files_at_output_level),
+          OptionType::kSizeT, OptionVerificationType::kNormal,
+          OptionTypeFlags::kNone}},
+        {"num_output_records",
+         {offsetof(struct CompactionJobStats, num_output_records),
+          OptionType::kUInt64T, OptionVerificationType::kNormal,
+          OptionTypeFlags::kNone}},
+        {"num_output_files",
+         {offsetof(struct CompactionJobStats, num_output_files),
+          OptionType::kSizeT, OptionVerificationType::kNormal,
+          OptionTypeFlags::kNone}},
+        {"num_output_files_blob",
+         {offsetof(struct CompactionJobStats, num_output_files_blob),
+          OptionType::kSizeT, OptionVerificationType::kNormal,
+          OptionTypeFlags::kNone}},
+        {"is_full_compaction",
+         {offsetof(struct CompactionJobStats, is_full_compaction),
+          OptionType::kBoolean, OptionVerificationType::kNormal,
+          OptionTypeFlags::kNone}},
+        {"is_manual_compaction",
+         {offsetof(struct CompactionJobStats, is_manual_compaction),
+          OptionType::kBoolean, OptionVerificationType::kNormal,
+          OptionTypeFlags::kNone}},
+        {"total_input_bytes",
+         {offsetof(struct CompactionJobStats, total_input_bytes),
+          OptionType::kUInt64T, OptionVerificationType::kNormal,
+          OptionTypeFlags::kNone}},
+        {"total_blob_bytes_read",
+         {offsetof(struct CompactionJobStats, total_blob_bytes_read),
+          OptionType::kUInt64T, OptionVerificationType::kNormal,
+          OptionTypeFlags::kNone}},
+        {"total_output_bytes",
+         {offsetof(struct CompactionJobStats, total_output_bytes),
+          OptionType::kUInt64T, OptionVerificationType::kNormal,
+          OptionTypeFlags::kNone}},
+        {"total_output_bytes_blob",
+         {offsetof(struct CompactionJobStats, total_output_bytes_blob),
+          OptionType::kUInt64T, OptionVerificationType::kNormal,
+          OptionTypeFlags::kNone}},
+        {"num_records_replaced",
+         {offsetof(struct CompactionJobStats, num_records_replaced),
+          OptionType::kUInt64T, OptionVerificationType::kNormal,
+          OptionTypeFlags::kNone}},
+        {"total_input_raw_key_bytes",
+         {offsetof(struct CompactionJobStats, total_input_raw_key_bytes),
+          OptionType::kUInt64T, OptionVerificationType::kNormal,
+          OptionTypeFlags::kNone}},
+        {"total_input_raw_value_bytes",
+         {offsetof(struct CompactionJobStats, total_input_raw_value_bytes),
+          OptionType::kUInt64T, OptionVerificationType::kNormal,
+          OptionTypeFlags::kNone}},
+        {"num_input_deletion_records",
+         {offsetof(struct CompactionJobStats, num_input_deletion_records),
+          OptionType::kUInt64T, OptionVerificationType::kNormal,
+          OptionTypeFlags::kNone}},
+        {"num_expired_deletion_records",
+         {offsetof(struct CompactionJobStats, num_expired_deletion_records),
+          OptionType::kUInt64T, OptionVerificationType::kNormal,
+          OptionTypeFlags::kNone}},
+        {"num_corrupt_keys",
+         {offsetof(struct CompactionJobStats, num_corrupt_keys),
+          OptionType::kUInt64T, OptionVerificationType::kNormal,
+          OptionTypeFlags::kNone}},
+        {"file_write_nanos",
+         {offsetof(struct CompactionJobStats, file_write_nanos),
+          OptionType::kUInt64T, OptionVerificationType::kNormal,
+          OptionTypeFlags::kNone}},
+        {"file_range_sync_nanos",
+         {offsetof(struct CompactionJobStats, file_range_sync_nanos),
+          OptionType::kUInt64T, OptionVerificationType::kNormal,
+          OptionTypeFlags::kNone}},
+        {"file_fsync_nanos",
+         {offsetof(struct CompactionJobStats, file_fsync_nanos),
+          OptionType::kUInt64T, OptionVerificationType::kNormal,
+          OptionTypeFlags::kNone}},
+        {"file_prepare_write_nanos",
+         {offsetof(struct CompactionJobStats, file_prepare_write_nanos),
+          OptionType::kUInt64T, OptionVerificationType::kNormal,
+          OptionTypeFlags::kNone}},
+        {"smallest_output_key_prefix",
+         {offsetof(struct CompactionJobStats, smallest_output_key_prefix),
+          OptionType::kEncodedString, OptionVerificationType::kNormal,
+          OptionTypeFlags::kNone}},
+        {"largest_output_key_prefix",
+         {offsetof(struct CompactionJobStats, largest_output_key_prefix),
+          OptionType::kEncodedString, OptionVerificationType::kNormal,
+          OptionTypeFlags::kNone}},
+        {"num_single_del_fallthru",
+         {offsetof(struct CompactionJobStats, num_single_del_fallthru),
+          OptionType::kUInt64T, OptionVerificationType::kNormal,
+          OptionTypeFlags::kNone}},
+        {"num_single_del_mismatch",
+         {offsetof(struct CompactionJobStats, num_single_del_mismatch),
+          OptionType::kUInt64T, OptionVerificationType::kNormal,
+          OptionTypeFlags::kNone}},
+};
+
+namespace {
+// this is a helper struct to serialize and deserialize class Status, because
+// Status's members are not public.
+struct StatusSerializationAdapter {
+  uint8_t code;
+  uint8_t subcode;
+  uint8_t severity;
+  std::string message;
+
+  StatusSerializationAdapter() = default;
+  explicit StatusSerializationAdapter(const Status& s) {
+    code = s.code();
+    subcode = s.subcode();
+    severity = s.severity();
+    auto msg = s.getState();
+    message = msg ? msg : "";
+  }
+
+  Status GetStatus() const {
+    return Status{static_cast<Status::Code>(code),
+                  static_cast<Status::SubCode>(subcode),
+                  static_cast<Status::Severity>(severity), message};
+  }
+};
+}  // namespace
+
+static std::unordered_map<std::string, OptionTypeInfo>
+    status_adapter_type_info = {
+        {"code",
+         {offsetof(struct StatusSerializationAdapter, code),
+          OptionType::kUInt8T, OptionVerificationType::kNormal,
+          OptionTypeFlags::kNone}},
+        {"subcode",
+         {offsetof(struct StatusSerializationAdapter, subcode),
+          OptionType::kUInt8T, OptionVerificationType::kNormal,
+          OptionTypeFlags::kNone}},
+        {"severity",
+         {offsetof(struct StatusSerializationAdapter, severity),
+          OptionType::kUInt8T, OptionVerificationType::kNormal,
+          OptionTypeFlags::kNone}},
+        {"message",
+         {offsetof(struct StatusSerializationAdapter, message),
+          OptionType::kEncodedString, OptionVerificationType::kNormal,
+          OptionTypeFlags::kNone}},
+};
+
+static std::unordered_map<std::string, OptionTypeInfo> cs_result_type_info = {
+    {"status",
+     {offsetof(struct CompactionServiceResult, status),
+      OptionType::kCustomizable, OptionVerificationType::kNormal,
+      OptionTypeFlags::kNone,
+      [](const ConfigOptions& opts, const std::string& /*name*/,
+         const std::string& value, void* addr) {
+        auto status_obj = static_cast<Status*>(addr);
+        StatusSerializationAdapter adapter;
+        Status s = OptionTypeInfo::ParseType(
+            opts, value, status_adapter_type_info, &adapter);
+        *status_obj = adapter.GetStatus();
+        return s;
+      },
+      [](const ConfigOptions& opts, const std::string& /*name*/,
+         const void* addr, std::string* value) {
+        const auto status_obj = static_cast<const Status*>(addr);
+        StatusSerializationAdapter adapter(*status_obj);
+        std::string result;
+        Status s = OptionTypeInfo::SerializeType(opts, status_adapter_type_info,
+                                                 &adapter, &result);
+        *value = "{" + result + "}";
+        return s;
+      },
+      [](const ConfigOptions& opts, const std::string& /*name*/,
+         const void* addr1, const void* addr2, std::string* mismatch) {
+        const auto status1 = static_cast<const Status*>(addr1);
+        const auto status2 = static_cast<const Status*>(addr2);
+
+        StatusSerializationAdapter adatper1(*status1);
+        StatusSerializationAdapter adapter2(*status2);
+        return OptionTypeInfo::TypesAreEqual(opts, status_adapter_type_info,
+                                             &adatper1, &adapter2, mismatch);
+      }}},
+    {"output_files",
+     OptionTypeInfo::Vector<CompactionServiceOutputFile>(
+         offsetof(struct CompactionServiceResult, output_files),
+         OptionVerificationType::kNormal, OptionTypeFlags::kNone,
+         OptionTypeInfo::Struct("output_files", &cs_output_file_type_info, 0,
+                                OptionVerificationType::kNormal,
+                                OptionTypeFlags::kNone))},
+    {"output_level",
+     {offsetof(struct CompactionServiceResult, output_level), OptionType::kInt,
+      OptionVerificationType::kNormal, OptionTypeFlags::kNone}},
+    {"output_path",
+     {offsetof(struct CompactionServiceResult, output_path),
+      OptionType::kEncodedString, OptionVerificationType::kNormal,
+      OptionTypeFlags::kNone}},
+    {"num_output_records",
+     {offsetof(struct CompactionServiceResult, num_output_records),
+      OptionType::kUInt64T, OptionVerificationType::kNormal,
+      OptionTypeFlags::kNone}},
+    {"total_bytes",
+     {offsetof(struct CompactionServiceResult, total_bytes),
+      OptionType::kUInt64T, OptionVerificationType::kNormal,
+      OptionTypeFlags::kNone}},
+    {"bytes_read",
+     {offsetof(struct CompactionServiceResult, bytes_read),
+      OptionType::kUInt64T, OptionVerificationType::kNormal,
+      OptionTypeFlags::kNone}},
+    {"bytes_written",
+     {offsetof(struct CompactionServiceResult, bytes_written),
+      OptionType::kUInt64T, OptionVerificationType::kNormal,
+      OptionTypeFlags::kNone}},
+    {"stats", OptionTypeInfo::Struct(
+                  "stats", &compaction_job_stats_type_info,
+                  offsetof(struct CompactionServiceResult, stats),
+                  OptionVerificationType::kNormal, OptionTypeFlags::kNone)},
+};
+
+Status CompactionServiceInput::Read(const std::string& data_str,
+                                    CompactionServiceInput* obj) {
+  if (data_str.size() <= sizeof(BinaryFormatVersion)) {
+    return Status::InvalidArgument("Invalid CompactionServiceInput string");
+  }
+  auto format_version = DecodeFixed32(data_str.data());
+  if (format_version == kOptionsString) {
+    ConfigOptions cf;
+    cf.invoke_prepare_options = false;
+    cf.ignore_unknown_options = true;
+    return OptionTypeInfo::ParseType(
+        cf, data_str.substr(sizeof(BinaryFormatVersion)), cs_input_type_info,
+        obj);
+  } else {
+    return Status::NotSupported(
+        "Compaction Service Input data version not supported: " +
+        std::to_string(format_version));
+  }
+}
+
+Status CompactionServiceInput::Write(std::string* output) {
+  char buf[sizeof(BinaryFormatVersion)];
+  EncodeFixed32(buf, kOptionsString);
+  output->append(buf, sizeof(BinaryFormatVersion));
+  ConfigOptions cf;
+  cf.invoke_prepare_options = false;
+  return OptionTypeInfo::SerializeType(cf, cs_input_type_info, this, output);
+}
+
+Status CompactionServiceResult::Read(const std::string& data_str,
+                                     CompactionServiceResult* obj) {
+  if (data_str.size() <= sizeof(BinaryFormatVersion)) {
+    return Status::InvalidArgument("Invalid CompactionServiceResult string");
+  }
+  auto format_version = DecodeFixed32(data_str.data());
+  if (format_version == kOptionsString) {
+    ConfigOptions cf;
+    cf.invoke_prepare_options = false;
+    cf.ignore_unknown_options = true;
+    return OptionTypeInfo::ParseType(
+        cf, data_str.substr(sizeof(BinaryFormatVersion)), cs_result_type_info,
+        obj);
+  } else {
+    return Status::NotSupported(
+        "Compaction Service Result data version not supported: " +
+        std::to_string(format_version));
+  }
+}
+
+Status CompactionServiceResult::Write(std::string* output) {
+  char buf[sizeof(BinaryFormatVersion)];
+  EncodeFixed32(buf, kOptionsString);
+  output->append(buf, sizeof(BinaryFormatVersion));
+  ConfigOptions cf;
+  cf.invoke_prepare_options = false;
+  return OptionTypeInfo::SerializeType(cf, cs_result_type_info, this, output);
+}
+
+#ifndef NDEBUG
+bool CompactionServiceResult::TEST_Equals(CompactionServiceResult* other) {
+  std::string mismatch;
+  return TEST_Equals(other, &mismatch);
+}
+
+bool CompactionServiceResult::TEST_Equals(CompactionServiceResult* other,
+                                          std::string* mismatch) {
+  ConfigOptions cf;
+  cf.invoke_prepare_options = false;
+  return OptionTypeInfo::TypesAreEqual(cf, cs_result_type_info, this, other,
+                                       mismatch);
+}
+
+bool CompactionServiceInput::TEST_Equals(CompactionServiceInput* other) {
+  std::string mismatch;
+  return TEST_Equals(other, &mismatch);
+}
+
+bool CompactionServiceInput::TEST_Equals(CompactionServiceInput* other,
+                                         std::string* mismatch) {
+  ConfigOptions cf;
+  cf.invoke_prepare_options = false;
+  return OptionTypeInfo::TypesAreEqual(cf, cs_input_type_info, this, other,
+                                       mismatch);
+}
+#endif  // NDEBUG
+}  // namespace ROCKSDB_NAMESPACE
+
+#endif  // !ROCKSDB_LITE

db/compaction/compaction_state.cc

@@ -0,0 +1,46 @@
+//  Copyright (c) Meta Platforms, Inc. and affiliates.
+//
+//  This source code is licensed under both the GPLv2 (found in the
+//  COPYING file in the root directory) and Apache 2.0 License
+//  (found in the LICENSE.Apache file in the root directory).
+//
+// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file. See the AUTHORS file for names of contributors.
+
+#include "db/compaction/compaction_state.h"
+
+namespace ROCKSDB_NAMESPACE {
+
+Slice CompactionState::SmallestUserKey() {
+  for (const auto& sub_compact_state : sub_compact_states) {
+    Slice smallest = sub_compact_state.SmallestUserKey();
+    if (!smallest.empty()) {
+      return smallest;
+    }
+  }
+  // If there is no finished output, return an empty slice.
+  return Slice{nullptr, 0};
+}
+
+Slice CompactionState::LargestUserKey() {
+  for (auto it = sub_compact_states.rbegin(); it < sub_compact_states.rend();
+       ++it) {
+    Slice largest = it->LargestUserKey();
+    if (!largest.empty()) {
+      return largest;
+    }
+  }
+  // If there is no finished output, return an empty slice.
+  return Slice{nullptr, 0};
+}
+
+void CompactionState::AggregateCompactionStats(
+    InternalStats::CompactionStatsFull& compaction_stats,
+    CompactionJobStats& compaction_job_stats) {
+  for (const auto& sc : sub_compact_states) {
+    sc.AggregateCompactionStats(compaction_stats);
+    compaction_job_stats.Add(sc.compaction_job_stats);
+  }
+}
+}  // namespace ROCKSDB_NAMESPACE

db/compaction/compaction_state.h

@@ -0,0 +1,42 @@
+//  Copyright (c) Meta Platforms, Inc. and affiliates.
+//
+//  This source code is licensed under both the GPLv2 (found in the
+//  COPYING file in the root directory) and Apache 2.0 License
+//  (found in the LICENSE.Apache file in the root directory).
+//
+// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file. See the AUTHORS file for names of contributors.
+
+#pragma once
+
+#include "db/compaction/compaction.h"
+#include "db/compaction/subcompaction_state.h"
+#include "db/internal_stats.h"
+
+// Data structures used for compaction_job and compaction_service_job which has
+// the list of sub_compact_states and the aggregated information for the
+// compaction.
+namespace ROCKSDB_NAMESPACE {
+
+// Maintains state for the entire compaction
+class CompactionState {
+ public:
+  Compaction* const compaction;
+
+  // REQUIRED: subcompaction states are stored in order of increasing key-range
+  std::vector<SubcompactionState> sub_compact_states;
+  Status status;
+
+  void AggregateCompactionStats(
+      InternalStats::CompactionStatsFull& compaction_stats,
+      CompactionJobStats& compaction_job_stats);
+
+  explicit CompactionState(Compaction* c) : compaction(c) {}
+
+  Slice SmallestUserKey();
+
+  Slice LargestUserKey();
+};
+
+}  // namespace ROCKSDB_NAMESPACE

db/compaction/subcompaction_state.cc

@@ -0,0 +1,223 @@
+//  Copyright (c) Meta Platforms, Inc. and affiliates.
+//
+//  This source code is licensed under both the GPLv2 (found in the
+//  COPYING file in the root directory) and Apache 2.0 License
+//  (found in the LICENSE.Apache file in the root directory).
+//
+// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file. See the AUTHORS file for names of contributors.
+
+#include "db/compaction/subcompaction_state.h"
+
+#include "rocksdb/sst_partitioner.h"
+
+namespace ROCKSDB_NAMESPACE {
+void SubcompactionState::AggregateCompactionStats(
+    InternalStats::CompactionStatsFull& compaction_stats) const {
+  compaction_stats.stats.Add(compaction_outputs_.stats_);
+  if (HasPenultimateLevelOutputs()) {
+    compaction_stats.has_penultimate_level_output = true;
+    compaction_stats.penultimate_level_stats.Add(
+        penultimate_level_outputs_.stats_);
+  }
+}
+
+void SubcompactionState::FillFilesToCutForTtl() {
+  if (compaction->immutable_options()->compaction_style !=
+          CompactionStyle::kCompactionStyleLevel ||
+      compaction->immutable_options()->compaction_pri !=
+          CompactionPri::kMinOverlappingRatio ||
+      compaction->mutable_cf_options()->ttl == 0 ||
+      compaction->num_input_levels() < 2 || compaction->bottommost_level()) {
+    return;
+  }
+
+  // We define new file with the oldest ancestor time to be younger than 1/4
+  // TTL, and an old one to be older than 1/2 TTL time.
+  int64_t temp_current_time;
+  auto get_time_status = compaction->immutable_options()->clock->GetCurrentTime(
+      &temp_current_time);
+  if (!get_time_status.ok()) {
+    return;
+  }
+  auto current_time = static_cast<uint64_t>(temp_current_time);
+  if (current_time < compaction->mutable_cf_options()->ttl) {
+    return;
+  }
+  uint64_t old_age_thres =
+      current_time - compaction->mutable_cf_options()->ttl / 2;
+
+  const std::vector<FileMetaData*>& olevel =
+      *(compaction->inputs(compaction->num_input_levels() - 1));
+  for (FileMetaData* file : olevel) {
+    // Worth filtering out by start and end?
+    uint64_t oldest_ancester_time = file->TryGetOldestAncesterTime();
+    // We put old files if they are not too small to prevent a flood
+    // of small files.
+    if (oldest_ancester_time < old_age_thres &&
+        file->fd.GetFileSize() >
+            compaction->mutable_cf_options()->target_file_size_base / 2) {
+      files_to_cut_for_ttl_.push_back(file);
+    }
+  }
+}
+
+OutputIterator SubcompactionState::GetOutputs() const {
+  return OutputIterator(penultimate_level_outputs_.outputs_,
+                        compaction_outputs_.outputs_);
+}
+
+void SubcompactionState::Cleanup(Cache* cache) {
+  penultimate_level_outputs_.Cleanup();
+  compaction_outputs_.Cleanup();
+
+  if (!status.ok()) {
+    for (const auto& out : GetOutputs()) {
+      // If this file was inserted into the table cache then remove
+      // them here because this compaction was not committed.
+      TableCache::Evict(cache, out.meta.fd.GetNumber());
+    }
+  }
+  // TODO: sub_compact.io_status is not checked like status. Not sure if thats
+  // intentional. So ignoring the io_status as of now.
+  io_status.PermitUncheckedError();
+}
+
+Slice SubcompactionState::SmallestUserKey() const {
+  if (has_penultimate_level_outputs_) {
+    Slice a = compaction_outputs_.SmallestUserKey();
+    Slice b = penultimate_level_outputs_.SmallestUserKey();
+    if (a.empty()) {
+      return b;
+    }
+    if (b.empty()) {
+      return a;
+    }
+    const Comparator* user_cmp =
+        compaction->column_family_data()->user_comparator();
+    if (user_cmp->Compare(a, b) > 0) {
+      return b;
+    } else {
+      return a;
+    }
+  } else {
+    return compaction_outputs_.SmallestUserKey();
+  }
+}
+
+Slice SubcompactionState::LargestUserKey() const {
+  if (has_penultimate_level_outputs_) {
+    Slice a = compaction_outputs_.LargestUserKey();
+    Slice b = penultimate_level_outputs_.LargestUserKey();
+    if (a.empty()) {
+      return b;
+    }
+    if (b.empty()) {
+      return a;
+    }
+    const Comparator* user_cmp =
+        compaction->column_family_data()->user_comparator();
+    if (user_cmp->Compare(a, b) < 0) {
+      return b;
+    } else {
+      return a;
+    }
+  } else {
+    return compaction_outputs_.LargestUserKey();
+  }
+}
+
+bool SubcompactionState::ShouldStopBefore(const Slice& internal_key) {
+  uint64_t curr_file_size = Current().GetCurrentOutputFileSize();
+  const InternalKeyComparator* icmp =
+      &compaction->column_family_data()->internal_comparator();
+
+  // Invalid local_output_split_key indicates that we do not need to split
+  if (local_output_split_key_ != nullptr && !is_split_) {
+    // Split occurs when the next key is larger than/equal to the cursor
+    if (icmp->Compare(internal_key, local_output_split_key_->Encode()) >= 0) {
+      is_split_ = true;
+      return true;
+    }
+  }
+
+  const std::vector<FileMetaData*>& grandparents = compaction->grandparents();
+  bool grandparant_file_switched = false;
+  // Scan to find the earliest grandparent file that contains key.
+  while (grandparent_index_ < grandparents.size() &&
+         icmp->Compare(internal_key,
+                       grandparents[grandparent_index_]->largest.Encode()) >
+             0) {
+    if (seen_key_) {
+      overlapped_bytes_ += grandparents[grandparent_index_]->fd.GetFileSize();
+      grandparant_file_switched = true;
+    }
+    assert(grandparent_index_ + 1 >= grandparents.size() ||
+           icmp->Compare(
+               grandparents[grandparent_index_]->largest.Encode(),
+               grandparents[grandparent_index_ + 1]->smallest.Encode()) <= 0);
+    grandparent_index_++;
+  }
+  seen_key_ = true;
+
+  if (grandparant_file_switched &&
+      overlapped_bytes_ + curr_file_size > compaction->max_compaction_bytes()) {
+    // Too much overlap for current output; start new output
+    overlapped_bytes_ = 0;
+    return true;
+  }
+
+  if (!files_to_cut_for_ttl_.empty()) {
+    if (cur_files_to_cut_for_ttl_ != -1) {
+      // Previous key is inside the range of a file
+      if (icmp->Compare(internal_key,
+                        files_to_cut_for_ttl_[cur_files_to_cut_for_ttl_]
+                            ->largest.Encode()) > 0) {
+        next_files_to_cut_for_ttl_ = cur_files_to_cut_for_ttl_ + 1;
+        cur_files_to_cut_for_ttl_ = -1;
+        return true;
+      }
+    } else {
+      // Look for the key position
+      while (next_files_to_cut_for_ttl_ <
+             static_cast<int>(files_to_cut_for_ttl_.size())) {
+        if (icmp->Compare(internal_key,
+                          files_to_cut_for_ttl_[next_files_to_cut_for_ttl_]
+                              ->smallest.Encode()) >= 0) {
+          if (icmp->Compare(internal_key,
+                            files_to_cut_for_ttl_[next_files_to_cut_for_ttl_]
+                                ->largest.Encode()) <= 0) {
+            // With in the current file
+            cur_files_to_cut_for_ttl_ = next_files_to_cut_for_ttl_;
+            return true;
+          }
+          // Beyond the current file
+          next_files_to_cut_for_ttl_++;
+        } else {
+          // Still fall into the gap
+          break;
+        }
+      }
+    }
+  }
+
+  return false;
+}
+
+Status SubcompactionState::AddToOutput(
+    const CompactionIterator& iter,
+    const CompactionFileOpenFunc& open_file_func,
+    const CompactionFileCloseFunc& close_file_func) {
+  // update target output first
+  is_current_penultimate_level_ = iter.output_to_penultimate_level();
+  current_outputs_ = is_current_penultimate_level_ ? &penultimate_level_outputs_
+                                                   : &compaction_outputs_;
+  if (is_current_penultimate_level_) {
+    has_penultimate_level_outputs_ = true;
+  }
+
+  return Current().AddToOutput(iter, open_file_func, close_file_func);
+}
+
+}  // namespace ROCKSDB_NAMESPACE

db/compaction/subcompaction_state.h

@@ -0,0 +1,257 @@
+//  Copyright (c) Meta Platforms, Inc. and affiliates.
+//
+//  This source code is licensed under both the GPLv2 (found in the
+//  COPYING file in the root directory) and Apache 2.0 License
+//  (found in the LICENSE.Apache file in the root directory).
+//
+// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file. See the AUTHORS file for names of contributors.
+
+#pragma once
+
+#include <optional>
+
+#include "db/blob/blob_file_addition.h"
+#include "db/blob/blob_garbage_meter.h"
+#include "db/compaction/compaction.h"
+#include "db/compaction/compaction_iterator.h"
+#include "db/compaction/compaction_outputs.h"
+#include "db/internal_stats.h"
+#include "db/output_validator.h"
+#include "db/range_del_aggregator.h"
+
+namespace ROCKSDB_NAMESPACE {
+
+// Maintains state and outputs for each sub-compaction
+// It contains 2 `CompactionOutputs`:
+//  1. one for the normal output files
+//  2. another for the penultimate level outputs
+// a `current` pointer maintains the current output group, when calling
+// `AddToOutput()`, it checks the output of the current compaction_iterator key
+// and point `current` to the target output group. By default, it just points to
+// normal compaction_outputs, if the compaction_iterator key should be placed on
+// the penultimate level, `current` is changed to point to
+// `penultimate_level_outputs`.
+// The later operations uses `Current()` to get the target group.
+//
+// +----------+          +-----------------------------+      +---------+
+// | *current |--------> | compaction_outputs          |----->| output  |
+// +----------+          +-----------------------------+      +---------+
+//       |                                                    | output  |
+//       |                                                    +---------+
+//       |                                                    |  ...    |
+//       |
+//       |               +-----------------------------+      +---------+
+//       +-------------> | penultimate_level_outputs   |----->| output  |
+//                       +-----------------------------+      +---------+
+//                                                            |  ...    |
+
+class SubcompactionState {
+ public:
+  const Compaction* compaction;
+
+  // The boundaries of the key-range this compaction is interested in. No two
+  // sub-compactions may have overlapping key-ranges.
+  // 'start' is inclusive, 'end' is exclusive, and nullptr means unbounded
+  const std::optional<Slice> start, end;
+
+  // The return status of this sub-compaction
+  Status status;
+
+  // The return IO Status of this sub-compaction
+  IOStatus io_status;
+
+  // Notify on sub-compaction completion only if listener was notified on
+  // sub-compaction begin.
+  bool notify_on_subcompaction_completion = false;
+
+  // compaction job stats for this sub-compaction
+  CompactionJobStats compaction_job_stats;
+
+  // sub-compaction job id, which is used to identify different sub-compaction
+  // within the same compaction job.
+  const uint32_t sub_job_id;
+
+  Slice SmallestUserKey() const;
+
+  Slice LargestUserKey() const;
+
+  // Get all outputs from the subcompaction. For per_key_placement compaction,
+  // it returns both the last level outputs and penultimate level outputs.
+  OutputIterator GetOutputs() const;
+
+  // Assign range dels aggregator, for each range_del, it can only be assigned
+  // to one output level, for per_key_placement, it's going to be the
+  // penultimate level.
+  void AssignRangeDelAggregator(
+      std::unique_ptr<CompactionRangeDelAggregator>&& range_del_agg) {
+    if (compaction->SupportsPerKeyPlacement()) {
+      penultimate_level_outputs_.AssignRangeDelAggregator(
+          std::move(range_del_agg));
+    } else {
+      compaction_outputs_.AssignRangeDelAggregator(std::move(range_del_agg));
+    }
+  }
+
+  void RemoveLastEmptyOutput() {
+    compaction_outputs_.RemoveLastEmptyOutput();
+    penultimate_level_outputs_.RemoveLastEmptyOutput();
+  }
+
+#ifndef ROCKSDB_LITE
+  void BuildSubcompactionJobInfo(
+      SubcompactionJobInfo& subcompaction_job_info) const {
+    const Compaction* c = compaction;
+    const ColumnFamilyData* cfd = c->column_family_data();
+
+    subcompaction_job_info.cf_id = cfd->GetID();
+    subcompaction_job_info.cf_name = cfd->GetName();
+    subcompaction_job_info.status = status;
+    subcompaction_job_info.subcompaction_job_id = static_cast<int>(sub_job_id);
+    subcompaction_job_info.base_input_level = c->start_level();
+    subcompaction_job_info.output_level = c->output_level();
+    subcompaction_job_info.stats = compaction_job_stats;
+  }
+#endif  // !ROCKSDB_LITE
+
+  SubcompactionState() = delete;
+  SubcompactionState(const SubcompactionState&) = delete;
+  SubcompactionState& operator=(const SubcompactionState&) = delete;
+
+  SubcompactionState(Compaction* c, const std::optional<Slice> _start,
+                     const std::optional<Slice> _end, uint32_t _sub_job_id)
+      : compaction(c),
+        start(_start),
+        end(_end),
+        sub_job_id(_sub_job_id),
+        compaction_outputs_(c, /*is_penultimate_level=*/false),
+        penultimate_level_outputs_(c, /*is_penultimate_level=*/true) {
+    assert(compaction != nullptr);
+    const InternalKeyComparator* icmp =
+        &compaction->column_family_data()->internal_comparator();
+    const InternalKey* output_split_key = compaction->GetOutputSplitKey();
+    // Invalid output_split_key indicates that we do not need to split
+    if (output_split_key != nullptr) {
+      // We may only split the output when the cursor is in the range. Split
+      if ((!end.has_value() ||
+           icmp->user_comparator()->Compare(
+               ExtractUserKey(output_split_key->Encode()), end.value()) < 0) &&
+          (!start.has_value() || icmp->user_comparator()->Compare(
+                                     ExtractUserKey(output_split_key->Encode()),
+                                     start.value()) > 0)) {
+        local_output_split_key_ = output_split_key;
+      }
+    }
+  }
+
+  SubcompactionState(SubcompactionState&& state) noexcept
+      : compaction(state.compaction),
+        start(state.start),
+        end(state.end),
+        status(std::move(state.status)),
+        io_status(std::move(state.io_status)),
+        notify_on_subcompaction_completion(
+            state.notify_on_subcompaction_completion),
+        compaction_job_stats(std::move(state.compaction_job_stats)),
+        sub_job_id(state.sub_job_id),
+        files_to_cut_for_ttl_(std::move(state.files_to_cut_for_ttl_)),
+        cur_files_to_cut_for_ttl_(state.cur_files_to_cut_for_ttl_),
+        next_files_to_cut_for_ttl_(state.next_files_to_cut_for_ttl_),
+        grandparent_index_(state.grandparent_index_),
+        overlapped_bytes_(state.overlapped_bytes_),
+        seen_key_(state.seen_key_),
+        compaction_outputs_(std::move(state.compaction_outputs_)),
+        penultimate_level_outputs_(std::move(state.penultimate_level_outputs_)),
+        is_current_penultimate_level_(state.is_current_penultimate_level_),
+        has_penultimate_level_outputs_(state.has_penultimate_level_outputs_) {
+    current_outputs_ = is_current_penultimate_level_
+                           ? &penultimate_level_outputs_
+                           : &compaction_outputs_;
+  }
+
+  bool HasPenultimateLevelOutputs() const {
+    return has_penultimate_level_outputs_ ||
+           penultimate_level_outputs_.HasRangeDel();
+  }
+
+  void FillFilesToCutForTtl();
+
+  // Returns true iff we should stop building the current output
+  // before processing "internal_key".
+  bool ShouldStopBefore(const Slice& internal_key);
+
+  bool IsCurrentPenultimateLevel() const {
+    return is_current_penultimate_level_;
+  }
+
+  // Add all the new files from this compaction to version_edit
+  void AddOutputsEdit(VersionEdit* out_edit) const {
+    for (const auto& file : penultimate_level_outputs_.outputs_) {
+      out_edit->AddFile(compaction->GetPenultimateLevel(), file.meta);
+    }
+    for (const auto& file : compaction_outputs_.outputs_) {
+      out_edit->AddFile(compaction->output_level(), file.meta);
+    }
+  }
+
+  void Cleanup(Cache* cache);
+
+  void AggregateCompactionStats(
+      InternalStats::CompactionStatsFull& compaction_stats) const;
+
+  CompactionOutputs& Current() const {
+    assert(current_outputs_);
+    return *current_outputs_;
+  }
+
+  // Add compaction_iterator key/value to the `Current` output group.
+  Status AddToOutput(const CompactionIterator& iter,
+                     const CompactionFileOpenFunc& open_file_func,
+                     const CompactionFileCloseFunc& close_file_func);
+
+  // Close all compaction output files, both output_to_penultimate_level outputs
+  // and normal outputs.
+  Status CloseCompactionFiles(const Status& curr_status,
+                              const CompactionFileOpenFunc& open_file_func,
+                              const CompactionFileCloseFunc& close_file_func) {
+    // Call FinishCompactionOutputFile() even if status is not ok: it needs to
+    // close the output file.
+    Status s = penultimate_level_outputs_.CloseOutput(
+        curr_status, open_file_func, close_file_func);
+    s = compaction_outputs_.CloseOutput(s, open_file_func, close_file_func);
+    return s;
+  }
+
+ private:
+  // Some identified files with old oldest ancester time and the range should be
+  // isolated out so that the output file(s) in that range can be merged down
+  // for TTL and clear the timestamps for the range.
+  std::vector<FileMetaData*> files_to_cut_for_ttl_;
+  int cur_files_to_cut_for_ttl_ = -1;
+  int next_files_to_cut_for_ttl_ = 0;
+
+  // An index that used to speed up ShouldStopBefore().
+  size_t grandparent_index_ = 0;
+  // The number of bytes overlapping between the current output and
+  // grandparent files used in ShouldStopBefore().
+  uint64_t overlapped_bytes_ = 0;
+  // A flag determines whether the key has been seen in ShouldStopBefore()
+  bool seen_key_ = false;
+
+  // A flag determines if this subcompaction has been split by the cursor
+  bool is_split_ = false;
+
+  // We also maintain the output split key for each subcompaction to avoid
+  // repetitive comparison in ShouldStopBefore()
+  const InternalKey* local_output_split_key_ = nullptr;
+
+  // State kept for output being generated
+  CompactionOutputs compaction_outputs_;
+  CompactionOutputs penultimate_level_outputs_;
+  CompactionOutputs* current_outputs_ = &compaction_outputs_;
+  bool is_current_penultimate_level_ = false;
+  bool has_penultimate_level_outputs_ = false;
+};
+
+}  // namespace ROCKSDB_NAMESPACE

db/corruption_test.cc

@@ -7,6 +7,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file. See the AUTHORS file for names of contributors.
 
+#include "rocksdb/options.h"
 #ifndef ROCKSDB_LITE
 
 #include <fcntl.h>
@@ -553,7 +554,10 @@ TEST_F(CorruptionTest, CorruptedDescriptor) {
   ASSERT_OK(db_->Put(WriteOptions(), "foo", "hello"));
   DBImpl* dbi = static_cast_with_check<DBImpl>(db_);
   ASSERT_OK(dbi->TEST_FlushMemTable());
-  ASSERT_OK(dbi->TEST_CompactRange(0, nullptr, nullptr));
+  CompactRangeOptions cro;
+  cro.bottommost_level_compaction = BottommostLevelCompaction::kForce;
+  ASSERT_OK(
+      dbi->CompactRange(cro, dbi->DefaultColumnFamily(), nullptr, nullptr));
 
   Corrupt(kDescriptorFile, 0, 1000);
   Status s = TryReopen();
@@ -760,6 +764,7 @@ TEST_F(CorruptionTest, ParanoidFileChecksOnCompact) {
     delete db_;
     db_ = nullptr;
     s = DestroyDB(dbname_, options);
+    ASSERT_OK(s);
     std::shared_ptr<mock::MockTableFactory> mock =
         std::make_shared<mock::MockTableFactory>();
     options.table_factory = mock;
@@ -770,7 +775,9 @@ TEST_F(CorruptionTest, ParanoidFileChecksOnCompact) {
     DBImpl* dbi = static_cast_with_check<DBImpl>(db_);
     ASSERT_OK(dbi->TEST_FlushMemTable());
     mock->SetCorruptionMode(mode);
-    s = dbi->TEST_CompactRange(0, nullptr, nullptr, nullptr, true);
+    CompactRangeOptions cro;
+    cro.bottommost_level_compaction = BottommostLevelCompaction::kForce;
+    s = dbi->CompactRange(cro, dbi->DefaultColumnFamily(), nullptr, nullptr);
     if (mode == mock::MockTableFactory::kCorruptNone) {
       ASSERT_OK(s);
     } else {
@@ -806,7 +813,10 @@ TEST_F(CorruptionTest, ParanoidFileChecksWithDeleteRangeFirst) {
     } else {
       DBImpl* dbi = static_cast_with_check<DBImpl>(db_);
       ASSERT_OK(dbi->TEST_FlushMemTable());
-      ASSERT_OK(dbi->TEST_CompactRange(0, nullptr, nullptr, nullptr, true));
+      CompactRangeOptions cro;
+      cro.bottommost_level_compaction = BottommostLevelCompaction::kForce;
+      ASSERT_OK(
+          dbi->CompactRange(cro, dbi->DefaultColumnFamily(), nullptr, nullptr));
     }
     db_->ReleaseSnapshot(snap);
   }
@@ -842,7 +852,10 @@ TEST_F(CorruptionTest, ParanoidFileChecksWithDeleteRange) {
     } else {
       DBImpl* dbi = static_cast_with_check<DBImpl>(db_);
       ASSERT_OK(dbi->TEST_FlushMemTable());
-      ASSERT_OK(dbi->TEST_CompactRange(0, nullptr, nullptr, nullptr, true));
+      CompactRangeOptions cro;
+      cro.bottommost_level_compaction = BottommostLevelCompaction::kForce;
+      ASSERT_OK(
+          dbi->CompactRange(cro, dbi->DefaultColumnFamily(), nullptr, nullptr));
     }
     db_->ReleaseSnapshot(snap);
   }
@@ -875,7 +888,10 @@ TEST_F(CorruptionTest, ParanoidFileChecksWithDeleteRangeLast) {
     } else {
       DBImpl* dbi = static_cast_with_check<DBImpl>(db_);
       ASSERT_OK(dbi->TEST_FlushMemTable());
-      ASSERT_OK(dbi->TEST_CompactRange(0, nullptr, nullptr, nullptr, true));
+      CompactRangeOptions cro;
+      cro.bottommost_level_compaction = BottommostLevelCompaction::kForce;
+      ASSERT_OK(
+          dbi->CompactRange(cro, dbi->DefaultColumnFamily(), nullptr, nullptr));
     }
     db_->ReleaseSnapshot(snap);
   }
@@ -902,7 +918,10 @@ TEST_F(CorruptionTest, LogCorruptionErrorsInCompactionIterator) {
 
   DBImpl* dbi = static_cast_with_check<DBImpl>(db_);
   ASSERT_OK(dbi->TEST_FlushMemTable());
-  Status s = dbi->TEST_CompactRange(0, nullptr, nullptr, nullptr, true);
+  CompactRangeOptions cro;
+  cro.bottommost_level_compaction = BottommostLevelCompaction::kForce;
+  Status s =
+      dbi->CompactRange(cro, dbi->DefaultColumnFamily(), nullptr, nullptr);
   ASSERT_NOK(s);
   ASSERT_TRUE(s.IsCorruption());
 }
@@ -928,7 +947,10 @@ TEST_F(CorruptionTest, CompactionKeyOrderCheck) {
 
   mock->SetCorruptionMode(mock::MockTableFactory::kCorruptNone);
   ASSERT_OK(db_->SetOptions({{"check_flush_compaction_key_order", "true"}}));
-  ASSERT_NOK(dbi->TEST_CompactRange(0, nullptr, nullptr, nullptr, true));
+  CompactRangeOptions cro;
+  cro.bottommost_level_compaction = BottommostLevelCompaction::kForce;
+  ASSERT_NOK(
+      dbi->CompactRange(cro, dbi->DefaultColumnFamily(), nullptr, nullptr));
 }
 
 TEST_F(CorruptionTest, FlushKeyOrderCheck) {
@@ -975,7 +997,10 @@ TEST_F(CorruptionTest, DisableKeyOrderCheck) {
   ASSERT_OK(db_->Put(WriteOptions(), "foo2", "v1"));
   ASSERT_OK(db_->Put(WriteOptions(), "foo4", "v1"));
   ASSERT_OK(dbi->TEST_FlushMemTable());
-  ASSERT_OK(dbi->TEST_CompactRange(0, nullptr, nullptr, nullptr, true));
+  CompactRangeOptions cro;
+  cro.bottommost_level_compaction = BottommostLevelCompaction::kForce;
+  ASSERT_OK(
+      dbi->CompactRange(cro, dbi->DefaultColumnFamily(), nullptr, nullptr));
   ROCKSDB_NAMESPACE::SyncPoint::GetInstance()->DisableProcessing();
   ROCKSDB_NAMESPACE::SyncPoint::GetInstance()->ClearAllCallBacks();
 }

db/db_basic_test.cc

@@ -1209,9 +1209,9 @@ TEST_F(DBBasicTest, DBCloseAllDirectoryFDs) {
   s = db->Close();
   auto* counted_fs =
       options.env->GetFileSystem()->CheckedCast<CountedFileSystem>();
-  assert(counted_fs);
-  ASSERT_TRUE(counted_fs->counters()->dir_opens ==
-              counted_fs->counters()->dir_closes);
+  ASSERT_TRUE(counted_fs != nullptr);
+  ASSERT_EQ(counted_fs->counters()->dir_opens,
+            counted_fs->counters()->dir_closes);
   ASSERT_OK(s);
   delete db;
 }
@@ -2013,12 +2013,10 @@ TEST_P(DBMultiGetTestWithParam, MultiGetBatchedValueSize) {
 }
 
 TEST_P(DBMultiGetTestWithParam, MultiGetBatchedValueSizeMultiLevelMerge) {
-#ifndef USE_COROUTINES
   if (std::get<1>(GetParam())) {
-    ROCKSDB_GTEST_SKIP("This test requires coroutine support");
+    ROCKSDB_GTEST_SKIP("This test needs to be fixed for async IO");
     return;
   }
-#endif  // USE_COROUTINES
   // Skip for unbatched MultiGet
   if (!std::get<0>(GetParam())) {
     ROCKSDB_GTEST_BYPASS("This test is only for batched MultiGet");
@@ -2131,7 +2129,8 @@ INSTANTIATE_TEST_CASE_P(DBMultiGetTestWithParam, DBMultiGetTestWithParam,
                         testing::Combine(testing::Bool(), testing::Bool()));
 
 #if USE_COROUTINES
-class DBMultiGetAsyncIOTest : public DBBasicTest {
+class DBMultiGetAsyncIOTest : public DBBasicTest,
+                              public ::testing::WithParamInterface<bool> {
  public:
   DBMultiGetAsyncIOTest()
       : DBBasicTest(), statistics_(ROCKSDB_NAMESPACE::CreateDBStatistics()) {
@@ -2146,7 +2145,7 @@ class DBMultiGetAsyncIOTest : public DBBasicTest {
 
     // Put all keys in the bottommost level, and overwrite some keys
     // in L0 and L1
-    for (int i = 0; i < 128; ++i) {
+    for (int i = 0; i < 256; ++i) {
       EXPECT_OK(Put(Key(i), "val_l2_" + std::to_string(i)));
       num_keys++;
       if (num_keys == 8) {
@@ -2172,6 +2171,21 @@ class DBMultiGetAsyncIOTest : public DBBasicTest {
       EXPECT_OK(Flush());
       num_keys = 0;
     }
+    // Put some range deletes in L1
+    for (int i = 128; i < 256; i += 32) {
+      std::string range_begin = Key(i);
+      std::string range_end = Key(i + 16);
+      EXPECT_OK(dbfull()->DeleteRange(WriteOptions(),
+                                      dbfull()->DefaultColumnFamily(),
+                                      range_begin, range_end));
+      // Also do some Puts to force creation of bloom filter
+      for (int j = i + 16; j < i + 32; ++j) {
+        if (j % 3 == 0) {
+          EXPECT_OK(Put(Key(j), "val_l1_" + std::to_string(j)));
+        }
+      }
+      EXPECT_OK(Flush());
+    }
     MoveFilesToLevel(1);
 
     for (int i = 0; i < 128; i += 5) {
@@ -2195,7 +2209,7 @@ class DBMultiGetAsyncIOTest : public DBBasicTest {
   std::shared_ptr<Statistics> statistics_;
 };
 
-TEST_F(DBMultiGetAsyncIOTest, GetFromL0) {
+TEST_P(DBMultiGetAsyncIOTest, GetFromL0) {
   // All 3 keys in L0. The L0 files should be read serially.
   std::vector<std::string> key_strs{Key(0), Key(40), Key(80)};
   std::vector<Slice> keys{key_strs[0], key_strs[1], key_strs[2]};
@@ -2204,6 +2218,7 @@ TEST_F(DBMultiGetAsyncIOTest, GetFromL0) {
 
   ReadOptions ro;
   ro.async_io = true;
+  ro.optimize_multiget_for_io = GetParam();
   dbfull()->MultiGet(ro, dbfull()->DefaultColumnFamily(), keys.size(),
                      keys.data(), values.data(), statuses.data());
   ASSERT_EQ(values.size(), 3);
@@ -2218,13 +2233,17 @@ TEST_F(DBMultiGetAsyncIOTest, GetFromL0) {
 
   statistics()->histogramData(MULTIGET_IO_BATCH_SIZE, &multiget_io_batch_size);
 
-  // No async IO in this case since we don't do parallel lookup in L0
-  ASSERT_EQ(multiget_io_batch_size.count, 0);
-  ASSERT_EQ(multiget_io_batch_size.max, 0);
-  ASSERT_EQ(statistics()->getTickerCount(MULTIGET_COROUTINE_COUNT), 0);
+  // With async IO, lookups will happen in parallel for each key
+  if (GetParam()) {
+    ASSERT_EQ(multiget_io_batch_size.count, 1);
+    ASSERT_EQ(multiget_io_batch_size.max, 3);
+    ASSERT_EQ(statistics()->getTickerCount(MULTIGET_COROUTINE_COUNT), 3);
+  } else {
+    ASSERT_EQ(multiget_io_batch_size.count, 0);
+  }
 }
 
-TEST_F(DBMultiGetAsyncIOTest, GetFromL1) {
+TEST_P(DBMultiGetAsyncIOTest, GetFromL1) {
   std::vector<std::string> key_strs;
   std::vector<Slice> keys;
   std::vector<PinnableSlice> values;
@@ -2241,6 +2260,7 @@ TEST_F(DBMultiGetAsyncIOTest, GetFromL1) {
 
   ReadOptions ro;
   ro.async_io = true;
+  ro.optimize_multiget_for_io = GetParam();
   dbfull()->MultiGet(ro, dbfull()->DefaultColumnFamily(), keys.size(),
                      keys.data(), values.data(), statuses.data());
   ASSERT_EQ(values.size(), 3);
@@ -2261,7 +2281,7 @@ TEST_F(DBMultiGetAsyncIOTest, GetFromL1) {
   ASSERT_EQ(statistics()->getTickerCount(MULTIGET_COROUTINE_COUNT), 3);
 }
 
-TEST_F(DBMultiGetAsyncIOTest, LastKeyInFile) {
+TEST_P(DBMultiGetAsyncIOTest, LastKeyInFile) {
   std::vector<std::string> key_strs;
   std::vector<Slice> keys;
   std::vector<PinnableSlice> values;
@@ -2279,6 +2299,7 @@ TEST_F(DBMultiGetAsyncIOTest, LastKeyInFile) {
 
   ReadOptions ro;
   ro.async_io = true;
+  ro.optimize_multiget_for_io = GetParam();
   dbfull()->MultiGet(ro, dbfull()->DefaultColumnFamily(), keys.size(),
                      keys.data(), values.data(), statuses.data());
   ASSERT_EQ(values.size(), 3);
@@ -2301,7 +2322,7 @@ TEST_F(DBMultiGetAsyncIOTest, LastKeyInFile) {
   ASSERT_EQ(multiget_io_batch_size.max, 2);
 }
 
-TEST_F(DBMultiGetAsyncIOTest, GetFromL1AndL2) {
+TEST_P(DBMultiGetAsyncIOTest, GetFromL1AndL2) {
   std::vector<std::string> key_strs;
   std::vector<Slice> keys;
   std::vector<PinnableSlice> values;
@@ -2319,6 +2340,7 @@ TEST_F(DBMultiGetAsyncIOTest, GetFromL1AndL2) {
 
   ReadOptions ro;
   ro.async_io = true;
+  ro.optimize_multiget_for_io = GetParam();
   dbfull()->MultiGet(ro, dbfull()->DefaultColumnFamily(), keys.size(),
                      keys.data(), values.data(), statuses.data());
   ASSERT_EQ(values.size(), 3);
@@ -2333,11 +2355,101 @@ TEST_F(DBMultiGetAsyncIOTest, GetFromL1AndL2) {
 
   statistics()->histogramData(MULTIGET_IO_BATCH_SIZE, &multiget_io_batch_size);
 
-  // There is only one MultiGet key in the bottommost level - 56. Thus
-  // the bottommost level will not use async IO.
+  // There are 2 keys in L1 in twp separate files, and 1 in L2. With
+  // async IO, all three lookups will happen in parallel
   ASSERT_EQ(multiget_io_batch_size.count, 1);
-  ASSERT_EQ(multiget_io_batch_size.max, 2);
+  ASSERT_EQ(multiget_io_batch_size.max, GetParam() ? 3 : 2);
 }
+
+TEST_P(DBMultiGetAsyncIOTest, GetFromL2WithRangeOverlapL0L1) {
+  std::vector<std::string> key_strs;
+  std::vector<Slice> keys;
+  std::vector<PinnableSlice> values;
+  std::vector<Status> statuses;
+
+  // 19 and 26 are in L2, but overlap with L0 and L1 file ranges
+  key_strs.push_back(Key(19));
+  key_strs.push_back(Key(26));
+  keys.push_back(key_strs[0]);
+  keys.push_back(key_strs[1]);
+  values.resize(keys.size());
+  statuses.resize(keys.size());
+
+  ReadOptions ro;
+  ro.async_io = true;
+  ro.optimize_multiget_for_io = GetParam();
+  dbfull()->MultiGet(ro, dbfull()->DefaultColumnFamily(), keys.size(),
+                     keys.data(), values.data(), statuses.data());
+  ASSERT_EQ(values.size(), 2);
+  ASSERT_EQ(statuses[0], Status::OK());
+  ASSERT_EQ(statuses[1], Status::OK());
+  ASSERT_EQ(values[0], "val_l2_" + std::to_string(19));
+  ASSERT_EQ(values[1], "val_l2_" + std::to_string(26));
+
+  // Bloom filters in L0/L1 will avoid the coroutine calls in those levels
+  ASSERT_EQ(statistics()->getTickerCount(MULTIGET_COROUTINE_COUNT), 2);
+}
+
+TEST_P(DBMultiGetAsyncIOTest, GetFromL2WithRangeDelInL1) {
+  std::vector<std::string> key_strs;
+  std::vector<Slice> keys;
+  std::vector<PinnableSlice> values;
+  std::vector<Status> statuses;
+
+  // 139 and 163 are in L2, but overlap with a range deletes in L1
+  key_strs.push_back(Key(139));
+  key_strs.push_back(Key(163));
+  keys.push_back(key_strs[0]);
+  keys.push_back(key_strs[1]);
+  values.resize(keys.size());
+  statuses.resize(keys.size());
+
+  ReadOptions ro;
+  ro.async_io = true;
+  ro.optimize_multiget_for_io = GetParam();
+  dbfull()->MultiGet(ro, dbfull()->DefaultColumnFamily(), keys.size(),
+                     keys.data(), values.data(), statuses.data());
+  ASSERT_EQ(values.size(), 2);
+  ASSERT_EQ(statuses[0], Status::NotFound());
+  ASSERT_EQ(statuses[1], Status::NotFound());
+
+  // Bloom filters in L0/L1 will avoid the coroutine calls in those levels
+  ASSERT_EQ(statistics()->getTickerCount(MULTIGET_COROUTINE_COUNT), 2);
+}
+
+TEST_P(DBMultiGetAsyncIOTest, GetFromL1AndL2WithRangeDelInL1) {
+  std::vector<std::string> key_strs;
+  std::vector<Slice> keys;
+  std::vector<PinnableSlice> values;
+  std::vector<Status> statuses;
+
+  // 139 and 163 are in L2, but overlap with a range deletes in L1
+  key_strs.push_back(Key(139));
+  key_strs.push_back(Key(144));
+  key_strs.push_back(Key(163));
+  keys.push_back(key_strs[0]);
+  keys.push_back(key_strs[1]);
+  keys.push_back(key_strs[2]);
+  values.resize(keys.size());
+  statuses.resize(keys.size());
+
+  ReadOptions ro;
+  ro.async_io = true;
+  ro.optimize_multiget_for_io = GetParam();
+  dbfull()->MultiGet(ro, dbfull()->DefaultColumnFamily(), keys.size(),
+                     keys.data(), values.data(), statuses.data());
+  ASSERT_EQ(values.size(), keys.size());
+  ASSERT_EQ(statuses[0], Status::NotFound());
+  ASSERT_EQ(statuses[1], Status::OK());
+  ASSERT_EQ(values[1], "val_l1_" + std::to_string(144));
+  ASSERT_EQ(statuses[2], Status::NotFound());
+
+  // Bloom filters in L0/L1 will avoid the coroutine calls in those levels
+  ASSERT_EQ(statistics()->getTickerCount(MULTIGET_COROUTINE_COUNT), 3);
+}
+
+INSTANTIATE_TEST_CASE_P(DBMultiGetAsyncIOTest, DBMultiGetAsyncIOTest,
+                        testing::Bool());
 #endif  // USE_COROUTINES
 
 TEST_F(DBBasicTest, MultiGetStats) {
@@ -2467,35 +2579,37 @@ TEST_P(MultiGetPrefixExtractorTest, Batched) {
   SetPerfLevel(kEnableCount);
   get_perf_context()->Reset();
 
-  // First key is not in the prefix_extractor domain
   ASSERT_OK(Put("k", "v0"));
   ASSERT_OK(Put("kk1", "v1"));
   ASSERT_OK(Put("kk2", "v2"));
   ASSERT_OK(Put("kk3", "v3"));
   ASSERT_OK(Put("kk4", "v4"));
-  std::vector<std::string> mem_keys(
+  std::vector<std::string> keys(
       {"k", "kk1", "kk2", "kk3", "kk4", "rofl", "lmho"});
-  std::vector<std::string> inmem_values;
-  inmem_values = MultiGet(mem_keys, nullptr);
-  ASSERT_EQ(inmem_values[0], "v0");
-  ASSERT_EQ(inmem_values[1], "v1");
-  ASSERT_EQ(inmem_values[2], "v2");
-  ASSERT_EQ(inmem_values[3], "v3");
-  ASSERT_EQ(inmem_values[4], "v4");
+  std::vector<std::string> expected(
+      {"v0", "v1", "v2", "v3", "v4", "NOT_FOUND", "NOT_FOUND"});
+  std::vector<std::string> values;
+  values = MultiGet(keys, nullptr);
+  ASSERT_EQ(values, expected);
+  // One key ("k") is not queried against the filter because it is outside
+  // the prefix_extractor domain, leaving 6 keys with queried prefixes.
   ASSERT_EQ(get_perf_context()->bloom_memtable_miss_count, 2);
-  ASSERT_EQ(get_perf_context()->bloom_memtable_hit_count, 5);
+  ASSERT_EQ(get_perf_context()->bloom_memtable_hit_count, 4);
   ASSERT_OK(Flush());
 
-  std::vector<std::string> keys({"k", "kk1", "kk2", "kk3", "kk4"});
-  std::vector<std::string> values;
   get_perf_context()->Reset();
   values = MultiGet(keys, nullptr);
-  ASSERT_EQ(values[0], "v0");
-  ASSERT_EQ(values[1], "v1");
-  ASSERT_EQ(values[2], "v2");
-  ASSERT_EQ(values[3], "v3");
-  ASSERT_EQ(values[4], "v4");
-  // Filter hits for 4 in-domain keys
+  ASSERT_EQ(values, expected);
+  ASSERT_EQ(get_perf_context()->bloom_sst_miss_count, 2);
+  ASSERT_EQ(get_perf_context()->bloom_sst_hit_count, 4);
+
+  // Also check Get stat
+  get_perf_context()->Reset();
+  for (size_t i = 0; i < keys.size(); ++i) {
+    values[i] = Get(keys[i]);
+  }
+  ASSERT_EQ(values, expected);
+  ASSERT_EQ(get_perf_context()->bloom_sst_miss_count, 2);
   ASSERT_EQ(get_perf_context()->bloom_sst_hit_count, 4);
 }
 
@@ -2616,13 +2730,20 @@ TEST_F(DBBasicTest, GetAllKeyVersions) {
     ASSERT_OK(Delete(std::to_string(i)));
   }
   std::vector<KeyVersion> key_versions;
-  ASSERT_OK(ROCKSDB_NAMESPACE::GetAllKeyVersions(
-      db_, Slice(), Slice(), std::numeric_limits<size_t>::max(),
-      &key_versions));
+  ASSERT_OK(GetAllKeyVersions(db_, Slice(), Slice(),
+                              std::numeric_limits<size_t>::max(),
+                              &key_versions));
   ASSERT_EQ(kNumInserts + kNumDeletes + kNumUpdates, key_versions.size());
-  ASSERT_OK(ROCKSDB_NAMESPACE::GetAllKeyVersions(
-      db_, handles_[0], Slice(), Slice(), std::numeric_limits<size_t>::max(),
-      &key_versions));
+  for (size_t i = 0; i < kNumInserts + kNumDeletes + kNumUpdates; i++) {
+    if (i % 3 == 0) {
+      ASSERT_EQ(key_versions[i].GetTypeName(), "TypeDeletion");
+    } else {
+      ASSERT_EQ(key_versions[i].GetTypeName(), "TypeValue");
+    }
+  }
+  ASSERT_OK(GetAllKeyVersions(db_, handles_[0], Slice(), Slice(),
+                              std::numeric_limits<size_t>::max(),
+                              &key_versions));
   ASSERT_EQ(kNumInserts + kNumDeletes + kNumUpdates, key_versions.size());
 
   // Check non-default column family
@@ -2635,11 +2756,21 @@ TEST_F(DBBasicTest, GetAllKeyVersions) {
   for (size_t i = 0; i + 1 != kNumDeletes; ++i) {
     ASSERT_OK(Delete(1, std::to_string(i)));
   }
-  ASSERT_OK(ROCKSDB_NAMESPACE::GetAllKeyVersions(
-      db_, handles_[1], Slice(), Slice(), std::numeric_limits<size_t>::max(),
-      &key_versions));
+  ASSERT_OK(GetAllKeyVersions(db_, handles_[1], Slice(), Slice(),
+                              std::numeric_limits<size_t>::max(),
+                              &key_versions));
   ASSERT_EQ(kNumInserts + kNumDeletes + kNumUpdates - 3, key_versions.size());
 }
+
+TEST_F(DBBasicTest, ValueTypeString) {
+  KeyVersion key_version;
+  // when adding new type, please also update `value_type_string_map`
+  for (unsigned char i = ValueType::kTypeDeletion; i < ValueType::kTypeMaxValid;
+       i++) {
+    key_version.type = i;
+    ASSERT_TRUE(key_version.GetTypeName() != "Invalid");
+  }
+}
 #endif  // !ROCKSDB_LITE
 
 TEST_F(DBBasicTest, MultiGetIOBufferOverrun) {
@@ -4143,7 +4274,7 @@ TEST_F(DBBasicTest, FailOpenIfLoggerCreationFail) {
 
   Status s = TryReopen(options);
   ASSERT_EQ(nullptr, options.info_log);
-  ASSERT_TRUE(s.IsAborted());
+  ASSERT_TRUE(s.IsIOError());
 
   SyncPoint::GetInstance()->DisableProcessing();
   SyncPoint::GetInstance()->ClearAllCallBacks();
@@ -4193,7 +4324,9 @@ TEST_F(DBBasicTest, VerifyFileChecksums) {
   ASSERT_TRUE(db_->VerifyFileChecksums(ReadOptions()).IsInvalidArgument());
 }
 
-TEST_F(DBBasicTest, ManualWalSync) {
+// TODO: re-enable after we provide finer-grained control for WAL tracking to
+// meet the needs of different use cases, durability levels and recovery modes.
+TEST_F(DBBasicTest, DISABLED_ManualWalSync) {
   Options options = CurrentOptions();
   options.track_and_verify_wals_in_manifest = true;
   options.wal_recovery_mode = WALRecoveryMode::kAbsoluteConsistency;

db/db_block_cache_test.cc

@@ -13,6 +13,7 @@
 
 #include "cache/cache_entry_roles.h"
 #include "cache/cache_key.h"
+#include "cache/clock_cache.h"
 #include "cache/fast_lru_cache.h"
 #include "cache/lru_cache.h"
 #include "db/column_family.h"
@@ -250,7 +251,7 @@ TEST_F(DBBlockCacheTest, TestWithoutCompressedBlockCache) {
   cache->SetStrictCapacityLimit(true);
   iter = db_->NewIterator(read_options);
   iter->Seek(std::to_string(kNumBlocks - 1));
-  ASSERT_TRUE(iter->status().IsIncomplete());
+  ASSERT_TRUE(iter->status().IsMemoryLimit());
   CheckCacheCounters(options, 1, 0, 0, 1);
   delete iter;
   iter = nullptr;
@@ -333,8 +334,10 @@ TEST_F(DBBlockCacheTest, TestWithCompressedBlockCache) {
   ASSERT_EQ(usage, cache->GetPinnedUsage());
 
   // Load last key block.
-  ASSERT_EQ("Result incomplete: Insert failed due to LRU cache being full.",
-            Get(std::to_string(kNumBlocks - 1)));
+  ASSERT_EQ(
+      "Operation aborted: Memory limit reached: Insert failed due to LRU cache "
+      "being full.",
+      Get(std::to_string(kNumBlocks - 1)));
   // Failure will also record the miss counter.
   CheckCacheCounters(options, 1, 0, 0, 1);
   CheckCompressedCacheCounters(options, 1, 0, 1, 0);
@@ -676,6 +679,7 @@ TEST_P(DBBlockCacheTest1, WarmCacheWithBlocksDuringFlush) {
   Options options = CurrentOptions();
   options.create_if_missing = true;
   options.statistics = ROCKSDB_NAMESPACE::CreateDBStatistics();
+  options.max_compaction_bytes = 2000;
 
   BlockBasedTableOptions table_options;
   table_options.block_cache = NewLRUCache(1 << 25, 0, false);
@@ -815,8 +819,8 @@ class MockCache : public LRUCache {
 
   MockCache()
       : LRUCache((size_t)1 << 25 /*capacity*/, 0 /*num_shard_bits*/,
-                 false /*strict_capacity_limit*/, 0.0 /*high_pri_pool_ratio*/) {
-  }
+                 false /*strict_capacity_limit*/, 0.0 /*high_pri_pool_ratio*/,
+                 0.0 /*low_pri_pool_ratio*/) {}
 
   using ShardedCache::Insert;
 
@@ -932,7 +936,9 @@ TEST_F(DBBlockCacheTest, AddRedundantStats) {
   int iterations_tested = 0;
   for (std::shared_ptr<Cache> base_cache :
        {NewLRUCache(capacity, num_shard_bits),
-        NewClockCache(capacity, num_shard_bits),
+        ExperimentalNewClockCache(
+            capacity, 1 /*estimated_value_size*/, num_shard_bits,
+            false /*strict_capacity_limit*/, kDefaultCacheMetadataChargePolicy),
         NewFastLRUCache(capacity, 1 /*estimated_value_size*/, num_shard_bits,
                         false /*strict_capacity_limit*/,
                         kDefaultCacheMetadataChargePolicy)}) {
@@ -1289,10 +1295,11 @@ TEST_F(DBBlockCacheTest, CacheEntryRoleStats) {
   int iterations_tested = 0;
   for (bool partition : {false, true}) {
     for (std::shared_ptr<Cache> cache :
-         {NewLRUCache(capacity), NewClockCache(capacity)}) {
-      // This test doesn't support FastLRUCache because the
-      // keys used are not 16B long.
-      // TODO(guido) Add support for FastLRUCache.
+         {NewLRUCache(capacity),
+          ExperimentalNewClockCache(capacity, 1 /*estimated_value_size*/,
+                                    -1 /*num_shard_bits*/,
+                                    false /*strict_capacity_limit*/,
+                                    kDefaultCacheMetadataChargePolicy)}) {
       if (!cache) {
         // Skip clock cache when not supported
         continue;
@@ -1445,9 +1452,16 @@ TEST_F(DBBlockCacheTest, CacheEntryRoleStats) {
       // even if the cache is full
       ClearCache(cache.get());
       Cache::Handle* h = nullptr;
-      ASSERT_OK(cache->Insert("Fill-it-up", nullptr, capacity + 1,
-                              GetNoopDeleterForRole<CacheEntryRole::kMisc>(),
-                              &h, Cache::Priority::HIGH));
+      if (strcmp(cache->Name(), "LRUCache") == 0) {
+        ASSERT_OK(cache->Insert("Fill-it-up", nullptr, capacity + 1,
+                                GetNoopDeleterForRole<CacheEntryRole::kMisc>(),
+                                &h, Cache::Priority::HIGH));
+      } else {
+        // For ClockCache we use a 16-byte key.
+        ASSERT_OK(cache->Insert("Fill-it-up-xxxxx", nullptr, capacity + 1,
+                                GetNoopDeleterForRole<CacheEntryRole::kMisc>(),
+                                &h, Cache::Priority::HIGH));
+      }
       ASSERT_GT(cache->GetUsage(), cache->GetCapacity());
       expected = {};
       // For CacheEntryStatsCollector
@@ -1704,7 +1718,7 @@ TEST_P(DBBlockCacheKeyTest, StableCacheKeys) {
   delete metadata_ptr_;
   metadata_ptr_ = nullptr;
 
-  DestroyDB(export_files_dir, options);
+  ASSERT_OK(DestroyDB(export_files_dir, options));
 
   ReopenWithColumnFamilies({"default", "yoyo"}, options);
 
@@ -1722,51 +1736,60 @@ TEST_P(DBBlockCacheKeyTest, StableCacheKeys) {
 
 class CacheKeyTest : public testing::Test {
  public:
-  void SetupStableBase() {
-    // Like SemiStructuredUniqueIdGen::GenerateNext
-    tp_.db_session_id = EncodeSessionId(base_session_upper_,
-                                        base_session_lower_ ^ session_counter_);
-    tp_.db_id = std::to_string(db_id_);
-    tp_.orig_file_number = file_number_;
-    bool is_stable;
-    std::string cur_session_id = "";  // ignored
-    uint64_t cur_file_number = 42;    // ignored
-    BlockBasedTable::SetupBaseCacheKey(&tp_, cur_session_id, cur_file_number,
-                                       file_size_, &base_cache_key_,
-                                       &is_stable);
-    ASSERT_TRUE(is_stable);
+  CacheKey GetBaseCacheKey() {
+    CacheKey rv = GetOffsetableCacheKey(0, /*min file_number*/ 1).WithOffset(0);
+    // Correct for file_number_ == 1
+    *reinterpret_cast<uint64_t*>(&rv) ^= ReverseBits(uint64_t{1});
+    return rv;
   }
-  CacheKey WithOffset(uint64_t offset) {
-    return BlockBasedTable::GetCacheKey(base_cache_key_,
-                                        BlockHandle(offset, /*size*/ 5));
+  CacheKey GetCacheKey(uint64_t session_counter, uint64_t file_number,
+                       uint64_t offset) {
+    OffsetableCacheKey offsetable =
+        GetOffsetableCacheKey(session_counter, file_number);
+    // * 4 to counteract optimization that strips lower 2 bits in encoding
+    // the offset in BlockBasedTable::GetCacheKey (which we prefer to include
+    // in unit tests to maximize functional coverage).
+    EXPECT_GE(offset * 4, offset);  // no overflow
+    return BlockBasedTable::GetCacheKey(offsetable,
+                                        BlockHandle(offset * 4, /*size*/ 5));
   }
 
  protected:
-  OffsetableCacheKey base_cache_key_;
+  OffsetableCacheKey GetOffsetableCacheKey(uint64_t session_counter,
+                                           uint64_t file_number) {
+    // Like SemiStructuredUniqueIdGen::GenerateNext
+    tp_.db_session_id = EncodeSessionId(base_session_upper_,
+                                        base_session_lower_ ^ session_counter);
+    tp_.db_id = std::to_string(db_id_);
+    tp_.orig_file_number = file_number;
+    bool is_stable;
+    std::string cur_session_id = "";  // ignored
+    uint64_t cur_file_number = 42;    // ignored
+    OffsetableCacheKey rv;
+    BlockBasedTable::SetupBaseCacheKey(&tp_, cur_session_id, cur_file_number,
+                                       &rv, &is_stable);
+    EXPECT_TRUE(is_stable);
+    EXPECT_TRUE(!rv.IsEmpty());
+    // BEGIN some assertions in relation to SST unique IDs
+    std::string external_unique_id_str;
+    EXPECT_OK(GetUniqueIdFromTableProperties(tp_, &external_unique_id_str));
+    UniqueId64x2 sst_unique_id = {};
+    EXPECT_OK(DecodeUniqueIdBytes(external_unique_id_str, &sst_unique_id));
+    ExternalUniqueIdToInternal(&sst_unique_id);
+    OffsetableCacheKey ock =
+        OffsetableCacheKey::FromInternalUniqueId(&sst_unique_id);
+    EXPECT_EQ(rv.WithOffset(0).AsSlice(), ock.WithOffset(0).AsSlice());
+    EXPECT_EQ(ock.ToInternalUniqueId(), sst_unique_id);
+    // END some assertions in relation to SST unique IDs
+    return rv;
+  }
+
   TableProperties tp_;
-  uint64_t file_size_ = 0;
   uint64_t base_session_upper_ = 0;
   uint64_t base_session_lower_ = 0;
-  uint64_t session_counter_ = 0;
-  uint64_t file_number_ = 0;
   uint64_t db_id_ = 0;
 };
 
-namespace {
-template <typename T>
-int CountBitsDifferent(const T& t1, const T& t2) {
-  int diff = 0;
-  const uint8_t* p1 = reinterpret_cast<const uint8_t*>(&t1);
-  const uint8_t* p2 = reinterpret_cast<const uint8_t*>(&t2);
-  static_assert(sizeof(*p1) == 1, "Expecting uint8_t byte");
-  for (size_t i = 0; i < sizeof(T); ++i) {
-    diff += BitsSetToOne(p1[i] ^ p2[i]);
-  }
-  return diff;
-}
-
-}  // namespace
-
 TEST_F(CacheKeyTest, DBImplSessionIdStructure) {
   // We have to generate our own session IDs for simulation purposes in other
   // tests. Here we verify that the DBImpl implementation seems to match
@@ -1785,171 +1808,202 @@ TEST_F(CacheKeyTest, DBImplSessionIdStructure) {
   ASSERT_NE(Lower32of64(lower1), Lower32of64(lower2));
 }
 
-TEST_F(CacheKeyTest, StandardEncodingLimit) {
-  base_session_upper_ = 1234;
-  base_session_lower_ = 5678;
-  session_counter_ = 42;
-  file_number_ = 42;
-  db_id_ = 1234;
-
-  file_size_ = 42;
-  SetupStableBase();
-  CacheKey ck1;
-  ASSERT_TRUE(ck1.IsEmpty());
-  ck1 = WithOffset(0);
-  ASSERT_FALSE(ck1.IsEmpty());
-
-  // Should use same encoding
-  file_size_ = BlockBasedTable::kMaxFileSizeStandardEncoding;
-  SetupStableBase();
-  CacheKey ck2 = WithOffset(0);
-  ASSERT_EQ(CountBitsDifferent(ck1, ck2), 0);
-
-  // Should use different encoding
-  ++file_size_;
-  SetupStableBase();
-  CacheKey ck3 = WithOffset(0);
-  ASSERT_GT(CountBitsDifferent(ck2, ck3), 0);
+namespace {
+// Deconstruct cache key, based on knowledge of implementation details.
+void DeconstructNonemptyCacheKey(const CacheKey& key, uint64_t* file_num_etc64,
+                                 uint64_t* offset_etc64) {
+  *file_num_etc64 = *reinterpret_cast<const uint64_t*>(key.AsSlice().data());
+  *offset_etc64 = *reinterpret_cast<const uint64_t*>(key.AsSlice().data() + 8);
+  assert(*file_num_etc64 != 0);
+  if (*offset_etc64 == 0) {
+    std::swap(*file_num_etc64, *offset_etc64);
+  }
+  assert(*offset_etc64 != 0);
 }
 
+// Make a bit mask of 0 to 64 bits
+uint64_t MakeMask64(int bits) {
+  if (bits >= 64) {
+    return uint64_t{0} - 1;
+  } else {
+    return (uint64_t{1} << bits) - 1;
+  }
+}
+
+// See CacheKeyTest::Encodings
+struct CacheKeyDecoder {
+  // Inputs
+  uint64_t base_file_num_etc64, base_offset_etc64;
+  int session_counter_bits, file_number_bits, offset_bits;
+
+  // Derived
+  uint64_t session_counter_mask, file_number_mask, offset_mask;
+
+  // Outputs
+  uint64_t decoded_session_counter, decoded_file_num, decoded_offset;
+
+  void SetBaseCacheKey(const CacheKey& base) {
+    DeconstructNonemptyCacheKey(base, &base_file_num_etc64, &base_offset_etc64);
+  }
+
+  void SetRanges(int _session_counter_bits, int _file_number_bits,
+                 int _offset_bits) {
+    session_counter_bits = _session_counter_bits;
+    session_counter_mask = MakeMask64(session_counter_bits);
+    file_number_bits = _file_number_bits;
+    file_number_mask = MakeMask64(file_number_bits);
+    offset_bits = _offset_bits;
+    offset_mask = MakeMask64(offset_bits);
+  }
+
+  void Decode(const CacheKey& key) {
+    uint64_t file_num_etc64, offset_etc64;
+    DeconstructNonemptyCacheKey(key, &file_num_etc64, &offset_etc64);
+
+    // First decode session counter
+    if (offset_bits + session_counter_bits <= 64) {
+      // fully recoverable from offset_etc64
+      decoded_session_counter =
+          ReverseBits((offset_etc64 ^ base_offset_etc64)) &
+          session_counter_mask;
+    } else if (file_number_bits + session_counter_bits <= 64) {
+      // fully recoverable from file_num_etc64
+      decoded_session_counter = DownwardInvolution(
+          (file_num_etc64 ^ base_file_num_etc64) & session_counter_mask);
+    } else {
+      // Need to combine parts from each word.
+      // Piece1 will contain some correct prefix of the bottom bits of
+      // session counter.
+      uint64_t piece1 =
+          ReverseBits((offset_etc64 ^ base_offset_etc64) & ~offset_mask);
+      int piece1_bits = 64 - offset_bits;
+      // Piece2 will contain involuded bits that we can combine with piece1
+      // to infer rest of session counter
+      int piece2_bits = std::min(64 - file_number_bits, 64 - piece1_bits);
+      ASSERT_LT(piece2_bits, 64);
+      uint64_t piece2_mask = MakeMask64(piece2_bits);
+      uint64_t piece2 = (file_num_etc64 ^ base_file_num_etc64) & piece2_mask;
+
+      // Cancel out the part of piece2 that we can infer from piece1
+      // (DownwardInvolution distributes over xor)
+      piece2 ^= DownwardInvolution(piece1) & piece2_mask;
+
+      // Now we need to solve for the unknown original bits in higher
+      // positions than piece1 provides. We use Gaussian elimination
+      // because we know that a piece2_bits X piece2_bits submatrix of
+      // the matrix underlying DownwardInvolution times the vector of
+      // unknown original bits equals piece2.
+      //
+      // Build an augmented row matrix for that submatrix, built column by
+      // column.
+      std::array<uint64_t, 64> aug_rows{};
+      for (int i = 0; i < piece2_bits; ++i) {  // over columns
+        uint64_t col_i = DownwardInvolution(uint64_t{1} << piece1_bits << i);
+        ASSERT_NE(col_i & 1U, 0);
+        for (int j = 0; j < piece2_bits; ++j) {  // over rows
+          aug_rows[j] |= (col_i & 1U) << i;
+          col_i >>= 1;
+        }
+      }
+      // Augment with right hand side
+      for (int j = 0; j < piece2_bits; ++j) {  // over rows
+        aug_rows[j] |= (piece2 & 1U) << piece2_bits;
+        piece2 >>= 1;
+      }
+      // Run Gaussian elimination
+      for (int i = 0; i < piece2_bits; ++i) {  // over columns
+        // Find a row that can be used to cancel others
+        uint64_t canceller = 0;
+        // Note: Rows 0 through i-1 contain 1s in columns already eliminated
+        for (int j = i; j < piece2_bits; ++j) {  // over rows
+          if (aug_rows[j] & (uint64_t{1} << i)) {
+            // Swap into appropriate row
+            std::swap(aug_rows[i], aug_rows[j]);
+            // Keep a handy copy for row reductions
+            canceller = aug_rows[i];
+            break;
+          }
+        }
+        ASSERT_NE(canceller, 0);
+        for (int j = 0; j < piece2_bits; ++j) {  // over rows
+          if (i != j && ((aug_rows[j] >> i) & 1) != 0) {
+            // Row reduction
+            aug_rows[j] ^= canceller;
+          }
+        }
+      }
+      // Extract result
+      decoded_session_counter = piece1;
+      for (int j = 0; j < piece2_bits; ++j) {  // over rows
+        ASSERT_EQ(aug_rows[j] & piece2_mask, uint64_t{1} << j);
+        decoded_session_counter |= aug_rows[j] >> piece2_bits << piece1_bits
+                                                              << j;
+      }
+    }
+
+    decoded_offset =
+        offset_etc64 ^ base_offset_etc64 ^ ReverseBits(decoded_session_counter);
+
+    decoded_file_num = ReverseBits(file_num_etc64 ^ base_file_num_etc64 ^
+                                   DownwardInvolution(decoded_session_counter));
+  }
+};
+}  // namespace
+
 TEST_F(CacheKeyTest, Encodings) {
-  // Claim from cache_key.cc:
-  // In fact, if our SST files are all < 4TB (see
-  // BlockBasedTable::kMaxFileSizeStandardEncoding), then SST files generated
-  // in a single process are guaranteed to have unique cache keys, unless/until
-  // number session ids * max file number = 2**86, e.g. 1 trillion DB::Open in
-  // a single process and 64 trillion files generated.
+  // This test primarily verifies this claim from cache_key.cc:
+  // // In fact, if DB ids were not involved, we would be guaranteed unique
+  // // cache keys for files generated in a single process until total bits for
+  // // biggest session_id_counter, orig_file_number, and offset_in_file
+  // // reach 128 bits.
+  //
+  // To demonstrate this, CacheKeyDecoder can reconstruct the structured inputs
+  // to the cache key when provided an output cache key, the unstructured
+  // inputs, and bounds on the structured inputs.
+  //
+  // See OffsetableCacheKey comments in cache_key.cc.
 
-  // We can generalize that. For
-  // * z bits in maximum file size
-  // * n bits in maximum file number
-  // * s bits in maximum session counter
-  // uniqueness is guaranteed at least when all of these hold:
-  // *  z + n + s <= 121  (128 - 2 meta + 2 offset trim - (8-1) byte granularity
-  //                       in encoding)
-  // *  n + s <= 86       (encoding limitation)
-  // *  s <= 62           (because of 2-bit metadata)
-
-  // We can verify this indirectly by how input bits get into the cache key,
-  // but we have to be mindful that for sufficiently large file sizes,
-  // different encodings might be used. But for cases mixing large and small
-  // files, we have to verify uniqueness between encodings.
-
-  // Going through all combinations would be a little expensive, so we test
-  // only one random "stripe" of the configuration space per run.
-  constexpr uint32_t kStripeBits = 8;
-  constexpr uint32_t kStripeMask = (uint32_t{1} << kStripeBits) - 1;
-
-  // Also cycle through stripes on repeated runs (not thread safe)
-  static uint32_t stripe =
-      static_cast<uint32_t>(std::random_device{}()) & kStripeMask;
-  stripe = (stripe + 1) & kStripeMask;
-
-  fprintf(stderr, "%u\n", stripe);
-
-  // We are going to randomly initialize some values which *should* not affect
+  // We are going to randomly initialize some values that *should* not affect
   // result
   Random64 r{std::random_device{}()};
 
-  int max_num_encodings = 0;
-  uint32_t config_num = 0;
-  uint32_t session_counter_bits, file_number_bits, max_file_size_bits;
+  CacheKeyDecoder decoder;
+  db_id_ = r.Next();
+  base_session_upper_ = r.Next();
+  base_session_lower_ = r.Next();
+  if (base_session_lower_ == 0) {
+    base_session_lower_ = 1;
+  }
 
-  // Inner loop body, used later in a loop over configurations
-  auto TestConfig = [&]() {
-    base_session_upper_ = r.Next();
-    base_session_lower_ = r.Next();
-    session_counter_ = r.Next();
-    if (session_counter_bits < 64) {
-      // Avoid shifting UB
-      session_counter_ = session_counter_ >> 1 >> (63 - session_counter_bits);
-    }
-    file_number_ = r.Next() >> (64 - file_number_bits);
-    // Need two bits set to avoid temporary zero below
-    if (BitsSetToOne(file_number_) < 2) {
-      file_number_ = 3;
-    }
-    db_id_ = r.Next();
+  decoder.SetBaseCacheKey(GetBaseCacheKey());
 
-    // Work-around clang-analyzer which thinks empty last_base is garbage
-    CacheKey last_base = CacheKey::CreateUniqueForProcessLifetime();
-
-    std::unordered_set<std::string> seen;
-    int num_encodings = 0;
-
-    // Loop over encodings by increasing file size bits
-    for (uint32_t file_size_bits = 1; file_size_bits <= max_file_size_bits;
-         ++file_size_bits) {
-      file_size_ = uint64_t{1} << (file_size_bits - 1);
-      SetupStableBase();
-      CacheKey new_base = WithOffset(0);
-      if (CountBitsDifferent(last_base, new_base) == 0) {
-        // Same as previous encoding
-        continue;
-      }
-
-      // New encoding
-      ++num_encodings;
-      ASSERT_TRUE(seen.insert(new_base.AsSlice().ToString()).second);
-      last_base = new_base;
-      for (uint32_t i = 0; i < file_size_bits; ++i) {
-        CacheKey ck = WithOffset(uint64_t{1} << i);
-        if (i < 2) {
-          // These cases are not relevant and optimized by dropping two
-          // lowest bits because there's always at least 5 bytes between
-          // blocks.
-          ASSERT_EQ(CountBitsDifferent(ck, new_base), 0);
-        } else {
-          // Normal case
-          // 1 bit different from base and never been seen implies the bit
-          // is encoded into cache key without overlapping other structured
-          // data.
-          ASSERT_EQ(CountBitsDifferent(ck, new_base), 1);
-          ASSERT_TRUE(seen.insert(ck.AsSlice().ToString()).second);
-        }
-      }
-      for (uint32_t i = 0; i < session_counter_bits; ++i) {
-        SaveAndRestore<uint64_t> tmp(&session_counter_,
-                                     session_counter_ ^ (uint64_t{1} << i));
-        SetupStableBase();
-        CacheKey ck = WithOffset(0);
-        ASSERT_EQ(CountBitsDifferent(ck, new_base), 1);
-        ASSERT_TRUE(seen.insert(ck.AsSlice().ToString()).second);
-      }
-      for (uint32_t i = 0; i < file_number_bits; ++i) {
-        SaveAndRestore<uint64_t> tmp(&file_number_,
-                                     file_number_ ^ (uint64_t{1} << i));
-        SetupStableBase();
-        CacheKey ck = WithOffset(0);
-        ASSERT_EQ(CountBitsDifferent(ck, new_base), 1);
-        ASSERT_TRUE(seen.insert(ck.AsSlice().ToString()).second);
-      }
-      max_num_encodings = std::max(max_num_encodings, num_encodings);
-    }
-  };
-
-  // Loop over configurations and test those in stripe
-  for (session_counter_bits = 0; session_counter_bits <= 62;
+  // Loop over configurations and test those
+  for (int session_counter_bits = 0; session_counter_bits <= 64;
        ++session_counter_bits) {
-    uint32_t max_file_number_bits =
-        std::min(uint32_t{64}, uint32_t{86} - session_counter_bits);
-    // Start with 2 to avoid file_number_ == 0 in testing
-    for (file_number_bits = 2; file_number_bits <= max_file_number_bits;
-         ++file_number_bits) {
-      uint32_t max_max_file_size_bits =
-          std::min(uint32_t{64},
-                   uint32_t{121} - file_number_bits - session_counter_bits);
-      for (max_file_size_bits = 1; max_file_size_bits <= max_max_file_size_bits;
-           ++max_file_size_bits) {
-        if ((config_num++ & kStripeMask) == stripe) {
-          TestConfig();
+    for (int file_number_bits = 1; file_number_bits <= 64; ++file_number_bits) {
+      // 62 bits max because unoptimized offset will be 64 bits in that case
+      for (int offset_bits = 0; offset_bits <= 62; ++offset_bits) {
+        if (session_counter_bits + file_number_bits + offset_bits > 128) {
+          break;
         }
+
+        decoder.SetRanges(session_counter_bits, file_number_bits, offset_bits);
+
+        uint64_t session_counter = r.Next() & decoder.session_counter_mask;
+        uint64_t file_number = r.Next() & decoder.file_number_mask;
+        if (file_number == 0) {
+          // Minimum
+          file_number = 1;
+        }
+        uint64_t offset = r.Next() & decoder.offset_mask;
+        decoder.Decode(GetCacheKey(session_counter, file_number, offset));
+
+        EXPECT_EQ(decoder.decoded_session_counter, session_counter);
+        EXPECT_EQ(decoder.decoded_file_num, file_number);
+        EXPECT_EQ(decoder.decoded_offset, offset);
       }
     }
   }
-
-  // Make sure the current implementation is exercised
-  ASSERT_EQ(max_num_encodings, 4);
 }
 
 INSTANTIATE_TEST_CASE_P(DBBlockCacheKeyTest, DBBlockCacheKeyTest,

db/db_bloom_filter_test.cc

@@ -3113,6 +3113,382 @@ TEST_F(DBBloomFilterTest, SeekForPrevWithPartitionedFilters) {
   it.reset();
 }
 
+namespace {
+class BackwardBytewiseComparator : public Comparator {
+ public:
+  const char* Name() const override { return "BackwardBytewiseComparator"; }
+
+  int Compare(const Slice& a, const Slice& b) const override {
+    int min_size_neg = -static_cast<int>(std::min(a.size(), b.size()));
+    const char* a_end = a.data() + a.size();
+    const char* b_end = b.data() + b.size();
+    for (int i = -1; i >= min_size_neg; --i) {
+      if (a_end[i] != b_end[i]) {
+        if (static_cast<unsigned char>(a_end[i]) <
+            static_cast<unsigned char>(b_end[i])) {
+          return -1;
+        } else {
+          return 1;
+        }
+      }
+    }
+    return static_cast<int>(a.size()) - static_cast<int>(b.size());
+  }
+
+  void FindShortestSeparator(std::string* /*start*/,
+                             const Slice& /*limit*/) const override {}
+
+  void FindShortSuccessor(std::string* /*key*/) const override {}
+};
+
+const BackwardBytewiseComparator kBackwardBytewiseComparator{};
+
+class FixedSuffix4Transform : public SliceTransform {
+  const char* Name() const override { return "FixedSuffixTransform"; }
+
+  Slice Transform(const Slice& src) const override {
+    return Slice(src.data() + src.size() - 4, 4);
+  }
+
+  bool InDomain(const Slice& src) const override { return src.size() >= 4; }
+};
+
+std::pair<uint64_t, uint64_t> GetBloomStat(const Options& options, bool sst) {
+  if (sst) {
+    return {
+        options.statistics->getAndResetTickerCount(BLOOM_FILTER_PREFIX_CHECKED),
+        options.statistics->getAndResetTickerCount(BLOOM_FILTER_PREFIX_USEFUL)};
+  } else {
+    auto hit = std::exchange(get_perf_context()->bloom_memtable_hit_count, 0);
+    auto miss = std::exchange(get_perf_context()->bloom_memtable_miss_count, 0);
+    return {hit + miss, miss};
+  }
+}
+
+std::pair<uint64_t, uint64_t> CheckedAndUseful(uint64_t checked,
+                                               uint64_t useful) {
+  return {checked, useful};
+}
+}  // namespace
+
+// This uses a prefix_extractor + comparator combination that violates
+// one of the old obsolete, unnecessary axioms of prefix extraction:
+// * key.starts_with(prefix(key))
+// This axiom is not really needed, and we validate that here.
+TEST_F(DBBloomFilterTest, WeirdPrefixExtractorWithFilter1) {
+  BlockBasedTableOptions bbto;
+  bbto.filter_policy.reset(ROCKSDB_NAMESPACE::NewBloomFilterPolicy(10));
+  bbto.whole_key_filtering = false;
+
+  Options options = CurrentOptions();
+  options.comparator = &kBackwardBytewiseComparator;
+  options.prefix_extractor = std::make_shared<FixedSuffix4Transform>();
+  options.table_factory.reset(NewBlockBasedTableFactory(bbto));
+  options.memtable_prefix_bloom_size_ratio = 0.1;
+  options.statistics = CreateDBStatistics();
+
+  DestroyAndReopen(options);
+
+  ASSERT_OK(Put("321aaaa", "val1"));
+  ASSERT_OK(Put("112aaaa", "val2"));
+  ASSERT_OK(Put("009aaaa", "val3"));
+  ASSERT_OK(Put("baa", "val4"));  // out of domain
+  ASSERT_OK(Put("321abaa", "val5"));
+  ASSERT_OK(Put("zzz", "val6"));  // out of domain
+
+  for (auto flushed : {false, true}) {
+    SCOPED_TRACE("flushed=" + std::to_string(flushed));
+    if (flushed) {
+      ASSERT_OK(Flush());
+    }
+    ReadOptions read_options;
+    if (flushed) {  // TODO: support auto_prefix_mode in memtable?
+      read_options.auto_prefix_mode = true;
+    }
+    EXPECT_EQ(GetBloomStat(options, flushed), CheckedAndUseful(0, 0));
+    {
+      Slice ub("999aaaa");
+      read_options.iterate_upper_bound = &ub;
+      std::unique_ptr<Iterator> iter(db_->NewIterator(read_options));
+      EXPECT_EQ(CountIter(iter, "aaaa"), 3);
+      EXPECT_EQ(GetBloomStat(options, flushed), CheckedAndUseful(1, 0));
+    }
+    {
+      Slice ub("999abaa");
+      read_options.iterate_upper_bound = &ub;
+      std::unique_ptr<Iterator> iter(db_->NewIterator(read_options));
+      EXPECT_EQ(CountIter(iter, "abaa"), 1);
+      EXPECT_EQ(GetBloomStat(options, flushed), CheckedAndUseful(1, 0));
+    }
+    {
+      Slice ub("999acaa");
+      read_options.iterate_upper_bound = &ub;
+      std::unique_ptr<Iterator> iter(db_->NewIterator(read_options));
+      EXPECT_EQ(CountIter(iter, "acaa"), 0);
+      EXPECT_EQ(GetBloomStat(options, flushed), CheckedAndUseful(1, 1));
+    }
+    {
+      Slice ub("zzzz");
+      read_options.iterate_upper_bound = &ub;
+      std::unique_ptr<Iterator> iter(db_->NewIterator(read_options));
+      EXPECT_EQ(CountIter(iter, "baa"), 3);
+      if (flushed) {  // TODO: fix memtable case
+        EXPECT_EQ(GetBloomStat(options, flushed), CheckedAndUseful(0, 0));
+      }
+    }
+  }
+}
+
+// This uses a prefix_extractor + comparator combination that violates
+// one of the old obsolete, unnecessary axioms of prefix extraction:
+// * Compare(prefix(key), key) <= 0
+// This axiom is not really needed, and we validate that here.
+TEST_F(DBBloomFilterTest, WeirdPrefixExtractorWithFilter2) {
+  BlockBasedTableOptions bbto;
+  bbto.filter_policy.reset(ROCKSDB_NAMESPACE::NewBloomFilterPolicy(10));
+  bbto.whole_key_filtering = false;
+
+  Options options = CurrentOptions();
+  options.comparator = ReverseBytewiseComparator();
+  options.prefix_extractor.reset(NewFixedPrefixTransform(4));
+  options.table_factory.reset(NewBlockBasedTableFactory(bbto));
+  options.memtable_prefix_bloom_size_ratio = 0.1;
+  options.statistics = CreateDBStatistics();
+
+  DestroyAndReopen(options);
+
+  ASSERT_OK(Put("aaaa123", "val1"));
+  ASSERT_OK(Put("aaaa211", "val2"));
+  ASSERT_OK(Put("aaaa900", "val3"));
+  ASSERT_OK(Put("aab", "val4"));  // out of domain
+  ASSERT_OK(Put("aaba123", "val5"));
+  ASSERT_OK(Put("qqqq123", "val7"));
+  ASSERT_OK(Put("qqqq", "val8"));
+  ASSERT_OK(Put("zzz", "val8"));  // out of domain
+
+  for (auto flushed : {false, true}) {
+    SCOPED_TRACE("flushed=" + std::to_string(flushed));
+    if (flushed) {
+      ASSERT_OK(Flush());
+    }
+    ReadOptions read_options;
+    if (flushed) {  // TODO: support auto_prefix_mode in memtable?
+      read_options.auto_prefix_mode = true;
+    } else {
+      // TODO: why needed?
+      get_perf_context()->bloom_memtable_hit_count = 0;
+      get_perf_context()->bloom_memtable_miss_count = 0;
+    }
+    EXPECT_EQ(GetBloomStat(options, flushed), CheckedAndUseful(0, 0));
+    {
+      Slice ub("aaaa000");
+      read_options.iterate_upper_bound = &ub;
+      std::unique_ptr<Iterator> iter(db_->NewIterator(read_options));
+      EXPECT_EQ(CountIter(iter, "aaaa999"), 3);
+      EXPECT_EQ(GetBloomStat(options, flushed), CheckedAndUseful(1, 0));
+    }
+    {
+      // Note: prefix does work as upper bound
+      Slice ub("aaaa");
+      read_options.iterate_upper_bound = &ub;
+      std::unique_ptr<Iterator> iter(db_->NewIterator(read_options));
+      EXPECT_EQ(CountIter(iter, "aaaa999"), 3);
+      EXPECT_EQ(GetBloomStat(options, flushed), CheckedAndUseful(1, 0));
+    }
+    {
+      // Note: prefix does not work here as seek key
+      Slice ub("aaaa500");
+      read_options.iterate_upper_bound = &ub;
+      std::unique_ptr<Iterator> iter(db_->NewIterator(read_options));
+      EXPECT_EQ(CountIter(iter, "aaaa"), 0);
+      EXPECT_EQ(GetBloomStat(options, flushed), CheckedAndUseful(1, 0));
+    }
+    {
+      Slice ub("aaba000");
+      read_options.iterate_upper_bound = &ub;
+      std::unique_ptr<Iterator> iter(db_->NewIterator(read_options));
+      EXPECT_EQ(CountIter(iter, "aaba999"), 1);
+      EXPECT_EQ(GetBloomStat(options, flushed), CheckedAndUseful(1, 0));
+    }
+    {
+      Slice ub("aaca000");
+      read_options.iterate_upper_bound = &ub;
+      std::unique_ptr<Iterator> iter(db_->NewIterator(read_options));
+      EXPECT_EQ(CountIter(iter, "aaca999"), 0);
+      EXPECT_EQ(GetBloomStat(options, flushed), CheckedAndUseful(1, 1));
+    }
+    {
+      Slice ub("aaaz");
+      read_options.iterate_upper_bound = &ub;
+      std::unique_ptr<Iterator> iter(db_->NewIterator(read_options));
+      EXPECT_EQ(CountIter(iter, "zzz"), 5);
+      EXPECT_EQ(GetBloomStat(options, flushed), CheckedAndUseful(0, 0));
+    }
+    {
+      // Note: prefix does work here as seek key, but only finds key equal
+      // to prefix (others with same prefix are less)
+      read_options.auto_prefix_mode = false;
+      read_options.iterate_upper_bound = nullptr;
+      read_options.prefix_same_as_start = true;
+      std::unique_ptr<Iterator> iter(db_->NewIterator(read_options));
+      EXPECT_EQ(CountIter(iter, "qqqq"), 1);
+      EXPECT_EQ(GetBloomStat(options, flushed), CheckedAndUseful(1, 0));
+    }
+  }
+}
+
+namespace {
+// A weird comparator that in combination with NonIdempotentFixed4Transform
+// breaks an old axiom of prefix filtering.
+class WeirdComparator : public Comparator {
+ public:
+  const char* Name() const override { return "WeirdComparator"; }
+
+  int Compare(const Slice& a, const Slice& b) const override {
+    bool a_in = a.size() >= 5;
+    bool b_in = b.size() >= 5;
+    if (a_in != b_in) {
+      // Order keys after prefixes
+      return a_in - b_in;
+    }
+    if (a_in) {
+      return BytewiseComparator()->Compare(a, b);
+    } else {
+      // Different ordering on the prefixes
+      return ReverseBytewiseComparator()->Compare(a, b);
+    }
+  }
+
+  void FindShortestSeparator(std::string* /*start*/,
+                             const Slice& /*limit*/) const override {}
+
+  void FindShortSuccessor(std::string* /*key*/) const override {}
+};
+const WeirdComparator kWeirdComparator{};
+
+// Non-idempotentent because prefix is always 4 bytes, but this is
+// out-of-domain for keys to be assigned prefixes (>= 5 bytes)
+class NonIdempotentFixed4Transform : public SliceTransform {
+  const char* Name() const override { return "NonIdempotentFixed4Transform"; }
+
+  Slice Transform(const Slice& src) const override {
+    return Slice(src.data(), 4);
+  }
+
+  bool InDomain(const Slice& src) const override { return src.size() >= 5; }
+};
+}  // namespace
+
+// This uses a prefix_extractor + comparator combination that violates
+// two of the old obsolete, unnecessary axioms of prefix extraction:
+// * prefix(prefix(key)) == prefix(key)
+// * If Compare(k1, k2) <= 0, then Compare(prefix(k1), prefix(k2)) <= 0
+// This axiom is not really needed, and we validate that here.
+TEST_F(DBBloomFilterTest, WeirdPrefixExtractorWithFilter3) {
+  BlockBasedTableOptions bbto;
+  bbto.filter_policy.reset(ROCKSDB_NAMESPACE::NewBloomFilterPolicy(10));
+  bbto.whole_key_filtering = false;
+
+  Options options = CurrentOptions();
+  options.prefix_extractor = std::make_shared<NonIdempotentFixed4Transform>();
+  options.table_factory.reset(NewBlockBasedTableFactory(bbto));
+  options.memtable_prefix_bloom_size_ratio = 0.1;
+  options.statistics = CreateDBStatistics();
+
+  for (auto weird_comparator : {false, true}) {
+    if (weird_comparator) {
+      options.comparator = &kWeirdComparator;
+    }
+    DestroyAndReopen(options);
+
+    ASSERT_OK(Put("aaaa123", "val1"));
+    ASSERT_OK(Put("aaaa211", "val2"));
+    ASSERT_OK(Put("aaaa900", "val3"));
+    ASSERT_OK(Put("aab", "val4"));  // out of domain
+    ASSERT_OK(Put("aaba123", "val5"));
+    ASSERT_OK(Put("qqqq123", "val7"));
+    ASSERT_OK(Put("qqqq", "val8"));  // out of domain
+    ASSERT_OK(Put("zzzz", "val8"));  // out of domain
+
+    for (auto flushed : {false, true}) {
+      SCOPED_TRACE("flushed=" + std::to_string(flushed));
+      if (flushed) {
+        ASSERT_OK(Flush());
+      }
+      ReadOptions read_options;
+      if (flushed) {  // TODO: support auto_prefix_mode in memtable?
+        read_options.auto_prefix_mode = true;
+      } else {
+        // TODO: why needed?
+        get_perf_context()->bloom_memtable_hit_count = 0;
+        get_perf_context()->bloom_memtable_miss_count = 0;
+      }
+      EXPECT_EQ(GetBloomStat(options, flushed), CheckedAndUseful(0, 0));
+      {
+        Slice ub("aaaa999");
+        read_options.iterate_upper_bound = &ub;
+        std::unique_ptr<Iterator> iter(db_->NewIterator(read_options));
+        EXPECT_EQ(CountIter(iter, "aaaa000"), 3);
+        EXPECT_EQ(GetBloomStat(options, flushed), CheckedAndUseful(1, 0));
+      }
+      {
+        // Note: prefix as seek key is not bloom-optimized
+        // Note: the count works with weird_comparator because "aaaa" is
+        // ordered as the last of the prefixes
+        Slice ub("aaaa999");
+        read_options.iterate_upper_bound = &ub;
+        std::unique_ptr<Iterator> iter(db_->NewIterator(read_options));
+        EXPECT_EQ(CountIter(iter, "aaaa"), 3);
+        EXPECT_EQ(GetBloomStat(options, flushed), CheckedAndUseful(0, 0));
+      }
+      {
+        Slice ub("aaba9");
+        read_options.iterate_upper_bound = &ub;
+        std::unique_ptr<Iterator> iter(db_->NewIterator(read_options));
+        EXPECT_EQ(CountIter(iter, "aaba0"), 1);
+        EXPECT_EQ(GetBloomStat(options, flushed), CheckedAndUseful(1, 0));
+      }
+      {
+        Slice ub("aaca9");
+        read_options.iterate_upper_bound = &ub;
+        std::unique_ptr<Iterator> iter(db_->NewIterator(read_options));
+        EXPECT_EQ(CountIter(iter, "aaca0"), 0);
+        EXPECT_EQ(GetBloomStat(options, flushed), CheckedAndUseful(1, 1));
+      }
+      {
+        Slice ub("qqqq9");
+        read_options.iterate_upper_bound = &ub;
+        std::unique_ptr<Iterator> iter(db_->NewIterator(read_options));
+        EXPECT_EQ(CountIter(iter, "qqqq0"), 1);
+        EXPECT_EQ(GetBloomStat(options, flushed), CheckedAndUseful(1, 0));
+      }
+      {
+        // Note: prefix as seek key is not bloom-optimized
+        Slice ub("qqqq9");
+        read_options.iterate_upper_bound = &ub;
+        std::unique_ptr<Iterator> iter(db_->NewIterator(read_options));
+        EXPECT_EQ(CountIter(iter, "qqqq"), weird_comparator ? 7 : 2);
+        EXPECT_EQ(GetBloomStat(options, flushed), CheckedAndUseful(0, 0));
+      }
+      {
+        // Note: prefix as seek key is not bloom-optimized
+        Slice ub("zzzz9");
+        read_options.iterate_upper_bound = &ub;
+        std::unique_ptr<Iterator> iter(db_->NewIterator(read_options));
+        EXPECT_EQ(CountIter(iter, "zzzz"), weird_comparator ? 8 : 1);
+        EXPECT_EQ(GetBloomStat(options, flushed), CheckedAndUseful(0, 0));
+      }
+      {
+        Slice ub("zzzz9");
+        read_options.iterate_upper_bound = &ub;
+        std::unique_ptr<Iterator> iter(db_->NewIterator(read_options));
+        EXPECT_EQ(CountIter(iter, "aab"), weird_comparator ? 6 : 5);
+        EXPECT_EQ(GetBloomStat(options, flushed), CheckedAndUseful(0, 0));
+      }
+    }
+  }
+}
+
 #endif  // ROCKSDB_LITE
 
 }  // namespace ROCKSDB_NAMESPACE

db/db_compaction_test.cc

@@ -30,10 +30,89 @@ namespace ROCKSDB_NAMESPACE {
 // SYNC_POINT is not supported in released Windows mode.
 #if !defined(ROCKSDB_LITE)
 
+class CompactionStatsCollector : public EventListener {
+ public:
+  CompactionStatsCollector()
+      : compaction_completed_(
+            static_cast<int>(CompactionReason::kNumOfReasons)) {
+    for (auto& v : compaction_completed_) {
+      v.store(0);
+    }
+  }
+
+  ~CompactionStatsCollector() override {}
+
+  void OnCompactionCompleted(DB* /* db */,
+                             const CompactionJobInfo& info) override {
+    int k = static_cast<int>(info.compaction_reason);
+    int num_of_reasons = static_cast<int>(CompactionReason::kNumOfReasons);
+    assert(k >= 0 && k < num_of_reasons);
+    compaction_completed_[k]++;
+  }
+
+  void OnExternalFileIngested(
+      DB* /* db */, const ExternalFileIngestionInfo& /* info */) override {
+    int k = static_cast<int>(CompactionReason::kExternalSstIngestion);
+    compaction_completed_[k]++;
+  }
+
+  void OnFlushCompleted(DB* /* db */, const FlushJobInfo& /* info */) override {
+    int k = static_cast<int>(CompactionReason::kFlush);
+    compaction_completed_[k]++;
+  }
+
+  int NumberOfCompactions(CompactionReason reason) const {
+    int num_of_reasons = static_cast<int>(CompactionReason::kNumOfReasons);
+    int k = static_cast<int>(reason);
+    assert(k >= 0 && k < num_of_reasons);
+    return compaction_completed_.at(k).load();
+  }
+
+ private:
+  std::vector<std::atomic<int>> compaction_completed_;
+};
+
 class DBCompactionTest : public DBTestBase {
  public:
   DBCompactionTest()
       : DBTestBase("db_compaction_test", /*env_do_fsync=*/true) {}
+
+ protected:
+  /*
+   * Verifies compaction stats of cfd are valid.
+   *
+   * For each level of cfd, its compaction stats are valid if
+   * 1) sum(stat.counts) == stat.count, and
+   * 2) stat.counts[i] == collector.NumberOfCompactions(i)
+   */
+  void VerifyCompactionStats(ColumnFamilyData& cfd,
+                             const CompactionStatsCollector& collector) {
+#ifndef NDEBUG
+    InternalStats* internal_stats_ptr = cfd.internal_stats();
+    ASSERT_NE(internal_stats_ptr, nullptr);
+    const std::vector<InternalStats::CompactionStats>& comp_stats =
+        internal_stats_ptr->TEST_GetCompactionStats();
+    const int num_of_reasons =
+        static_cast<int>(CompactionReason::kNumOfReasons);
+    std::vector<int> counts(num_of_reasons, 0);
+    // Count the number of compactions caused by each CompactionReason across
+    // all levels.
+    for (const auto& stat : comp_stats) {
+      int sum = 0;
+      for (int i = 0; i < num_of_reasons; i++) {
+        counts[i] += stat.counts[i];
+        sum += stat.counts[i];
+      }
+      ASSERT_EQ(sum, stat.count);
+    }
+    // Verify InternalStats bookkeeping matches that of
+    // CompactionStatsCollector, assuming that all compactions complete.
+    for (int i = 0; i < num_of_reasons; i++) {
+      ASSERT_EQ(collector.NumberOfCompactions(static_cast<CompactionReason>(i)),
+                counts[i]);
+    }
+#endif /* NDEBUG */
+  }
 };
 
 class DBCompactionTestWithParam
@@ -82,8 +161,32 @@ class ChangeLevelConflictsWithAuto
   ChangeLevelConflictsWithAuto() : DBCompactionTest() {}
 };
 
-namespace {
+// Param = true: grab the compaction pressure token (enable
+// parallel compactions)
+// Param = false: Not grab the token (no parallel compactions)
+class RoundRobinSubcompactionsAgainstPressureToken
+    : public DBCompactionTest,
+      public ::testing::WithParamInterface<bool> {
+ public:
+  RoundRobinSubcompactionsAgainstPressureToken() {
+    grab_pressure_token_ = GetParam();
+  }
+  bool grab_pressure_token_;
+};
 
+class RoundRobinSubcompactionsAgainstResources
+    : public DBCompactionTest,
+      public ::testing::WithParamInterface<std::tuple<int, int>> {
+ public:
+  RoundRobinSubcompactionsAgainstResources() {
+    total_low_pri_threads_ = std::get<0>(GetParam());
+    max_compaction_limits_ = std::get<1>(GetParam());
+  }
+  int total_low_pri_threads_;
+  int max_compaction_limits_;
+};
+
+namespace {
 class FlushedFileCollector : public EventListener {
  public:
   FlushedFileCollector() {}
@@ -110,47 +213,6 @@ class FlushedFileCollector : public EventListener {
   std::mutex mutex_;
 };
 
-class CompactionStatsCollector : public EventListener {
-public:
-  CompactionStatsCollector()
-      : compaction_completed_(static_cast<int>(CompactionReason::kNumOfReasons)) {
-    for (auto& v : compaction_completed_) {
-      v.store(0);
-    }
-  }
-
-  ~CompactionStatsCollector() override {}
-
-  void OnCompactionCompleted(DB* /* db */,
-                             const CompactionJobInfo& info) override {
-    int k = static_cast<int>(info.compaction_reason);
-    int num_of_reasons = static_cast<int>(CompactionReason::kNumOfReasons);
-    assert(k >= 0 && k < num_of_reasons);
-    compaction_completed_[k]++;
-  }
-
-  void OnExternalFileIngested(
-      DB* /* db */, const ExternalFileIngestionInfo& /* info */) override {
-    int k = static_cast<int>(CompactionReason::kExternalSstIngestion);
-    compaction_completed_[k]++;
-  }
-
-  void OnFlushCompleted(DB* /* db */, const FlushJobInfo& /* info */) override {
-    int k = static_cast<int>(CompactionReason::kFlush);
-    compaction_completed_[k]++;
-  }
-
-  int NumberOfCompactions(CompactionReason reason) const {
-    int num_of_reasons = static_cast<int>(CompactionReason::kNumOfReasons);
-    int k = static_cast<int>(reason);
-    assert(k >= 0 && k < num_of_reasons);
-    return compaction_completed_.at(k).load();
-  }
-
-private:
-  std::vector<std::atomic<int>> compaction_completed_;
-};
-
 class SstStatsCollector : public EventListener {
  public:
   SstStatsCollector() : num_ssts_creation_started_(0) {}
@@ -247,40 +309,6 @@ void VerifyCompactionResult(
 #endif
 }
 
-/*
- * Verifies compaction stats of cfd are valid.
- *
- * For each level of cfd, its compaction stats are valid if
- * 1) sum(stat.counts) == stat.count, and
- * 2) stat.counts[i] == collector.NumberOfCompactions(i)
- */
-void VerifyCompactionStats(ColumnFamilyData& cfd,
-    const CompactionStatsCollector& collector) {
-#ifndef NDEBUG
-  InternalStats* internal_stats_ptr = cfd.internal_stats();
-  ASSERT_NE(internal_stats_ptr, nullptr);
-  const std::vector<InternalStats::CompactionStats>& comp_stats =
-      internal_stats_ptr->TEST_GetCompactionStats();
-  const int num_of_reasons = static_cast<int>(CompactionReason::kNumOfReasons);
-  std::vector<int> counts(num_of_reasons, 0);
-  // Count the number of compactions caused by each CompactionReason across
-  // all levels.
-  for (const auto& stat : comp_stats) {
-    int sum = 0;
-    for (int i = 0; i < num_of_reasons; i++) {
-      counts[i] += stat.counts[i];
-      sum += stat.counts[i];
-    }
-    ASSERT_EQ(sum, stat.count);
-  }
-  // Verify InternalStats bookkeeping matches that of CompactionStatsCollector,
-  // assuming that all compactions complete.
-  for (int i = 0; i < num_of_reasons; i++) {
-    ASSERT_EQ(collector.NumberOfCompactions(static_cast<CompactionReason>(i)), counts[i]);
-  }
-#endif /* NDEBUG */
-}
-
 const SstFileMetaData* PickFileRandomly(
     const ColumnFamilyMetaData& cf_meta,
     Random* rand,
@@ -1093,16 +1121,20 @@ TEST_F(DBCompactionTest, ManualCompactionUnknownOutputSize) {
   // create two files in l1 that we can compact
   for (int i = 0; i < 2; ++i) {
     for (int j = 0; j < options.level0_file_num_compaction_trigger; j++) {
-      // make l0 files' ranges overlap to avoid trivial move
       ASSERT_OK(Put(std::to_string(2 * i), std::string(1, 'A')));
       ASSERT_OK(Put(std::to_string(2 * i + 1), std::string(1, 'A')));
       ASSERT_OK(Flush());
       ASSERT_OK(dbfull()->TEST_WaitForFlushMemTable());
     }
     ASSERT_OK(dbfull()->TEST_WaitForCompact());
-    ASSERT_EQ(NumTableFilesAtLevel(0, 0), 0);
-    ASSERT_EQ(NumTableFilesAtLevel(1, 0), i + 1);
   }
+  ASSERT_OK(
+      dbfull()->SetOptions({{"level0_file_num_compaction_trigger", "2"}}));
+  ASSERT_OK(dbfull()->TEST_WaitForCompact());
+  ASSERT_EQ(NumTableFilesAtLevel(0, 0), 0);
+  ASSERT_EQ(NumTableFilesAtLevel(1, 0), 2);
+  ASSERT_OK(
+      dbfull()->SetOptions({{"level0_file_num_compaction_trigger", "3"}}));
 
   ColumnFamilyMetaData cf_meta;
   dbfull()->GetColumnFamilyMetaData(dbfull()->DefaultColumnFamily(), &cf_meta);
@@ -2628,8 +2660,9 @@ TEST_F(DBCompactionTest, ManualAutoRace) {
   TEST_SYNC_POINT("DBCompactionTest::ManualAutoRace:1");
   // The auto compaction will wait until the manual compaction is registerd
   // before processing so that it will be cancelled.
-  ASSERT_OK(dbfull()->CompactRange(CompactRangeOptions(), handles_[1], nullptr,
-                                   nullptr));
+  CompactRangeOptions cro;
+  cro.exclusive_manual_compaction = true;
+  ASSERT_OK(dbfull()->CompactRange(cro, handles_[1], nullptr, nullptr));
   ASSERT_EQ("0,1", FilesPerLevel(1));
 
   // Eventually the cancelled compaction will be rescheduled and executed.
@@ -4366,7 +4399,13 @@ TEST_F(DBCompactionTest, LevelTtlBooster) {
     ASSERT_OK(Flush());
     ASSERT_OK(dbfull()->TEST_WaitForCompact());
   }
+  // Force files to be compacted to L1
+  ASSERT_OK(
+      dbfull()->SetOptions({{"level0_file_num_compaction_trigger", "1"}}));
+  ASSERT_OK(dbfull()->TEST_WaitForCompact());
   ASSERT_EQ("0,1,2", FilesPerLevel());
+  ASSERT_OK(
+      dbfull()->SetOptions({{"level0_file_num_compaction_trigger", "2"}}));
 
   ASSERT_GT(SizeAtLevel(1), kNumKeysPerFile * 4 * kValueSize);
 }
@@ -5219,7 +5258,384 @@ INSTANTIATE_TEST_CASE_P(
     ::testing::Values(CompactionPri::kByCompensatedSize,
                       CompactionPri::kOldestLargestSeqFirst,
                       CompactionPri::kOldestSmallestSeqFirst,
-                      CompactionPri::kMinOverlappingRatio));
+                      CompactionPri::kMinOverlappingRatio,
+                      CompactionPri::kRoundRobin));
+
+TEST_F(DBCompactionTest, PersistRoundRobinCompactCursor) {
+  Options options = CurrentOptions();
+  options.write_buffer_size = 16 * 1024;
+  options.max_bytes_for_level_base = 128 * 1024;
+  options.target_file_size_base = 64 * 1024;
+  options.level0_file_num_compaction_trigger = 4;
+  options.compaction_pri = CompactionPri::kRoundRobin;
+  options.max_bytes_for_level_multiplier = 4;
+  options.num_levels = 3;
+  options.compression = kNoCompression;
+
+  DestroyAndReopen(options);
+
+  Random rnd(301);
+
+  // 30 Files in L0 to trigger compactions between L1 and L2
+  for (int i = 0; i < 30; i++) {
+    for (int j = 0; j < 16; j++) {
+      ASSERT_OK(Put(rnd.RandomString(24), rnd.RandomString(1000)));
+    }
+    ASSERT_OK(Flush());
+  }
+
+  ASSERT_OK(dbfull()->TEST_WaitForCompact());
+
+  VersionSet* const versions = dbfull()->GetVersionSet();
+  assert(versions);
+
+  ColumnFamilyData* const cfd = versions->GetColumnFamilySet()->GetDefault();
+  ASSERT_NE(cfd, nullptr);
+
+  Version* const current = cfd->current();
+  ASSERT_NE(current, nullptr);
+
+  const VersionStorageInfo* const storage_info = current->storage_info();
+  ASSERT_NE(storage_info, nullptr);
+
+  const std::vector<InternalKey> compact_cursors =
+      storage_info->GetCompactCursors();
+
+  Reopen(options);
+
+  VersionSet* const reopened_versions = dbfull()->GetVersionSet();
+  assert(reopened_versions);
+
+  ColumnFamilyData* const reopened_cfd =
+      reopened_versions->GetColumnFamilySet()->GetDefault();
+  ASSERT_NE(reopened_cfd, nullptr);
+
+  Version* const reopened_current = reopened_cfd->current();
+  ASSERT_NE(reopened_current, nullptr);
+
+  const VersionStorageInfo* const reopened_storage_info =
+      reopened_current->storage_info();
+  ASSERT_NE(reopened_storage_info, nullptr);
+
+  const std::vector<InternalKey> reopened_compact_cursors =
+      reopened_storage_info->GetCompactCursors();
+  const auto icmp = reopened_storage_info->InternalComparator();
+  ASSERT_EQ(compact_cursors.size(), reopened_compact_cursors.size());
+  for (size_t i = 0; i < compact_cursors.size(); i++) {
+    if (compact_cursors[i].Valid()) {
+      ASSERT_EQ(0,
+                icmp->Compare(compact_cursors[i], reopened_compact_cursors[i]));
+    } else {
+      ASSERT_TRUE(!reopened_compact_cursors[i].Valid());
+    }
+  }
+}
+
+TEST_P(RoundRobinSubcompactionsAgainstPressureToken, PressureTokenTest) {
+  const int kKeysPerBuffer = 100;
+  Options options = CurrentOptions();
+  options.num_levels = 4;
+  options.max_bytes_for_level_multiplier = 2;
+  options.level0_file_num_compaction_trigger = 4;
+  options.target_file_size_base = kKeysPerBuffer * 1024;
+  options.compaction_pri = CompactionPri::kRoundRobin;
+  options.max_bytes_for_level_base = 8 * kKeysPerBuffer * 1024;
+  options.disable_auto_compactions = true;
+  // Setup 7 threads but limited subcompactions so that
+  // RoundRobin requires extra compactions from reserved threads
+  options.max_subcompactions = 1;
+  options.max_background_compactions = 7;
+  options.max_compaction_bytes = 100000000;
+  DestroyAndReopen(options);
+  env_->SetBackgroundThreads(7, Env::LOW);
+
+  Random rnd(301);
+  const std::vector<int> files_per_level = {0, 15, 25};
+  for (int lvl = 2; lvl > 0; lvl--) {
+    for (int i = 0; i < files_per_level[lvl]; i++) {
+      for (int j = 0; j < kKeysPerBuffer; j++) {
+        // Add (lvl-1) to ensure nearly equivallent number of files
+        // in L2 are overlapped with fils selected to compact from
+        // L1
+        ASSERT_OK(Put(Key(2 * i * kKeysPerBuffer + 2 * j + (lvl - 1)),
+                      rnd.RandomString(1010)));
+      }
+      ASSERT_OK(Flush());
+    }
+    MoveFilesToLevel(lvl);
+    ASSERT_EQ(files_per_level[lvl], NumTableFilesAtLevel(lvl, 0));
+  }
+  // 15 files in L1; 25 files in L2
+
+  // This is a variable for making sure the following callback is called
+  // and the assertions in it are indeed excuted.
+  bool num_planned_subcompactions_verified = false;
+  ROCKSDB_NAMESPACE::SyncPoint::GetInstance()->SetCallBack(
+      "CompactionJob::GenSubcompactionBoundaries:0", [&](void* arg) {
+        uint64_t num_planned_subcompactions = *(static_cast<uint64_t*>(arg));
+        if (grab_pressure_token_) {
+          // 7 files are selected for round-robin under auto
+          // compaction. The number of planned subcompaction is restricted by
+          // the limited number of max_background_compactions
+          ASSERT_EQ(num_planned_subcompactions, 7);
+        } else {
+          ASSERT_EQ(num_planned_subcompactions, 1);
+        }
+        num_planned_subcompactions_verified = true;
+      });
+
+  // The following 3 dependencies have to be added to ensure the auto
+  // compaction and the pressure token is correctly enabled. Same for
+  // RoundRobinSubcompactionsUsingResources and
+  // DBCompactionTest.RoundRobinSubcompactionsShrinkResources
+  SyncPoint::GetInstance()->LoadDependency(
+      {{"RoundRobinSubcompactionsAgainstPressureToken:0",
+        "BackgroundCallCompaction:0"},
+       {"CompactionJob::AcquireSubcompactionResources:0",
+        "RoundRobinSubcompactionsAgainstPressureToken:1"},
+       {"RoundRobinSubcompactionsAgainstPressureToken:2",
+        "CompactionJob::AcquireSubcompactionResources:1"}});
+  SyncPoint::GetInstance()->EnableProcessing();
+
+  ASSERT_OK(dbfull()->EnableAutoCompaction({dbfull()->DefaultColumnFamily()}));
+  TEST_SYNC_POINT("RoundRobinSubcompactionsAgainstPressureToken:0");
+  TEST_SYNC_POINT("RoundRobinSubcompactionsAgainstPressureToken:1");
+  std::unique_ptr<WriteControllerToken> pressure_token;
+  if (grab_pressure_token_) {
+    pressure_token =
+        dbfull()->TEST_write_controler().GetCompactionPressureToken();
+  }
+  TEST_SYNC_POINT("RoundRobinSubcompactionsAgainstPressureToken:2");
+
+  ASSERT_OK(dbfull()->WaitForCompact());
+  ASSERT_TRUE(num_planned_subcompactions_verified);
+  SyncPoint::GetInstance()->DisableProcessing();
+  SyncPoint::GetInstance()->ClearAllCallBacks();
+}
+
+INSTANTIATE_TEST_CASE_P(RoundRobinSubcompactionsAgainstPressureToken,
+                        RoundRobinSubcompactionsAgainstPressureToken,
+                        testing::Bool());
+
+TEST_P(RoundRobinSubcompactionsAgainstResources, SubcompactionsUsingResources) {
+  const int kKeysPerBuffer = 200;
+  Options options = CurrentOptions();
+  options.num_levels = 4;
+  options.level0_file_num_compaction_trigger = 3;
+  options.target_file_size_base = kKeysPerBuffer * 1024;
+  options.compaction_pri = CompactionPri::kRoundRobin;
+  options.max_bytes_for_level_base = 30 * kKeysPerBuffer * 1024;
+  options.disable_auto_compactions = true;
+  options.max_subcompactions = 1;
+  options.max_background_compactions = max_compaction_limits_;
+  // Set a large number for max_compaction_bytes so that one round-robin
+  // compaction is enough to make post-compaction L1 size less than
+  // the maximum size (this test assumes only one round-robin compaction
+  // is triggered by kLevelMaxLevelSize)
+  options.max_compaction_bytes = 100000000;
+
+  DestroyAndReopen(options);
+  env_->SetBackgroundThreads(total_low_pri_threads_, Env::LOW);
+
+  Random rnd(301);
+  const std::vector<int> files_per_level = {0, 40, 100};
+  for (int lvl = 2; lvl > 0; lvl--) {
+    for (int i = 0; i < files_per_level[lvl]; i++) {
+      for (int j = 0; j < kKeysPerBuffer; j++) {
+        // Add (lvl-1) to ensure nearly equivallent number of files
+        // in L2 are overlapped with fils selected to compact from
+        // L1
+        ASSERT_OK(Put(Key(2 * i * kKeysPerBuffer + 2 * j + (lvl - 1)),
+                      rnd.RandomString(1010)));
+      }
+      ASSERT_OK(Flush());
+    }
+    MoveFilesToLevel(lvl);
+    ASSERT_OK(dbfull()->TEST_WaitForCompact());
+    ASSERT_EQ(files_per_level[lvl], NumTableFilesAtLevel(lvl, 0));
+  }
+
+  // 40 files in L1; 100 files in L2
+  // This is a variable for making sure the following callback is called
+  // and the assertions in it are indeed excuted.
+  bool num_planned_subcompactions_verified = false;
+  ROCKSDB_NAMESPACE::SyncPoint::GetInstance()->SetCallBack(
+      "CompactionJob::GenSubcompactionBoundaries:0", [&](void* arg) {
+        uint64_t num_planned_subcompactions = *(static_cast<uint64_t*>(arg));
+        // More than 10 files are selected for round-robin under auto
+        // compaction. The number of planned subcompaction is restricted by
+        // the minimum number between available threads and compaction limits
+        ASSERT_EQ(num_planned_subcompactions - options.max_subcompactions,
+                  std::min(total_low_pri_threads_, max_compaction_limits_) - 1);
+        num_planned_subcompactions_verified = true;
+      });
+  SyncPoint::GetInstance()->LoadDependency(
+      {{"RoundRobinSubcompactionsAgainstResources:0",
+        "BackgroundCallCompaction:0"},
+       {"CompactionJob::AcquireSubcompactionResources:0",
+        "RoundRobinSubcompactionsAgainstResources:1"},
+       {"RoundRobinSubcompactionsAgainstResources:2",
+        "CompactionJob::AcquireSubcompactionResources:1"},
+       {"CompactionJob::ReleaseSubcompactionResources:0",
+        "RoundRobinSubcompactionsAgainstResources:3"},
+       {"RoundRobinSubcompactionsAgainstResources:4",
+        "CompactionJob::ReleaseSubcompactionResources:1"}});
+  SyncPoint::GetInstance()->EnableProcessing();
+
+  ASSERT_OK(dbfull()->WaitForCompact());
+  ASSERT_OK(dbfull()->EnableAutoCompaction({dbfull()->DefaultColumnFamily()}));
+  TEST_SYNC_POINT("RoundRobinSubcompactionsAgainstResources:0");
+  TEST_SYNC_POINT("RoundRobinSubcompactionsAgainstResources:1");
+  auto pressure_token =
+      dbfull()->TEST_write_controler().GetCompactionPressureToken();
+
+  TEST_SYNC_POINT("RoundRobinSubcompactionsAgainstResources:2");
+  TEST_SYNC_POINT("RoundRobinSubcompactionsAgainstResources:3");
+  // We can reserve more threads now except one is being used
+  ASSERT_EQ(total_low_pri_threads_ - 1,
+            env_->ReserveThreads(total_low_pri_threads_, Env::Priority::LOW));
+  ASSERT_EQ(
+      total_low_pri_threads_ - 1,
+      env_->ReleaseThreads(total_low_pri_threads_ - 1, Env::Priority::LOW));
+  TEST_SYNC_POINT("RoundRobinSubcompactionsAgainstResources:4");
+  ASSERT_OK(dbfull()->WaitForCompact());
+  ASSERT_TRUE(num_planned_subcompactions_verified);
+  SyncPoint::GetInstance()->DisableProcessing();
+  SyncPoint::GetInstance()->ClearAllCallBacks();
+}
+
+INSTANTIATE_TEST_CASE_P(RoundRobinSubcompactionsAgainstResources,
+                        RoundRobinSubcompactionsAgainstResources,
+                        ::testing::Values(std::make_tuple(1, 5),
+                                          std::make_tuple(5, 1),
+                                          std::make_tuple(10, 5),
+                                          std::make_tuple(5, 10),
+                                          std::make_tuple(10, 10)));
+
+TEST_P(DBCompactionTestWithParam, RoundRobinWithoutAdditionalResources) {
+  const int kKeysPerBuffer = 200;
+  Options options = CurrentOptions();
+  options.num_levels = 4;
+  options.level0_file_num_compaction_trigger = 3;
+  options.target_file_size_base = kKeysPerBuffer * 1024;
+  options.compaction_pri = CompactionPri::kRoundRobin;
+  options.max_bytes_for_level_base = 30 * kKeysPerBuffer * 1024;
+  options.disable_auto_compactions = true;
+  options.max_subcompactions = max_subcompactions_;
+  options.max_background_compactions = 1;
+  options.max_compaction_bytes = 100000000;
+  // Similar experiment setting as above except the max_subcompactions
+  // is given by max_subcompactions_ (1 or 4), and we fix the
+  // additional resources as (1, 1) and thus no more extra resources
+  // can be used
+  DestroyAndReopen(options);
+  env_->SetBackgroundThreads(1, Env::LOW);
+
+  Random rnd(301);
+  const std::vector<int> files_per_level = {0, 33, 100};
+  for (int lvl = 2; lvl > 0; lvl--) {
+    for (int i = 0; i < files_per_level[lvl]; i++) {
+      for (int j = 0; j < kKeysPerBuffer; j++) {
+        // Add (lvl-1) to ensure nearly equivallent number of files
+        // in L2 are overlapped with fils selected to compact from
+        // L1
+        ASSERT_OK(Put(Key(2 * i * kKeysPerBuffer + 2 * j + (lvl - 1)),
+                      rnd.RandomString(1010)));
+      }
+      ASSERT_OK(Flush());
+    }
+    MoveFilesToLevel(lvl);
+    ASSERT_OK(dbfull()->TEST_WaitForCompact());
+    ASSERT_EQ(files_per_level[lvl], NumTableFilesAtLevel(lvl, 0));
+  }
+
+  // 33 files in L1; 100 files in L2
+  // This is a variable for making sure the following callback is called
+  // and the assertions in it are indeed excuted.
+  bool num_planned_subcompactions_verified = false;
+  ROCKSDB_NAMESPACE::SyncPoint::GetInstance()->SetCallBack(
+      "CompactionJob::GenSubcompactionBoundaries:0", [&](void* arg) {
+        uint64_t num_planned_subcompactions = *(static_cast<uint64_t*>(arg));
+        // At most 4 files are selected for round-robin under auto
+        // compaction. The number of planned subcompaction is restricted by
+        // the max_subcompactions since no extra resources can be used
+        ASSERT_EQ(num_planned_subcompactions, options.max_subcompactions);
+        num_planned_subcompactions_verified = true;
+      });
+  // No need to setup dependency for pressure token since
+  // AcquireSubcompactionResources may not be called and it anyway cannot
+  // reserve any additional resources
+  SyncPoint::GetInstance()->LoadDependency(
+      {{"DBCompactionTest::RoundRobinWithoutAdditionalResources:0",
+        "BackgroundCallCompaction:0"}});
+  SyncPoint::GetInstance()->EnableProcessing();
+
+  ASSERT_OK(dbfull()->WaitForCompact());
+  ASSERT_OK(dbfull()->EnableAutoCompaction({dbfull()->DefaultColumnFamily()}));
+  TEST_SYNC_POINT("DBCompactionTest::RoundRobinWithoutAdditionalResources:0");
+
+  ASSERT_OK(dbfull()->WaitForCompact());
+  ASSERT_TRUE(num_planned_subcompactions_verified);
+  SyncPoint::GetInstance()->DisableProcessing();
+  SyncPoint::GetInstance()->ClearAllCallBacks();
+}
+
+TEST_F(DBCompactionTest, RoundRobinCutOutputAtCompactCursor) {
+  Options options = CurrentOptions();
+  options.num_levels = 3;
+  options.compression = kNoCompression;
+  options.write_buffer_size = 4 * 1024;
+  options.max_bytes_for_level_base = 64 * 1024;
+  options.max_bytes_for_level_multiplier = 4;
+  options.level0_file_num_compaction_trigger = 4;
+  options.compaction_pri = CompactionPri::kRoundRobin;
+
+  DestroyAndReopen(options);
+
+  VersionSet* const versions = dbfull()->GetVersionSet();
+  assert(versions);
+
+  ColumnFamilyData* const cfd = versions->GetColumnFamilySet()->GetDefault();
+  ASSERT_NE(cfd, nullptr);
+
+  Version* const current = cfd->current();
+  ASSERT_NE(current, nullptr);
+
+  VersionStorageInfo* storage_info = current->storage_info();
+  ASSERT_NE(storage_info, nullptr);
+
+  const InternalKey split_cursor = InternalKey(Key(600), 100, kTypeValue);
+  storage_info->AddCursorForOneLevel(2, split_cursor);
+
+  Random rnd(301);
+
+  for (int i = 0; i < 50; i++) {
+    for (int j = 0; j < 50; j++) {
+      ASSERT_OK(Put(Key(j * 2 + i * 100), rnd.RandomString(102)));
+    }
+  }
+  // Add more overlapping files (avoid trivial move) to trigger compaction that
+  // output files in L2. Note that trivial move does not trigger compaction and
+  // in that case the cursor is not necessarily the boundary of file.
+  for (int i = 0; i < 50; i++) {
+    for (int j = 0; j < 50; j++) {
+      ASSERT_OK(Put(Key(j * 2 + 1 + i * 100), rnd.RandomString(1014)));
+    }
+  }
+
+  ASSERT_OK(dbfull()->TEST_WaitForCompact());
+
+  std::vector<std::vector<FileMetaData>> level_to_files;
+  dbfull()->TEST_GetFilesMetaData(dbfull()->DefaultColumnFamily(),
+                                  &level_to_files);
+  const auto icmp = cfd->current()->storage_info()->InternalComparator();
+  // Files in level 2 should be split by the cursor
+  for (const auto& file : level_to_files[2]) {
+    ASSERT_TRUE(
+        icmp->Compare(file.smallest.Encode(), split_cursor.Encode()) >= 0 ||
+        icmp->Compare(file.largest.Encode(), split_cursor.Encode()) < 0);
+  }
+}
 
 class NoopMergeOperator : public MergeOperator {
  public:
@@ -5517,18 +5933,10 @@ TEST_P(DBCompactionTestWithParam, FixFileIngestionCompactionDeadlock) {
     for (int j = 0; j != kNumKeysPerFile; ++j) {
       ASSERT_OK(Put(Key(j), rnd.RandomString(990)));
     }
-    if (0 == i) {
-      // When we reach here, the memtables have kNumKeysPerFile keys. Note that
-      // flush is not yet triggered. We need to write an extra key so that the
-      // write path will call PreprocessWrite and flush the previous key-value
-      // pairs to e flushed. After that, there will be the newest key in the
-      // memtable, and a bunch of L0 files. Since there is already one key in
-      // the memtable, then for i = 1, 2, ..., we do not have to write this
-      // extra key to trigger flush.
-      ASSERT_OK(Put("", ""));
+    if (i > 0) {
+      ASSERT_OK(dbfull()->TEST_WaitForFlushMemTable());
+      ASSERT_EQ(NumTableFilesAtLevel(0 /*level*/, 0 /*cf*/), i);
     }
-    ASSERT_OK(dbfull()->TEST_WaitForFlushMemTable());
-    ASSERT_EQ(NumTableFilesAtLevel(0 /*level*/, 0 /*cf*/), i + 1);
   }
   // When we reach this point, there will be level0_stop_writes_trigger L0
   // files and one extra key (99) in memory, which overlaps with the external

db/db_flush_test.cc

@@ -777,13 +777,25 @@ TEST_F(DBFlushTest, MemPurgeBasic) {
 
   // Enforce size of a single MemTable to 64MB (64MB = 67108864 bytes).
   options.write_buffer_size = 1 << 20;
-  // Activate the MemPurge prototype.
-  options.experimental_mempurge_threshold = 1.0;
 #ifndef ROCKSDB_LITE
+  // Initially deactivate the MemPurge prototype.
+  options.experimental_mempurge_threshold = 0.0;
   TestFlushListener* listener = new TestFlushListener(options.env, this);
   options.listeners.emplace_back(listener);
+#else
+  // Activate directly the MemPurge prototype.
+  // (RocksDB lite does not support dynamic options)
+  options.experimental_mempurge_threshold = 1.0;
 #endif  // !ROCKSDB_LITE
   ASSERT_OK(TryReopen(options));
+
+  // RocksDB lite does not support dynamic options
+#ifndef ROCKSDB_LITE
+  // Dynamically activate the MemPurge prototype without restarting the DB.
+  ColumnFamilyHandle* cfh = db_->DefaultColumnFamily();
+  ASSERT_OK(db_->SetOptions(cfh, {{"experimental_mempurge_threshold", "1.0"}}));
+#endif
+
   std::atomic<uint32_t> mempurge_count{0};
   std::atomic<uint32_t> sst_count{0};
   ROCKSDB_NAMESPACE::SyncPoint::GetInstance()->SetCallBack(
@@ -914,6 +926,234 @@ TEST_F(DBFlushTest, MemPurgeBasic) {
   Close();
 }
 
+// RocksDB lite does not support dynamic options
+#ifndef ROCKSDB_LITE
+TEST_F(DBFlushTest, MemPurgeBasicToggle) {
+  Options options = CurrentOptions();
+
+  // The following options are used to enforce several values that
+  // may already exist as default values to make this test resilient
+  // to default value updates in the future.
+  options.statistics = CreateDBStatistics();
+
+  // Record all statistics.
+  options.statistics->set_stats_level(StatsLevel::kAll);
+
+  // create the DB if it's not already present
+  options.create_if_missing = true;
+
+  // Useful for now as we are trying to compare uncompressed data savings on
+  // flush().
+  options.compression = kNoCompression;
+
+  // Prevent memtable in place updates. Should already be disabled
+  // (from Wiki:
+  //  In place updates can be enabled by toggling on the bool
+  //  inplace_update_support flag. However, this flag is by default set to
+  //  false
+  //  because this thread-safe in-place update support is not compatible
+  //  with concurrent memtable writes. Note that the bool
+  //  allow_concurrent_memtable_write is set to true by default )
+  options.inplace_update_support = false;
+  options.allow_concurrent_memtable_write = true;
+
+  // Enforce size of a single MemTable to 64MB (64MB = 67108864 bytes).
+  options.write_buffer_size = 1 << 20;
+  // Initially deactivate the MemPurge prototype.
+  // (negative values are equivalent to 0.0).
+  options.experimental_mempurge_threshold = -25.3;
+  TestFlushListener* listener = new TestFlushListener(options.env, this);
+  options.listeners.emplace_back(listener);
+
+  ASSERT_OK(TryReopen(options));
+  // Dynamically activate the MemPurge prototype without restarting the DB.
+  ColumnFamilyHandle* cfh = db_->DefaultColumnFamily();
+  // Values greater than 1.0 are equivalent to 1.0
+  ASSERT_OK(
+      db_->SetOptions(cfh, {{"experimental_mempurge_threshold", "3.7898"}}));
+  std::atomic<uint32_t> mempurge_count{0};
+  std::atomic<uint32_t> sst_count{0};
+  ROCKSDB_NAMESPACE::SyncPoint::GetInstance()->SetCallBack(
+      "DBImpl::FlushJob:MemPurgeSuccessful",
+      [&](void* /*arg*/) { mempurge_count++; });
+  ROCKSDB_NAMESPACE::SyncPoint::GetInstance()->SetCallBack(
+      "DBImpl::FlushJob:SSTFileCreated", [&](void* /*arg*/) { sst_count++; });
+  ROCKSDB_NAMESPACE::SyncPoint::GetInstance()->EnableProcessing();
+  const size_t KVSIZE = 3;
+  std::vector<std::string> KEYS(KVSIZE);
+  for (size_t k = 0; k < KVSIZE; k++) {
+    KEYS[k] = "IamKey" + std::to_string(k);
+  }
+
+  std::vector<std::string> RNDVALS(KVSIZE);
+  const std::string NOT_FOUND = "NOT_FOUND";
+
+  // Heavy overwrite workload,
+  // more than would fit in maximum allowed memtables.
+  Random rnd(719);
+  const size_t NUM_REPEAT = 100;
+  const size_t RAND_VALUES_LENGTH = 10240;
+
+  // Insertion of of K-V pairs, multiple times (overwrites).
+  for (size_t i = 0; i < NUM_REPEAT; i++) {
+    for (size_t j = 0; j < KEYS.size(); j++) {
+      RNDVALS[j] = rnd.RandomString(RAND_VALUES_LENGTH);
+      ASSERT_OK(Put(KEYS[j], RNDVALS[j]));
+      ASSERT_EQ(Get(KEYS[j]), RNDVALS[j]);
+    }
+    for (size_t j = 0; j < KEYS.size(); j++) {
+      ASSERT_EQ(Get(KEYS[j]), RNDVALS[j]);
+    }
+  }
+
+  // Check that there was at least one mempurge
+  const uint32_t EXPECTED_MIN_MEMPURGE_COUNT = 1;
+  // Check that there was no SST files created during flush.
+  const uint32_t EXPECTED_SST_COUNT = 0;
+
+  EXPECT_GE(mempurge_count.exchange(0), EXPECTED_MIN_MEMPURGE_COUNT);
+  EXPECT_EQ(sst_count.exchange(0), EXPECTED_SST_COUNT);
+
+  // Dynamically deactivate MemPurge.
+  ASSERT_OK(
+      db_->SetOptions(cfh, {{"experimental_mempurge_threshold", "-1023.0"}}));
+
+  // Insertion of of K-V pairs, multiple times (overwrites).
+  for (size_t i = 0; i < NUM_REPEAT; i++) {
+    for (size_t j = 0; j < KEYS.size(); j++) {
+      RNDVALS[j] = rnd.RandomString(RAND_VALUES_LENGTH);
+      ASSERT_OK(Put(KEYS[j], RNDVALS[j]));
+      ASSERT_EQ(Get(KEYS[j]), RNDVALS[j]);
+    }
+    for (size_t j = 0; j < KEYS.size(); j++) {
+      ASSERT_EQ(Get(KEYS[j]), RNDVALS[j]);
+    }
+  }
+
+  // Check that there was at least one mempurge
+  const uint32_t ZERO = 0;
+  // Assert that at least one flush to storage has been performed
+  EXPECT_GT(sst_count.exchange(0), EXPECTED_SST_COUNT);
+  // The mempurge count is expected to be set to 0 when the options are updated.
+  // We expect no mempurge at all.
+  EXPECT_EQ(mempurge_count.exchange(0), ZERO);
+
+  Close();
+}
+// Closes the "#ifndef ROCKSDB_LITE"
+// End of MemPurgeBasicToggle, which is not
+// supported with RocksDB LITE because it
+// relies on dynamically changing the option
+// flag experimental_mempurge_threshold.
+#endif
+
+// At the moment, MemPurge feature is deactivated
+// when atomic_flush is enabled. This is because the level
+// of garbage between Column Families is not guaranteed to
+// be consistent, therefore a CF could hypothetically
+// trigger a MemPurge while another CF would trigger
+// a regular Flush.
+TEST_F(DBFlushTest, MemPurgeWithAtomicFlush) {
+  Options options = CurrentOptions();
+
+  // The following options are used to enforce several values that
+  // may already exist as default values to make this test resilient
+  // to default value updates in the future.
+  options.statistics = CreateDBStatistics();
+
+  // Record all statistics.
+  options.statistics->set_stats_level(StatsLevel::kAll);
+
+  // create the DB if it's not already present
+  options.create_if_missing = true;
+
+  // Useful for now as we are trying to compare uncompressed data savings on
+  // flush().
+  options.compression = kNoCompression;
+
+  // Prevent memtable in place updates. Should already be disabled
+  // (from Wiki:
+  //  In place updates can be enabled by toggling on the bool
+  //  inplace_update_support flag. However, this flag is by default set to
+  //  false
+  //  because this thread-safe in-place update support is not compatible
+  //  with concurrent memtable writes. Note that the bool
+  //  allow_concurrent_memtable_write is set to true by default )
+  options.inplace_update_support = false;
+  options.allow_concurrent_memtable_write = true;
+
+  // Enforce size of a single MemTable to 64KB (64KB = 65,536 bytes).
+  options.write_buffer_size = 1 << 20;
+  // Activate the MemPurge prototype.
+  options.experimental_mempurge_threshold = 153.245;
+  // Activate atomic_flush.
+  options.atomic_flush = true;
+
+  const std::vector<std::string> new_cf_names = {"pikachu", "eevie"};
+  CreateColumnFamilies(new_cf_names, options);
+
+  Close();
+
+  // 3 CFs: default will be filled with overwrites (would normally trigger
+  // mempurge)
+  //        new_cf_names[1] will be filled with random values (would trigger
+  //        flush) new_cf_names[2] not filled with anything.
+  ReopenWithColumnFamilies(
+      {kDefaultColumnFamilyName, new_cf_names[0], new_cf_names[1]}, options);
+  size_t num_cfs = handles_.size();
+  ASSERT_EQ(3, num_cfs);
+  ASSERT_OK(Put(1, "foo", "bar"));
+  ASSERT_OK(Put(2, "bar", "baz"));
+
+  std::atomic<uint32_t> mempurge_count{0};
+  std::atomic<uint32_t> sst_count{0};
+  ROCKSDB_NAMESPACE::SyncPoint::GetInstance()->SetCallBack(
+      "DBImpl::FlushJob:MemPurgeSuccessful",
+      [&](void* /*arg*/) { mempurge_count++; });
+  ROCKSDB_NAMESPACE::SyncPoint::GetInstance()->SetCallBack(
+      "DBImpl::FlushJob:SSTFileCreated", [&](void* /*arg*/) { sst_count++; });
+  ROCKSDB_NAMESPACE::SyncPoint::GetInstance()->EnableProcessing();
+
+  const size_t KVSIZE = 3;
+  std::vector<std::string> KEYS(KVSIZE);
+  for (size_t k = 0; k < KVSIZE; k++) {
+    KEYS[k] = "IamKey" + std::to_string(k);
+  }
+
+  std::string RNDKEY;
+  std::vector<std::string> RNDVALS(KVSIZE);
+  const std::string NOT_FOUND = "NOT_FOUND";
+
+  // Heavy overwrite workload,
+  // more than would fit in maximum allowed memtables.
+  Random rnd(106);
+  const size_t NUM_REPEAT = 100;
+  const size_t RAND_KEY_LENGTH = 128;
+  const size_t RAND_VALUES_LENGTH = 10240;
+
+  // Insertion of of K-V pairs, multiple times (overwrites).
+  for (size_t i = 0; i < NUM_REPEAT; i++) {
+    for (size_t j = 0; j < KEYS.size(); j++) {
+      RNDKEY = rnd.RandomString(RAND_KEY_LENGTH);
+      RNDVALS[j] = rnd.RandomString(RAND_VALUES_LENGTH);
+      ASSERT_OK(Put(KEYS[j], RNDVALS[j]));
+      ASSERT_OK(Put(1, RNDKEY, RNDVALS[j]));
+      ASSERT_EQ(Get(KEYS[j]), RNDVALS[j]);
+      ASSERT_EQ(Get(1, RNDKEY), RNDVALS[j]);
+    }
+  }
+
+  // Check that there was no mempurge because atomic_flush option is true.
+  const uint32_t EXPECTED_MIN_MEMPURGE_COUNT = 0;
+  // Check that there was at least one SST files created during flush.
+  const uint32_t EXPECTED_SST_COUNT = 1;
+
+  EXPECT_EQ(mempurge_count.exchange(0), EXPECTED_MIN_MEMPURGE_COUNT);
+  EXPECT_GE(sst_count.exchange(0), EXPECTED_SST_COUNT);
+
+  Close();
+}
+
 TEST_F(DBFlushTest, MemPurgeDeleteAndDeleteRange) {
   Options options = CurrentOptions();
 
@@ -930,7 +1170,7 @@ TEST_F(DBFlushTest, MemPurgeDeleteAndDeleteRange) {
   // Enforce size of a single MemTable to 64MB (64MB = 67108864 bytes).
   options.write_buffer_size = 1 << 20;
   // Activate the MemPurge prototype.
-  options.experimental_mempurge_threshold = 1.0;
+  options.experimental_mempurge_threshold = 15.0;
 
   ASSERT_OK(TryReopen(options));
 
@@ -1137,7 +1377,7 @@ TEST_F(DBFlushTest, MemPurgeAndCompactionFilter) {
   // Enforce size of a single MemTable to 64MB (64MB = 67108864 bytes).
   options.write_buffer_size = 1 << 20;
   // Activate the MemPurge prototype.
-  options.experimental_mempurge_threshold = 1.0;
+  options.experimental_mempurge_threshold = 26.55;
 
   ASSERT_OK(TryReopen(options));
 
@@ -1212,8 +1452,9 @@ TEST_F(DBFlushTest, DISABLED_MemPurgeWALSupport) {
 
   // Enforce size of a single MemTable to 128KB.
   options.write_buffer_size = 128 << 10;
-  // Activate the MemPurge prototype.
-  options.experimental_mempurge_threshold = 1.0;
+  // Activate the MemPurge prototype
+  // (values >1.0 are equivalent to 1.0).
+  options.experimental_mempurge_threshold = 2.5;
 
   ASSERT_OK(TryReopen(options));
 

db/db_impl/compacted_db_impl.cc

@@ -72,9 +72,9 @@ Status CompactedDBImpl::Get(const ReadOptions& options, ColumnFamilyHandle*,
       user_comparator_->timestamp_size() > 0 ? timestamp : nullptr;
   LookupKey lkey(key, kMaxSequenceNumber, options.timestamp);
   GetContext get_context(user_comparator_, nullptr, nullptr, nullptr,
-                         GetContext::kNotFound, lkey.user_key(), value, ts,
-                         nullptr, nullptr, true, nullptr, nullptr, nullptr,
-                         nullptr, &read_cb);
+                         GetContext::kNotFound, lkey.user_key(), value,
+                         /*columns=*/nullptr, ts, nullptr, nullptr, true,
+                         nullptr, nullptr, nullptr, nullptr, &read_cb);
 
   const FdWithKeyRange& f = files_.files[FindFile(lkey.user_key())];
   if (user_comparator_->CompareWithoutTimestamp(
@@ -159,7 +159,7 @@ std::vector<Status> CompactedDBImpl::MultiGet(
       std::string* timestamp = timestamps ? &(*timestamps)[idx] : nullptr;
       GetContext get_context(
           user_comparator_, nullptr, nullptr, nullptr, GetContext::kNotFound,
-          lkey.user_key(), &pinnable_val,
+          lkey.user_key(), &pinnable_val, /*columns=*/nullptr,
           user_comparator_->timestamp_size() > 0 ? timestamp : nullptr, nullptr,
           nullptr, true, nullptr, nullptr, nullptr, nullptr, &read_cb);
       Status s = r->Get(options, lkey.internal_key(), &get_context, nullptr);

db/db_impl/compacted_db_impl.h

@@ -54,12 +54,22 @@ class CompactedDBImpl : public DBImpl {
                      const Slice& /*key*/, const Slice& /*value*/) override {
     return Status::NotSupported("Not supported in compacted db mode.");
   }
+
+  using DBImpl::PutEntity;
+  Status PutEntity(const WriteOptions& /* options */,
+                   ColumnFamilyHandle* /* column_family */,
+                   const Slice& /* key */,
+                   const WideColumns& /* columns */) override {
+    return Status::NotSupported("Not supported in compacted db mode.");
+  }
+
   using DBImpl::Merge;
   virtual Status Merge(const WriteOptions& /*options*/,
                        ColumnFamilyHandle* /*column_family*/,
                        const Slice& /*key*/, const Slice& /*value*/) override {
     return Status::NotSupported("Not supported in compacted db mode.");
   }
+
   using DBImpl::Delete;
   virtual Status Delete(const WriteOptions& /*options*/,
                         ColumnFamilyHandle* /*column_family*/,

db/db_impl/db_impl.cc

@@ -156,7 +156,9 @@ DBImpl::DBImpl(const DBOptions& options, const std::string& dbname,
                bool read_only)
     : dbname_(dbname),
       own_info_log_(options.info_log == nullptr),
-      initial_db_options_(SanitizeOptions(dbname, options, read_only)),
+      init_logger_creation_s_(),
+      initial_db_options_(SanitizeOptions(dbname, options, read_only,
+                                          &init_logger_creation_s_)),
       env_(initial_db_options_.env),
       io_tracer_(std::make_shared<IOTracer>()),
       immutable_db_options_(initial_db_options_),
@@ -183,7 +185,7 @@ DBImpl::DBImpl(const DBOptions& options, const std::string& dbname,
       log_dir_synced_(false),
       log_empty_(true),
       persist_stats_cf_handle_(nullptr),
-      log_sync_cv_(&mutex_),
+      log_sync_cv_(&log_write_mutex_),
       total_log_size_(0),
       is_snapshot_supported_(true),
       write_buffer_manager_(immutable_db_options_.write_buffer_manager.get()),
@@ -244,8 +246,6 @@ DBImpl::DBImpl(const DBOptions& options, const std::string& dbname,
   // !batch_per_trx_ implies seq_per_batch_ because it is only unset for
   // WriteUnprepared, which should use seq_per_batch_.
   assert(batch_per_txn_ || seq_per_batch_);
-  // TODO: Check for an error here
-  env_->GetAbsolutePath(dbname, &db_absolute_path_).PermitUncheckedError();
 
   // Reserve ten files or so for other uses and give the rest to TableCache.
   // Give a large number for setting of "infinite" open files.
@@ -263,7 +263,7 @@ DBImpl::DBImpl(const DBOptions& options, const std::string& dbname,
   versions_.reset(new VersionSet(dbname_, &immutable_db_options_, file_options_,
                                  table_cache_.get(), write_buffer_manager_,
                                  &write_controller_, &block_cache_tracer_,
-                                 io_tracer_, db_session_id_));
+                                 io_tracer_, db_id_, db_session_id_));
   column_family_memtables_.reset(
       new ColumnFamilyMemTablesImpl(versions_->GetColumnFamilySet()));
 
@@ -273,6 +273,8 @@ DBImpl::DBImpl(const DBOptions& options, const std::string& dbname,
   mutable_db_options_.Dump(immutable_db_options_.info_log.get());
   DumpSupportInfo(immutable_db_options_.info_log.get());
 
+  max_total_wal_size_.store(mutable_db_options_.max_total_wal_size,
+                            std::memory_order_relaxed);
   if (write_buffer_manager_) {
     wbm_stall_.reset(new WBMStallInterface());
   }
@@ -480,6 +482,7 @@ void DBImpl::CancelAllBackgroundWork(bool wait) {
 #ifndef ROCKSDB_LITE
   if (periodic_work_scheduler_ != nullptr) {
     periodic_work_scheduler_->Unregister(this);
+    periodic_work_scheduler_->UnregisterRecordSeqnoTimeWorker(this);
   }
 #endif  // !ROCKSDB_LITE
 
@@ -576,38 +579,6 @@ Status DBImpl::CloseHelper() {
   flush_scheduler_.Clear();
   trim_history_scheduler_.Clear();
 
-  // For now, simply trigger a manual flush at close time
-  // on all the column families.
-  // TODO(bjlemaire): Check if this is needed. Also, in the
-  // future we can contemplate doing a more fine-grained
-  // flushing by first checking if there is a need for
-  // flushing (but need to implement something
-  // else than imm()->IsFlushPending() because the output
-  // memtables added to imm() don't trigger flushes).
-  if (immutable_db_options_.experimental_mempurge_threshold > 0.0) {
-    Status flush_ret;
-    mutex_.Unlock();
-    for (ColumnFamilyData* cf : *versions_->GetColumnFamilySet()) {
-      if (immutable_db_options_.atomic_flush) {
-        flush_ret = AtomicFlushMemTables({cf}, FlushOptions(),
-                                         FlushReason::kManualFlush);
-        if (!flush_ret.ok()) {
-          ROCKS_LOG_INFO(
-              immutable_db_options_.info_log,
-              "Atomic flush memtables failed upon closing (mempurge).");
-        }
-      } else {
-        flush_ret =
-            FlushMemTable(cf, FlushOptions(), FlushReason::kManualFlush);
-        if (!flush_ret.ok()) {
-          ROCKS_LOG_INFO(immutable_db_options_.info_log,
-                         "Flush memtables failed upon closing (mempurge).");
-        }
-      }
-    }
-    mutex_.Lock();
-  }
-
   while (!flush_queue_.empty()) {
     const FlushRequest& flush_req = PopFirstFromFlushQueue();
     for (const auto& iter : flush_req) {
@@ -656,26 +627,28 @@ Status DBImpl::CloseHelper() {
     job_context.Clean();
     mutex_.Lock();
   }
-
-  for (auto l : logs_to_free_) {
-    delete l;
-  }
-  for (auto& log : logs_) {
-    uint64_t log_number = log.writer->get_log_number();
-    Status s = log.ClearWriter();
-    if (!s.ok()) {
-      ROCKS_LOG_WARN(
-          immutable_db_options_.info_log,
-          "Unable to Sync WAL file %s with error -- %s",
-          LogFileName(immutable_db_options_.GetWalDir(), log_number).c_str(),
-          s.ToString().c_str());
-      // Retain the first error
-      if (ret.ok()) {
-        ret = s;
+  {
+    InstrumentedMutexLock lock(&log_write_mutex_);
+    for (auto l : logs_to_free_) {
+      delete l;
+    }
+    for (auto& log : logs_) {
+      uint64_t log_number = log.writer->get_log_number();
+      Status s = log.ClearWriter();
+      if (!s.ok()) {
+        ROCKS_LOG_WARN(
+            immutable_db_options_.info_log,
+            "Unable to Sync WAL file %s with error -- %s",
+            LogFileName(immutable_db_options_.GetWalDir(), log_number).c_str(),
+            s.ToString().c_str());
+        // Retain the first error
+        if (ret.ok()) {
+          ret = s;
+        }
       }
     }
+    logs_.clear();
   }
-  logs_.clear();
 
   // Table cache may have table handles holding blocks from the block cache.
   // We need to release them before the block cache is destroyed. The block
@@ -747,6 +720,9 @@ Status DBImpl::CloseHelper() {
 Status DBImpl::CloseImpl() { return CloseHelper(); }
 
 DBImpl::~DBImpl() {
+  // TODO: remove this.
+  init_logger_creation_s_.PermitUncheckedError();
+
   InstrumentedMutexLock closing_lock_guard(&closing_mutex_);
   if (closed_) {
     return;
@@ -820,6 +796,66 @@ Status DBImpl::StartPeriodicWorkScheduler() {
 #endif  // !ROCKSDB_LITE
 }
 
+Status DBImpl::RegisterRecordSeqnoTimeWorker() {
+#ifndef ROCKSDB_LITE
+  if (!periodic_work_scheduler_) {
+    return Status::OK();
+  }
+  uint64_t min_time_duration = std::numeric_limits<uint64_t>::max();
+  uint64_t max_time_duration = std::numeric_limits<uint64_t>::min();
+  {
+    InstrumentedMutexLock l(&mutex_);
+
+    for (auto cfd : *versions_->GetColumnFamilySet()) {
+      uint64_t preclude_last_option =
+          cfd->ioptions()->preclude_last_level_data_seconds;
+      if (!cfd->IsDropped() && preclude_last_option > 0) {
+        min_time_duration = std::min(preclude_last_option, min_time_duration);
+        max_time_duration = std::max(preclude_last_option, max_time_duration);
+      }
+    }
+    if (min_time_duration == std::numeric_limits<uint64_t>::max()) {
+      seqno_time_mapping_.Resize(0, 0);
+    } else {
+      seqno_time_mapping_.Resize(min_time_duration, max_time_duration);
+    }
+  }
+
+  uint64_t seqno_time_cadence = 0;
+  if (min_time_duration != std::numeric_limits<uint64_t>::max()) {
+    seqno_time_cadence =
+        min_time_duration / SeqnoToTimeMapping::kMaxSeqnoTimePairsPerCF;
+  }
+
+  Status s;
+  if (seqno_time_cadence != record_seqno_time_cadence_) {
+    if (seqno_time_cadence == 0) {
+      periodic_work_scheduler_->UnregisterRecordSeqnoTimeWorker(this);
+    } else {
+      s = periodic_work_scheduler_->RegisterRecordSeqnoTimeWorker(
+          this, seqno_time_cadence);
+    }
+
+    if (s.ok()) {
+      record_seqno_time_cadence_ = seqno_time_cadence;
+    }
+
+    if (s.IsNotSupported()) {
+      // TODO: Fix the timer cannot cancel and re-add the same task
+      ROCKS_LOG_WARN(
+          immutable_db_options_.info_log,
+          "Updating seqno to time worker cadence is not supported yet, to make "
+          "the change effective, please reopen the DB instance.");
+      s = Status::OK();
+    }
+  }
+
+  return s;
+#else
+  return Status::OK();
+#endif  // !ROCKSDB_LITE
+}
+
 // esitmate the total size of stats_history_
 size_t DBImpl::EstimateInMemoryStatsHistorySize() const {
   size_t size_total =
@@ -1076,6 +1112,7 @@ Status DBImpl::TablesRangeTombstoneSummary(ColumnFamilyHandle* column_family,
 }
 
 void DBImpl::ScheduleBgLogWriterClose(JobContext* job_context) {
+  mutex_.AssertHeld();
   if (!job_context->logs_to_free.empty()) {
     for (auto l : job_context->logs_to_free) {
       AddToLogsToFreeQueue(l);
@@ -1253,6 +1290,11 @@ Status DBImpl::SetDBOptions(
             new_options.stats_persist_period_sec);
         mutex_.Lock();
       }
+      if (new_options.max_total_wal_size !=
+          mutable_db_options_.max_total_wal_size) {
+        max_total_wal_size_.store(new_options.max_total_wal_size,
+                                  std::memory_order_release);
+      }
       write_controller_.set_max_delayed_write_rate(
           new_options.delayed_write_rate);
       table_cache_.get()->SetCapacity(new_options.max_open_files == -1
@@ -1373,7 +1415,7 @@ Status DBImpl::SyncWAL() {
   uint64_t current_log_number;
 
   {
-    InstrumentedMutexLock l(&mutex_);
+    InstrumentedMutexLock l(&log_write_mutex_);
     assert(!logs_.empty());
 
     // This SyncWAL() call only cares about logs up to this number.
@@ -1430,19 +1472,37 @@ Status DBImpl::SyncWAL() {
   TEST_SYNC_POINT("DBWALTest::SyncWALNotWaitWrite:2");
 
   TEST_SYNC_POINT("DBImpl::SyncWAL:BeforeMarkLogsSynced:1");
+  VersionEdit synced_wals;
   {
-    InstrumentedMutexLock l(&mutex_);
+    InstrumentedMutexLock l(&log_write_mutex_);
     if (status.ok()) {
-      status = MarkLogsSynced(current_log_number, need_log_dir_sync);
+      MarkLogsSynced(current_log_number, need_log_dir_sync, &synced_wals);
     } else {
       MarkLogsNotSynced(current_log_number);
     }
   }
+  if (status.ok() && synced_wals.IsWalAddition()) {
+    InstrumentedMutexLock l(&mutex_);
+    status = ApplyWALToManifest(&synced_wals);
+  }
+
   TEST_SYNC_POINT("DBImpl::SyncWAL:BeforeMarkLogsSynced:2");
 
   return status;
 }
 
+Status DBImpl::ApplyWALToManifest(VersionEdit* synced_wals) {
+  // not empty, write to MANIFEST.
+  mutex_.AssertHeld();
+  Status status =
+      versions_->LogAndApplyToDefaultColumnFamily(synced_wals, &mutex_);
+  if (!status.ok() && versions_->io_status().IsIOError()) {
+    status = error_handler_.SetBGError(versions_->io_status(),
+                                       BackgroundErrorReason::kManifestWrite);
+  }
+  return status;
+}
+
 Status DBImpl::LockWAL() {
   log_write_mutex_.Lock();
   auto cur_log_writer = logs_.back().writer;
@@ -1462,24 +1522,22 @@ Status DBImpl::UnlockWAL() {
   return Status::OK();
 }
 
-Status DBImpl::MarkLogsSynced(uint64_t up_to, bool synced_dir) {
-  mutex_.AssertHeld();
+void DBImpl::MarkLogsSynced(uint64_t up_to, bool synced_dir,
+                            VersionEdit* synced_wals) {
+  log_write_mutex_.AssertHeld();
   if (synced_dir && logfile_number_ == up_to) {
     log_dir_synced_ = true;
   }
-  VersionEdit synced_wals;
   for (auto it = logs_.begin(); it != logs_.end() && it->number <= up_to;) {
     auto& wal = *it;
     assert(wal.IsSyncing());
-    if (immutable_db_options_.track_and_verify_wals_in_manifest &&
-        wal.GetPreSyncSize() > 0) {
-      synced_wals.AddWal(wal.number, WalMetadata(wal.GetPreSyncSize()));
-    }
 
     if (logs_.size() > 1) {
+      if (immutable_db_options_.track_and_verify_wals_in_manifest &&
+          wal.GetPreSyncSize() > 0) {
+        synced_wals->AddWal(wal.number, WalMetadata(wal.GetPreSyncSize()));
+      }
       logs_to_free_.push_back(wal.ReleaseWriter());
-      // To modify logs_ both mutex_ and log_write_mutex_ must be held
-      InstrumentedMutexLock l(&log_write_mutex_);
       it = logs_.erase(it);
     } else {
       wal.FinishSync();
@@ -1488,22 +1546,11 @@ Status DBImpl::MarkLogsSynced(uint64_t up_to, bool synced_dir) {
   }
   assert(logs_.empty() || logs_[0].number > up_to ||
          (logs_.size() == 1 && !logs_[0].IsSyncing()));
-
-  Status s;
-  if (synced_wals.IsWalAddition()) {
-    // not empty, write to MANIFEST.
-    s = versions_->LogAndApplyToDefaultColumnFamily(&synced_wals, &mutex_);
-    if (!s.ok() && versions_->io_status().IsIOError()) {
-      s = error_handler_.SetBGError(versions_->io_status(),
-                                    BackgroundErrorReason::kManifestWrite);
-    }
-  }
   log_sync_cv_.SignalAll();
-  return s;
 }
 
 void DBImpl::MarkLogsNotSynced(uint64_t up_to) {
-  mutex_.AssertHeld();
+  log_write_mutex_.AssertHeld();
   for (auto it = logs_.begin(); it != logs_.end() && it->number <= up_to;
        ++it) {
     auto& wal = *it;
@@ -1627,9 +1674,16 @@ void DBImpl::BackgroundCallPurge() {
 }
 
 namespace {
-struct IterState {
-  IterState(DBImpl* _db, InstrumentedMutex* _mu, SuperVersion* _super_version,
-            bool _background_purge)
+
+// A `SuperVersionHandle` holds a non-null `SuperVersion*` pointing at a
+// `SuperVersion` referenced once for this object. It also contains the state
+// needed to clean up the `SuperVersion` reference from outside of `DBImpl`
+// using `CleanupSuperVersionHandle()`.
+struct SuperVersionHandle {
+  // `_super_version` must be non-nullptr and `Ref()`'d once as long as the
+  // `SuperVersionHandle` may use it.
+  SuperVersionHandle(DBImpl* _db, InstrumentedMutex* _mu,
+                     SuperVersion* _super_version, bool _background_purge)
       : db(_db),
         mu(_mu),
         super_version(_super_version),
@@ -1641,35 +1695,49 @@ struct IterState {
   bool background_purge;
 };
 
-static void CleanupIteratorState(void* arg1, void* /*arg2*/) {
-  IterState* state = reinterpret_cast<IterState*>(arg1);
+static void CleanupSuperVersionHandle(void* arg1, void* /*arg2*/) {
+  SuperVersionHandle* sv_handle = reinterpret_cast<SuperVersionHandle*>(arg1);
 
-  if (state->super_version->Unref()) {
+  if (sv_handle->super_version->Unref()) {
     // Job id == 0 means that this is not our background process, but rather
     // user thread
     JobContext job_context(0);
 
-    state->mu->Lock();
-    state->super_version->Cleanup();
-    state->db->FindObsoleteFiles(&job_context, false, true);
-    if (state->background_purge) {
-      state->db->ScheduleBgLogWriterClose(&job_context);
-      state->db->AddSuperVersionsToFreeQueue(state->super_version);
-      state->db->SchedulePurge();
+    sv_handle->mu->Lock();
+    sv_handle->super_version->Cleanup();
+    sv_handle->db->FindObsoleteFiles(&job_context, false, true);
+    if (sv_handle->background_purge) {
+      sv_handle->db->ScheduleBgLogWriterClose(&job_context);
+      sv_handle->db->AddSuperVersionsToFreeQueue(sv_handle->super_version);
+      sv_handle->db->SchedulePurge();
     }
-    state->mu->Unlock();
+    sv_handle->mu->Unlock();
 
-    if (!state->background_purge) {
-      delete state->super_version;
+    if (!sv_handle->background_purge) {
+      delete sv_handle->super_version;
     }
     if (job_context.HaveSomethingToDelete()) {
-      state->db->PurgeObsoleteFiles(job_context, state->background_purge);
+      sv_handle->db->PurgeObsoleteFiles(job_context,
+                                        sv_handle->background_purge);
     }
     job_context.Clean();
   }
 
+  delete sv_handle;
+}
+
+struct GetMergeOperandsState {
+  MergeContext merge_context;
+  PinnedIteratorsManager pinned_iters_mgr;
+  SuperVersionHandle* sv_handle;
+};
+
+static void CleanupGetMergeOperandsState(void* arg1, void* /*arg2*/) {
+  GetMergeOperandsState* state = static_cast<GetMergeOperandsState*>(arg1);
+  CleanupSuperVersionHandle(state->sv_handle /* arg1 */, nullptr /* arg2 */);
   delete state;
 }
+
 }  // namespace
 
 InternalIterator* DBImpl::NewInternalIterator(const ReadOptions& read_options,
@@ -1693,8 +1761,8 @@ InternalIterator* DBImpl::NewInternalIterator(const ReadOptions& read_options,
   std::unique_ptr<FragmentedRangeTombstoneIterator> range_del_iter;
   Status s;
   if (!read_options.ignore_range_deletions) {
-    range_del_iter.reset(
-        super_version->mem->NewRangeTombstoneIterator(read_options, sequence));
+    range_del_iter.reset(super_version->mem->NewRangeTombstoneIterator(
+        read_options, sequence, false /* immutable_memtable */));
     range_del_agg->AddTombstones(std::move(range_del_iter));
   }
   // Collect all needed child iterators for immutable memtables
@@ -1714,11 +1782,11 @@ InternalIterator* DBImpl::NewInternalIterator(const ReadOptions& read_options,
                                            allow_unprepared_value);
     }
     internal_iter = merge_iter_builder.Finish();
-    IterState* cleanup =
-        new IterState(this, &mutex_, super_version,
-                      read_options.background_purge_on_iterator_cleanup ||
-                      immutable_db_options_.avoid_unnecessary_blocking_io);
-    internal_iter->RegisterCleanup(CleanupIteratorState, cleanup, nullptr);
+    SuperVersionHandle* cleanup = new SuperVersionHandle(
+        this, &mutex_, super_version,
+        read_options.background_purge_on_iterator_cleanup ||
+            immutable_db_options_.avoid_unnecessary_blocking_io);
+    internal_iter->RegisterCleanup(CleanupSuperVersionHandle, cleanup, nullptr);
 
     return internal_iter;
   } else {
@@ -1754,10 +1822,61 @@ Status DBImpl::Get(const ReadOptions& read_options,
   return s;
 }
 
+Status DBImpl::GetEntity(const ReadOptions& read_options,
+                         ColumnFamilyHandle* column_family, const Slice& key,
+                         PinnableWideColumns* columns) {
+  if (!column_family) {
+    return Status::InvalidArgument(
+        "Cannot call GetEntity without a column family handle");
+  }
+
+  if (!columns) {
+    return Status::InvalidArgument(
+        "Cannot call GetEntity without a PinnableWideColumns object");
+  }
+
+  columns->Reset();
+
+  GetImplOptions get_impl_options;
+  get_impl_options.column_family = column_family;
+  get_impl_options.columns = columns;
+
+  return GetImpl(read_options, key, get_impl_options);
+}
+
+bool DBImpl::ShouldReferenceSuperVersion(const MergeContext& merge_context) {
+  // If both thresholds are reached, a function returning merge operands as
+  // `PinnableSlice`s should reference the `SuperVersion` to avoid large and/or
+  // numerous `memcpy()`s.
+  //
+  // The below constants enable the optimization conservatively. They are
+  // verified to not regress `GetMergeOperands()` latency in the following
+  // scenarios.
+  //
+  // - CPU: two socket Intel(R) Xeon(R) Gold 6138 CPU @ 2.00GHz
+  // - `GetMergeOperands()` threads: 1 - 32
+  // - Entry size: 32 bytes - 4KB
+  // - Merges per key: 1 - 16K
+  // - LSM component: memtable
+  //
+  // TODO(ajkr): expand measurement to SST files.
+  static const size_t kNumBytesForSvRef = 32768;
+  static const size_t kLog2AvgBytesForSvRef = 8;  // 256 bytes
+
+  size_t num_bytes = 0;
+  for (const Slice& sl : merge_context.GetOperands()) {
+    num_bytes += sl.size();
+  }
+  return num_bytes >= kNumBytesForSvRef &&
+         (num_bytes >> kLog2AvgBytesForSvRef) >=
+             merge_context.GetOperands().size();
+}
+
 Status DBImpl::GetImpl(const ReadOptions& read_options, const Slice& key,
                        GetImplOptions& get_impl_options) {
   assert(get_impl_options.value != nullptr ||
-         get_impl_options.merge_operands != nullptr);
+         get_impl_options.merge_operands != nullptr ||
+         get_impl_options.columns != nullptr);
 
   assert(get_impl_options.column_family);
 
@@ -1801,6 +1920,14 @@ Status DBImpl::GetImpl(const ReadOptions& read_options, const Slice& key,
     }
   }
 
+  if (get_impl_options.get_merge_operands_options != nullptr) {
+    for (int i = 0; i < get_impl_options.get_merge_operands_options
+                            ->expected_max_number_of_operands;
+         ++i) {
+      get_impl_options.merge_operands[i].Reset();
+    }
+  }
+
   // Acquire SuperVersion
   SuperVersion* sv = GetAndRefSuperVersion(cfd);
 
@@ -1876,29 +2003,46 @@ Status DBImpl::GetImpl(const ReadOptions& read_options, const Slice& key,
   if (!skip_memtable) {
     // Get value associated with key
     if (get_impl_options.get_value) {
-      if (sv->mem->Get(lkey, get_impl_options.value->GetSelf(), timestamp, &s,
-                       &merge_context, &max_covering_tombstone_seq,
-                       read_options, get_impl_options.callback,
-                       get_impl_options.is_blob_index)) {
+      if (sv->mem->Get(
+              lkey,
+              get_impl_options.value ? get_impl_options.value->GetSelf()
+                                     : nullptr,
+              get_impl_options.columns, timestamp, &s, &merge_context,
+              &max_covering_tombstone_seq, read_options,
+              false /* immutable_memtable */, get_impl_options.callback,
+              get_impl_options.is_blob_index)) {
         done = true;
-        get_impl_options.value->PinSelf();
+
+        if (get_impl_options.value) {
+          get_impl_options.value->PinSelf();
+        }
+
         RecordTick(stats_, MEMTABLE_HIT);
       } else if ((s.ok() || s.IsMergeInProgress()) &&
-                 sv->imm->Get(lkey, get_impl_options.value->GetSelf(),
-                              timestamp, &s, &merge_context,
-                              &max_covering_tombstone_seq, read_options,
-                              get_impl_options.callback,
+                 sv->imm->Get(lkey,
+                              get_impl_options.value
+                                  ? get_impl_options.value->GetSelf()
+                                  : nullptr,
+                              get_impl_options.columns, timestamp, &s,
+                              &merge_context, &max_covering_tombstone_seq,
+                              read_options, get_impl_options.callback,
                               get_impl_options.is_blob_index)) {
         done = true;
-        get_impl_options.value->PinSelf();
+
+        if (get_impl_options.value) {
+          get_impl_options.value->PinSelf();
+        }
+
         RecordTick(stats_, MEMTABLE_HIT);
       }
     } else {
       // Get Merge Operands associated with key, Merge Operands should not be
       // merged and raw values should be returned to the user.
-      if (sv->mem->Get(lkey, /*value*/ nullptr, /*timestamp=*/nullptr, &s,
-                       &merge_context, &max_covering_tombstone_seq,
-                       read_options, nullptr, nullptr, false)) {
+      if (sv->mem->Get(lkey, /*value=*/nullptr, /*columns=*/nullptr,
+                       /*timestamp=*/nullptr, &s, &merge_context,
+                       &max_covering_tombstone_seq, read_options,
+                       false /* immutable_memtable */, nullptr, nullptr,
+                       false)) {
         done = true;
         RecordTick(stats_, MEMTABLE_HIT);
       } else if ((s.ok() || s.IsMergeInProgress()) &&
@@ -1920,8 +2064,9 @@ Status DBImpl::GetImpl(const ReadOptions& read_options, const Slice& key,
   if (!done) {
     PERF_TIMER_GUARD(get_from_output_files_time);
     sv->current->Get(
-        read_options, lkey, get_impl_options.value, timestamp, &s,
-        &merge_context, &max_covering_tombstone_seq, &pinned_iters_mgr,
+        read_options, lkey, get_impl_options.value, get_impl_options.columns,
+        timestamp, &s, &merge_context, &max_covering_tombstone_seq,
+        &pinned_iters_mgr,
         get_impl_options.get_value ? get_impl_options.value_found : nullptr,
         nullptr, nullptr,
         get_impl_options.get_value ? get_impl_options.callback : nullptr,
@@ -1937,7 +2082,11 @@ Status DBImpl::GetImpl(const ReadOptions& read_options, const Slice& key,
     size_t size = 0;
     if (s.ok()) {
       if (get_impl_options.get_value) {
-        size = get_impl_options.value->size();
+        if (get_impl_options.value) {
+          size = get_impl_options.value->size();
+        } else if (get_impl_options.columns) {
+          size = get_impl_options.columns->serialized_size();
+        }
       } else {
         // Return all merge operands for get_impl_options.key
         *get_impl_options.number_of_operands =
@@ -1948,19 +2097,68 @@ Status DBImpl::GetImpl(const ReadOptions& read_options, const Slice& key,
           s = Status::Incomplete(
               Status::SubCode::KMergeOperandsInsufficientCapacity);
         } else {
-          for (const Slice& sl : merge_context.GetOperands()) {
-            size += sl.size();
-            get_impl_options.merge_operands->PinSelf(sl);
-            get_impl_options.merge_operands++;
+          // Each operand depends on one of the following resources: `sv`,
+          // `pinned_iters_mgr`, or `merge_context`. It would be crazy expensive
+          // to reference `sv` for each operand relying on it because `sv` is
+          // (un)ref'd in all threads using the DB. Furthermore, we do not track
+          // on which resource each operand depends.
+          //
+          // To solve this, we bundle the resources in a `GetMergeOperandsState`
+          // and manage them with a `SharedCleanablePtr` shared among the
+          // `PinnableSlice`s we return. This bundle includes one `sv` reference
+          // and ownership of the `merge_context` and `pinned_iters_mgr`
+          // objects.
+          bool ref_sv = ShouldReferenceSuperVersion(merge_context);
+          if (ref_sv) {
+            assert(!merge_context.GetOperands().empty());
+            SharedCleanablePtr shared_cleanable;
+            GetMergeOperandsState* state = nullptr;
+            state = new GetMergeOperandsState();
+            state->merge_context = std::move(merge_context);
+            state->pinned_iters_mgr = std::move(pinned_iters_mgr);
+
+            sv->Ref();
+
+            state->sv_handle = new SuperVersionHandle(
+                this, &mutex_, sv,
+                immutable_db_options_.avoid_unnecessary_blocking_io);
+
+            shared_cleanable.Allocate();
+            shared_cleanable->RegisterCleanup(CleanupGetMergeOperandsState,
+                                              state /* arg1 */,
+                                              nullptr /* arg2 */);
+            for (size_t i = 0; i < state->merge_context.GetOperands().size();
+                 ++i) {
+              const Slice& sl = state->merge_context.GetOperands()[i];
+              size += sl.size();
+
+              get_impl_options.merge_operands->PinSlice(
+                  sl, nullptr /* cleanable */);
+              if (i == state->merge_context.GetOperands().size() - 1) {
+                shared_cleanable.MoveAsCleanupTo(
+                    get_impl_options.merge_operands);
+              } else {
+                shared_cleanable.RegisterCopyWith(
+                    get_impl_options.merge_operands);
+              }
+              get_impl_options.merge_operands++;
+            }
+          } else {
+            for (const Slice& sl : merge_context.GetOperands()) {
+              size += sl.size();
+              get_impl_options.merge_operands->PinSelf(sl);
+              get_impl_options.merge_operands++;
+            }
           }
         }
       }
       RecordTick(stats_, BYTES_READ, size);
       PERF_COUNTER_ADD(get_read_bytes, size);
     }
-    RecordInHistogram(stats_, BYTES_PER_READ, size);
 
     ReturnAndCleanupSuperVersion(cfd, sv);
+
+    RecordInHistogram(stats_, BYTES_PER_READ, size);
   }
   return s;
 }
@@ -2097,13 +2295,14 @@ std::vector<Status> DBImpl::MultiGet(
          has_unpersisted_data_.load(std::memory_order_relaxed));
     bool done = false;
     if (!skip_memtable) {
-      if (super_version->mem->Get(lkey, value, timestamp, &s, &merge_context,
-                                  &max_covering_tombstone_seq, read_options,
-                                  read_callback)) {
+      if (super_version->mem->Get(
+              lkey, value, /*columns=*/nullptr, timestamp, &s, &merge_context,
+              &max_covering_tombstone_seq, read_options,
+              false /* immutable_memtable */, read_callback)) {
         done = true;
         RecordTick(stats_, MEMTABLE_HIT);
-      } else if (super_version->imm->Get(lkey, value, timestamp, &s,
-                                         &merge_context,
+      } else if (super_version->imm->Get(lkey, value, /*columns=*/nullptr,
+                                         timestamp, &s, &merge_context,
                                          &max_covering_tombstone_seq,
                                          read_options, read_callback)) {
         done = true;
@@ -2114,9 +2313,9 @@ std::vector<Status> DBImpl::MultiGet(
       PinnableSlice pinnable_val;
       PERF_TIMER_GUARD(get_from_output_files_time);
       PinnedIteratorsManager pinned_iters_mgr;
-      super_version->current->Get(read_options, lkey, &pinnable_val, timestamp,
-                                  &s, &merge_context,
-                                  &max_covering_tombstone_seq,
+      super_version->current->Get(read_options, lkey, &pinnable_val,
+                                  /*columns=*/nullptr, timestamp, &s,
+                                  &merge_context, &max_covering_tombstone_seq,
                                   &pinned_iters_mgr, /*value_found=*/nullptr,
                                   /*key_exists=*/nullptr,
                                   /*seq=*/nullptr, read_callback);
@@ -2635,7 +2834,8 @@ Status DBImpl::MultiGetImpl(
         (read_options.read_tier == kPersistedTier &&
          has_unpersisted_data_.load(std::memory_order_relaxed));
     if (!skip_memtable) {
-      super_version->mem->MultiGet(read_options, &range, callback);
+      super_version->mem->MultiGet(read_options, &range, callback,
+                                   false /* immutable_memtable */);
       if (!range.empty()) {
         super_version->imm->MultiGet(read_options, &range, callback);
       }
@@ -2834,6 +3034,14 @@ Status DBImpl::CreateColumnFamilyImpl(const ColumnFamilyOptions& cf_options,
     }
   }  // InstrumentedMutexLock l(&mutex_)
 
+  if (cf_options.preclude_last_level_data_seconds > 0) {
+    // TODO(zjay): Fix the timer issue and re-enable this.
+    ROCKS_LOG_ERROR(
+        immutable_db_options_.info_log,
+        "Creating column family with `preclude_last_level_data_seconds` needs "
+        "to restart DB to take effect");
+    //    s = RegisterRecordSeqnoTimeWorker();
+  }
   sv_context.Clean();
   // this is outside the mutex
   if (s.ok()) {
@@ -2922,6 +3130,10 @@ Status DBImpl::DropColumnFamilyImpl(ColumnFamilyHandle* column_family) {
     bg_cv_.SignalAll();
   }
 
+  if (cfd->ioptions()->preclude_last_level_data_seconds > 0) {
+    s = RegisterRecordSeqnoTimeWorker();
+  }
+
   if (s.ok()) {
     // Note that here we erase the associated cf_info of the to-be-dropped
     // cfd before its ref-count goes to zero to avoid having to erase cf_info
@@ -4692,9 +4904,10 @@ Status DBImpl::GetLatestSequenceForKey(
   *found_record_for_key = false;
 
   // Check if there is a record for this key in the latest memtable
-  sv->mem->Get(lkey, /*value=*/nullptr, timestamp, &s, &merge_context,
-               &max_covering_tombstone_seq, seq, read_options,
-               nullptr /*read_callback*/, is_blob_index);
+  sv->mem->Get(lkey, /*value=*/nullptr, /*columns=*/nullptr, timestamp, &s,
+               &merge_context, &max_covering_tombstone_seq, seq, read_options,
+               false /* immutable_memtable */, nullptr /*read_callback*/,
+               is_blob_index);
 
   if (!(s.ok() || s.IsNotFound() || s.IsMergeInProgress())) {
     // unexpected error reading memtable.
@@ -4725,8 +4938,8 @@ Status DBImpl::GetLatestSequenceForKey(
   }
 
   // Check if there is a record for this key in the immutable memtables
-  sv->imm->Get(lkey, /*value=*/nullptr, timestamp, &s, &merge_context,
-               &max_covering_tombstone_seq, seq, read_options,
+  sv->imm->Get(lkey, /*value=*/nullptr, /*columns=*/nullptr, timestamp, &s,
+               &merge_context, &max_covering_tombstone_seq, seq, read_options,
                nullptr /*read_callback*/, is_blob_index);
 
   if (!(s.ok() || s.IsNotFound() || s.IsMergeInProgress())) {
@@ -4757,9 +4970,10 @@ Status DBImpl::GetLatestSequenceForKey(
   }
 
   // Check if there is a record for this key in the immutable memtables
-  sv->imm->GetFromHistory(lkey, /*value=*/nullptr, timestamp, &s,
-                          &merge_context, &max_covering_tombstone_seq, seq,
-                          read_options, is_blob_index);
+  sv->imm->GetFromHistory(lkey, /*value=*/nullptr, /*columns=*/nullptr,
+                          timestamp, &s, &merge_context,
+                          &max_covering_tombstone_seq, seq, read_options,
+                          is_blob_index);
 
   if (!(s.ok() || s.IsNotFound() || s.IsMergeInProgress())) {
     // unexpected error reading memtable.
@@ -4792,8 +5006,8 @@ Status DBImpl::GetLatestSequenceForKey(
   if (!cache_only) {
     // Check tables
     PinnedIteratorsManager pinned_iters_mgr;
-    sv->current->Get(read_options, lkey, /*value=*/nullptr, timestamp, &s,
-                     &merge_context, &max_covering_tombstone_seq,
+    sv->current->Get(read_options, lkey, /*value=*/nullptr, /*columns=*/nullptr,
+                     timestamp, &s, &merge_context, &max_covering_tombstone_seq,
                      &pinned_iters_mgr, nullptr /* value_found */,
                      found_record_for_key, seq, nullptr /*read_callback*/,
                      is_blob_index);
@@ -5565,6 +5779,26 @@ Status DBImpl::GetCreationTimeOfOldestFile(uint64_t* creation_time) {
     return Status::NotSupported("This API only works if max_open_files = -1");
   }
 }
+
+void DBImpl::RecordSeqnoToTimeMapping() {
+  // Get time first then sequence number, so the actual time of seqno is <=
+  // unix_time recorded
+  int64_t unix_time = 0;
+  immutable_db_options_.clock->GetCurrentTime(&unix_time)
+      .PermitUncheckedError();  // Ignore error
+  SequenceNumber seqno = GetLatestSequenceNumber();
+  bool appended = false;
+  {
+    InstrumentedMutexLock l(&mutex_);
+    appended = seqno_time_mapping_.Append(seqno, unix_time);
+  }
+  if (!appended) {
+    ROCKS_LOG_WARN(immutable_db_options_.info_log,
+                   "Failed to insert sequence number to time entry: %" PRIu64
+                   " -> %" PRIu64,
+                   seqno, unix_time);
+  }
+}
 #endif  // ROCKSDB_LITE
 
 }  // namespace ROCKSDB_NAMESPACE

db/db_impl/db_impl.h

@@ -36,6 +36,7 @@
 #include "db/pre_release_callback.h"
 #include "db/range_del_aggregator.h"
 #include "db/read_callback.h"
+#include "db/seqno_to_time_mapping.h"
 #include "db/snapshot_checker.h"
 #include "db/snapshot_impl.h"
 #include "db/trim_history_scheduler.h"
@@ -117,7 +118,6 @@ class Directories {
   IOStatus Close(const IOOptions& options, IODebugContext* dbg) {
     // close all directories for all database paths
     IOStatus s = IOStatus::OK();
-    IOStatus temp_s = IOStatus::OK();
 
     // The default implementation for Close() in Directory/FSDirectory class
     // "NotSupported" status, the upper level interface should be able to
@@ -126,53 +126,35 @@ class Directories {
     // `FSDirectory::Close()` yet
 
     if (db_dir_) {
-      temp_s = db_dir_->Close(options, dbg);
-      if (!temp_s.ok()) {
-        if (temp_s.IsNotSupported()) {
-          temp_s.PermitUncheckedError();
-        } else {
-          s = temp_s;
-        }
+      IOStatus temp_s = db_dir_->Close(options, dbg);
+      if (!temp_s.ok() && !temp_s.IsNotSupported() && s.ok()) {
+        s = std::move(temp_s);
       }
     }
 
-    if (!s.ok()) {
-      return s;
-    }
+    // Attempt to close everything even if one fails
+    s.PermitUncheckedError();
 
     if (wal_dir_) {
-      s = wal_dir_->Close(options, dbg);
-      if (!temp_s.ok()) {
-        if (temp_s.IsNotSupported()) {
-          temp_s.PermitUncheckedError();
-        } else {
-          s = temp_s;
+      IOStatus temp_s = wal_dir_->Close(options, dbg);
+      if (!temp_s.ok() && !temp_s.IsNotSupported() && s.ok()) {
+        s = std::move(temp_s);
+      }
+    }
+
+    s.PermitUncheckedError();
+
+    for (auto& data_dir_ptr : data_dirs_) {
+      if (data_dir_ptr) {
+        IOStatus temp_s = data_dir_ptr->Close(options, dbg);
+        if (!temp_s.ok() && !temp_s.IsNotSupported() && s.ok()) {
+          s = std::move(temp_s);
         }
       }
     }
 
-    if (!s.ok()) {
-      return s;
-    }
-
-    if (data_dirs_.size() > 0 && s.ok()) {
-      for (auto& data_dir_ptr : data_dirs_) {
-        if (data_dir_ptr) {
-          temp_s = data_dir_ptr->Close(options, dbg);
-          if (!temp_s.ok()) {
-            if (temp_s.IsNotSupported()) {
-              temp_s.PermitUncheckedError();
-            } else {
-              return temp_s;
-            }
-          }
-        }
-      }
-    }
-
-    // Mark temp_s as checked when temp_s is still the initial status
-    // (IOStatus::OK(), not checked yet)
-    temp_s.PermitUncheckedError();
+    // Ready for caller
+    s.MustCheck();
     return s;
   }
 
@@ -217,6 +199,11 @@ class DBImpl : public DB {
   Status Put(const WriteOptions& options, ColumnFamilyHandle* column_family,
              const Slice& key, const Slice& ts, const Slice& value) override;
 
+  using DB::PutEntity;
+  Status PutEntity(const WriteOptions& options,
+                   ColumnFamilyHandle* column_family, const Slice& key,
+                   const WideColumns& columns) override;
+
   using DB::Merge;
   Status Merge(const WriteOptions& options, ColumnFamilyHandle* column_family,
                const Slice& key, const Slice& value) override;
@@ -251,6 +238,11 @@ class DBImpl : public DB {
                      ColumnFamilyHandle* column_family, const Slice& key,
                      PinnableSlice* value, std::string* timestamp) override;
 
+  using DB::GetEntity;
+  Status GetEntity(const ReadOptions& options,
+                   ColumnFamilyHandle* column_family, const Slice& key,
+                   PinnableWideColumns* columns) override;
+
   using DB::GetMergeOperands;
   Status GetMergeOperands(const ReadOptions& options,
                           ColumnFamilyHandle* column_family, const Slice& key,
@@ -605,6 +597,7 @@ class DBImpl : public DB {
   struct GetImplOptions {
     ColumnFamilyHandle* column_family = nullptr;
     PinnableSlice* value = nullptr;
+    PinnableWideColumns* columns = nullptr;
     std::string* timestamp = nullptr;
     bool* value_found = nullptr;
     ReadCallback* callback = nullptr;
@@ -992,6 +985,7 @@ class DBImpl : public DB {
   }
 
   void AddToLogsToFreeQueue(log::Writer* log_writer) {
+    mutex_.AssertHeld();
     logs_to_free_queue_.push_back(log_writer);
   }
 
@@ -1153,7 +1147,8 @@ class DBImpl : public DB {
   int TEST_BGCompactionsAllowed() const;
   int TEST_BGFlushesAllowed() const;
   size_t TEST_GetWalPreallocateBlockSize(uint64_t write_buffer_size) const;
-  void TEST_WaitForStatsDumpRun(std::function<void()> callback) const;
+  void TEST_WaitForPeridicWorkerRun(std::function<void()> callback) const;
+  SeqnoToTimeMapping TEST_GetSeqnoToTimeMapping() const;
   size_t TEST_EstimateInMemoryStatsHistorySize() const;
 
   uint64_t TEST_GetCurrentLogNumber() const {
@@ -1181,6 +1176,9 @@ class DBImpl : public DB {
   // flush LOG out of application buffer
   void FlushInfoLog();
 
+  // record current sequence number to time mapping
+  void RecordSeqnoToTimeMapping();
+
   // Interface to block and signal the DB in case of stalling writes by
   // WriteBufferManager. Each DBImpl object contains ptr to WBMStallInterface.
   // When DB needs to be blocked or signalled by WriteBufferManager,
@@ -1248,6 +1246,7 @@ class DBImpl : public DB {
   std::unique_ptr<VersionSet> versions_;
   // Flag to check whether we allocated and own the info log file
   bool own_info_log_;
+  Status init_logger_creation_s_;
   const DBOptions initial_db_options_;
   Env* const env_;
   std::shared_ptr<IOTracer> io_tracer_;
@@ -1287,7 +1286,7 @@ class DBImpl : public DB {
 
   // only used for dynamically adjusting max_total_wal_size. it is a sum of
   // [write_buffer_size * max_write_buffer_number] over all column families
-  uint64_t max_total_in_memory_state_;
+  std::atomic<uint64_t> max_total_in_memory_state_;
 
   // The options to access storage files
   const FileOptions file_options_;
@@ -1517,6 +1516,16 @@ class DBImpl : public DB {
   // recovery.
   Status LogAndApplyForRecovery(const RecoveryContext& recovery_ctx);
 
+  void InvokeWalFilterIfNeededOnColumnFamilyToWalNumberMap();
+
+  // Return true to proceed with current WAL record whose content is stored in
+  // `batch`. Return false to skip current WAL record.
+  bool InvokeWalFilterIfNeededOnWalRecord(uint64_t wal_number,
+                                          const std::string& wal_fname,
+                                          log::Reader::Reporter& reporter,
+                                          Status& status, bool& stop_replay,
+                                          WriteBatch& batch);
+
  private:
   friend class DB;
   friend class ErrorHandler;
@@ -1627,6 +1636,15 @@ class DBImpl : public DB {
     uint64_t pre_sync_size = 0;
   };
 
+  struct LogContext {
+    explicit LogContext(bool need_sync = false)
+        : need_log_sync(need_sync), need_log_dir_sync(need_sync) {}
+    bool need_log_sync = false;
+    bool need_log_dir_sync = false;
+    log::Writer* writer = nullptr;
+    LogFileNumberSize* log_file_number_size = nullptr;
+  };
+
   // PurgeFileInfo is a structure to hold information of files to be deleted in
   // purge_files_
   struct PurgeFileInfo {
@@ -1780,7 +1798,7 @@ class DBImpl : public DB {
   void ReleaseFileNumberFromPendingOutputs(
       std::unique_ptr<std::list<uint64_t>::iterator>& v);
 
-  IOStatus SyncClosedLogs(JobContext* job_context);
+  IOStatus SyncClosedLogs(JobContext* job_context, VersionEdit* synced_wals);
 
   // Flush the in-memory write buffer to storage.  Switches to a new
   // log-file/memtable and writes a new descriptor iff successful. Then
@@ -1940,8 +1958,8 @@ class DBImpl : public DB {
   Status HandleWriteBufferManagerFlush(WriteContext* write_context);
 
   // REQUIRES: mutex locked
-  Status PreprocessWrite(const WriteOptions& write_options, bool* need_log_sync,
-                         WriteContext* write_context);
+  Status PreprocessWrite(const WriteOptions& write_options,
+                         LogContext* log_context, WriteContext* write_context);
 
   // Merge write batches in the write group into merged_batch.
   // Returns OK if merge is successful.
@@ -1983,7 +2001,6 @@ class DBImpl : public DB {
   void MemTableInsertStatusCheck(const Status& memtable_insert_status);
 
 #ifndef ROCKSDB_LITE
-
   Status CompactFilesImpl(const CompactionOptions& compact_options,
                           ColumnFamilyData* cfd, Version* version,
                           const std::vector<std::string>& input_file_names,
@@ -1995,7 +2012,6 @@ class DBImpl : public DB {
   // Wait for current IngestExternalFile() calls to finish.
   // REQUIRES: mutex_ held
   void WaitForIngestFile();
-
 #else
   // IngestExternalFile is not supported in ROCKSDB_LITE so this function
   // will be no-op
@@ -2055,6 +2071,8 @@ class DBImpl : public DB {
   // Schedule background tasks
   Status StartPeriodicWorkScheduler();
 
+  Status RegisterRecordSeqnoTimeWorker();
+
   void PrintStatistics();
 
   size_t EstimateInMemoryStatsHistorySize() const;
@@ -2080,7 +2098,8 @@ class DBImpl : public DB {
       std::unique_ptr<TaskLimiterToken>* token, LogBuffer* log_buffer);
 
   // helper function to call after some of the logs_ were synced
-  Status MarkLogsSynced(uint64_t up_to, bool synced_dir);
+  void MarkLogsSynced(uint64_t up_to, bool synced_dir, VersionEdit* edit);
+  Status ApplyWALToManifest(VersionEdit* edit);
   // WALs with log number up to up_to are not synced successfully.
   void MarkLogsNotSynced(uint64_t up_to);
 
@@ -2247,6 +2266,8 @@ class DBImpl : public DB {
   Status IncreaseFullHistoryTsLowImpl(ColumnFamilyData* cfd,
                                       std::string ts_low);
 
+  bool ShouldReferenceSuperVersion(const MergeContext& merge_context);
+
   // Lock over the persistent DB state.  Non-nullptr iff successfully acquired.
   FileLock* db_lock_;
 
@@ -2286,8 +2307,9 @@ class DBImpl : public DB {
   // logfile_number_ is currently updated only in write_thread_, it can be read
   // from the same write_thread_ without any locks.
   uint64_t logfile_number_;
-  std::deque<uint64_t>
-      log_recycle_files_;  // a list of log files that we can recycle
+  // Log files that we can recycle. Must be protected by db mutex_.
+  std::deque<uint64_t> log_recycle_files_;
+  // Protected by log_write_mutex_.
   bool log_dir_synced_;
   // Without two_write_queues, read and writes to log_empty_ are protected by
   // mutex_. Since it is currently updated/read only in write_thread_, it can be
@@ -2301,26 +2323,93 @@ class DBImpl : public DB {
 
   bool persistent_stats_cfd_exists_ = true;
 
-  // Without two_write_queues, read and writes to alive_log_files_ are
-  // protected by mutex_. With two_write_queues_, writes
-  // are protected by locking both mutex_ and log_write_mutex_, and reads must
-  // be under either mutex_ or log_write_mutex_.
+  // alive_log_files_ is protected by mutex_ and log_write_mutex_ with details
+  // as follows:
+  // 1. read by FindObsoleteFiles() which can be called in either application
+  //    thread or RocksDB bg threads, both mutex_ and log_write_mutex_ are
+  //    held.
+  // 2. pop_front() by FindObsoleteFiles(), both mutex_ and log_write_mutex_
+  //    are held.
+  // 3. push_back() by DBImpl::Open() and DBImpl::RestoreAliveLogFiles()
+  //    (actually called by Open()), only mutex_ is held because at this point,
+  //    the DB::Open() call has not returned success to application, and the
+  //    only other thread(s) that can conflict are bg threads calling
+  //    FindObsoleteFiles() which ensure that both mutex_ and log_write_mutex_
+  //    are held when accessing alive_log_files_.
+  // 4. read by DBImpl::Open() is protected by mutex_.
+  // 5. push_back() by SwitchMemtable(). Both mutex_ and log_write_mutex_ are
+  //    held. This is done by the write group leader. Note that in the case of
+  //    two-write-queues, another WAL-only write thread can be writing to the
+  //    WAL concurrently. See 9.
+  // 6. read by SwitchWAL() with both mutex_ and log_write_mutex_ held. This is
+  //    done by write group leader.
+  // 7. read by ConcurrentWriteToWAL() by the write group leader in the case of
+  //    two-write-queues. Only log_write_mutex_ is held to protect concurrent
+  //    pop_front() by FindObsoleteFiles().
+  // 8. read by PreprocessWrite() by the write group leader. log_write_mutex_
+  //    is held to protect the data structure from concurrent pop_front() by
+  //    FindObsoleteFiles().
+  // 9. read by ConcurrentWriteToWAL() by a WAL-only write thread in the case
+  //    of two-write-queues. Only log_write_mutex_ is held. This suffices to
+  //    protect the data structure from concurrent push_back() by current
+  //    write group leader as well as pop_front() by FindObsoleteFiles().
   std::deque<LogFileNumberSize> alive_log_files_;
 
   // Log files that aren't fully synced, and the current log file.
   // Synchronization:
-  //  - push_back() is done from write_thread_ with locked mutex_ and
-  //  log_write_mutex_
-  //  - pop_front() is done from any thread with locked mutex_ and
-  //  log_write_mutex_
-  //  - reads are done with either locked mutex_ or log_write_mutex_
+  // 1. read by FindObsoleteFiles() which can be called either in application
+  //    thread or RocksDB bg threads. log_write_mutex_ is always held, while
+  //    some reads are performed without mutex_.
+  // 2. pop_front() by FindObsoleteFiles() with only log_write_mutex_ held.
+  // 3. read by DBImpl::Open() with both mutex_ and log_write_mutex_.
+  // 4. emplace_back() by DBImpl::Open() with both mutex_ and log_write_mutex.
+  //    Note that at this point, DB::Open() has not returned success to
+  //    application, thus the only other thread(s) that can conflict are bg
+  //    threads calling FindObsoleteFiles(). See 1.
+  // 5. iteration and clear() from CloseHelper() always hold log_write_mutex
+  //    and mutex_.
+  // 6. back() called by APIs FlushWAL() and LockWAL() are protected by only
+  //    log_write_mutex_. These two can be called by application threads after
+  //    DB::Open() returns success to applications.
+  // 7. read by SyncWAL(), another API, protected by only log_write_mutex_.
+  // 8. read by MarkLogsNotSynced() and MarkLogsSynced() are protected by
+  //    log_write_mutex_.
+  // 9. erase() by MarkLogsSynced() protected by log_write_mutex_.
+  // 10. read by SyncClosedLogs() protected by only log_write_mutex_. This can
+  //     happen in bg flush threads after DB::Open() returns success to
+  //     applications.
+  // 11. reads, e.g. front(), iteration, and back() called by PreprocessWrite()
+  //     holds only the log_write_mutex_. This is done by the write group
+  //     leader. A bg thread calling FindObsoleteFiles() or MarkLogsSynced()
+  //     can happen concurrently. This is fine because log_write_mutex_ is used
+  //     by all parties. See 2, 5, 9.
+  // 12. reads, empty(), back() called by SwitchMemtable() hold both mutex_ and
+  //     log_write_mutex_. This happens in the write group leader.
+  // 13. emplace_back() by SwitchMemtable() hold both mutex_ and
+  //     log_write_mutex_. This happens in the write group leader. Can conflict
+  //     with bg threads calling FindObsoleteFiles(), MarkLogsSynced(),
+  //     SyncClosedLogs(), etc. as well as application threads calling
+  //     FlushWAL(), SyncWAL(), LockWAL(). This is fine because all parties
+  //     require at least log_write_mutex_.
+  // 14. iteration called in WriteToWAL(write_group) protected by
+  //     log_write_mutex_. This is done by write group leader when
+  //     two-write-queues is disabled and write needs to sync logs.
+  // 15. back() called in ConcurrentWriteToWAL() protected by log_write_mutex_.
+  //     This can be done by the write group leader if two-write-queues is
+  //     enabled. It can also be done by another WAL-only write thread.
+  //
+  // Other observations:
   //  - back() and items with getting_synced=true are not popped,
   //  - The same thread that sets getting_synced=true will reset it.
   //  - it follows that the object referred by back() can be safely read from
-  //  the write_thread_ without using mutex
+  //  the write_thread_ without using mutex. Note that calling back() without
+  //  mutex may be unsafe because different implementations of deque::back() may
+  //  access other member variables of deque, causing undefined behaviors.
+  //  Generally, do not access stl containers without proper synchronization.
   //  - it follows that the items with getting_synced=true can be safely read
   //  from the same thread that has set getting_synced=true
   std::deque<LogWriterNumber> logs_;
+
   // Signaled when getting_synced becomes false for some of the logs_.
   InstrumentedCondVar log_sync_cv_;
   // This is the app-level state that is written to the WAL but will be used
@@ -2335,7 +2424,7 @@ class DBImpl : public DB {
   std::atomic<uint64_t> total_log_size_;
 
   // If this is non-empty, we need to delete these log files in background
-  // threads. Protected by db mutex.
+  // threads. Protected by log_write_mutex_.
   autovector<log::Writer*> logs_to_free_;
 
   bool is_snapshot_supported_;
@@ -2415,10 +2504,13 @@ class DBImpl : public DB {
   // JobContext. Current implementation tracks table and blob files only.
   std::unordered_set<uint64_t> files_grabbed_for_purge_;
 
-  // A queue to store log writers to close
+  // A queue to store log writers to close. Protected by db mutex_.
   std::deque<log::Writer*> logs_to_free_queue_;
+
   std::deque<SuperVersion*> superversions_to_free_queue_;
+
   int unscheduled_flushes_;
+
   int unscheduled_compactions_;
 
   // count how many background compactions are running or have been scheduled in
@@ -2482,12 +2574,6 @@ class DBImpl : public DB {
   // log is fully commited.
   bool unable_to_release_oldest_log_;
 
-  static const int KEEP_LOG_FILE_NUM = 1000;
-  // MSVC version 1800 still does not have constexpr for ::max()
-  static const uint64_t kNoTimeOut = std::numeric_limits<uint64_t>::max();
-
-  std::string db_absolute_path_;
-
   // Number of running IngestExternalFile() or CreateColumnFamilyWithImport()
   // calls.
   // REQUIRES: mutex held
@@ -2529,6 +2615,10 @@ class DBImpl : public DB {
   // PeriodicWorkScheduler::Default(). Only in unittest, it can be overrided by
   // PeriodicWorkTestScheduler.
   PeriodicWorkScheduler* periodic_work_scheduler_;
+
+  // Current cadence of the periodic worker for recording sequence number to
+  // time.
+  uint64_t record_seqno_time_cadence_ = 0;
 #endif
 
   // When set, we use a separate queue for writes that don't write to memtable.
@@ -2573,11 +2663,16 @@ class DBImpl : public DB {
   InstrumentedCondVar atomic_flush_install_cv_;
 
   bool wal_in_db_path_;
+  std::atomic<uint64_t> max_total_wal_size_;
 
   BlobFileCompletionCallback blob_callback_;
 
   // Pointer to WriteBufferManager stalling interface.
   std::unique_ptr<StallInterface> wbm_stall_;
+
+  // seqno_time_mapping_ stores the sequence number to time mapping, it's not
+  // thread safe, both read and write need db mutex hold.
+  SeqnoToTimeMapping seqno_time_mapping_;
 };
 
 class GetWithTimestampReadCallback : public ReadCallback {
@@ -2590,10 +2685,12 @@ class GetWithTimestampReadCallback : public ReadCallback {
 };
 
 extern Options SanitizeOptions(const std::string& db, const Options& src,
-                               bool read_only = false);
+                               bool read_only = false,
+                               Status* logger_creation_s = nullptr);
 
 extern DBOptions SanitizeOptions(const std::string& db, const DBOptions& src,
-                                 bool read_only = false);
+                                 bool read_only = false,
+                                 Status* logger_creation_s = nullptr);
 
 extern CompressionType GetCompressionFlush(
     const ImmutableCFOptions& ioptions,

db/db_impl/db_impl_compaction_flush.cc

@@ -82,9 +82,10 @@ bool DBImpl::RequestCompactionToken(ColumnFamilyData* cfd, bool force,
   return false;
 }
 
-IOStatus DBImpl::SyncClosedLogs(JobContext* job_context) {
+IOStatus DBImpl::SyncClosedLogs(JobContext* job_context,
+                                VersionEdit* synced_wals) {
   TEST_SYNC_POINT("DBImpl::SyncClosedLogs:Start");
-  mutex_.AssertHeld();
+  InstrumentedMutexLock l(&log_write_mutex_);
   autovector<log::Writer*, 1> logs_to_sync;
   uint64_t current_log_number = logfile_number_;
   while (logs_.front().number < current_log_number &&
@@ -100,7 +101,7 @@ IOStatus DBImpl::SyncClosedLogs(JobContext* job_context) {
 
   IOStatus io_s;
   if (!logs_to_sync.empty()) {
-    mutex_.Unlock();
+    log_write_mutex_.Unlock();
 
     assert(job_context);
 
@@ -108,12 +109,18 @@ IOStatus DBImpl::SyncClosedLogs(JobContext* job_context) {
       ROCKS_LOG_INFO(immutable_db_options_.info_log,
                      "[JOB %d] Syncing log #%" PRIu64, job_context->job_id,
                      log->get_log_number());
+      if (error_handler_.IsRecoveryInProgress()) {
+        log->file()->reset_seen_error();
+      }
       io_s = log->file()->Sync(immutable_db_options_.use_fsync);
       if (!io_s.ok()) {
         break;
       }
 
       if (immutable_db_options_.recycle_log_file_num > 0) {
+        if (error_handler_.IsRecoveryInProgress()) {
+          log->file()->reset_seen_error();
+        }
         io_s = log->Close();
         if (!io_s.ok()) {
           break;
@@ -128,12 +135,12 @@ IOStatus DBImpl::SyncClosedLogs(JobContext* job_context) {
 
     TEST_SYNC_POINT_CALLBACK("DBImpl::SyncClosedLogs:BeforeReLock",
                              /*arg=*/nullptr);
-    mutex_.Lock();
+    log_write_mutex_.Lock();
 
     // "number <= current_log_number - 1" is equivalent to
     // "number < current_log_number".
     if (io_s.ok()) {
-      io_s = status_to_io_status(MarkLogsSynced(current_log_number - 1, true));
+      MarkLogsSynced(current_log_number - 1, true, synced_wals);
     } else {
       MarkLogsNotSynced(current_log_number - 1);
     }
@@ -212,16 +219,26 @@ Status DBImpl::FlushMemTableToOutputFile(
       GetCompressionFlush(*cfd->ioptions(), mutable_cf_options), stats_,
       &event_logger_, mutable_cf_options.report_bg_io_stats,
       true /* sync_output_directory */, true /* write_manifest */, thread_pri,
-      io_tracer_, db_id_, db_session_id_, cfd->GetFullHistoryTsLow(),
-      &blob_callback_);
+      io_tracer_, seqno_time_mapping_, db_id_, db_session_id_,
+      cfd->GetFullHistoryTsLow(), &blob_callback_);
   FileMetaData file_meta;
 
   Status s;
   bool need_cancel = false;
   IOStatus log_io_s = IOStatus::OK();
   if (needs_to_sync_closed_wals) {
-    // SyncClosedLogs() may unlock and re-lock the db_mutex.
-    log_io_s = SyncClosedLogs(job_context);
+    // SyncClosedLogs() may unlock and re-lock the log_write_mutex multiple
+    // times.
+    VersionEdit synced_wals;
+    mutex_.Unlock();
+    log_io_s = SyncClosedLogs(job_context, &synced_wals);
+    mutex_.Lock();
+    if (log_io_s.ok() && synced_wals.IsWalAddition()) {
+      log_io_s = status_to_io_status(ApplyWALToManifest(&synced_wals));
+      TEST_SYNC_POINT_CALLBACK("DBImpl::FlushMemTableToOutputFile:CommitWal:1",
+                               nullptr);
+    }
+
     if (!log_io_s.ok() && !log_io_s.IsShutdownInProgress() &&
         !log_io_s.IsColumnFamilyDropped()) {
       error_handler_.SetBGError(log_io_s, BackgroundErrorReason::kFlush);
@@ -450,7 +467,7 @@ Status DBImpl::AtomicFlushMemTablesToOutputFiles(
         data_dir, GetCompressionFlush(*cfd->ioptions(), mutable_cf_options),
         stats_, &event_logger_, mutable_cf_options.report_bg_io_stats,
         false /* sync_output_directory */, false /* write_manifest */,
-        thread_pri, io_tracer_, db_id_, db_session_id_,
+        thread_pri, io_tracer_, seqno_time_mapping_, db_id_, db_session_id_,
         cfd->GetFullHistoryTsLow(), &blob_callback_));
   }
 
@@ -474,7 +491,14 @@ Status DBImpl::AtomicFlushMemTablesToOutputFiles(
   if (logfile_number_ > 0) {
     // TODO (yanqin) investigate whether we should sync the closed logs for
     // single column family case.
-    log_io_s = SyncClosedLogs(job_context);
+    VersionEdit synced_wals;
+    mutex_.Unlock();
+    log_io_s = SyncClosedLogs(job_context, &synced_wals);
+    mutex_.Lock();
+    if (log_io_s.ok() && synced_wals.IsWalAddition()) {
+      log_io_s = status_to_io_status(ApplyWALToManifest(&synced_wals));
+    }
+
     if (!log_io_s.ok() && !log_io_s.IsShutdownInProgress() &&
         !log_io_s.IsColumnFamilyDropped()) {
       if (total_log_size_ > 0) {
@@ -1392,7 +1416,8 @@ Status DBImpl::CompactFilesImpl(
       &compaction_job_stats, Env::Priority::USER, io_tracer_,
       kManualCompactionCanceledFalse_, db_id_, db_session_id_,
       c->column_family_data()->GetFullHistoryTsLow(), c->trim_ts(),
-      &blob_callback_);
+      &blob_callback_, &bg_compaction_scheduled_,
+      &bg_bottom_compaction_scheduled_);
 
   // Creating a compaction influences the compaction score because the score
   // takes running compactions into account (by skipping files that are already
@@ -1669,8 +1694,7 @@ Status DBImpl::ReFitLevel(ColumnFamilyData* cfd, int level, int target_level) {
           f->smallest, f->largest, f->fd.smallest_seqno, f->fd.largest_seqno,
           f->marked_for_compaction, f->temperature, f->oldest_blob_file_number,
           f->oldest_ancester_time, f->file_creation_time, f->file_checksum,
-          f->file_checksum_func_name, f->min_timestamp, f->max_timestamp,
-          f->unique_id);
+          f->file_checksum_func_name, f->unique_id);
     }
     ROCKS_LOG_DEBUG(immutable_db_options_.info_log,
                     "[%s] Apply version edit:\n%s", cfd->GetName().c_str(),
@@ -1836,8 +1860,7 @@ Status DBImpl::RunManualCompaction(
   // jobs drops to zero. This used to be needed to ensure that this manual
   // compaction can compact any range of keys/files. Now it is optional
   // (see `CompactRangeOptions::exclusive_manual_compaction`). The use case for
-  // `exclusive_manual_compaction=true` (the default) is unclear beyond not
-  // trusting the new code.
+  // `exclusive_manual_compaction=true` is unclear beyond not trusting the code.
   //
   // HasPendingManualCompaction() is true when at least one thread is inside
   // RunManualCompaction(), i.e. during that time no other compaction will
@@ -2237,7 +2260,7 @@ Status DBImpl::AtomicFlushMemTables(
 // This method tries to avoid write stall (similar to CompactRange() behavior)
 // it emulates how the SuperVersion / LSM would change if flush happens, checks
 // it against various constrains and delays flush if it'd cause write stall.
-// Called should check status and flush_needed to see if flush already happened.
+// Caller should check status and flush_needed to see if flush already happened.
 Status DBImpl::WaitUntilFlushWouldNotStallWrites(ColumnFamilyData* cfd,
                                                  bool* flush_needed) {
   {
@@ -2616,17 +2639,7 @@ void DBImpl::SchedulePendingFlush(const FlushRequest& flush_req,
     assert(flush_req.size() == 1);
     ColumnFamilyData* cfd = flush_req[0].first;
     assert(cfd);
-    // Note: SchedulePendingFlush is always preceded
-    // with an imm()->FlushRequested() call. However,
-    // we want to make this code snipper more resilient to
-    // future changes. Therefore, we add the following if
-    // statement - note that calling it twice (or more)
-    // doesn't break anything.
-    if (immutable_db_options_.experimental_mempurge_threshold > 0.0) {
-      // If imm() contains silent memtables,
-      // requesting a flush will mark the imm_needed as true.
-      cfd->imm()->FlushRequested();
-    }
+
     if (!cfd->queued_for_flush() && cfd->imm()->IsFlushPending()) {
       cfd->Ref();
       cfd->set_queued_for_flush(true);
@@ -2775,11 +2788,13 @@ Status DBImpl::BackgroundFlush(bool* made_progress, JobContext* job_context,
 
     for (const auto& iter : flush_req) {
       ColumnFamilyData* cfd = iter.first;
-      if (immutable_db_options_.experimental_mempurge_threshold > 0.0) {
-        // If imm() contains silent memtables,
-        // requesting a flush will mark the imm_needed as true.
+      if (cfd->GetMempurgeUsed()) {
+        // If imm() contains silent memtables (e.g.: because
+        // MemPurge was activated), requesting a flush will
+        // mark the imm_needed as true.
         cfd->imm()->FlushRequested();
       }
+
       if (cfd->IsDropped() || !cfd->imm()->IsFlushPending()) {
         // can't flush this CF, try next one
         column_families_not_to_flush.push_back(cfd);
@@ -3305,7 +3320,7 @@ Status DBImpl::BackgroundCompaction(bool* made_progress,
             f->fd.largest_seqno, f->marked_for_compaction, f->temperature,
             f->oldest_blob_file_number, f->oldest_ancester_time,
             f->file_creation_time, f->file_checksum, f->file_checksum_func_name,
-            f->min_timestamp, f->max_timestamp, f->unique_id);
+            f->unique_id);
 
         ROCKS_LOG_BUFFER(
             log_buffer,
@@ -3316,7 +3331,16 @@ Status DBImpl::BackgroundCompaction(bool* made_progress,
         moved_bytes += f->fd.GetFileSize();
       }
     }
-
+    if (c->compaction_reason() == CompactionReason::kLevelMaxLevelSize &&
+        c->immutable_options()->compaction_pri == kRoundRobin) {
+      int start_level = c->start_level();
+      if (start_level > 0) {
+        auto vstorage = c->input_version()->storage_info();
+        c->edit()->AddCompactCursor(
+            start_level,
+            vstorage->GetNextCompactCursor(start_level, c->num_input_files(0)));
+      }
+    }
     status = versions_->LogAndApply(c->column_family_data(),
                                     *c->mutable_cf_options(), c->edit(),
                                     &mutex_, directories_.GetDbDir());
@@ -3399,7 +3423,8 @@ Status DBImpl::BackgroundCompaction(bool* made_progress,
         is_manual ? manual_compaction->canceled
                   : kManualCompactionCanceledFalse_,
         db_id_, db_session_id_, c->column_family_data()->GetFullHistoryTsLow(),
-        c->trim_ts(), &blob_callback_);
+        c->trim_ts(), &blob_callback_, &bg_compaction_scheduled_,
+        &bg_bottom_compaction_scheduled_);
     compaction_job.Prepare();
 
     NotifyOnCompactionBegin(c->column_family_data(), c.get(), status,
@@ -3802,11 +3827,6 @@ void DBImpl::GetSnapshotContext(
 
 Status DBImpl::WaitForCompact(bool wait_unscheduled) {
   // Wait until the compaction completes
-
-  // TODO: a bug here. This function actually does not necessarily
-  // wait for compact. It actually waits for scheduled compaction
-  // OR flush to finish.
-
   InstrumentedMutexLock l(&mutex_);
   while ((bg_bottom_compaction_scheduled_ || bg_compaction_scheduled_ ||
           bg_flush_scheduled_ ||

db/db_impl/db_impl_debug.cc

@@ -223,7 +223,7 @@ void DBImpl::TEST_EndWrite(void* w) {
 }
 
 size_t DBImpl::TEST_LogsToFreeSize() {
-  InstrumentedMutexLock l(&mutex_);
+  InstrumentedMutexLock l(&log_write_mutex_);
   return logs_to_free_.size();
 }
 
@@ -302,7 +302,8 @@ size_t DBImpl::TEST_GetWalPreallocateBlockSize(
 }
 
 #ifndef ROCKSDB_LITE
-void DBImpl::TEST_WaitForStatsDumpRun(std::function<void()> callback) const {
+void DBImpl::TEST_WaitForPeridicWorkerRun(
+    std::function<void()> callback) const {
   if (periodic_work_scheduler_ != nullptr) {
     static_cast<PeriodicWorkTestScheduler*>(periodic_work_scheduler_)
         ->TEST_WaitForRun(callback);
@@ -312,6 +313,12 @@ void DBImpl::TEST_WaitForStatsDumpRun(std::function<void()> callback) const {
 PeriodicWorkTestScheduler* DBImpl::TEST_GetPeriodicWorkScheduler() const {
   return static_cast<PeriodicWorkTestScheduler*>(periodic_work_scheduler_);
 }
+
+SeqnoToTimeMapping DBImpl::TEST_GetSeqnoToTimeMapping() const {
+  InstrumentedMutexLock l(&mutex_);
+  return seqno_time_mapping_;
+}
+
 #endif  // !ROCKSDB_LITE
 
 size_t DBImpl::TEST_EstimateInMemoryStatsHistorySize() const {

db/db_impl/db_impl_experimental.cc

@@ -131,13 +131,13 @@ Status DBImpl::PromoteL0(ColumnFamilyHandle* column_family, int target_level) {
     edit.SetColumnFamily(cfd->GetID());
     for (const auto& f : l0_files) {
       edit.DeleteFile(0, f->fd.GetNumber());
-      edit.AddFile(
-          target_level, f->fd.GetNumber(), f->fd.GetPathId(),
-          f->fd.GetFileSize(), f->smallest, f->largest, f->fd.smallest_seqno,
-          f->fd.largest_seqno, f->marked_for_compaction, f->temperature,
-          f->oldest_blob_file_number, f->oldest_ancester_time,
-          f->file_creation_time, f->file_checksum, f->file_checksum_func_name,
-          f->min_timestamp, f->max_timestamp, f->unique_id);
+      edit.AddFile(target_level, f->fd.GetNumber(), f->fd.GetPathId(),
+                   f->fd.GetFileSize(), f->smallest, f->largest,
+                   f->fd.smallest_seqno, f->fd.largest_seqno,
+                   f->marked_for_compaction, f->temperature,
+                   f->oldest_blob_file_number, f->oldest_ancester_time,
+                   f->file_creation_time, f->file_checksum,
+                   f->file_checksum_func_name, f->unique_id);
     }
 
     status = versions_->LogAndApply(cfd, *cfd->GetLatestMutableCFOptions(),

db/db_impl/db_impl_files.cc

@@ -19,6 +19,7 @@
 #include "logging/logging.h"
 #include "port/port.h"
 #include "util/autovector.h"
+#include "util/defer.h"
 
 namespace ROCKSDB_NAMESPACE {
 
@@ -252,8 +253,33 @@ void DBImpl::FindObsoleteFiles(JobContext* job_context, bool force,
                                job_context->blob_delete_files);
   }
 
+  // Before potentially releasing mutex and waiting on condvar, increment
+  // pending_purge_obsolete_files_ so that another thread executing
+  // `GetSortedWals` will wait until this thread finishes execution since the
+  // other thread will be waiting for `pending_purge_obsolete_files_`.
+  // pending_purge_obsolete_files_ MUST be decremented if there is nothing to
+  // delete.
+  ++pending_purge_obsolete_files_;
+
+  Defer cleanup([job_context, this]() {
+    assert(job_context != nullptr);
+    if (!job_context->HaveSomethingToDelete()) {
+      mutex_.AssertHeld();
+      --pending_purge_obsolete_files_;
+    }
+  });
+
   // logs_ is empty when called during recovery, in which case there can't yet
   // be any tracked obsolete logs
+  log_write_mutex_.Lock();
+
+  if (alive_log_files_.empty() || logs_.empty()) {
+    mutex_.AssertHeld();
+    // We may reach here if the db is DBImplSecondary
+    log_write_mutex_.Unlock();
+    return;
+  }
+
   if (!alive_log_files_.empty() && !logs_.empty()) {
     uint64_t min_log_number = job_context->log_number;
     size_t num_alive_log_files = alive_log_files_.size();
@@ -275,17 +301,15 @@ void DBImpl::FindObsoleteFiles(JobContext* job_context, bool force,
       }
       job_context->size_log_to_delete += earliest.size;
       total_log_size_ -= earliest.size;
-      if (two_write_queues_) {
-        log_write_mutex_.Lock();
-      }
       alive_log_files_.pop_front();
-      if (two_write_queues_) {
-        log_write_mutex_.Unlock();
-      }
+
       // Current log should always stay alive since it can't have
       // number < MinLogNumber().
       assert(alive_log_files_.size());
     }
+    log_write_mutex_.Unlock();
+    mutex_.Unlock();
+    log_write_mutex_.Lock();
     while (!logs_.empty() && logs_.front().number < min_log_number) {
       auto& log = logs_.front();
       if (log.IsSyncing()) {
@@ -294,10 +318,7 @@ void DBImpl::FindObsoleteFiles(JobContext* job_context, bool force,
         continue;
       }
       logs_to_free_.push_back(log.ReleaseWriter());
-      {
-        InstrumentedMutexLock wl(&log_write_mutex_);
-        logs_.pop_front();
-      }
+      logs_.pop_front();
     }
     // Current log cannot be obsolete.
     assert(!logs_.empty());
@@ -306,27 +327,14 @@ void DBImpl::FindObsoleteFiles(JobContext* job_context, bool force,
   // We're just cleaning up for DB::Write().
   assert(job_context->logs_to_free.empty());
   job_context->logs_to_free = logs_to_free_;
+
+  logs_to_free_.clear();
+  log_write_mutex_.Unlock();
+  mutex_.Lock();
   job_context->log_recycle_files.assign(log_recycle_files_.begin(),
                                         log_recycle_files_.end());
-  if (job_context->HaveSomethingToDelete()) {
-    ++pending_purge_obsolete_files_;
-  }
-  logs_to_free_.clear();
 }
 
-namespace {
-bool CompareCandidateFile(const JobContext::CandidateFileInfo& first,
-                          const JobContext::CandidateFileInfo& second) {
-  if (first.file_name > second.file_name) {
-    return true;
-  } else if (first.file_name < second.file_name) {
-    return false;
-  } else {
-    return (first.file_path > second.file_path);
-  }
-}
-}  // namespace
-
 // Delete obsolete files and log status and information of file deletion
 void DBImpl::DeleteObsoleteFileImpl(int job_id, const std::string& fname,
                                     const std::string& path_to_sync,
@@ -431,7 +439,16 @@ void DBImpl::PurgeObsoleteFiles(JobContext& state, bool schedule_only) {
   // dedup state.candidate_files so we don't try to delete the same
   // file twice
   std::sort(candidate_files.begin(), candidate_files.end(),
-            CompareCandidateFile);
+            [](const JobContext::CandidateFileInfo& lhs,
+               const JobContext::CandidateFileInfo& rhs) {
+              if (lhs.file_name > rhs.file_name) {
+                return true;
+              } else if (lhs.file_name < rhs.file_name) {
+                return false;
+              } else {
+                return (lhs.file_path > rhs.file_path);
+              }
+            });
   candidate_files.erase(
       std::unique(candidate_files.begin(), candidate_files.end()),
       candidate_files.end());

db/db_impl/db_impl_open.cc

@@ -27,8 +27,9 @@
 
 namespace ROCKSDB_NAMESPACE {
 Options SanitizeOptions(const std::string& dbname, const Options& src,
-                        bool read_only) {
-  auto db_options = SanitizeOptions(dbname, DBOptions(src), read_only);
+                        bool read_only, Status* logger_creation_s) {
+  auto db_options =
+      SanitizeOptions(dbname, DBOptions(src), read_only, logger_creation_s);
   ImmutableDBOptions immutable_db_options(db_options);
   auto cf_options =
       SanitizeOptions(immutable_db_options, ColumnFamilyOptions(src));
@@ -36,7 +37,7 @@ Options SanitizeOptions(const std::string& dbname, const Options& src,
 }
 
 DBOptions SanitizeOptions(const std::string& dbname, const DBOptions& src,
-                          bool read_only) {
+                          bool read_only, Status* logger_creation_s) {
   DBOptions result(src);
 
   if (result.env == nullptr) {
@@ -59,6 +60,9 @@ DBOptions SanitizeOptions(const std::string& dbname, const DBOptions& src,
     if (!s.ok()) {
       // No place suitable for logging
       result.info_log = nullptr;
+      if (logger_creation_s) {
+        *logger_creation_s = s;
+      }
     }
   }
 
@@ -437,11 +441,14 @@ Status DBImpl::Recover(
         uint64_t number = 0;
         FileType type = kWalFile;  // initialize
         if (ParseFileName(file, &number, &type) && type == kDescriptorFile) {
-          // Found MANIFEST (descriptor log), thus best-efforts recovery does
-          // not have to treat the db as empty.
-          s = Status::OK();
-          manifest_path = dbname_ + "/" + file;
-          break;
+          uint64_t bytes;
+          s = env_->GetFileSize(DescriptorFileName(dbname_, number), &bytes);
+          if (s.ok() && bytes != 0) {
+            // Found non-empty MANIFEST (descriptor log), thus best-efforts
+            // recovery does not have to treat the db as empty.
+            manifest_path = dbname_ + "/" + file;
+            break;
+          }
         }
       }
     }
@@ -534,6 +541,7 @@ Status DBImpl::Recover(
     s = CheckConsistency();
   }
   if (s.ok() && !read_only) {
+    // TODO: share file descriptors (FSDirectory) with SetDirectories above
     std::map<std::string, std::shared_ptr<FSDirectory>> created_dirs;
     for (auto cfd : *versions_->GetColumnFamilySet()) {
       s = cfd->AddDirectories(&created_dirs);
@@ -714,6 +722,12 @@ Status DBImpl::VerifySstUniqueIdInManifest() {
       status = version->VerifySstUniqueIds();
       mutex_.Lock();
       version->Unref();
+      if (!status.ok()) {
+        ROCKS_LOG_WARN(immutable_db_options_.info_log,
+                       "SST unique id mismatch in column family \"%s\": %s",
+                       cfd->GetName().c_str(), status.ToString().c_str());
+        return status;
+      }
     }
   }
   return status;
@@ -845,6 +859,131 @@ Status DBImpl::LogAndApplyForRecovery(const RecoveryContext& recovery_ctx) {
   return s;
 }
 
+void DBImpl::InvokeWalFilterIfNeededOnColumnFamilyToWalNumberMap() {
+#ifndef ROCKSDB_LITE
+  if (immutable_db_options_.wal_filter == nullptr) {
+    return;
+  }
+  assert(immutable_db_options_.wal_filter != nullptr);
+  WalFilter& wal_filter = *(immutable_db_options_.wal_filter);
+
+  std::map<std::string, uint32_t> cf_name_id_map;
+  std::map<uint32_t, uint64_t> cf_lognumber_map;
+  assert(versions_);
+  assert(versions_->GetColumnFamilySet());
+  for (auto cfd : *versions_->GetColumnFamilySet()) {
+    assert(cfd);
+    cf_name_id_map.insert(std::make_pair(cfd->GetName(), cfd->GetID()));
+    cf_lognumber_map.insert(std::make_pair(cfd->GetID(), cfd->GetLogNumber()));
+  }
+
+  wal_filter.ColumnFamilyLogNumberMap(cf_lognumber_map, cf_name_id_map);
+#endif  // !ROCKSDB_LITE
+}
+
+bool DBImpl::InvokeWalFilterIfNeededOnWalRecord(uint64_t wal_number,
+                                                const std::string& wal_fname,
+                                                log::Reader::Reporter& reporter,
+                                                Status& status,
+                                                bool& stop_replay,
+                                                WriteBatch& batch) {
+#ifndef ROCKSDB_LITE
+  if (immutable_db_options_.wal_filter == nullptr) {
+    return true;
+  }
+  assert(immutable_db_options_.wal_filter != nullptr);
+  WalFilter& wal_filter = *(immutable_db_options_.wal_filter);
+
+  WriteBatch new_batch;
+  bool batch_changed = false;
+
+  bool process_current_record = true;
+
+  WalFilter::WalProcessingOption wal_processing_option =
+      wal_filter.LogRecordFound(wal_number, wal_fname, batch, &new_batch,
+                                &batch_changed);
+
+  switch (wal_processing_option) {
+    case WalFilter::WalProcessingOption::kContinueProcessing:
+      // do nothing, proceeed normally
+      break;
+    case WalFilter::WalProcessingOption::kIgnoreCurrentRecord:
+      // skip current record
+      process_current_record = false;
+      break;
+    case WalFilter::WalProcessingOption::kStopReplay:
+      // skip current record and stop replay
+      process_current_record = false;
+      stop_replay = true;
+      break;
+    case WalFilter::WalProcessingOption::kCorruptedRecord: {
+      status = Status::Corruption("Corruption reported by Wal Filter ",
+                                  wal_filter.Name());
+      MaybeIgnoreError(&status);
+      if (!status.ok()) {
+        process_current_record = false;
+        reporter.Corruption(batch.GetDataSize(), status);
+      }
+      break;
+    }
+    default: {
+      // logical error which should not happen. If RocksDB throws, we would
+      // just do `throw std::logic_error`.
+      assert(false);
+      status = Status::NotSupported(
+          "Unknown WalProcessingOption returned by Wal Filter ",
+          wal_filter.Name());
+      MaybeIgnoreError(&status);
+      if (!status.ok()) {
+        // Ignore the error with current record processing.
+        stop_replay = true;
+      }
+      break;
+    }
+  }
+
+  if (!process_current_record) {
+    return false;
+  }
+
+  if (batch_changed) {
+    // Make sure that the count in the new batch is
+    // within the orignal count.
+    int new_count = WriteBatchInternal::Count(&new_batch);
+    int original_count = WriteBatchInternal::Count(&batch);
+    if (new_count > original_count) {
+      ROCKS_LOG_FATAL(
+          immutable_db_options_.info_log,
+          "Recovering log #%" PRIu64
+          " mode %d log filter %s returned "
+          "more records (%d) than original (%d) which is not allowed. "
+          "Aborting recovery.",
+          wal_number, static_cast<int>(immutable_db_options_.wal_recovery_mode),
+          wal_filter.Name(), new_count, original_count);
+      status = Status::NotSupported(
+          "More than original # of records "
+          "returned by Wal Filter ",
+          wal_filter.Name());
+      return false;
+    }
+    // Set the same sequence number in the new_batch
+    // as the original batch.
+    WriteBatchInternal::SetSequence(&new_batch,
+                                    WriteBatchInternal::Sequence(&batch));
+    batch = new_batch;
+  }
+  return true;
+#else   // !ROCKSDB_LITE
+  (void)wal_number;
+  (void)wal_fname;
+  (void)reporter;
+  (void)status;
+  (void)stop_replay;
+  (void)batch;
+  return true;
+#endif  // ROCKSDB_LITE
+}
+
 // REQUIRES: wal_numbers are sorted in ascending order
 Status DBImpl::RecoverLogFiles(const std::vector<uint64_t>& wal_numbers,
                                SequenceNumber* next_sequence, bool read_only,
@@ -887,20 +1026,8 @@ Status DBImpl::RecoverLogFiles(const std::vector<uint64_t>& wal_numbers,
     stream.EndArray();
   }
 
-#ifndef ROCKSDB_LITE
-  if (immutable_db_options_.wal_filter != nullptr) {
-    std::map<std::string, uint32_t> cf_name_id_map;
-    std::map<uint32_t, uint64_t> cf_lognumber_map;
-    for (auto cfd : *versions_->GetColumnFamilySet()) {
-      cf_name_id_map.insert(std::make_pair(cfd->GetName(), cfd->GetID()));
-      cf_lognumber_map.insert(
-          std::make_pair(cfd->GetID(), cfd->GetLogNumber()));
-    }
-
-    immutable_db_options_.wal_filter->ColumnFamilyLogNumberMap(cf_lognumber_map,
-                                                               cf_name_id_map);
-  }
-#endif
+  // No-op for immutable_db_options_.wal_filter == nullptr.
+  InvokeWalFilterIfNeededOnColumnFamilyToWalNumberMap();
 
   bool stop_replay_by_wal_filter = false;
   bool stop_replay_for_corruption = false;
@@ -991,9 +1118,11 @@ Status DBImpl::RecoverLogFiles(const std::vector<uint64_t>& wal_numbers,
 
     TEST_SYNC_POINT_CALLBACK("DBImpl::RecoverLogFiles:BeforeReadWal",
                              /*arg=*/nullptr);
+    uint64_t record_checksum;
     while (!stop_replay_by_wal_filter &&
            reader.ReadRecord(&record, &scratch,
-                             immutable_db_options_.wal_recovery_mode) &&
+                             immutable_db_options_.wal_recovery_mode,
+                             &record_checksum) &&
            status.ok()) {
       if (record.size() < WriteBatchInternal::kHeader) {
         reporter.Corruption(record.size(),
@@ -1009,8 +1138,13 @@ Status DBImpl::RecoverLogFiles(const std::vector<uint64_t>& wal_numbers,
       if (!status.ok()) {
         return status;
       }
-      status = WriteBatchInternal::UpdateProtectionInfo(&batch,
-                                                        8 /* bytes_per_key */);
+      TEST_SYNC_POINT_CALLBACK(
+          "DBImpl::RecoverLogFiles:BeforeUpdateProtectionInfo:batch", &batch);
+      TEST_SYNC_POINT_CALLBACK(
+          "DBImpl::RecoverLogFiles:BeforeUpdateProtectionInfo:checksum",
+          &record_checksum);
+      status = WriteBatchInternal::UpdateProtectionInfo(
+          &batch, 8 /* bytes_per_key */, &record_checksum);
       if (!status.ok()) {
         return status;
       }
@@ -1032,83 +1166,13 @@ Status DBImpl::RecoverLogFiles(const std::vector<uint64_t>& wal_numbers,
         }
       }
 
-#ifndef ROCKSDB_LITE
-      if (immutable_db_options_.wal_filter != nullptr) {
-        WriteBatch new_batch;
-        bool batch_changed = false;
-
-        WalFilter::WalProcessingOption wal_processing_option =
-            immutable_db_options_.wal_filter->LogRecordFound(
-                wal_number, fname, batch, &new_batch, &batch_changed);
-
-        switch (wal_processing_option) {
-          case WalFilter::WalProcessingOption::kContinueProcessing:
-            // do nothing, proceeed normally
-            break;
-          case WalFilter::WalProcessingOption::kIgnoreCurrentRecord:
-            // skip current record
-            continue;
-          case WalFilter::WalProcessingOption::kStopReplay:
-            // skip current record and stop replay
-            stop_replay_by_wal_filter = true;
-            continue;
-          case WalFilter::WalProcessingOption::kCorruptedRecord: {
-            status =
-                Status::Corruption("Corruption reported by Wal Filter ",
-                                   immutable_db_options_.wal_filter->Name());
-            MaybeIgnoreError(&status);
-            if (!status.ok()) {
-              reporter.Corruption(record.size(), status);
-              continue;
-            }
-            break;
-          }
-          default: {
-            assert(false);  // unhandled case
-            status = Status::NotSupported(
-                "Unknown WalProcessingOption returned"
-                " by Wal Filter ",
-                immutable_db_options_.wal_filter->Name());
-            MaybeIgnoreError(&status);
-            if (!status.ok()) {
-              return status;
-            } else {
-              // Ignore the error with current record processing.
-              continue;
-            }
-          }
-        }
-
-        if (batch_changed) {
-          // Make sure that the count in the new batch is
-          // within the orignal count.
-          int new_count = WriteBatchInternal::Count(&new_batch);
-          int original_count = WriteBatchInternal::Count(&batch);
-          if (new_count > original_count) {
-            ROCKS_LOG_FATAL(
-                immutable_db_options_.info_log,
-                "Recovering log #%" PRIu64
-                " mode %d log filter %s returned "
-                "more records (%d) than original (%d) which is not allowed. "
-                "Aborting recovery.",
-                wal_number,
-                static_cast<int>(immutable_db_options_.wal_recovery_mode),
-                immutable_db_options_.wal_filter->Name(), new_count,
-                original_count);
-            status = Status::NotSupported(
-                "More than original # of records "
-                "returned by Wal Filter ",
-                immutable_db_options_.wal_filter->Name());
-            return status;
-          }
-          // Set the same sequence number in the new_batch
-          // as the original batch.
-          WriteBatchInternal::SetSequence(&new_batch,
-                                          WriteBatchInternal::Sequence(&batch));
-          batch = new_batch;
-        }
+      // For the default case of wal_filter == nullptr, always performs no-op
+      // and returns true.
+      if (!InvokeWalFilterIfNeededOnWalRecord(wal_number, fname, reporter,
+                                              status, stop_replay_by_wal_filter,
+                                              batch)) {
+        continue;
       }
-#endif  // ROCKSDB_LITE
 
       // If column family was not found, it might mean that the WAL write
       // batch references to the column family that was dropped after the
@@ -1399,9 +1463,6 @@ Status DBImpl::RestoreAliveLogFiles(const std::vector<uint64_t>& wal_numbers) {
   Status s;
   mutex_.AssertHeld();
   assert(immutable_db_options_.avoid_flush_during_recovery);
-  if (two_write_queues_) {
-    log_write_mutex_.Lock();
-  }
   // Mark these as alive so they'll be considered for deletion later by
   // FindObsoleteFiles()
   total_log_size_ = 0;
@@ -1426,9 +1487,6 @@ Status DBImpl::RestoreAliveLogFiles(const std::vector<uint64_t>& wal_numbers) {
     total_log_size_ += log.size;
     alive_log_files_.push_back(log);
   }
-  if (two_write_queues_) {
-    log_write_mutex_.Unlock();
-  }
   return s;
 }
 
@@ -1488,7 +1546,11 @@ Status DBImpl::WriteLevel0TableForRecovery(int job_id, ColumnFamilyData* cfd,
       std::vector<std::unique_ptr<FragmentedRangeTombstoneIterator>>
           range_del_iters;
       auto range_del_iter =
-          mem->NewRangeTombstoneIterator(ro, kMaxSequenceNumber);
+          // This is called during recovery, where a live memtable is flushed
+          // directly. In this case, no fragmented tombstone list is cached in
+          // this memtable yet.
+          mem->NewRangeTombstoneIterator(ro, kMaxSequenceNumber,
+                                         false /* immutable_memtable */);
       if (range_del_iter != nullptr) {
         range_del_iters.emplace_back(range_del_iter);
       }
@@ -1500,17 +1562,19 @@ Status DBImpl::WriteLevel0TableForRecovery(int job_id, ColumnFamilyData* cfd,
           GetCompressionFlush(*cfd->ioptions(), mutable_cf_options),
           mutable_cf_options.compression_opts, cfd->GetID(), cfd->GetName(),
           0 /* level */, false /* is_bottommost */,
-          TableFileCreationReason::kRecovery, current_time,
-          0 /* oldest_key_time */, 0 /* file_creation_time */, db_id_,
-          db_session_id_, 0 /* target_file_size */, meta.fd.GetNumber());
+          TableFileCreationReason::kRecovery, 0 /* oldest_key_time */,
+          0 /* file_creation_time */, db_id_, db_session_id_,
+          0 /* target_file_size */, meta.fd.GetNumber());
+      SeqnoToTimeMapping empty_seqno_time_mapping;
       s = BuildTable(
           dbname_, versions_.get(), immutable_db_options_, tboptions,
           file_options_for_compaction_, cfd->table_cache(), iter.get(),
           std::move(range_del_iters), &meta, &blob_file_additions,
           snapshot_seqs, earliest_write_conflict_snapshot, kMaxSequenceNumber,
           snapshot_checker, paranoid_file_checks, cfd->internal_stats(), &io_s,
-          io_tracer_, BlobFileCreationReason::kRecovery, &event_logger_, job_id,
-          Env::IO_HIGH, nullptr /* table_properties */, write_hint,
+          io_tracer_, BlobFileCreationReason::kRecovery,
+          empty_seqno_time_mapping, &event_logger_, job_id, Env::IO_HIGH,
+          nullptr /* table_properties */, write_hint,
           nullptr /*full_history_ts_low*/, &blob_callback_);
       LogFlush(immutable_db_options_.info_log);
       ROCKS_LOG_DEBUG(immutable_db_options_.info_log,
@@ -1541,8 +1605,7 @@ Status DBImpl::WriteLevel0TableForRecovery(int job_id, ColumnFamilyData* cfd,
                   meta.marked_for_compaction, meta.temperature,
                   meta.oldest_blob_file_number, meta.oldest_ancester_time,
                   meta.file_creation_time, meta.file_checksum,
-                  meta.file_checksum_func_name, meta.min_timestamp,
-                  meta.max_timestamp, meta.unique_id);
+                  meta.file_checksum_func_name, meta.unique_id);
 
     for (const auto& blob : blob_file_additions) {
       edit->AddBlobFile(blob);
@@ -1747,9 +1810,11 @@ Status DBImpl::Open(const DBOptions& db_options, const std::string& dbname,
 
   DBImpl* impl = new DBImpl(db_options, dbname, seq_per_batch, batch_per_txn);
   if (!impl->immutable_db_options_.info_log) {
-    s = Status::Aborted("Failed to create logger");
+    s = impl->init_logger_creation_s_;
     delete impl;
     return s;
+  } else {
+    assert(impl->init_logger_creation_s_.ok());
   }
   s = impl->env_->CreateDirIfMissing(impl->immutable_db_options_.GetWalDir());
   if (s.ok()) {
@@ -1807,16 +1872,8 @@ Status DBImpl::Open(const DBOptions& db_options, const std::string& dbname,
     }
 
     if (s.ok()) {
-      if (impl->two_write_queues_) {
-        impl->log_write_mutex_.Lock();
-      }
       impl->alive_log_files_.push_back(
           DBImpl::LogFileNumberSize(impl->logfile_number_));
-      if (impl->two_write_queues_) {
-        impl->log_write_mutex_.Unlock();
-      }
-    }
-    if (s.ok()) {
       // In WritePrepared there could be gap in sequence numbers. This breaks
       // the trick we use in kPointInTimeRecovery which assumes the first seq in
       // the log right after the corrupted log is one larger than the last seq
@@ -2050,6 +2107,10 @@ Status DBImpl::Open(const DBOptions& db_options, const std::string& dbname,
   if (s.ok()) {
     s = impl->StartPeriodicWorkScheduler();
   }
+
+  if (s.ok()) {
+    s = impl->RegisterRecordSeqnoTimeWorker();
+  }
   if (!s.ok()) {
     for (auto* h : *handles) {
       delete h;

db/db_impl/db_impl_readonly.cc

@@ -85,17 +85,18 @@ Status DBImplReadOnly::Get(const ReadOptions& read_options,
   SequenceNumber max_covering_tombstone_seq = 0;
   LookupKey lkey(key, snapshot, read_options.timestamp);
   PERF_TIMER_STOP(get_snapshot_time);
-  if (super_version->mem->Get(lkey, pinnable_val->GetSelf(), ts, &s,
-                              &merge_context, &max_covering_tombstone_seq,
-                              read_options, &read_cb)) {
+  if (super_version->mem->Get(lkey, pinnable_val->GetSelf(),
+                              /*columns=*/nullptr, ts, &s, &merge_context,
+                              &max_covering_tombstone_seq, read_options,
+                              false /* immutable_memtable */, &read_cb)) {
     pinnable_val->PinSelf();
     RecordTick(stats_, MEMTABLE_HIT);
   } else {
     PERF_TIMER_GUARD(get_from_output_files_time);
     PinnedIteratorsManager pinned_iters_mgr;
     super_version->current->Get(
-        read_options, lkey, pinnable_val, ts, &s, &merge_context,
-        &max_covering_tombstone_seq, &pinned_iters_mgr,
+        read_options, lkey, pinnable_val, /*columns=*/nullptr, ts, &s,
+        &merge_context, &max_covering_tombstone_seq, &pinned_iters_mgr,
         /*value_found*/ nullptr,
         /*key_exists*/ nullptr, /*seq*/ nullptr, &read_cb,
         /*is_blob*/ nullptr,

db/db_impl/db_impl_readonly.h

@@ -48,6 +48,15 @@ class DBImplReadOnly : public DBImpl {
                      const Slice& /*key*/, const Slice& /*value*/) override {
     return Status::NotSupported("Not supported operation in read only mode.");
   }
+
+  using DBImpl::PutEntity;
+  Status PutEntity(const WriteOptions& /* options */,
+                   ColumnFamilyHandle* /* column_family */,
+                   const Slice& /* key */,
+                   const WideColumns& /* columns */) override {
+    return Status::NotSupported("Not supported operation in read only mode.");
+  }
+
   using DBImpl::Merge;
   virtual Status Merge(const WriteOptions& /*options*/,
                        ColumnFamilyHandle* /*column_family*/,