Skip CancelAllBackgroundWork if DBImpl is already closed (#6268 )

Summary: WritePreparedTxnDB calls CancelAllBackgroundWork in its destructor to avoid dangling references to it from background job's SnapshotChecker callback. However, if the DBImpl is already closed, the info log might be closed with it, which causes memory leak when CancelAllBackgroundWork tries to print to the info log. The patch fixes that by calling CancelAllBackgroundWork only if the db is not closed already. Pull Request resolved: https://github.com/facebook/rocksdb/pull/6268 Differential Revision: D19303439 Pulled By: maysamyabandeh fbshipit-source-id: 4228a6be7e78d43c90630347baa89b008200bd15
parallel occ (#6240 )
2026-11-06 11:02:36 -05:00 · 2020-01-07 15:34:27 -08:00 · 2020-01-07 14:20:38 -08:00 · 2020-01-07 13:56:13 -08:00 · 2020-01-07 13:47:03 -08:00 · 2020-01-07 12:32:20 -08:00
326 changed files with 16590 additions and 7874 deletions
@@ -6,25 +6,34 @@ os:
 compiler:
  - clang
  - gcc
-osx_image: xcode8.3
+osx_image: xcode9.4
 jdk:
  - openjdk7
 cache:
  - ccache
-  - apt

 addons:
  apt:
    sources:
      - ubuntu-toolchain-r-test
    packages:
-      - curl
-      - g++-8
-      - libbz2-dev
      - libgflags-dev
+      - libbz2-dev
+      - liblz4-dev
      - libsnappy-dev
-      - mingw-w64
+      - liblzma-dev  # xv
+      - libzstd-dev
      - zlib1g-dev
+  homebrew:
+    update: true
+    packages:
+      - ccache
+      - gflags
+      - lz4
+      - snappy
+      - xz
+      - zstd
+
 env:
  - TEST_GROUP=platform_dependent # 16-18 minutes
  - TEST_GROUP=1 # 33-35 minutes
@@ -60,15 +69,17 @@ matrix:
  - os : osx
    compiler: gcc

-# https://docs.travis-ci.com/user/caching/#ccache-cache
 install:
  - if [ "${TRAVIS_OS_NAME}" == osx ]; then
-      brew install ccache zstd lz4 snappy xz;
      PATH=$PATH:/usr/local/opt/ccache/libexec;
    fi
  - if [ "${JOB_NAME}" == cmake-gcc8 ]; then
+      sudo apt-get install -y g++-8;
      CC=gcc-8 && CXX=g++-8;
    fi
+  - if [ "${JOB_NAME}" == cmake-mingw ]; then
+      sudo apt-get install -y mingw-w64 ;
+    fi
  - if [[ "${JOB_NAME}" == cmake* ]] && [ "${TRAVIS_OS_NAME}" == linux ]; then
      mkdir cmake-dist && curl -sfSL https://github.com/Kitware/CMake/releases/download/v3.14.5/cmake-3.14.5-Linux-x86_64.tar.gz | tar --strip-components=1 -C cmake-dist -xz && export PATH=$PWD/cmake-dist/bin:$PATH;
    fi
@@ -113,7 +124,7 @@ script:
      ;;
    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 .. -DCMAKE_C_COMPILER=x86_64-w64-mingw32-gcc -DCMAKE_CXX_COMPILER=x86_64-w64-mingw32-g++ -DCMAKE_SYSTEM_NAME=Windows && make -j4 rocksdb rocksdbjni
+      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*)
      mkdir build && cd build && cmake -DJNI=1 .. -DCMAKE_BUILD_TYPE=Release && make -j4 rocksdb rocksdbjni
@@ -14,7 +14,7 @@
 #        cd build
 # 3. Run cmake to generate project files for Windows, add more options to enable required third-party libraries.
 #    See thirdparty.inc for more information.
-#        sample command: cmake -G "Visual Studio 15 Win64" -DWITH_GFLAGS=1 -DWITH_SNAPPY=1 -DWITH_JEMALLOC=1 -DWITH_JNI=1 ..
+#        sample command: cmake -G "Visual Studio 15 Win64" -DCMAKE_BUILD_TYPE=Release -DWITH_GFLAGS=1 -DWITH_SNAPPY=1 -DWITH_JEMALLOC=1 -DWITH_JNI=1 ..
 # 4. Then build the project in debug mode (you may want to add /m[:<N>] flag to run msbuild in <N> parallel threads
 #                                          or simply /m to use all avail cores)
 #        msbuild rocksdb.sln
@@ -45,6 +45,16 @@ if(POLICY CMP0042)
  cmake_policy(SET CMP0042 NEW)
 endif()

+if(NOT CMAKE_BUILD_TYPE)
+  if(EXISTS "${CMAKE_SOURCE_DIR}/.git")
+    set(default_build_type "Debug")
+  else()
+    set(default_build_type "RelWithDebInfo")
+  endif()
+  set(CMAKE_BUILD_TYPE "${default_build_type}" CACHE STRING
+    "Default BUILD_TYPE is ${default_build_type}" FORCE)
+endif()
+
 find_program(CCACHE_FOUND ccache)
 if(CCACHE_FOUND)
  set_property(GLOBAL PROPERTY RULE_LAUNCH_COMPILE ccache)
@@ -62,15 +72,22 @@ if (WITH_WINDOWS_UTF8_FILENAMES)
 endif()
 # third-party/folly is only validated to work on Linux and Windows for now.
 # So only turn it on there by default.
-if(CMAKE_SYSTEM_NAME MATCHES "Linux" OR CMAKE_SYSTEM_NAME MATCHES "Windows")
-  option(WITH_FOLLY_DISTRIBUTED_MUTEX "build with folly::DistributedMutex" ON)
+if(CMAKE_SYSTEM_NAME MATCHES "Linux|Windows")
+  if(MSVC AND MSVC_VERSION LESS 1910)
+    # Folly does not compile with MSVC older than VS2017
+    option(WITH_FOLLY_DISTRIBUTED_MUTEX "build with folly::DistributedMutex" OFF)
+  else()
+    option(WITH_FOLLY_DISTRIBUTED_MUTEX "build with folly::DistributedMutex" ON)
+  endif()
 else()
  option(WITH_FOLLY_DISTRIBUTED_MUTEX "build with folly::DistributedMutex" OFF)
 endif()
+
+include(CMakeDependentOption)
+CMAKE_DEPENDENT_OPTION(WITH_GFLAGS "build with GFlags" ON
+  "NOT MSVC;NOT MINGW" OFF)
+
 if(MSVC)
-  # Defaults currently different for GFLAGS.
-  #  We will address find_package work a little later
-  option(WITH_GFLAGS "build with GFlags" OFF)
  option(WITH_XPRESS "build with windows built in compression" OFF)
  include(${CMAKE_CURRENT_SOURCE_DIR}/thirdparty.inc)
 else()
@@ -87,14 +104,11 @@ else()
  endif()

  # No config file for this
-  option(WITH_GFLAGS "build with GFlags" ON)
  if(WITH_GFLAGS)
-    find_package(gflags)
-    if(gflags_FOUND)
-      add_definitions(-DGFLAGS=1)
-      include_directories(${gflags_INCLUDE_DIR})
-      list(APPEND THIRDPARTY_LIBS ${gflags_LIBRARIES})
-    endif()
+    find_package(gflags REQUIRED)
+    add_definitions(-DGFLAGS=1)
+    include_directories(${gflags_INCLUDE_DIR})
+    list(APPEND THIRDPARTY_LIBS gflags::gflags)
  endif()

  if(WITH_SNAPPY)
@@ -174,7 +188,7 @@ else()
  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -W -Wextra -Wall")
  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wsign-compare -Wshadow -Wno-unused-parameter -Wno-unused-variable -Woverloaded-virtual -Wnon-virtual-dtor -Wno-missing-field-initializers -Wno-strict-aliasing")
  if(MINGW)
-    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wno-format")
+    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wno-format -fno-asynchronous-unwind-tables")
    add_definitions(-D_POSIX_C_SOURCE=1)
  endif()
  set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++11")
@@ -545,6 +559,7 @@ set(SOURCES
        env/env_chroot.cc
        env/env_encryption.cc
        env/env_hdfs.cc
+        env/file_system.cc
        env/mock_env.cc
        file/delete_scheduler.cc
        file/file_prefetch_buffer.cc
@@ -631,7 +646,6 @@ set(SOURCES
        test_util/testutil.cc
        test_util/transaction_test_util.cc
        tools/block_cache_analyzer/block_cache_trace_analyzer.cc
-        tools/db_bench_tool.cc
        tools/dump/db_dump_tool.cc
        tools/ldb_cmd.cc
        tools/ldb_tool.cc
@@ -753,6 +767,7 @@ else()
  list(APPEND SOURCES
    port/port_posix.cc
    env/env_posix.cc
+    env/fs_posix.cc
    env/io_posix.cc)
 endif()

@@ -767,7 +782,8 @@ endif()

 set(ROCKSDB_STATIC_LIB rocksdb${ARTIFACT_SUFFIX})
 set(ROCKSDB_SHARED_LIB rocksdb-shared${ARTIFACT_SUFFIX})
-set(ROCKSDB_IMPORT_LIB ${ROCKSDB_SHARED_LIB})
+
+option(ROCKSDB_BUILD_SHARED "Build shared versions of the RocksDB libraries" ON)

 option(WITH_LIBRADOS "Build with librados" OFF)
 if(WITH_LIBRADOS)
@@ -778,40 +794,44 @@ endif()

 if(WIN32)
  set(SYSTEM_LIBS ${SYSTEM_LIBS} shlwapi.lib rpcrt4.lib)
-  set(LIBS ${ROCKSDB_STATIC_LIB} ${THIRDPARTY_LIBS} ${SYSTEM_LIBS})
 else()
  set(SYSTEM_LIBS ${CMAKE_THREAD_LIBS_INIT})
-  set(LIBS ${ROCKSDB_SHARED_LIB} ${THIRDPARTY_LIBS} ${SYSTEM_LIBS})
-
-  add_library(${ROCKSDB_SHARED_LIB} SHARED ${SOURCES})
-  target_link_libraries(${ROCKSDB_SHARED_LIB}
-    ${THIRDPARTY_LIBS} ${SYSTEM_LIBS})
-  set_target_properties(${ROCKSDB_SHARED_LIB} PROPERTIES
-                        LINKER_LANGUAGE CXX
-                        VERSION ${rocksdb_VERSION}
-                        SOVERSION ${rocksdb_VERSION_MAJOR}
-                        CXX_STANDARD 11
-                        OUTPUT_NAME "rocksdb")
 endif()

 add_library(${ROCKSDB_STATIC_LIB} STATIC ${SOURCES})
 target_link_libraries(${ROCKSDB_STATIC_LIB}
  ${THIRDPARTY_LIBS} ${SYSTEM_LIBS})

-if(WIN32)
-  add_library(${ROCKSDB_IMPORT_LIB} SHARED ${SOURCES})
-  target_link_libraries(${ROCKSDB_IMPORT_LIB}
+if(ROCKSDB_BUILD_SHARED)
+  add_library(${ROCKSDB_SHARED_LIB} SHARED ${SOURCES})
+  target_link_libraries(${ROCKSDB_SHARED_LIB}
    ${THIRDPARTY_LIBS} ${SYSTEM_LIBS})
-  set_target_properties(${ROCKSDB_IMPORT_LIB} PROPERTIES
-    COMPILE_DEFINITIONS "ROCKSDB_DLL;ROCKSDB_LIBRARY_EXPORTS")
-  if(MSVC)
-    set_target_properties(${ROCKSDB_STATIC_LIB} PROPERTIES
-      COMPILE_FLAGS "/Fd${CMAKE_CFG_INTDIR}/${ROCKSDB_STATIC_LIB}.pdb")
-    set_target_properties(${ROCKSDB_IMPORT_LIB} PROPERTIES
-      COMPILE_FLAGS "/Fd${CMAKE_CFG_INTDIR}/${ROCKSDB_IMPORT_LIB}.pdb")
+
+  if(WIN32)
+    set_target_properties(${ROCKSDB_SHARED_LIB} PROPERTIES
+      COMPILE_DEFINITIONS "ROCKSDB_DLL;ROCKSDB_LIBRARY_EXPORTS")
+    if(MSVC)
+      set_target_properties(${ROCKSDB_STATIC_LIB} PROPERTIES
+        COMPILE_FLAGS "/Fd${CMAKE_CFG_INTDIR}/${ROCKSDB_STATIC_LIB}.pdb")
+      set_target_properties(${ROCKSDB_SHARED_LIB} PROPERTIES
+        COMPILE_FLAGS "/Fd${CMAKE_CFG_INTDIR}/${ROCKSDB_SHARED_LIB}.pdb")
+    endif()
+  else()
+    set_target_properties(${ROCKSDB_SHARED_LIB} PROPERTIES
+                          LINKER_LANGUAGE CXX
+                          VERSION ${rocksdb_VERSION}
+                          SOVERSION ${rocksdb_VERSION_MAJOR}
+                          CXX_STANDARD 11
+                          OUTPUT_NAME "rocksdb")
  endif()
 endif()

+if(ROCKSDB_BUILD_SHARED AND NOT WIN32)
+  set(ROCKSDB_LIB ${ROCKSDB_SHARED_LIB})
+else()
+  set(ROCKSDB_LIB ${ROCKSDB_STATIC_LIB})
+endif()
+
 option(WITH_JNI "build with JNI" OFF)
 if(WITH_JNI OR JNI)
  message(STATUS "JNI library is enabled")
@@ -858,15 +878,17 @@ if(NOT WIN32 OR ROCKSDB_INSTALL_ON_WINDOWS)
    INCLUDES DESTINATION "${CMAKE_INSTALL_INCLUDEDIR}"
  )

-  install(
-    TARGETS ${ROCKSDB_SHARED_LIB}
-    EXPORT RocksDBTargets
-    COMPONENT runtime
-    ARCHIVE DESTINATION "${CMAKE_INSTALL_LIBDIR}"
-    RUNTIME DESTINATION "${CMAKE_INSTALL_BINDIR}"
-    LIBRARY DESTINATION "${CMAKE_INSTALL_LIBDIR}"
-    INCLUDES DESTINATION "${CMAKE_INSTALL_INCLUDEDIR}"
-  )
+  if(ROCKSDB_BUILD_SHARED)
+    install(
+      TARGETS ${ROCKSDB_SHARED_LIB}
+      EXPORT RocksDBTargets
+      COMPONENT runtime
+      ARCHIVE DESTINATION "${CMAKE_INSTALL_LIBDIR}"
+      RUNTIME DESTINATION "${CMAKE_INSTALL_BINDIR}"
+      LIBRARY DESTINATION "${CMAKE_INSTALL_LIBDIR}"
+      INCLUDES DESTINATION "${CMAKE_INSTALL_INCLUDEDIR}"
+    )
+  endif()

  install(
    EXPORT RocksDBTargets
@@ -884,9 +906,15 @@ if(NOT WIN32 OR ROCKSDB_INSTALL_ON_WINDOWS)
  )
 endif()

-option(WITH_TESTS "build with tests" ON)
+add_subdirectory(third-party/gtest-1.8.1/fused-src/gtest)
+add_library(testharness STATIC
+  test_util/testharness.cc)
+target_link_libraries(testharness gtest)
+
+# Tests are excluded from Release builds
+CMAKE_DEPENDENT_OPTION(WITH_TESTS "build with tests" ON
+  "CMAKE_BUILD_TYPE STREQUAL Debug" OFF)
 if(WITH_TESTS)
-  add_subdirectory(third-party/gtest-1.8.1/fused-src/gtest)
  set(TESTS
        cache/cache_test.cc
        cache/lru_cache_test.cc
@@ -1002,6 +1030,7 @@ if(WITH_TESTS)
        util/filelock_test.cc
        util/hash_test.cc
        util/heap_test.cc
+        util/random_test.cc
        util/rate_limiter_test.cc
        util/repeatable_thread_test.cc
        util/slice_transform_test.cc
@@ -1040,24 +1069,6 @@ if(WITH_TESTS)
    list(APPEND TESTS third-party/folly/folly/synchronization/test/DistributedMutexTest.cpp)
  endif()

-  set(BENCHMARKS
-    cache/cache_bench.cc
-    memtable/memtablerep_bench.cc
-    db/range_del_aggregator_bench.cc
-    tools/db_bench.cc
-    table/table_reader_bench.cc
-    util/filter_bench.cc
-    utilities/persistent_cache/hash_table_bench.cc)
-  add_library(testharness OBJECT test_util/testharness.cc)
-  foreach(sourcefile ${BENCHMARKS})
-    get_filename_component(exename ${sourcefile} NAME_WE)
-    add_executable(${exename}${ARTIFACT_SUFFIX} ${sourcefile}
-      $<TARGET_OBJECTS:testharness>)
-    target_link_libraries(${exename}${ARTIFACT_SUFFIX} gtest ${LIBS})
-  endforeach(sourcefile ${BENCHMARKS})
-
-  # For test util library that is build only in DEBUG mode
-  # and linked to tests. Add test only code that is not #ifdefed for Release here.
  set(TESTUTIL_SOURCE
      db/db_test_util.cc
      monitoring/thread_status_updater_debug.cc
@@ -1065,12 +1076,11 @@ if(WITH_TESTS)
      test_util/fault_injection_test_env.cc
      utilities/cassandra/test_utils.cc
  )
-  # test utilities are only build in debug
  enable_testing()
  add_custom_target(check COMMAND ${CMAKE_CTEST_COMMAND})
  set(TESTUTILLIB testutillib${ARTIFACT_SUFFIX})
  add_library(${TESTUTILLIB} STATIC ${TESTUTIL_SOURCE})
-  target_link_libraries(${TESTUTILLIB} ${LIBS})
+  target_link_libraries(${TESTUTILLIB} ${ROCKSDB_LIB})
  if(MSVC)
    set_target_properties(${TESTUTILLIB} PROPERTIES COMPILE_FLAGS "/Fd${CMAKE_CFG_INTDIR}/testutillib${ARTIFACT_SUFFIX}.pdb")
  endif()
@@ -1080,46 +1090,86 @@ if(WITH_TESTS)
        EXCLUDE_FROM_DEFAULT_BUILD_RELWITHDEBINFO 1
        )

-  # Tests are excluded from Release builds
-  set(TEST_EXES ${TESTS})
-
-  foreach(sourcefile ${TEST_EXES})
+  foreach(sourcefile ${TESTS})
      get_filename_component(exename ${sourcefile} NAME_WE)
-      add_executable(${CMAKE_PROJECT_NAME}_${exename}${ARTIFACT_SUFFIX} ${sourcefile}
-        $<TARGET_OBJECTS:testharness>)
+      add_executable(${CMAKE_PROJECT_NAME}_${exename}${ARTIFACT_SUFFIX} ${sourcefile})
      set_target_properties(${CMAKE_PROJECT_NAME}_${exename}${ARTIFACT_SUFFIX}
        PROPERTIES EXCLUDE_FROM_DEFAULT_BUILD_RELEASE 1
        EXCLUDE_FROM_DEFAULT_BUILD_MINRELEASE 1
        EXCLUDE_FROM_DEFAULT_BUILD_RELWITHDEBINFO 1
        OUTPUT_NAME ${exename}${ARTIFACT_SUFFIX}
        )
-      target_link_libraries(${CMAKE_PROJECT_NAME}_${exename}${ARTIFACT_SUFFIX} testutillib${ARTIFACT_SUFFIX} gtest ${LIBS})
+      target_link_libraries(${CMAKE_PROJECT_NAME}_${exename}${ARTIFACT_SUFFIX} testutillib${ARTIFACT_SUFFIX} testharness gtest ${ROCKSDB_LIB})
      if(NOT "${exename}" MATCHES "db_sanity_test")
        add_test(NAME ${exename} COMMAND ${exename}${ARTIFACT_SUFFIX})
        add_dependencies(check ${CMAKE_PROJECT_NAME}_${exename}${ARTIFACT_SUFFIX})
      endif()
-  endforeach(sourcefile ${TEST_EXES})
+  endforeach(sourcefile ${TESTS})

-  # C executables must link to a shared object
-  set(C_TESTS db/c_test.c)
-  set(C_TEST_EXES ${C_TESTS})
+  if(WIN32)
+    # C executables must link to a shared object
+    if(ROCKSDB_BUILD_SHARED)
+      set(ROCKSDB_LIB_FOR_C ${ROCKSDB_SHARED_LIB})
+    else()
+      set(ROCKSDB_LIB_FOR_C OFF)
+    endif()
+  else()
+    set(ROCKSDB_LIB_FOR_C ${ROCKSDB_LIB})
+  endif()

-  foreach(sourcefile ${C_TEST_EXES})
-      string(REPLACE ".c" "" exename ${sourcefile})
-      string(REGEX REPLACE "^((.+)/)+" "" exename ${exename})
-      add_executable(${exename}${ARTIFACT_SUFFIX} ${sourcefile})
-      set_target_properties(${exename}${ARTIFACT_SUFFIX}
-        PROPERTIES EXCLUDE_FROM_DEFAULT_BUILD_RELEASE 1
-        EXCLUDE_FROM_DEFAULT_BUILD_MINRELEASE 1
-        EXCLUDE_FROM_DEFAULT_BUILD_RELWITHDEBINFO 1
-        )
-      target_link_libraries(${exename}${ARTIFACT_SUFFIX} ${ROCKSDB_IMPORT_LIB} testutillib${ARTIFACT_SUFFIX})
-      add_test(NAME ${exename} COMMAND ${exename}${ARTIFACT_SUFFIX})
-      add_dependencies(check ${exename}${ARTIFACT_SUFFIX})
-  endforeach(sourcefile ${C_TEST_EXES})
+  if(ROCKSDB_LIB_FOR_C)
+    set(C_TESTS db/c_test.c)
+    # C executables must link to a shared object
+    add_executable(c_test db/c_test.c)
+    target_link_libraries(c_test ${ROCKSDB_SHARED_LIB} testharness)
+    add_test(NAME c_test COMMAND c_test${ARTIFACT_SUFFIX})
+    add_dependencies(check c_test)
+  endif()
+endif()
+
+option(WITH_BENCHMARK_TOOLS "build with benchmarks" ON)
+if(WITH_BENCHMARK_TOOLS)
+  add_executable(db_bench
+    tools/db_bench.cc
+    tools/db_bench_tool.cc)
+  target_link_libraries(db_bench
+    ${ROCKSDB_LIB})
+
+  add_executable(cache_bench
+    cache/cache_bench.cc)
+  target_link_libraries(cache_bench
+    ${ROCKSDB_LIB})
+
+  add_executable(memtablerep_bench
+    memtable/memtablerep_bench.cc)
+  target_link_libraries(memtablerep_bench
+    ${ROCKSDB_LIB})
+
+  add_executable(range_del_aggregator_bench
+    db/range_del_aggregator_bench.cc)
+  target_link_libraries(range_del_aggregator_bench
+    ${ROCKSDB_LIB})
+
+  add_executable(table_reader_bench
+    table/table_reader_bench.cc)
+  target_link_libraries(table_reader_bench
+    ${ROCKSDB_LIB} testharness)
+
+  add_executable(filter_bench
+    util/filter_bench.cc)
+  target_link_libraries(filter_bench
+    ${ROCKSDB_LIB})
+
+  add_executable(hash_table_bench
+    utilities/persistent_cache/hash_table_bench.cc)
+  target_link_libraries(hash_table_bench
+    ${ROCKSDB_LIB})
 endif()

 option(WITH_TOOLS "build with tools" ON)
 if(WITH_TOOLS)
  add_subdirectory(tools)
+  add_subdirectory(db_stress_tool)
+  add_custom_target(tools
+    DEPENDS ${tool_deps})
 endif()
@@ -1,10 +1,32 @@
 # Rocksdb Change Log
+## Unreleased
+### Public API Change
+* Added a rocksdb::FileSystem class in include/rocksdb/file_system.h to encapsulate file creation/read/write operations, and an option DBOptions::file_system to allow a user to pass in an instance of rocksdb::FileSystem. If its a non-null value, this will take precendence over DBOptions::env for file operations. A new API rocksdb::FileSystem::Default() returns a platform default object. The DBOptions::env option and Env::Default() API will continue to be used for threading and other OS related functions, and where DBOptions::file_system is not specified, for file operations. For storage developers who are accustomed to rocksdb::Env, the interface in rocksdb::FileSystem is new and will probably undergo some changes as more storage systems are ported to it from rocksdb::Env. As of now, no env other than Posix has been ported to the new interface.
+* A new rocksdb::NewSstFileManager() API that allows the caller to pass in separate Env and FileSystem objects.
+* Changed Java API for RocksDB.keyMayExist functions to use Holder<byte[]> instead of StringBuilder, so that retrieved values need not decode to Strings.
+* A new `OptimisticTransactionDBOptions` Option that allows users to configure occ validation policy. The default policy changes from kValidateSerial to kValidateParallel to reduce mutex contention.
+
+### Bug Fixes
+* Fix a bug that can cause unnecessary bg thread to be scheduled(#6104).
+* Fix a bug in which a snapshot read could be affected by a DeleteRange after the snapshot (#6062).
+* Fix crash caused by concurrent CF iterations and drops(#6147).
+* Fixed two performance issues related to memtable history trimming. First, a new SuperVersion is now created only if some memtables were actually trimmed. Second, trimming is only scheduled if there is at least one flushed memtable that is kept in memory for the purposes of transaction conflict checking.
+* Fix a bug in WriteBatchWithIndex::MultiGetFromBatchAndDB, which is called by Transaction::MultiGet, that causes due to stale pointer access when the number of keys is > 32
+* BlobDB no longer updates the SST to blob file mapping upon failed compactions.
+* Fixed a bug where BlobDB was comparing the `ColumnFamilyHandle` pointers themselves instead of only the column family IDs when checking whether an API call uses the default column family or not.
+* Fix a race condition for cfd->log_number_ between manifest switch and memtable switch (PR 6249) when number of column families is greater than 1.
+
+### New Features
+* It is now possible to enable periodic compactions for the base DB when using BlobDB.
+* BlobDB now garbage collects non-TTL blobs when `enable_garbage_collection` is set to `true` in `BlobDBOptions`. Garbage collection is performed during compaction: any valid blobs located in the oldest N files (where N is the number of non-TTL blob files multiplied by the value of `BlobDBOptions::garbage_collection_cutoff`) encountered during compaction get relocated to new blob files, and old blob files are dropped once they are no longer needed. Note: we recommend enabling periodic compactions for the base DB when using this feature to deal with the case when some old blob files are kept alive by SSTs that otherwise do not get picked for compaction.
+* `db_bench` now supports the `garbage_collection_cutoff` option for BlobDB.
+
 ## 6.6.0 (11/25/2019)
 ### Bug Fixes
-* Fix data corruption casued by output of intra-L0 compaction on ingested file not being placed in correct order in L0.
+* Fix data corruption caused by output of intra-L0 compaction on ingested file not being placed in correct order in L0.
 * Fix a data race between Version::GetColumnFamilyMetaData() and Compaction::MarkFilesBeingCompacted() for access to being_compacted (#6056). The current fix acquires the db mutex during Version::GetColumnFamilyMetaData(), which may cause regression.
 * Fix a bug in DBIter that is_blob_ state isn't updated when iterating backward using seek.
-* Fix a bug when format_version=3, partitioned fitlers, and prefix search are used in conjunction. The bug could result into Seek::(prefix) returning NotFound for an existing prefix.
+* Fix a bug when format_version=3, partitioned filters, and prefix search are used in conjunction. The bug could result into Seek::(prefix) returning NotFound for an existing prefix.
 * Revert the feature "Merging iterator to avoid child iterator reseek for some cases (#5286)" since it might cause strong results when reseek happens with a different iterator upper bound.
 * Fix a bug causing a crash during ingest external file when background compaction cause severe error (file not found).
 * Fix a bug when partitioned filters and prefix search are used in conjunction, ::SeekForPrev could return invalid for an existing prefix. ::SeekForPrev might be called by the user, or internally on ::Prev, or within ::Seek if the return value involves Delete or a Merge operand.
@@ -17,12 +39,13 @@
 * Universal compaction to support options.periodic_compaction_seconds. A full compaction will be triggered if any file is over the threshold.
 * `GetLiveFilesMetaData` and `GetColumnFamilyMetaData` now expose the file number of SST files as well as the oldest blob file referenced by each SST.
 * A batched MultiGet API (DB::MultiGet()) that supports retrieving keys from multiple column families.
-* Full and partitioned filters in the block-based table use an improved Bloom filter implementation, enabled with format_version 5 (or above) because previous releases cannot read this filter. This replacement is faster and more accurate, especially for high bits per key or millions of keys in a single (full) filter. For example, the new Bloom filter has the same false postive rate at 9.55 bits per key as the old one at 10 bits per key, and a lower false positive rate at 16 bits per key than the old one at 100 bits per key.
+* Full and partitioned filters in the block-based table use an improved Bloom filter implementation, enabled with format_version 5 (or above) because previous releases cannot read this filter. This replacement is faster and more accurate, especially for high bits per key or millions of keys in a single (full) filter. For example, the new Bloom filter has the same false positive rate at 9.55 bits per key as the old one at 10 bits per key, and a lower false positive rate at 16 bits per key than the old one at 100 bits per key.
 * Added AVX2 instructions to USE_SSE builds to accelerate the new Bloom filter and XXH3-based hash function on compatible x86_64 platforms (Haswell and later, ~2014).
-* Support options.ttl with options.max_open_files = -1. File's oldest ancester time will be written to manifest. If it is availalbe, this information will be used instead of creation_time in table properties.
+* Support options.ttl or options.periodic_compaction_seconds with options.max_open_files = -1. File's oldest ancester time and file creation time will be written to manifest. If it is availalbe, this information will be used instead of creation_time and file_creation_time in table properties.
 * Setting options.ttl for universal compaction now has the same meaning as setting periodic_compaction_seconds.
+* SstFileMetaData also returns file creation time and oldest ancester time.
 * The `sst_dump` command line tool `recompress` command now displays how many blocks were compressed and how many were not, in particular how many were not compressed because the compression ratio was not met (12.5% threshold for GoodCompressionRatio), as seen in the `number.block.not_compressed` counter stat since version 6.0.0.
-* The block cache usage is now takes into account the overhead of metadata per each entry. This results into more accurate managment of memory. A side-effect of this feature is that less items are fit into the block cache of the same size, which would result to higher cache miss rates. This can be remedied by increasing the block cache size or passing kDontChargeCacheMetadata to its constuctor to restore the old behavior.
+* The block cache usage is now takes into account the overhead of metadata per each entry. This results into more accurate management of memory. A side-effect of this feature is that less items are fit into the block cache of the same size, which would result to higher cache miss rates. This can be remedied by increasing the block cache size or passing kDontChargeCacheMetadata to its constuctor to restore the old behavior.
 * When using BlobDB, a mapping is maintained and persisted in the MANIFEST between each SST file and the oldest non-TTL blob file it references.
 * `db_bench` now supports and by default issues non-TTL Puts to BlobDB. TTL Puts can be enabled by specifying a non-zero value for the `blob_db_max_ttl_range` command line parameter explicitly.
 * `sst_dump` now supports printing BlobDB blob indexes in a human-readable format. This can be enabled by specifying the `decode_blob_index` flag on the command line.
@@ -45,7 +68,7 @@

 ### Default Option Changes
 * Changed the default value of periodic_compaction_seconds to `UINT64_MAX - 1` which allows RocksDB to auto-tune periodic compaction scheduling. When using the default value, periodic compactions are now auto-enabled if a compaction filter is used. A value of `0` will turn off the feature completely.
-* Changed the default value of ttl to `UINT64_MAX - 1` which allows RocksDB to auto-tune ttl value. When using the default value, TTL will be auto-enabled to 30 days, when the feature is supported. To revert the old behavior, you can explictly set it to 0.
+* Changed the default value of ttl to `UINT64_MAX - 1` which allows RocksDB to auto-tune ttl value. When using the default value, TTL will be auto-enabled to 30 days, when the feature is supported. To revert the old behavior, you can explicitly set it to 0.

 ### Performance Improvements
 * For 64-bit hashing, RocksDB is standardizing on a slightly modified preview version of XXH3. This function is now used for many non-persisted hashes, along with fastrange64() in place of the modulus operator, and some benchmarks show a slight improvement.
@@ -86,7 +109,7 @@

 ## 6.4.0 (7/30/2019)
 ### Default Option Change
-* LRUCacheOptions.high_pri_pool_ratio is set to 0.5 (previously 0.0) by default, which means that by default midpoint insertion is enabled. The same change is made for the default value of high_pri_pool_ratio argument in NewLRUCache(). When block cache is not explictly created, the small block cache created by BlockBasedTable will still has this option to be 0.0.
+* LRUCacheOptions.high_pri_pool_ratio is set to 0.5 (previously 0.0) by default, which means that by default midpoint insertion is enabled. The same change is made for the default value of high_pri_pool_ratio argument in NewLRUCache(). When block cache is not explicitly created, the small block cache created by BlockBasedTable will still has this option to be 0.0.
 * Change BlockBasedTableOptions.cache_index_and_filter_blocks_with_high_priority's default value from false to true.

 ### Public API Change
@@ -110,7 +133,7 @@
 * Support loading custom objects in unit tests. In the affected unit tests, RocksDB will create custom Env objects based on environment variable TEST_ENV_URI. Users need to make sure custom object types are properly registered. For example, a static library should expose a `RegisterCustomObjects` function. By linking the unit test binary with the static library, the unit test can execute this function.

 ### Performance Improvements
-* Reduce iterator key comparision for upper/lower bound check.
+* Reduce iterator key comparison for upper/lower bound check.
 * Improve performance of row_cache: make reads with newer snapshots than data in an SST file share the same cache key, except in some transaction cases.
 * The compression dictionary is no longer copied to a new object upon retrieval.

@@ -206,7 +229,7 @@
 * Introduce two more stats levels, kExceptHistogramOrTimers and kExceptTimers.
 * Added a feature to perform data-block sampling for compressibility, and report stats to user.
 * Add support for trace filtering.
-* Add DBOptions.avoid_unnecessary_blocking_io. If true, we avoid file deletion when destorying ColumnFamilyHandle and Iterator. Instead, a job is scheduled to delete the files in background.
+* Add DBOptions.avoid_unnecessary_blocking_io. If true, we avoid file deletion when destroying ColumnFamilyHandle and Iterator. Instead, a job is scheduled to delete the files in background.

 ### Public API Change
 * Remove bundled fbson library.
@@ -585,7 +608,7 @@ if set to something > 0 user will see 2 changes in iterators behavior 1) only ke

 ## 5.2.0 (02/08/2017)
 ### Public API Change
-* NewLRUCache() will determine number of shard bits automatically based on capacity, if the user doesn't pass one. This also impacts the default block cache when the user doesn't explict provide one.
+* NewLRUCache() will determine number of shard bits automatically based on capacity, if the user doesn't pass one. This also impacts the default block cache when the user doesn't explicit provide one.
 * Change the default of delayed slowdown value to 16MB/s and further increase the L0 stop condition to 36 files.
 * Options::use_direct_writes and Options::use_direct_reads are now ready to use.
 * (Experimental) Two-level indexing that partition the index and creates a 2nd level index on the partitions. The feature can be enabled by setting kTwoLevelIndexSearch as IndexType and configuring index_per_partition.
@@ -656,7 +679,7 @@ if set to something > 0 user will see 2 changes in iterators behavior 1) only ke

 ### New Features
 * A tool to migrate DB after options change. See include/rocksdb/utilities/option_change_migration.h.
-* Add ReadOptions.background_purge_on_iterator_cleanup. If true, we avoid file deletion when destorying iterators.
+* Add ReadOptions.background_purge_on_iterator_cleanup. If true, we avoid file deletion when destroying iterators.

 ## 4.10.0 (7/5/2016)
 ### Public API Change
@@ -460,6 +460,7 @@ TESTS = \
 	env_test \
 	env_logger_test \
 	hash_test \
+	random_test \
 	thread_local_test \
 	rate_limiter_test \
 	perf_context_test \
@@ -743,7 +744,8 @@ endif  # PLATFORM_SHARED_EXT
 	release tags tags0 valgrind_check whitebox_crash_test format static_lib shared_lib all \
 	dbg rocksdbjavastatic rocksdbjava install install-static install-shared uninstall \
 	analyze tools tools_lib \
-	blackbox_crash_test_with_atomic_flush whitebox_crash_test_with_atomic_flush
+	blackbox_crash_test_with_atomic_flush whitebox_crash_test_with_atomic_flush  \
+	blackbox_crash_test_with_txn whitebox_crash_test_with_txn


 all: $(LIBRARY) $(BENCHMARKS) tools tools_lib test_libs $(TESTS)
@@ -937,6 +939,7 @@ check: all
 	fi
 	rm -rf $(TMPD)
 ifneq ($(PLATFORM), OS_AIX)
+	python tools/check_all_python.py
 ifeq ($(filter -DROCKSDB_LITE,$(OPT)),)
 	python tools/ldb_test.py
 	sh tools/rocksdb_dump_test.sh
@@ -955,6 +958,8 @@ crash_test: whitebox_crash_test blackbox_crash_test

 crash_test_with_atomic_flush: whitebox_crash_test_with_atomic_flush blackbox_crash_test_with_atomic_flush

+crash_test_with_txn: whitebox_crash_test_with_txn blackbox_crash_test_with_txn
+
 blackbox_crash_test: db_stress
 	python -u tools/db_crashtest.py --simple blackbox $(CRASH_TEST_EXT_ARGS)
 	python -u tools/db_crashtest.py blackbox $(CRASH_TEST_EXT_ARGS)
@@ -962,6 +967,9 @@ blackbox_crash_test: db_stress
 blackbox_crash_test_with_atomic_flush: db_stress
 	python -u tools/db_crashtest.py --cf_consistency blackbox $(CRASH_TEST_EXT_ARGS)

+blackbox_crash_test_with_txn: db_stress
+	python -u tools/db_crashtest.py --txn blackbox $(CRASH_TEST_EXT_ARGS)
+
 ifeq ($(CRASH_TEST_KILL_ODD),)
  CRASH_TEST_KILL_ODD=888887
 endif
@@ -976,6 +984,10 @@ whitebox_crash_test_with_atomic_flush: db_stress
 	python -u tools/db_crashtest.py --cf_consistency whitebox  --random_kill_odd \
      $(CRASH_TEST_KILL_ODD) $(CRASH_TEST_EXT_ARGS)

+whitebox_crash_test_with_txn: db_stress
+	python -u tools/db_crashtest.py --txn whitebox --random_kill_odd \
+      $(CRASH_TEST_KILL_ODD) $(CRASH_TEST_EXT_ARGS)
+
 asan_check:
 	$(MAKE) clean
 	COMPILE_WITH_ASAN=1 $(MAKE) check -j32
@@ -991,6 +1003,11 @@ asan_crash_test_with_atomic_flush:
 	COMPILE_WITH_ASAN=1 $(MAKE) crash_test_with_atomic_flush
 	$(MAKE) clean

+asan_crash_test_with_txn:
+	$(MAKE) clean
+	COMPILE_WITH_ASAN=1 $(MAKE) crash_test_with_txn
+	$(MAKE) clean
+
 ubsan_check:
 	$(MAKE) clean
 	COMPILE_WITH_UBSAN=1 $(MAKE) check -j32
@@ -1006,6 +1023,11 @@ ubsan_crash_test_with_atomic_flush:
 	COMPILE_WITH_UBSAN=1 $(MAKE) crash_test_with_atomic_flush
 	$(MAKE) clean

+ubsan_crash_test_with_txn:
+	$(MAKE) clean
+	COMPILE_WITH_UBSAN=1 $(MAKE) crash_test_with_txn
+	$(MAKE) clean
+
 valgrind_test:
 	ROCKSDB_VALGRIND_RUN=1 DISABLE_JEMALLOC=1 $(MAKE) valgrind_check

@@ -1075,6 +1097,9 @@ parallel_check: $(TESTS)
 		TMPD=$(TMPD) J=$(J) db_test=0 parloop;

 analyze: clean
+	USE_CLANG=1 $(MAKE) analyze_incremental
+
+analyze_incremental:
 	$(CLANG_SCAN_BUILD) --use-analyzer=$(CLANG_ANALYZER) \
 		--use-c++=$(CXX) --use-cc=$(CC) --status-bugs \
 		-o $(CURDIR)/scan_build_report \
@@ -1183,7 +1208,7 @@ memtablerep_bench: memtable/memtablerep_bench.o $(LIBOBJECTS) $(TESTUTIL)
 filter_bench: util/filter_bench.o $(LIBOBJECTS) $(TESTUTIL)
 	$(AM_LINK)

-db_stress: tools/db_stress.o $(STRESSTOOLOBJECTS)
+db_stress: db_stress_tool/db_stress.o $(STRESSTOOLOBJECTS)
 	$(AM_LINK)

 write_stress: tools/write_stress.o $(LIBOBJECTS) $(TESTUTIL)
@@ -1225,6 +1250,9 @@ coding_test: util/coding_test.o $(LIBOBJECTS) $(TESTHARNESS)
 hash_test: util/hash_test.o $(LIBOBJECTS) $(TESTHARNESS)
 	$(AM_LINK)

+random_test: util/random_test.o $(LIBOBJECTS) $(TESTHARNESS)
+	$(AM_LINK)
+
 option_change_migration_test: utilities/option_change_migration/option_change_migration_test.o db/db_test_util.o $(LIBOBJECTS) $(TESTHARNESS)
 	$(AM_LINK)

@@ -2027,6 +2055,7 @@ jtest_run:

 jtest: rocksdbjava
 	cd java;$(MAKE) sample;$(MAKE) test;
+	python tools/check_all_python.py # TODO peterd: find a better place for this check in CI targets

 jdb_bench:
 	cd java;$(MAKE) db_bench;
@@ -2074,6 +2103,9 @@ endif
 .cc.o:
 	$(AM_V_CC)$(CXX) $(CXXFLAGS) -c $< -o $@ $(COVERAGEFLAGS)

+.cpp.o:
+	$(AM_V_CC)$(CXX) $(CXXFLAGS) -c $< -o $@ $(COVERAGEFLAGS)
+
 .c.o:
 	$(AM_V_CC)$(CC) $(CFLAGS) -c $< -o $@
 endif
@@ -2084,6 +2116,10 @@ endif
 all_sources = $(LIB_SOURCES) $(MAIN_SOURCES) $(MOCK_LIB_SOURCES) $(TOOL_LIB_SOURCES) $(BENCH_LIB_SOURCES) $(TEST_LIB_SOURCES) $(ANALYZER_LIB_SOURCES) $(STRESS_LIB_SOURCES)
 DEPFILES = $(all_sources:.cc=.cc.d)

+ifeq ($(USE_FOLLY_DISTRIBUTED_MUTEX),1)
+  DEPFILES += $(FOLLY_SOURCES:.cpp=.cpp.d)
+endif
+
 # Add proper dependency support so changing a .h file forces a .cc file to
 # rebuild.

@@ -2093,6 +2129,10 @@ DEPFILES = $(all_sources:.cc=.cc.d)
 	@$(CXX) $(CXXFLAGS) $(PLATFORM_SHARED_CFLAGS) \
 	  -MM -MT'$@' -MT'$(<:.cc=.o)' "$<" -o '$@'

+%.cpp.d: %.cpp
+	@$(CXX) $(CXXFLAGS) $(PLATFORM_SHARED_CFLAGS) \
+	  -MM -MT'$@' -MT'$(<:.cpp=.o)' "$<" -o '$@'
+
 ifeq ($(HAVE_POWER8),1)
 DEPFILES_C = $(LIB_SOURCES_C:.c=.c.d)
 DEPFILES_ASM = $(LIB_SOURCES_ASM:.S=.S.d)
@@ -26,6 +26,7 @@ ROCKSDB_EXTERNAL_DEPS = [
    ("lz4", None, "lz4"),
    ("zstd", None),
    ("tbb", None),
+    ("liburing", None, "uring"),
    ("googletest", None, "gtest"),
 ]

@@ -46,6 +47,7 @@ ROCKSDB_OS_PREPROCESSOR_FLAGS = [
            "-DROCKSDB_PTHREAD_ADAPTIVE_MUTEX",
            "-DROCKSDB_RANGESYNC_PRESENT",
            "-DROCKSDB_SCHED_GETCPU_PRESENT",
+            "-DROCKSDB_IOURING_PRESENT",
            "-DHAVE_SSE42",
            "-DNUMA",
        ],
@@ -70,6 +72,7 @@ ROCKSDB_PREPROCESSOR_FLAGS = [
    "-DZSTD_STATIC_LINKING_ONLY",
    "-DGFLAGS=gflags",
    "-DTBB",
+    "-DLIBURING",

    # Added missing flags from output of build_detect_platform
    "-DROCKSDB_BACKTRACE",
@@ -178,6 +181,8 @@ cpp_library(
        "env/env_encryption.cc",
        "env/env_hdfs.cc",
        "env/env_posix.cc",
+        "env/file_system.cc",
+        "env/fs_posix.cc",
        "env/io_posix.cc",
        "env/mock_env.cc",
        "file/delete_scheduler.cc",
@@ -399,9 +404,17 @@ cpp_library(
 cpp_library(
    name = "rocksdb_stress_lib",
    srcs = [
+        "db_stress_tool/batched_ops_stress.cc",
+        "db_stress_tool/cf_consistency_stress.cc",
+        "db_stress_tool/db_stress_common.cc",
+        "db_stress_tool/db_stress_driver.cc",
+        "db_stress_tool/db_stress_gflags.cc",
+        "db_stress_tool/db_stress_shared_state.cc",
+        "db_stress_tool/db_stress_test_base.cc",
+        "db_stress_tool/db_stress_tool.cc",
+        "db_stress_tool/no_batched_ops_stress.cc",
        "test_util/testutil.cc",
        "tools/block_cache_analyzer/block_cache_trace_analyzer.cc",
-        "tools/db_stress_tool.cc",
        "tools/trace_analyzer_tool.cc",
    ],
    auto_headers = AutoHeaders.RECURSIVE_GLOB,
@@ -1234,6 +1247,13 @@ ROCKS_TESTS = [
        [],
        [],
    ],
+    [
+        "random_test",
+        "util/random_test.cc",
+        "serial",
+        [],
+        [],
+    ],
    [
        "range_del_aggregator_test",
        "db/range_del_aggregator_test.cc",
@@ -17,6 +17,13 @@ environment:
  ZSTD_INCLUDE: $(ZSTD_HOME)\lib;$(ZSTD_HOME)\lib\dictBuilder
  ZSTD_LIB_DEBUG: $(ZSTD_HOME)\build\VS2010\bin\x64_Debug\libzstd_static.lib
  ZSTD_LIB_RELEASE: $(ZSTD_HOME)\build\VS2010\bin\x64_Release\libzstd_static.lib
+  matrix:
+    - APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2015
+      CMAKE_GENERATOR: Visual Studio 14 Win64
+      DEV_ENV: C:\Program Files (x86)\Microsoft Visual Studio 14.0\Common7\IDE\devenv.com
+    - APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2017
+      CMAKE_GENERATOR: Visual Studio 15 Win64
+      DEV_ENV: C:\Program Files (x86)\Microsoft Visual Studio\2017\Community\Common7\IDE\devenv.com

 install:
  - md %THIRDPARTY_HOME%
@@ -27,7 +34,7 @@ install:
  - cd snappy-1.1.7
  - mkdir build
  - cd build
-  - cmake -DCMAKE_GENERATOR_PLATFORM=x64 ..
+  - cmake -G "%CMAKE_GENERATOR%" ..
  - msbuild Snappy.sln /p:Configuration=Debug /p:Platform=x64
  - msbuild Snappy.sln /p:Configuration=Release /p:Platform=x64
  - echo "Building LZ4 dependency..."
@@ -35,7 +42,7 @@ install:
  - curl -fsSL -o lz4-1.8.3.zip https://github.com/lz4/lz4/archive/v1.8.3.zip
  - unzip lz4-1.8.3.zip
  - cd lz4-1.8.3\visual\VS2010
-  - ps: $CMD="C:\Program Files (x86)\Microsoft Visual Studio\2017\Community\Common7\IDE\devenv.com"; & $CMD lz4.sln /upgrade
+  - ps: $CMD="$Env:DEV_ENV"; & $CMD lz4.sln /upgrade
  - msbuild lz4.sln /p:Configuration=Debug /p:Platform=x64
  - msbuild lz4.sln /p:Configuration=Release /p:Platform=x64
  - echo "Building ZStd dependency..."
@@ -43,15 +50,16 @@ install:
  - curl -fsSL -o zstd-1.4.0.zip https://github.com/facebook/zstd/archive/v1.4.0.zip
  - unzip zstd-1.4.0.zip
  - cd zstd-1.4.0\build\VS2010
-  - ps: $CMD="C:\Program Files (x86)\Microsoft Visual Studio\2017\Community\Common7\IDE\devenv.com"; & $CMD zstd.sln /upgrade
+  - ps: $CMD="$Env:DEV_ENV"; & $CMD zstd.sln /upgrade
  - msbuild zstd.sln /p:Configuration=Debug /p:Platform=x64
  - msbuild zstd.sln /p:Configuration=Release /p:Platform=x64

 before_build:
  - md %APPVEYOR_BUILD_FOLDER%\build
  - cd %APPVEYOR_BUILD_FOLDER%\build
-  - cmake -G "Visual Studio 15 Win64" -DOPTDBG=1 -DPORTABLE=1 -DSNAPPY=1 -DLZ4=1 -DZSTD=1 -DXPRESS=1 -DJNI=1 ..
+  - cmake -G "%CMAKE_GENERATOR%" -DCMAKE_BUILD_TYPE=Debug -DOPTDBG=1 -DPORTABLE=1 -DSNAPPY=1 -DLZ4=1 -DZSTD=1 -DXPRESS=1 -DJNI=1 ..
  - cd ..
+
 build:
  project: build\rocksdb.sln
  parallel: true
@@ -32,6 +32,7 @@ ROCKSDB_EXTERNAL_DEPS = [
    ("lz4", None, "lz4"),
    ("zstd", None),
    ("tbb", None),
+    ("liburing", None, "uring"),
    ("googletest", None, "gtest"),
 ]

@@ -52,6 +53,7 @@ ROCKSDB_OS_PREPROCESSOR_FLAGS = [
            "-DROCKSDB_PTHREAD_ADAPTIVE_MUTEX",
            "-DROCKSDB_RANGESYNC_PRESENT",
            "-DROCKSDB_SCHED_GETCPU_PRESENT",
+            "-DROCKSDB_IOURING_PRESENT",
            "-DHAVE_SSE42",
            "-DNUMA",
        ],
@@ -76,6 +78,7 @@ ROCKSDB_PREPROCESSOR_FLAGS = [
    "-DZSTD_STATIC_LINKING_ONLY",
    "-DGFLAGS=gflags",
    "-DTBB",
+    "-DLIBURING",

    # Added missing flags from output of build_detect_platform
    "-DROCKSDB_BACKTRACE",
@@ -150,6 +150,19 @@ case "$TARGET_OS" in
            PLATFORM_LDFLAGS="$PLATFORM_LDFLAGS -latomic"
        fi
        PLATFORM_LDFLAGS="$PLATFORM_LDFLAGS -lpthread -lrt"
+        # check for liburing
+        $CXX $CFLAGS -x c++ - -luring -o /dev/null 2>/dev/null  <<EOF
+          #include <liburing.h>
+          int main() {
+            struct io_uring ring;
+            io_uring_queue_init(1, &ring, 0);
+            return 0;
+          }
+EOF
+        if [ "$?" = 0 ]; then
+          PLATFORM_LDFLAGS="$PLATFORM_LDFLAGS -luring"
+          COMMON_FLAGS="$COMMON_FLAGS -DROCKSDB_IOURING_PRESENT"
+        fi
        if test -z "$USE_FOLLY_DISTRIBUTED_MUTEX"; then
          USE_FOLLY_DISTRIBUTED_MUTEX=1
        fi
@@ -13,6 +13,7 @@ JEMALLOC_BASE=/mnt/gvfs/third-party2/jemalloc/c26f08f47ac35fc31da2633b7da92d6b86
 NUMA_BASE=/mnt/gvfs/third-party2/numa/3f3fb57a5ccc5fd21c66416c0b83e0aa76a05376/2.0.11/platform007/ca4da3d
 LIBUNWIND_BASE=/mnt/gvfs/third-party2/libunwind/40c73d874898b386a71847f1b99115d93822d11f/1.4/platform007/6f3e0a9
 TBB_BASE=/mnt/gvfs/third-party2/tbb/4ce8e8dba77cdbd81b75d6f0c32fd7a1b76a11ec/2018_U5/platform007/ca4da3d
+LIBURING_BASE=/mnt/gvfs/third-party2/liburing/79427253fd0d42677255aacfe6d13bfe63f752eb/20190828/platform007/ca4da3d
 KERNEL_HEADERS_BASE=/mnt/gvfs/third-party2/kernel-headers/fb251ecd2f5ae16f8671f7014c246e52a748fe0b/fb/platform007/da39a3e
 BINUTILS_BASE=/mnt/gvfs/third-party2/binutils/ab9f09bba370e7066cafd4eb59752db93f2e8312/2.29.1/platform007/15a3614
 VALGRIND_BASE=/mnt/gvfs/third-party2/valgrind/d42d152a15636529b0861ec493927200ebebca8e/3.15.0/platform007/ca4da3d
@@ -133,13 +133,16 @@ _TEST_NAME_TO_PARSERS = {
    'lite_test': [CompilerErrorParser, GTestErrorParser],
    'stress_crash': [CompilerErrorParser, DbCrashErrorParser],
    'stress_crash_with_atomic_flush': [CompilerErrorParser, DbCrashErrorParser],
+    'stress_crash_with_txn': [CompilerErrorParser, DbCrashErrorParser],
    'write_stress': [CompilerErrorParser, WriteStressErrorParser],
    'asan': [CompilerErrorParser, GTestErrorParser, AsanErrorParser],
    'asan_crash': [CompilerErrorParser, AsanErrorParser, DbCrashErrorParser],
    'asan_crash_with_atomic_flush': [CompilerErrorParser, AsanErrorParser, DbCrashErrorParser],
+    'asan_crash_with_txn': [CompilerErrorParser, AsanErrorParser, DbCrashErrorParser],
    'ubsan': [CompilerErrorParser, GTestErrorParser, UbsanErrorParser],
    'ubsan_crash': [CompilerErrorParser, UbsanErrorParser, DbCrashErrorParser],
    'ubsan_crash_with_atomic_flush': [CompilerErrorParser, UbsanErrorParser, DbCrashErrorParser],
+    'ubsan_crash_with_txn': [CompilerErrorParser, UbsanErrorParser, DbCrashErrorParser],
    'valgrind': [CompilerErrorParser, GTestErrorParser, ValgrindErrorParser],
    'tsan': [CompilerErrorParser, GTestErrorParser, TsanErrorParser],
    'format_compatible': [CompilerErrorParser, CompatErrorParser],
@@ -86,6 +86,15 @@ else
 fi
 CFLAGS+=" -DTBB"

+# location of LIBURING
+LIBURING_INCLUDE=" -isystem $LIBURING_BASE/include/"
+if test -z $PIC_BUILD; then
+  LIBURING_LIBS="$LIBURING_BASE/lib/liburing.a"
+else
+  LIBURING_LIBS="$LIBURING_BASE/lib/liburing_pic.a"
+fi
+CFLAGS+=" -DLIBURING"
+
 test "$USE_SSE" || USE_SSE=1
 export USE_SSE
 test "$PORTABLE" || PORTABLE=1
@@ -94,7 +103,7 @@ export PORTABLE
 BINUTILS="$BINUTILS_BASE/bin"
 AR="$BINUTILS/ar"

-DEPS_INCLUDE="$SNAPPY_INCLUDE $ZLIB_INCLUDE $BZIP_INCLUDE $LZ4_INCLUDE $ZSTD_INCLUDE $GFLAGS_INCLUDE $NUMA_INCLUDE $TBB_INCLUDE"
+DEPS_INCLUDE="$SNAPPY_INCLUDE $ZLIB_INCLUDE $BZIP_INCLUDE $LZ4_INCLUDE $ZSTD_INCLUDE $GFLAGS_INCLUDE $NUMA_INCLUDE $TBB_INCLUDE $LIBURING_INCLUDE"

 STDLIBS="-L $GCC_BASE/lib64"

@@ -135,10 +144,10 @@ else
 fi

 CFLAGS+=" $DEPS_INCLUDE"
-CFLAGS+=" -DROCKSDB_PLATFORM_POSIX -DROCKSDB_LIB_IO_POSIX -DROCKSDB_FALLOCATE_PRESENT -DROCKSDB_MALLOC_USABLE_SIZE -DROCKSDB_RANGESYNC_PRESENT -DROCKSDB_SCHED_GETCPU_PRESENT -DROCKSDB_SUPPORT_THREAD_LOCAL -DHAVE_SSE42"
+CFLAGS+=" -DROCKSDB_PLATFORM_POSIX -DROCKSDB_LIB_IO_POSIX -DROCKSDB_FALLOCATE_PRESENT -DROCKSDB_MALLOC_USABLE_SIZE -DROCKSDB_RANGESYNC_PRESENT -DROCKSDB_SCHED_GETCPU_PRESENT -DROCKSDB_SUPPORT_THREAD_LOCAL -DHAVE_SSE42 -DROCKSDB_IOURING_PRESENT"
 CXXFLAGS+=" $CFLAGS"

-EXEC_LDFLAGS=" $SNAPPY_LIBS $ZLIB_LIBS $BZIP_LIBS $LZ4_LIBS $ZSTD_LIBS $GFLAGS_LIBS $NUMA_LIB $TBB_LIBS"
+EXEC_LDFLAGS=" $SNAPPY_LIBS $ZLIB_LIBS $BZIP_LIBS $LZ4_LIBS $ZSTD_LIBS $GFLAGS_LIBS $NUMA_LIB $TBB_LIBS $LIBURING_LIBS"
 EXEC_LDFLAGS+=" -B$BINUTILS/gold"
 EXEC_LDFLAGS+=" -Wl,--dynamic-linker,/usr/local/fbcode/platform007/lib/ld.so"
 EXEC_LDFLAGS+=" $LIBUNWIND"
@@ -148,7 +157,7 @@ EXEC_LDFLAGS+=" -ldl"

 PLATFORM_LDFLAGS="$LIBGCC_LIBS $GLIBC_LIBS $STDLIBS -lgcc -lstdc++"

-EXEC_LDFLAGS_SHARED="$SNAPPY_LIBS $ZLIB_LIBS $BZIP_LIBS $LZ4_LIBS $ZSTD_LIBS $GFLAGS_LIBS $TBB_LIBS"
+EXEC_LDFLAGS_SHARED="$SNAPPY_LIBS $ZLIB_LIBS $BZIP_LIBS $LZ4_LIBS $ZSTD_LIBS $GFLAGS_LIBS $TBB_LIBS $LIBURING_LIBS"

 VALGRIND_VER="$VALGRIND_BASE/bin/"

@@ -13,9 +13,14 @@ then
  echo "You didn't have clang-format-diff.py and/or clang-format available in your computer!"
  echo "You can download clang-format-diff.py by running: "
  echo "    curl --location http://goo.gl/iUW1u2 -o ${CLANG_FORMAT_DIFF}"
-  echo "You can download clang-format by running: "
+  echo "You can download clang-format by running:"
  echo "    brew install clang-format"
+  echo "  Or"
+  echo "    apt install clang-format"
+  echo "  This might work too:"
+  echo "    yum install git-clang-format"
  echo "Then, move both files (i.e. ${CLANG_FORMAT_DIFF} and clang-format) to some directory within PATH=${PATH}"
+  echo "and make sure ${CLANG_FORMAT_DIFF} is executable."
  exit 128
 fi

@@ -1,4 +1,4 @@
-#!/usr/local/fbcode/gcc-4.9-glibc-2.20-fb/bin/python2.7
+#!/usr/bin/env python2.7
 # Copyright (c) Facebook, Inc. and its affiliates. All Rights Reserved.

 from __future__ import absolute_import
@@ -450,6 +450,36 @@ STRESS_CRASH_TEST_WITH_ATOMIC_FLUSH_COMMANDS="[
    }
 ]"

+#
+# RocksDB stress/crash test with txn
+#
+STRESS_CRASH_TEST_WITH_TXN_COMMANDS="[
+    {
+        'name':'Rocksdb Stress and Crash Test with txn',
+        'oncall':'$ONCALL',
+        'executeLocal': 'true',
+        'timeout': 86400,
+        'steps': [
+            $CLEANUP_ENV,
+            {
+                'name':'Build and run RocksDB debug stress tests',
+                'shell':'$SHM $DEBUG $NON_TSAN_CRASH make J=1 db_stress || $CONTRUN_NAME=db_stress $TASK_CREATION_TOOL',
+                'user':'root',
+                $PARSER
+            },
+            {
+                'name':'Build and run RocksDB debug crash tests with txn',
+                'timeout': 86400,
+                'shell':'$SHM $DEBUG $NON_TSAN_CRASH make J=1 crash_test_with_txn || $CONTRUN_NAME=crash_test_with_txn $TASK_CREATION_TOOL',
+                'user':'root',
+                $PARSER
+            },
+            $UPLOAD_DB_DIR,
+        ],
+        $REPORT
+    }
+]"
+
 # RocksDB write stress test.
 # We run on disk device on purpose (i.e. no $SHM)
 # because we want to add some randomness to fsync commands
@@ -541,6 +571,30 @@ ASAN_CRASH_TEST_WITH_ATOMIC_FLUSH_COMMANDS="[
    }
 ]"

+#
+# RocksDB crash testing with txn under address sanitizer
+#
+ASAN_CRASH_TEST_WITH_TXN_COMMANDS="[
+    {
+        'name':'Rocksdb crash test with txn under ASAN',
+        'oncall':'$ONCALL',
+        'executeLocal': 'true',
+        'timeout': 86400,
+        'steps': [
+            $CLEANUP_ENV,
+            {
+                'name':'Build and run RocksDB debug asan_crash_test_with_txn',
+                'timeout': 86400,
+                'shell':'$SHM $DEBUG $NON_TSAN_CRASH make J=1 asan_crash_test_with_txn || $CONTRUN_NAME=asan_crash_test_with_txn $TASK_CREATION_TOOL',
+                'user':'root',
+                $PARSER
+            },
+            $UPLOAD_DB_DIR,
+        ],
+        $REPORT
+    }
+]"
+
 #
 # RocksDB test under undefined behavior sanitizer
 #
@@ -609,6 +663,30 @@ UBSAN_CRASH_TEST_WITH_ATOMIC_FLUSH_COMMANDS="[
    }
 ]"

+#
+# RocksDB crash testing with txn under undefined behavior sanitizer
+#
+UBSAN_CRASH_TEST_WITH_TXN_COMMANDS="[
+    {
+        'name':'Rocksdb crash test with txn under UBSAN',
+        'oncall':'$ONCALL',
+        'executeLocal': 'true',
+        'timeout': 86400,
+        'steps': [
+            $CLEANUP_ENV,
+            {
+                'name':'Build and run RocksDB debug ubsan_crash_test_with_txn',
+                'timeout': 86400,
+                'shell':'$SHM $DEBUG $NON_TSAN_CRASH $CLANG make J=1 ubsan_crash_test_with_txn || $CONTRUN_NAME=ubsan_crash_test_with_txn $TASK_CREATION_TOOL',
+                'user':'root',
+                $PARSER
+            },
+            $UPLOAD_DB_DIR,
+        ],
+        $REPORT
+    }
+]"
+
 #
 # RocksDB unit test under valgrind
 #
@@ -702,6 +780,30 @@ TSAN_CRASH_TEST_WITH_ATOMIC_FLUSH_COMMANDS="[
    }
 ]"

+#
+# RocksDB crash test with txn under TSAN
+#
+TSAN_CRASH_TEST_WITH_TXN_COMMANDS="[
+    {
+        'name':'Rocksdb Crash Test with txn under TSAN',
+        'oncall':'$ONCALL',
+        'executeLocal': 'true',
+        'timeout': 86400,
+        'steps': [
+            $CLEANUP_ENV,
+            {
+                'name':'Compile and run',
+                'timeout': 86400,
+                'shell':'set -o pipefail && $SHM $DEBUG $TSAN $TSAN_CRASH CRASH_TEST_KILL_ODD=1887 make J=1 crash_test_with_txn || $CONTRUN_NAME=tsan_crash_test_with_txn $TASK_CREATION_TOOL',
+                'user':'root',
+                $PARSER
+            },
+            $UPLOAD_DB_DIR,
+        ],
+        $REPORT
+    }
+]"
+
 #
 # RocksDB format compatible
 #
@@ -889,6 +991,9 @@ case $1 in
  stress_crash_with_atomic_flush)
    echo $STRESS_CRASH_TEST_WITH_ATOMIC_FLUSH_COMMANDS
    ;;
+  stress_crash_with_txn)
+    echo $STRESS_CRASH_TEST_WITH_TXN_COMMANDS
+    ;;
  write_stress)
    echo $WRITE_STRESS_COMMANDS
    ;;
@@ -901,6 +1006,9 @@ case $1 in
  asan_crash_with_atomic_flush)
    echo $ASAN_CRASH_TEST_WITH_ATOMIC_FLUSH_COMMANDS
    ;;
+  asan_crash_with_txn)
+    echo $ASAN_CRASH_TEST_WITH_TXN_COMMANDS
+    ;;
  ubsan)
    echo $UBSAN_TEST_COMMANDS
    ;;
@@ -910,6 +1018,9 @@ case $1 in
  ubsan_crash_with_atomic_flush)
    echo $UBSAN_CRASH_TEST_WITH_ATOMIC_FLUSH_COMMANDS
    ;;
+  ubsan_crash_with_txn)
+    echo $UBSAN_CRASH_TEST_WITH_TXN_COMMANDS
+    ;;
  valgrind)
    echo $VALGRIND_TEST_COMMANDS
    ;;
@@ -922,6 +1033,9 @@ case $1 in
  tsan_crash_with_atomic_flush)
    echo $TSAN_CRASH_TEST_WITH_ATOMIC_FLUSH_COMMANDS
    ;;
+  tsan_crash_with_txn)
+    echo $TSAN_CRASH_TEST_WITH_TXN_COMMANDS
+    ;;
  format_compatible)
    echo $FORMAT_COMPATIBLE_COMMANDS
    ;;
@@ -92,6 +92,7 @@ get_lib_base jemalloc   LATEST  platform007
 get_lib_base numa       LATEST  platform007
 get_lib_base libunwind  LATEST  platform007
 get_lib_base tbb        LATEST  platform007
+get_lib_base liburing   LATEST  platform007

 get_lib_base kernel-headers fb platform007
 get_lib_base binutils   LATEST centos7-native
@@ -133,7 +133,6 @@ struct LRUHandle {
  // Caclculate the memory usage by metadata
  inline size_t CalcTotalCharge(
      CacheMetadataChargePolicy metadata_charge_policy) {
-    assert(key_length);
    size_t meta_charge = 0;
    if (metadata_charge_policy == kFullChargeCacheMetadata) {
 #ifdef ROCKSDB_MALLOC_USABLE_SIZE
@@ -0,0 +1,29 @@
+# - Find gflags library
+# Find the gflags includes and library
+#
+# gflags_INCLUDE_DIR - where to find gflags.h.
+# gflags_LIBRARIES - List of libraries when using gflags.
+# gflags_FOUND - True if gflags found.
+
+find_path(GFLAGS_INCLUDE_DIR
+  NAMES gflags/gflags.h)
+
+find_library(GFLAGS_LIBRARIES
+  NAMES gflags)
+
+include(FindPackageHandleStandardArgs)
+find_package_handle_standard_args(gflags
+  DEFAULT_MSG GFLAGS_LIBRARIES GFLAGS_INCLUDE_DIR)
+
+mark_as_advanced(
+  GFLAGS_LIBRARIES
+  GFLAGS_INCLUDE_DIR)
+
+if(gflags_FOUND AND NOT (TARGET gflags::gflags))
+  add_library(gflags::gflags UNKNOWN IMPORTED)
+  set_target_properties(gflags::gflags
+    PROPERTIES
+      IMPORTED_LOCATION ${GFLAGS_LIBRARIES}
+      INTERFACE_INCLUDE_DIRECTORIES ${GFLAGS_INCLUDE_DIR}
+      IMPORTED_LINK_INTERFACE_LANGUAGES "CXX")
+endif()
@@ -64,7 +64,7 @@ Status ArenaWrappedDBIter::Refresh() {
    arena_.~Arena();
    new (&arena_) Arena();

-    SuperVersion* sv = cfd_->GetReferencedSuperVersion(db_impl_->mutex());
+    SuperVersion* sv = cfd_->GetReferencedSuperVersion(db_impl_);
    if (read_callback_) {
      read_callback_->Refresh(latest_seq);
    }
@@ -111,7 +111,7 @@ class BlobIndex {
    return Status::OK();
  }

-  std::string DebugString(bool output_hex) {
+  std::string DebugString(bool output_hex) const {
    std::ostringstream oss;

    if (IsInlined()) {
@@ -66,8 +66,9 @@ TableBuilder* NewTableBuilder(
 }

 Status BuildTable(
-    const std::string& dbname, Env* env, const ImmutableCFOptions& ioptions,
-    const MutableCFOptions& mutable_cf_options, const EnvOptions& env_options,
+    const std::string& dbname, Env* env, FileSystem* fs,
+    const ImmutableCFOptions& ioptions,
+    const MutableCFOptions& mutable_cf_options, const FileOptions& file_options,
    TableCache* table_cache, InternalIterator* iter,
    std::vector<std::unique_ptr<FragmentedRangeTombstoneIterator>>
        range_del_iters,
@@ -115,12 +116,12 @@ Status BuildTable(
    compression_opts_for_flush.max_dict_bytes = 0;
    compression_opts_for_flush.zstd_max_train_bytes = 0;
    {
-      std::unique_ptr<WritableFile> file;
+      std::unique_ptr<FSWritableFile> file;
 #ifndef NDEBUG
-      bool use_direct_writes = env_options.use_direct_writes;
+      bool use_direct_writes = file_options.use_direct_writes;
      TEST_SYNC_POINT_CALLBACK("BuildTable:create_file", &use_direct_writes);
 #endif  // !NDEBUG
-      s = NewWritableFile(env, fname, &file, env_options);
+      s = NewWritableFile(fs, fname, &file, file_options);
      if (!s.ok()) {
        EventHelpers::LogAndNotifyTableFileCreationFinished(
            event_logger, ioptions.listeners, dbname, column_family_name, fname,
@@ -131,7 +132,7 @@ Status BuildTable(
      file->SetWriteLifeTimeHint(write_hint);

      file_writer.reset(
-          new WritableFileWriter(std::move(file), fname, env_options, env,
+          new WritableFileWriter(std::move(file), fname, file_options, env,
                                 ioptions.statistics, ioptions.listeners));
      builder = NewTableBuilder(
          ioptions, mutable_cf_options, internal_comparator,
@@ -218,7 +219,7 @@ Status BuildTable(
      // we will regrad this verification as user reads since the goal is
      // to cache it here for further user reads
      std::unique_ptr<InternalIterator> it(table_cache->NewIterator(
-          ReadOptions(), env_options, internal_comparator, *meta,
+          ReadOptions(), file_options, internal_comparator, *meta,
          nullptr /* range_del_agg */,
          mutable_cf_options.prefix_extractor.get(), nullptr,
          (internal_stats == nullptr) ? nullptr
@@ -241,7 +242,7 @@ Status BuildTable(
  }

  if (!s.ok() || meta->fd.GetFileSize() == 0) {
-    env->DeleteFile(fname);
+    fs->DeleteFile(fname, IOOptions(), nullptr);
  }

  if (meta->fd.GetFileSize() == 0) {
@@ -62,8 +62,9 @@ TableBuilder* NewTableBuilder(
 // @param column_family_name Name of the column family that is also identified
 //    by column_family_id, or empty string if unknown.
 extern Status BuildTable(
-    const std::string& dbname, Env* env, const ImmutableCFOptions& options,
-    const MutableCFOptions& mutable_cf_options, const EnvOptions& env_options,
+    const std::string& dbname, Env* env, FileSystem* fs,
+    const ImmutableCFOptions& options,
+    const MutableCFOptions& mutable_cf_options, const FileOptions& file_options,
    TableCache* table_cache, InternalIterator* iter,
    std::vector<std::unique_ptr<FragmentedRangeTombstoneIterator>>
        range_del_iters,
@@ -852,6 +852,17 @@ void rocksdb_delete_cf(
        Slice(key, keylen)));
 }

+void rocksdb_delete_range_cf(rocksdb_t* db,
+                             const rocksdb_writeoptions_t* options,
+                             rocksdb_column_family_handle_t* column_family,
+                             const char* start_key, size_t start_key_len,
+                             const char* end_key, size_t end_key_len,
+                             char** errptr) {
+  SaveError(errptr, db->rep->DeleteRange(options->rep, column_family->rep,
+                                         Slice(start_key, start_key_len),
+                                         Slice(end_key, end_key_len)));
+}
+
 void rocksdb_merge(
    rocksdb_t* db,
    const rocksdb_writeoptions_t* options,
@@ -2032,6 +2043,17 @@ void rocksdb_block_based_options_set_index_type(
  options->rep.index_type = static_cast<BlockBasedTableOptions::IndexType>(v);
 }

+void rocksdb_block_based_options_set_data_block_index_type(
+    rocksdb_block_based_table_options_t* options, int v) {
+  options->rep.data_block_index_type =
+          static_cast<BlockBasedTableOptions::DataBlockIndexType>(v);
+}
+
+void rocksdb_block_based_options_set_data_block_hash_ratio(
+    rocksdb_block_based_table_options_t* options, double v) {
+  options->rep.data_block_hash_table_util_ratio = v;
+}
+
 void rocksdb_block_based_options_set_hash_index_allow_collision(
    rocksdb_block_based_table_options_t* options, unsigned char v) {
  options->rep.hash_index_allow_collision = v;
@@ -3037,7 +3059,16 @@ rocksdb_filterpolicy_t* rocksdb_filterpolicy_create_bloom_format(int bits_per_ke
    bool KeyMayMatch(const Slice& key, const Slice& filter) const override {
      return rep_->KeyMayMatch(key, filter);
    }
-    static void DoNothing(void*) { }
+    // No need to override GetFilterBitsBuilder if this one is overridden
+    rocksdb::FilterBitsBuilder* GetBuilderWithContext(
+        const rocksdb::FilterBuildingContext& context) const override {
+      return rep_->GetBuilderWithContext(context);
+    }
+    rocksdb::FilterBitsReader* GetFilterBitsReader(
+        const Slice& contents) const override {
+      return rep_->GetFilterBitsReader(contents);
+    }
+    static void DoNothing(void*) {}
  };
  Wrapper* wrapper = new Wrapper;
  wrapper->rep_ = NewBloomFilterPolicy(bits_per_key, original_format);
@@ -487,8 +487,11 @@ int main(int argc, char** argv) {
  rocksdb_options_set_paranoid_checks(options, 1);
  rocksdb_options_set_max_open_files(options, 10);
  rocksdb_options_set_base_background_compactions(options, 1);
+
  table_options = rocksdb_block_based_options_create();
  rocksdb_block_based_options_set_block_cache(table_options, cache);
+  rocksdb_block_based_options_set_data_block_index_type(table_options, 1);
+  rocksdb_block_based_options_set_data_block_hash_ratio(table_options, 0.75);
  rocksdb_options_set_block_based_table_factory(options, table_options);

  rocksdb_options_set_compression(options, rocksdb_no_compression);
@@ -1048,17 +1051,20 @@ int main(int argc, char** argv) {
  }

  StartPhase("filter");
-  for (run = 0; run < 2; run++) {
-    // First run uses custom filter, second run uses bloom filter
+  for (run = 0; run <= 2; run++) {
+    // First run uses custom filter
+    // Second run uses old block-based bloom filter
+    // Third run uses full bloom filter
    CheckNoError(err);
    rocksdb_filterpolicy_t* policy;
    if (run == 0) {
-      policy = rocksdb_filterpolicy_create(
-          NULL, FilterDestroy, FilterCreate, FilterKeyMatch, NULL, FilterName);
+      policy = rocksdb_filterpolicy_create(NULL, FilterDestroy, FilterCreate,
+                                           FilterKeyMatch, NULL, FilterName);
+    } else if (run == 1) {
+      policy = rocksdb_filterpolicy_create_bloom(8);
    } else {
-      policy = rocksdb_filterpolicy_create_bloom(10);
+      policy = rocksdb_filterpolicy_create_bloom_full(8);
    }
-
    rocksdb_block_based_options_set_filter_policy(table_options, policy);

    // Create new database
@@ -1071,12 +1077,24 @@ int main(int argc, char** argv) {
    CheckNoError(err);
    rocksdb_put(db, woptions, "bar", 3, "barvalue", 8, &err);
    CheckNoError(err);
+
+    {
+      // Add enough keys to get just one reasonably populated Bloom filter
+      const int keys_to_add = 1500;
+      int i;
+      char keybuf[100];
+      for (i = 0; i < keys_to_add; i++) {
+        snprintf(keybuf, sizeof(keybuf), "yes%020d", i);
+        rocksdb_put(db, woptions, keybuf, strlen(keybuf), "val", 3, &err);
+        CheckNoError(err);
+      }
+    }
    rocksdb_compact_range(db, NULL, 0, NULL, 0);

    fake_filter_result = 1;
    CheckGet(db, roptions, "foo", "foovalue");
    CheckGet(db, roptions, "bar", "barvalue");
-    if (phase == 0) {
+    if (run == 0) {
      // Must not find value when custom filter returns false
      fake_filter_result = 0;
      CheckGet(db, roptions, "foo", NULL);
@@ -1086,6 +1104,43 @@ int main(int argc, char** argv) {
      CheckGet(db, roptions, "foo", "foovalue");
      CheckGet(db, roptions, "bar", "barvalue");
    }
+
+    {
+      // Query some keys not added to identify Bloom filter implementation
+      // from false positive queries, using perfcontext to detect Bloom
+      // filter behavior
+      rocksdb_perfcontext_t* perf = rocksdb_perfcontext_create();
+      rocksdb_perfcontext_reset(perf);
+
+      const int keys_to_query = 10000;
+      int i;
+      char keybuf[100];
+      for (i = 0; i < keys_to_query; i++) {
+        fake_filter_result = i % 2;
+        snprintf(keybuf, sizeof(keybuf), "no%020d", i);
+        CheckGet(db, roptions, keybuf, NULL);
+      }
+
+      const int hits =
+          (int)rocksdb_perfcontext_metric(perf, rocksdb_bloom_sst_hit_count);
+      if (run == 0) {
+        // Due to half true, half false with fake filter result
+        CheckCondition(hits == keys_to_query / 2);
+      } else if (run == 1) {
+        // Essentially a fingerprint of the block-based Bloom schema
+        CheckCondition(hits == 241);
+      } else {
+        // Essentially a fingerprint of the full Bloom schema(s),
+        // format_version < 5, which vary for three different CACHE_LINE_SIZEs
+        CheckCondition(hits == 224 || hits == 180 || hits == 125);
+      }
+      CheckCondition(
+          (keys_to_query - hits) ==
+          (int)rocksdb_perfcontext_metric(perf, rocksdb_bloom_sst_miss_count));
+
+      rocksdb_perfcontext_destroy(perf);
+    }
+
    // Reset the policy
    rocksdb_block_based_options_set_filter_policy(table_options, NULL);
    rocksdb_options_set_block_based_table_factory(options, table_options);
@@ -1189,6 +1244,15 @@ int main(int argc, char** argv) {
    rocksdb_put_cf(db, woptions, handles[1], "foo", 3, "hello", 5, &err);
    CheckNoError(err);

+    rocksdb_put_cf(db, woptions, handles[1], "foobar1", 7, "hello1", 6, &err);
+    CheckNoError(err);
+    rocksdb_put_cf(db, woptions, handles[1], "foobar2", 7, "hello2", 6, &err);
+    CheckNoError(err);
+    rocksdb_put_cf(db, woptions, handles[1], "foobar3", 7, "hello3", 6, &err);
+    CheckNoError(err);
+    rocksdb_put_cf(db, woptions, handles[1], "foobar4", 7, "hello4", 6, &err);
+    CheckNoError(err);
+
    rocksdb_flushoptions_t *flush_options = rocksdb_flushoptions_create();
    rocksdb_flushoptions_set_wait(flush_options, 1);
    rocksdb_flush_cf(db, flush_options, handles[1], &err);
@@ -1201,6 +1265,10 @@ int main(int argc, char** argv) {
    rocksdb_delete_cf(db, woptions, handles[1], "foo", 3, &err);
    CheckNoError(err);

+    rocksdb_delete_range_cf(db, woptions, handles[1], "foobar2", 7, "foobar4",
+                            7, &err);
+    CheckNoError(err);
+
    CheckGetCF(db, roptions, handles[1], "foo", NULL);
    CheckPinGetCF(db, roptions, handles[1], "foo", NULL);

@@ -1253,7 +1321,7 @@ int main(int argc, char** argv) {
    for (i = 0; rocksdb_iter_valid(iter) != 0; rocksdb_iter_next(iter)) {
      i++;
    }
-    CheckCondition(i == 1);
+    CheckCondition(i == 3);
    rocksdb_iter_get_error(iter, &err);
    CheckNoError(err);
    rocksdb_iter_destroy(iter);
@@ -1277,7 +1345,7 @@ int main(int argc, char** argv) {
    for (i = 0; rocksdb_iter_valid(iter) != 0; rocksdb_iter_next(iter)) {
      i++;
    }
-    CheckCondition(i == 1);
+    CheckCondition(i == 3);
    rocksdb_iter_get_error(iter, &err);
    CheckNoError(err);
    rocksdb_iter_destroy(iter);
@@ -60,11 +60,8 @@ ColumnFamilyHandleImpl::~ColumnFamilyHandleImpl() {
    ColumnFamilyOptions initial_cf_options_copy = cfd_->initial_cf_options();
    JobContext job_context(0);
    mutex_->Lock();
-    if (cfd_->Unref()) {
-      bool dropped = cfd_->IsDropped();
-
-      delete cfd_;
-
+    bool dropped = cfd_->IsDropped();
+    if (cfd_->UnrefAndTryDelete()) {
      if (dropped) {
        db_->FindObsoleteFiles(&job_context, false, true);
      }
@@ -163,6 +160,11 @@ Status CheckConcurrentWritesSupported(const ColumnFamilyOptions& cf_options) {
    return Status::InvalidArgument(
        "Memtable doesn't concurrent writes (allow_concurrent_memtable_write)");
  }
+  if (cf_options.max_successive_merges != 0) {
+    return Status::InvalidArgument(
+        "max_successive_merges > 0 is incompatible "
+        "with concurrent writes (allow_concurrent_memtable_write)");
+  }
  return Status::OK();
 }

@@ -439,13 +441,18 @@ void SuperVersion::Cleanup() {
    to_delete.push_back(m);
  }
  current->Unref();
+  if (cfd->Unref()) {
+    delete cfd;
+  }
 }

-void SuperVersion::Init(MemTable* new_mem, MemTableListVersion* new_imm,
-                        Version* new_current) {
+void SuperVersion::Init(ColumnFamilyData* new_cfd, MemTable* new_mem,
+                        MemTableListVersion* new_imm, Version* new_current) {
+  cfd = new_cfd;
  mem = new_mem;
  imm = new_imm;
  current = new_current;
+  cfd->Ref();
  mem->Ref();
  imm->Ref();
  current->Ref();
@@ -473,7 +480,7 @@ ColumnFamilyData::ColumnFamilyData(
    uint32_t id, const std::string& name, Version* _dummy_versions,
    Cache* _table_cache, WriteBufferManager* write_buffer_manager,
    const ColumnFamilyOptions& cf_options, const ImmutableDBOptions& db_options,
-    const EnvOptions& env_options, ColumnFamilySet* column_family_set,
+    const FileOptions& file_options, ColumnFamilySet* column_family_set,
    BlockCacheTracer* const block_cache_tracer)
    : id_(id),
      name_(name),
@@ -515,7 +522,7 @@ ColumnFamilyData::ColumnFamilyData(
  if (_dummy_versions != nullptr) {
    internal_stats_.reset(
        new InternalStats(ioptions_.num_levels, db_options.env, this));
-    table_cache_.reset(new TableCache(ioptions_, env_options, _table_cache,
+    table_cache_.reset(new TableCache(ioptions_, file_options, _table_cache,
                                      block_cache_tracer));
    if (ioptions_.compaction_style == kCompactionStyleLevel) {
      compaction_picker_.reset(
@@ -581,21 +588,7 @@ ColumnFamilyData::~ColumnFamilyData() {
  // compaction_queue_ and we destroyed it
  assert(!queued_for_flush_);
  assert(!queued_for_compaction_);
-
-  if (super_version_ != nullptr) {
-    // Release SuperVersion reference kept in ThreadLocalPtr.
-    // This must be done outside of mutex_ since unref handler can lock mutex.
-    super_version_->db_mutex->Unlock();
-    local_sv_.reset();
-    super_version_->db_mutex->Lock();
-
-    bool is_last_reference __attribute__((__unused__));
-    is_last_reference = super_version_->Unref();
-    assert(is_last_reference);
-    super_version_->Cleanup();
-    delete super_version_;
-    super_version_ = nullptr;
-  }
+  assert(super_version_ == nullptr);

  if (dummy_versions_ != nullptr) {
    // List must be empty
@@ -615,6 +608,36 @@ ColumnFamilyData::~ColumnFamilyData() {
  }
 }

+bool ColumnFamilyData::UnrefAndTryDelete() {
+  int old_refs = refs_.fetch_sub(1);
+  assert(old_refs > 0);
+
+  if (old_refs == 1) {
+    assert(super_version_ == nullptr);
+    delete this;
+    return true;
+  }
+
+  if (old_refs == 2 && super_version_ != nullptr) {
+    // Only the super_version_ holds me
+    SuperVersion* sv = super_version_;
+    super_version_ = nullptr;
+    // Release SuperVersion reference kept in ThreadLocalPtr.
+    // This must be done outside of mutex_ since unref handler can lock mutex.
+    sv->db_mutex->Unlock();
+    local_sv_.reset();
+    sv->db_mutex->Lock();
+
+    if (sv->Unref()) {
+      // May delete this ColumnFamilyData after calling Cleanup()
+      sv->Cleanup();
+      delete sv;
+      return true;
+    }
+  }
+  return false;
+}
+
 void ColumnFamilyData::SetDropped() {
  // can't drop default CF
  assert(id_ != 0);
@@ -949,8 +972,8 @@ WriteStallCondition ColumnFamilyData::RecalculateWriteStallConditions(
  return write_stall_condition;
 }

-const EnvOptions* ColumnFamilyData::soptions() const {
-  return &(column_family_set_->env_options_);
+const FileOptions* ColumnFamilyData::soptions() const {
+  return &(column_family_set_->file_options_);
 }

 void ColumnFamilyData::SetCurrent(Version* current_version) {
@@ -1080,9 +1103,8 @@ Compaction* ColumnFamilyData::CompactRange(
  return result;
 }

-SuperVersion* ColumnFamilyData::GetReferencedSuperVersion(
-    InstrumentedMutex* db_mutex) {
-  SuperVersion* sv = GetThreadLocalSuperVersion(db_mutex);
+SuperVersion* ColumnFamilyData::GetReferencedSuperVersion(DBImpl* db) {
+  SuperVersion* sv = GetThreadLocalSuperVersion(db);
  sv->Ref();
  if (!ReturnThreadLocalSuperVersion(sv)) {
    // This Unref() corresponds to the Ref() in GetThreadLocalSuperVersion()
@@ -1094,8 +1116,7 @@ SuperVersion* ColumnFamilyData::GetReferencedSuperVersion(
  return sv;
 }

-SuperVersion* ColumnFamilyData::GetThreadLocalSuperVersion(
-    InstrumentedMutex* db_mutex) {
+SuperVersion* ColumnFamilyData::GetThreadLocalSuperVersion(DBImpl* db) {
  // The SuperVersion is cached in thread local storage to avoid acquiring
  // mutex when SuperVersion does not change since the last use. When a new
  // SuperVersion is installed, the compaction or flush thread cleans up
@@ -1122,16 +1143,21 @@ SuperVersion* ColumnFamilyData::GetThreadLocalSuperVersion(

    if (sv && sv->Unref()) {
      RecordTick(ioptions_.statistics, NUMBER_SUPERVERSION_CLEANUPS);
-      db_mutex->Lock();
+      db->mutex()->Lock();
      // NOTE: underlying resources held by superversion (sst files) might
      // not be released until the next background job.
      sv->Cleanup();
-      sv_to_delete = sv;
+      if (db->immutable_db_options().avoid_unnecessary_blocking_io) {
+        db->AddSuperVersionsToFreeQueue(sv);
+        db->SchedulePurge();
+      } else {
+        sv_to_delete = sv;
+      }
    } else {
-      db_mutex->Lock();
+      db->mutex()->Lock();
    }
    sv = super_version_->Ref();
-    db_mutex->Unlock();
+    db->mutex()->Unlock();

    delete sv_to_delete;
  }
@@ -1169,7 +1195,7 @@ void ColumnFamilyData::InstallSuperVersion(
  SuperVersion* new_superversion = sv_context->new_superversion.release();
  new_superversion->db_mutex = db_mutex;
  new_superversion->mutable_cf_options = mutable_cf_options;
-  new_superversion->Init(mem_, imm_.current(), current_);
+  new_superversion->Init(this, mem_, imm_.current(), current_);
  SuperVersion* old_superversion = super_version_;
  super_version_ = new_superversion;
  ++super_version_number_;
@@ -1285,6 +1311,10 @@ Env::WriteLifeTimeHint ColumnFamilyData::CalculateSSTWriteHint(int level) {
  // L1: medium, L2: long, ...
  if (level - base_level >= 2) {
    return Env::WLTH_EXTREME;
+  } else if (level < base_level) {
+    // There is no restriction which prevents level passed in to be smaller
+    // than base_level.
+    return Env::WLTH_MEDIUM;
  }
  return static_cast<Env::WriteLifeTimeHint>(level - base_level +
                            static_cast<int>(Env::WLTH_MEDIUM));
@@ -1317,7 +1347,7 @@ Directory* ColumnFamilyData::GetDataDir(size_t path_id) const {

 ColumnFamilySet::ColumnFamilySet(const std::string& dbname,
                                 const ImmutableDBOptions* db_options,
-                                 const EnvOptions& env_options,
+                                 const FileOptions& file_options,
                                 Cache* table_cache,
                                 WriteBufferManager* write_buffer_manager,
                                 WriteController* write_controller,
@@ -1325,11 +1355,11 @@ ColumnFamilySet::ColumnFamilySet(const std::string& dbname,
    : max_column_family_(0),
      dummy_cfd_(new ColumnFamilyData(
          0, "", nullptr, nullptr, nullptr, ColumnFamilyOptions(), *db_options,
-          env_options, nullptr, block_cache_tracer)),
+          file_options, nullptr, block_cache_tracer)),
      default_cfd_cache_(nullptr),
      db_name_(dbname),
      db_options_(db_options),
-      env_options_(env_options),
+      file_options_(file_options),
      table_cache_(table_cache),
      write_buffer_manager_(write_buffer_manager),
      write_controller_(write_controller),
@@ -1344,14 +1374,12 @@ ColumnFamilySet::~ColumnFamilySet() {
    // cfd destructor will delete itself from column_family_data_
    auto cfd = column_family_data_.begin()->second;
    bool last_ref __attribute__((__unused__));
-    last_ref = cfd->Unref();
+    last_ref = cfd->UnrefAndTryDelete();
    assert(last_ref);
-    delete cfd;
  }
  bool dummy_last_ref __attribute__((__unused__));
-  dummy_last_ref = dummy_cfd_->Unref();
+  dummy_last_ref = dummy_cfd_->UnrefAndTryDelete();
  assert(dummy_last_ref);
-  delete dummy_cfd_;
 }

 ColumnFamilyData* ColumnFamilySet::GetDefault() const {
@@ -1401,7 +1429,7 @@ ColumnFamilyData* ColumnFamilySet::CreateColumnFamily(
  assert(column_families_.find(name) == column_families_.end());
  ColumnFamilyData* new_cfd = new ColumnFamilyData(
      id, name, dummy_versions, table_cache_, write_buffer_manager_, options,
-      *db_options_, env_options_, this, block_cache_tracer_);
+      *db_options_, file_options_, this, block_cache_tracer_);
  column_families_.insert({name, id});
  column_family_data_.insert({id, new_cfd});
  max_column_family_ = std::max(max_column_family_, id);
@@ -198,6 +198,7 @@ class ColumnFamilyHandleInternal : public ColumnFamilyHandleImpl {
 struct SuperVersion {
  // Accessing members of this class is not thread-safe and requires external
  // synchronization (ie db mutex held or on write thread).
+  ColumnFamilyData* cfd;
  MemTable* mem;
  MemTableListVersion* imm;
  Version* current;
@@ -221,8 +222,8 @@ struct SuperVersion {
  // that needs to be deleted in to_delete vector. Unrefing those
  // objects needs to be done in the mutex
  void Cleanup();
-  void Init(MemTable* new_mem, MemTableListVersion* new_imm,
-            Version* new_current);
+  void Init(ColumnFamilyData* new_cfd, MemTable* new_mem,
+            MemTableListVersion* new_imm, Version* new_current);

  // The value of dummy is not actually used. kSVInUse takes its address as a
  // mark in the thread local storage to indicate the SuperVersion is in use
@@ -288,6 +289,11 @@ class ColumnFamilyData {
    return old_refs == 1;
  }

+  // UnrefAndTryDelete() decreases the reference count and do free if needed,
+  // return true if this is freed else false, UnrefAndTryDelete() can only
+  // be called while holding a DB mutex, or during single-threaded recovery.
+  bool UnrefAndTryDelete();
+
  // SetDropped() can only be called under following conditions:
  // 1) Holding a DB mutex,
  // 2) from single-threaded write thread, AND
@@ -318,7 +324,7 @@ class ColumnFamilyData {
  }
  FlushReason GetFlushReason() const { return flush_reason_; }
  // thread-safe
-  const EnvOptions* soptions() const;
+  const FileOptions* soptions() const;
  const ImmutableCFOptions* ioptions() const { return &ioptions_; }
  // REQUIRES: DB mutex held
  // This returns the MutableCFOptions used by current SuperVersion
@@ -430,11 +436,11 @@ class ColumnFamilyData {
  SuperVersion* GetSuperVersion() { return super_version_; }
  // thread-safe
  // Return a already referenced SuperVersion to be used safely.
-  SuperVersion* GetReferencedSuperVersion(InstrumentedMutex* db_mutex);
+  SuperVersion* GetReferencedSuperVersion(DBImpl* db);
  // thread-safe
  // Get SuperVersion stored in thread local storage. If it does not exist,
  // get a reference from a current SuperVersion.
-  SuperVersion* GetThreadLocalSuperVersion(InstrumentedMutex* db_mutex);
+  SuperVersion* GetThreadLocalSuperVersion(DBImpl* db);
  // Try to return SuperVersion back to thread local storage. Retrun true on
  // success and false on failure. It fails when the thread local storage
  // contains anything other than SuperVersion::kSVInUse flag.
@@ -504,7 +510,7 @@ class ColumnFamilyData {
                   WriteBufferManager* write_buffer_manager,
                   const ColumnFamilyOptions& options,
                   const ImmutableDBOptions& db_options,
-                   const EnvOptions& env_options,
+                   const FileOptions& file_options,
                   ColumnFamilySet* column_family_set,
                   BlockCacheTracer* const block_cache_tracer);

@@ -632,7 +638,7 @@ class ColumnFamilySet {

  ColumnFamilySet(const std::string& dbname,
                  const ImmutableDBOptions* db_options,
-                  const EnvOptions& env_options, Cache* table_cache,
+                  const FileOptions& file_options, Cache* table_cache,
                  WriteBufferManager* write_buffer_manager,
                  WriteController* write_controller,
                  BlockCacheTracer* const block_cache_tracer);
@@ -690,7 +696,7 @@ class ColumnFamilySet {

  const std::string db_name_;
  const ImmutableDBOptions* const db_options_;
-  const EnvOptions env_options_;
+  const FileOptions file_options_;
  Cache* table_cache_;
  WriteBufferManager* write_buffer_manager_;
  WriteController* write_controller_;
@@ -67,9 +67,9 @@ class ColumnFamilyTestBase : public testing::Test {
 #ifndef ROCKSDB_LITE
    const char* test_env_uri = getenv("TEST_ENV_URI");
    if (test_env_uri) {
-      Status s = ObjectRegistry::NewInstance()->NewSharedObject(test_env_uri,
-                                                                &env_guard_);
-      base_env = env_guard_.get();
+      Env* test_env = nullptr;
+      Status s = Env::LoadEnv(test_env_uri, &test_env, &env_guard_);
+      base_env = test_env;
      EXPECT_OK(s);
      EXPECT_NE(Env::Default(), base_env);
    }
@@ -2365,6 +2365,45 @@ TEST_P(ColumnFamilyTest, ReadDroppedColumnFamily) {
  }
 }

+TEST_P(ColumnFamilyTest, LiveIteratorWithDroppedColumnFamily) {
+  db_options_.create_missing_column_families = true;
+  db_options_.max_open_files = 20;
+  // delete obsolete files always
+  db_options_.delete_obsolete_files_period_micros = 0;
+  Open({"default", "one", "two"});
+  ColumnFamilyOptions options;
+  options.level0_file_num_compaction_trigger = 100;
+  options.level0_slowdown_writes_trigger = 200;
+  options.level0_stop_writes_trigger = 200;
+  options.write_buffer_size = 100000;  // small write buffer size
+  Reopen({options, options, options});
+
+  // 1MB should create ~10 files for each CF
+  int kKeysNum = 10000;
+  PutRandomData(1, kKeysNum, 100);
+
+  {
+    std::unique_ptr<Iterator> iterator(
+        db_->NewIterator(ReadOptions(), handles_[1]));
+    iterator->SeekToFirst();
+
+    DropColumnFamilies({1});
+
+    // Make sure iterator created can still be used.
+    int count = 0;
+    for (; iterator->Valid(); iterator->Next()) {
+      ASSERT_OK(iterator->status());
+      ++count;
+    }
+    ASSERT_OK(iterator->status());
+    ASSERT_EQ(count, kKeysNum);
+  }
+
+  Reopen();
+  Close();
+  Destroy();
+}
+
 TEST_P(ColumnFamilyTest, FlushAndDropRaceCondition) {
  db_options_.create_missing_column_families = true;
  Open({"default", "one"});
@@ -275,9 +275,7 @@ Compaction::~Compaction() {
    input_version_->Unref();
  }
  if (cfd_ != nullptr) {
-    if (cfd_->Unref()) {
-      delete cfd_;
-    }
+    cfd_->UnrefAndTryDelete();
  }
 }

@@ -639,28 +639,48 @@ void CompactionIterator::NextFromInput() {
 }

 void CompactionIterator::PrepareOutput() {
-  // 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
-  // and the userkey differs from the last userkey in compaction
-  // then we can squash the seqno to zero.
-  //
-  // This is safe for TransactionDB write-conflict checking since transactions
-  // only care about sequence number larger than any active snapshots.
-  //
-  // Can we do the same for levels above bottom level as long as
-  // KeyNotExistsBeyondOutputLevel() return true?
-  if ((compaction_ != nullptr && !compaction_->allow_ingest_behind()) &&
-      ikeyNotNeededForIncrementalSnapshot() && bottommost_level_ && valid_ &&
-      IN_EARLIEST_SNAPSHOT(ikey_.sequence) && ikey_.type != kTypeMerge) {
-    assert(ikey_.type != kTypeDeletion && ikey_.type != kTypeSingleDeletion);
-    if (ikey_.type == kTypeDeletion || ikey_.type == kTypeSingleDeletion) {
-      ROCKS_LOG_FATAL(info_log_,
-                      "Unexpected key type %d for seq-zero optimization",
-                      ikey_.type);
+  if (valid_) {
+    if (compaction_filter_ && ikey_.type == kTypeBlobIndex) {
+      const auto blob_decision = compaction_filter_->PrepareBlobOutput(
+          user_key(), value_, &compaction_filter_value_);
+
+      if (blob_decision == CompactionFilter::BlobDecision::kCorruption) {
+        status_ = Status::Corruption(
+            "Corrupted blob reference encountered during GC");
+        valid_ = false;
+      } else if (blob_decision == CompactionFilter::BlobDecision::kIOError) {
+        status_ = Status::IOError("Could not relocate blob during GC");
+        valid_ = false;
+      } else if (blob_decision ==
+                 CompactionFilter::BlobDecision::kChangeValue) {
+        value_ = compaction_filter_value_;
+      }
+    }
+
+    // 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
+    // and the userkey differs from the last userkey in compaction
+    // then we can squash the seqno to zero.
+    //
+    // This is safe for TransactionDB write-conflict checking since transactions
+    // only care about sequence number larger than any active snapshots.
+    //
+    // Can we do the same for levels above bottom level as long as
+    // KeyNotExistsBeyondOutputLevel() return true?
+    if (valid_ && compaction_ != nullptr &&
+        !compaction_->allow_ingest_behind() &&
+        ikeyNotNeededForIncrementalSnapshot() && bottommost_level_ &&
+        IN_EARLIEST_SNAPSHOT(ikey_.sequence) && ikey_.type != kTypeMerge) {
+      assert(ikey_.type != kTypeDeletion && ikey_.type != kTypeSingleDeletion);
+      if (ikey_.type == kTypeDeletion || ikey_.type == kTypeSingleDeletion) {
+        ROCKS_LOG_FATAL(info_log_,
+                        "Unexpected key type %d for seq-zero optimization",
+                        ikey_.type);
+      }
+      ikey_.sequence = 0;
+      current_key_.UpdateInternalKey(0, ikey_.type);
    }
-    ikey_.sequence = 0;
-    current_key_.UpdateInternalKey(0, ikey_.type);
  }
 }

@@ -301,7 +301,7 @@ void CompactionJob::AggregateStatistics() {

 CompactionJob::CompactionJob(
    int job_id, Compaction* compaction, const ImmutableDBOptions& db_options,
-    const EnvOptions env_options, VersionSet* versions,
+    const FileOptions& file_options, VersionSet* versions,
    const std::atomic<bool>* shutting_down,
    const SequenceNumber preserve_deletes_seqnum, LogBuffer* log_buffer,
    Directory* db_directory, Directory* output_directory, Statistics* stats,
@@ -318,10 +318,11 @@ CompactionJob::CompactionJob(
      compaction_stats_(compaction->compaction_reason(), 1),
      dbname_(dbname),
      db_options_(db_options),
-      env_options_(env_options),
+      file_options_(file_options),
      env_(db_options.env),
-      env_options_for_read_(
-          env_->OptimizeForCompactionTableRead(env_options, db_options_)),
+      fs_(db_options.fs.get()),
+      file_options_for_read_(
+          fs_->OptimizeForCompactionTableRead(file_options, db_options_)),
      versions_(versions),
      shutting_down_(shutting_down),
      manual_compaction_paused_(manual_compaction_paused),
@@ -647,7 +648,7 @@ Status CompactionJob::Run() {
        // we will regard this verification as user reads since the goal is
        // to cache it here for further user reads
        InternalIterator* iter = cfd->table_cache()->NewIterator(
-            ReadOptions(), env_options_, cfd->internal_comparator(),
+            ReadOptions(), file_options_, cfd->internal_comparator(),
            *files_meta[file_idx], /*range_del_agg=*/nullptr, prefix_extractor,
            /*table_reader_ptr=*/nullptr,
            cfd->internal_stats()->GetFileReadHist(
@@ -836,7 +837,7 @@ void CompactionJob::ProcessKeyValueCompaction(SubcompactionState* sub_compact) {
  // Although the v2 aggregator is what the level iterator(s) know about,
  // the AddTombstones calls will be propagated down to the v1 aggregator.
  std::unique_ptr<InternalIterator> input(versions_->MakeInputIterator(
-      sub_compact->compaction, &range_del_agg, env_options_for_read_));
+      sub_compact->compaction, &range_del_agg, file_options_for_read_));

  AutoThreadOperationStageUpdater stage_updater(
      ThreadStatus::STAGE_COMPACTION_PROCESS_KV);
@@ -1457,13 +1458,13 @@ Status CompactionJob::OpenCompactionOutputFile(
      TableFileCreationReason::kCompaction);
 #endif  // !ROCKSDB_LITE
  // Make the output file
-  std::unique_ptr<WritableFile> writable_file;
+  std::unique_ptr<FSWritableFile> writable_file;
 #ifndef NDEBUG
-  bool syncpoint_arg = env_options_.use_direct_writes;
+  bool syncpoint_arg = file_options_.use_direct_writes;
  TEST_SYNC_POINT_CALLBACK("CompactionJob::OpenCompactionOutputFile",
                           &syncpoint_arg);
 #endif
-  Status s = NewWritableFile(env_, fname, &writable_file, env_options_);
+  Status s = NewWritableFile(fs_, fname, &writable_file, file_options_);
  if (!s.ok()) {
    ROCKS_LOG_ERROR(
        db_options_.info_log,
@@ -1501,18 +1502,19 @@ Status CompactionJob::OpenCompactionOutputFile(
    out.meta.fd = FileDescriptor(file_number,
                                 sub_compact->compaction->output_path_id(), 0);
    out.meta.oldest_ancester_time = oldest_ancester_time;
+    out.meta.file_creation_time = current_time;
    out.finished = false;
    sub_compact->outputs.push_back(out);
  }

-  writable_file->SetIOPriority(Env::IO_LOW);
+  writable_file->SetIOPriority(Env::IOPriority::IO_LOW);
  writable_file->SetWriteLifeTimeHint(write_hint_);
  writable_file->SetPreallocationBlockSize(static_cast<size_t>(
      sub_compact->compaction->OutputFilePreallocationSize()));
  const auto& listeners =
      sub_compact->compaction->immutable_cf_options()->listeners;
  sub_compact->outfile.reset(
-      new WritableFileWriter(std::move(writable_file), fname, env_options_,
+      new WritableFileWriter(std::move(writable_file), fname, file_options_,
                             env_, db_options_.statistics.get(), listeners));

  // If the Column family flag is to only optimize filters for hits,
@@ -64,7 +64,7 @@ class CompactionJob {
 public:
  CompactionJob(int job_id, Compaction* compaction,
                const ImmutableDBOptions& db_options,
-                const EnvOptions env_options, VersionSet* versions,
+                const FileOptions& file_options, VersionSet* versions,
                const std::atomic<bool>* shutting_down,
                const SequenceNumber preserve_deletes_seqnum,
                LogBuffer* log_buffer, Directory* db_directory,
@@ -150,11 +150,12 @@ class CompactionJob {
  // DBImpl state
  const std::string& dbname_;
  const ImmutableDBOptions& db_options_;
-  const EnvOptions env_options_;
+  const FileOptions file_options_;

  Env* env_;
+  FileSystem* fs_;
  // env_option optimized for compaction table reads
-  EnvOptions env_options_for_read_;
+  FileOptions file_options_for_read_;
  VersionSet* versions_;
  const std::atomic<bool>* shutting_down_;
  const std::atomic<bool>* manual_compaction_paused_;
@@ -72,6 +72,7 @@ class CompactionJobTest : public testing::Test {
 public:
  CompactionJobTest()
      : env_(Env::Default()),
+        fs_(std::make_shared<LegacyFileSystemWrapper>(env_)),
        dbname_(test::PerThreadDBPath("compaction_job_test")),
        db_options_(),
        mutable_cf_options_(cf_options_),
@@ -86,6 +87,8 @@ class CompactionJobTest : public testing::Test {
        mock_table_factory_(new mock::MockTableFactory()),
        error_handler_(nullptr, db_options_, &mutex_) {
    EXPECT_OK(env_->CreateDirIfMissing(dbname_));
+    db_options_.env = env_;
+    db_options_.fs = fs_;
    db_options_.db_paths.emplace_back(dbname_,
                                      std::numeric_limits<uint64_t>::max());
  }
@@ -184,7 +187,7 @@ class CompactionJobTest : public testing::Test {
    VersionEdit edit;
    edit.AddFile(level, file_number, 0, 10, smallest_key, largest_key,
                 smallest_seqno, largest_seqno, false, oldest_blob_file_number,
-                 kUnknownOldestAncesterTime);
+                 kUnknownOldestAncesterTime, kUnknownFileCreationTime);

    mutex_.Lock();
    versions_->LogAndApply(versions_->GetColumnFamilySet()->GetDefault(),
@@ -267,8 +270,8 @@ class CompactionJobTest : public testing::Test {
    Status s = env_->NewWritableFile(
        manifest, &file, env_->OptimizeForManifestWrite(env_options_));
    ASSERT_OK(s);
-    std::unique_ptr<WritableFileWriter> file_writer(
-        new WritableFileWriter(std::move(file), manifest, env_options_));
+    std::unique_ptr<WritableFileWriter> file_writer(new WritableFileWriter(
+        NewLegacyWritableFileWrapper(std::move(file)), manifest, env_options_));
    {
      log::Writer log(std::move(file_writer), 0, false);
      std::string record;
@@ -360,6 +363,7 @@ class CompactionJobTest : public testing::Test {
  }

  Env* env_;
+  std::shared_ptr<FileSystem> fs_;
  std::string dbname_;
  EnvOptions env_options_;
  ImmutableDBOptions db_options_;
@@ -95,7 +95,7 @@ class CompactionPickerTest : public testing::Test {
        InternalKey(smallest, smallest_seq, kTypeValue),
        InternalKey(largest, largest_seq, kTypeValue), smallest_seq,
        largest_seq, /* marked_for_compact */ false, kInvalidBlobFileNumber,
-        kUnknownOldestAncesterTime);
+        kUnknownOldestAncesterTime, kUnknownFileCreationTime);
    f->compensated_file_size =
        (compensated_file_size != 0) ? compensated_file_size : file_size;
    vstorage_->AddFile(level, f);
@@ -247,7 +247,8 @@ bool UniversalCompactionBuilder::IsInputFilesNonOverlapping(Compaction* c) {

    next.f = nullptr;

-    if (curr.level != 0 && curr.index < c->num_input_files(curr.level) - 1) {
+    if (c->level(curr.level) != 0 &&
+        curr.index < c->num_input_files(curr.level) - 1) {
      next.f = c->input(curr.level, curr.index + 1);
      next.level = curr.level;
      next.index = curr.index + 1;
@@ -41,14 +41,16 @@ Status VerifySstFileChecksum(const Options& options,
                             const EnvOptions& env_options,
                             const ReadOptions& read_options,
                             const std::string& file_path) {
-  std::unique_ptr<RandomAccessFile> file;
+  std::unique_ptr<FSRandomAccessFile> file;
  uint64_t file_size;
  InternalKeyComparator internal_comparator(options.comparator);
  ImmutableCFOptions ioptions(options);

-  Status s = ioptions.env->NewRandomAccessFile(file_path, &file, env_options);
+  Status s = ioptions.fs->NewRandomAccessFile(file_path,
+                                              FileOptions(env_options),
+                                              &file, nullptr);
  if (s.ok()) {
-    s = ioptions.env->GetFileSize(file_path, &file_size);
+    s = ioptions.fs->GetFileSize(file_path, IOOptions(), &file_size, nullptr);
  } else {
    return s;
  }
@@ -20,6 +20,7 @@
 #include "db/db_test_util.h"
 #include "db/log_format.h"
 #include "db/version_set.h"
+#include "env/composite_env_wrapper.h"
 #include "file/filename.h"
 #include "rocksdb/cache.h"
 #include "rocksdb/convenience.h"
@@ -189,6 +190,7 @@ class CorruptionTest : public testing::Test {
    ASSERT_TRUE(s.ok()) << s.ToString();
    Options options;
    EnvOptions env_options;
+    options.file_system.reset(new LegacyFileSystemWrapper(options.env));
    ASSERT_NOK(VerifySstFileChecksum(options, env_options, fname));
  }

@@ -539,7 +541,8 @@ TEST_F(CorruptionTest, RangeDeletionCorrupted) {
  std::unique_ptr<RandomAccessFile> file;
  ASSERT_OK(options_.env->NewRandomAccessFile(filename, &file, EnvOptions()));
  std::unique_ptr<RandomAccessFileReader> file_reader(
-      new RandomAccessFileReader(std::move(file), filename));
+      new RandomAccessFileReader(NewLegacyRandomAccessFileWrapper(file),
+                                 filename));

  uint64_t file_size;
  ASSERT_OK(options_.env->GetFileSize(filename, &file_size));
@@ -6,7 +6,6 @@
 // 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 <iostream>
 #include "db/db_test_util.h"
 #include "port/stack_trace.h"
 #include "rocksdb/perf_context.h"
@@ -525,6 +524,7 @@ TEST_F(DBBasicTest, Snapshot) {
    ASSERT_EQ(1U, GetNumSnapshots());
    uint64_t time_snap1 = GetTimeOldestSnapshots();
    ASSERT_GT(time_snap1, 0U);
+    ASSERT_EQ(GetSequenceOldestSnapshots(), s1->GetSequenceNumber());
    Put(0, "foo", "0v2");
    Put(1, "foo", "1v2");

@@ -533,6 +533,7 @@ TEST_F(DBBasicTest, Snapshot) {
    const Snapshot* s2 = db_->GetSnapshot();
    ASSERT_EQ(2U, GetNumSnapshots());
    ASSERT_EQ(time_snap1, GetTimeOldestSnapshots());
+    ASSERT_EQ(GetSequenceOldestSnapshots(), s1->GetSequenceNumber());
    Put(0, "foo", "0v3");
    Put(1, "foo", "1v3");

@@ -540,6 +541,7 @@ TEST_F(DBBasicTest, Snapshot) {
      ManagedSnapshot s3(db_);
      ASSERT_EQ(3U, GetNumSnapshots());
      ASSERT_EQ(time_snap1, GetTimeOldestSnapshots());
+      ASSERT_EQ(GetSequenceOldestSnapshots(), s1->GetSequenceNumber());

      Put(0, "foo", "0v4");
      Put(1, "foo", "1v4");
@@ -555,6 +557,7 @@ TEST_F(DBBasicTest, Snapshot) {

    ASSERT_EQ(2U, GetNumSnapshots());
    ASSERT_EQ(time_snap1, GetTimeOldestSnapshots());
+    ASSERT_EQ(GetSequenceOldestSnapshots(), s1->GetSequenceNumber());
    ASSERT_EQ("0v1", Get(0, "foo", s1));
    ASSERT_EQ("1v1", Get(1, "foo", s1));
    ASSERT_EQ("0v2", Get(0, "foo", s2));
@@ -569,9 +572,11 @@ TEST_F(DBBasicTest, Snapshot) {
    ASSERT_EQ("1v4", Get(1, "foo"));
    ASSERT_EQ(1U, GetNumSnapshots());
    ASSERT_LT(time_snap1, GetTimeOldestSnapshots());
+    ASSERT_EQ(GetSequenceOldestSnapshots(), s2->GetSequenceNumber());

    db_->ReleaseSnapshot(s2);
    ASSERT_EQ(0U, GetNumSnapshots());
+    ASSERT_EQ(GetSequenceOldestSnapshots(), 0);
    ASSERT_EQ("0v4", Get(0, "foo"));
    ASSERT_EQ("1v4", Get(1, "foo"));
  } while (ChangeOptions());
@@ -1706,6 +1711,14 @@ class DBBasicTestWithParallelIO
      assert(Put(Key(i), values_[i]) == Status::OK());
    }
    Flush();
+
+    for (int i = 0; i < 100; ++i) {
+      // block cannot gain space by compression
+      uncompressable_values_.emplace_back(RandomString(&rnd, 256) + '\0');
+      std::string tmp_key = "a" + Key(i);
+      assert(Put(tmp_key, uncompressable_values_[i]) == Status::OK());
+    }
+    Flush();
  }

  bool CheckValue(int i, const std::string& value) {
@@ -1715,6 +1728,13 @@ class DBBasicTestWithParallelIO
    return false;
  }

+  bool CheckUncompressableValue(int i, const std::string& value) {
+    if (uncompressable_values_[i].compare(value) == 0) {
+      return true;
+    }
+    return false;
+  }
+
  int num_lookups() { return uncompressed_cache_->num_lookups(); }
  int num_found() { return uncompressed_cache_->num_found(); }
  int num_inserts() { return uncompressed_cache_->num_inserts(); }
@@ -1864,6 +1884,7 @@ class DBBasicTestWithParallelIO
  std::shared_ptr<MyBlockCache> uncompressed_cache_;
  bool compression_enabled_;
  std::vector<std::string> values_;
+  std::vector<std::string> uncompressable_values_;
  bool fill_cache_;
 };

@@ -1928,8 +1949,66 @@ TEST_P(DBBasicTestWithParallelIO, MultiGet) {
    ASSERT_OK(statuses[i]);
    ASSERT_TRUE(CheckValue(key_ints[i], values[i].ToString()));
  }
-  expected_reads += (read_from_cache ? 2 : 4);
+  if (compression_enabled() && !has_compressed_cache()) {
+    expected_reads += (read_from_cache ? 2 : 3);
+  } else {
+    expected_reads += (read_from_cache ? 2 : 4);
+  }
  ASSERT_EQ(env_->random_read_counter_.Read(), expected_reads);
+
+  keys.resize(10);
+  statuses.resize(10);
+  std::vector<int> key_uncmp{1, 2, 15, 16, 55, 81, 82, 83, 84, 85};
+  for (size_t i = 0; i < key_uncmp.size(); ++i) {
+    key_data[i] = "a" + Key(key_uncmp[i]);
+    keys[i] = Slice(key_data[i]);
+    statuses[i] = Status::OK();
+    values[i].Reset();
+  }
+  dbfull()->MultiGet(ro, dbfull()->DefaultColumnFamily(), keys.size(),
+                     keys.data(), values.data(), statuses.data(), true);
+  for (size_t i = 0; i < key_uncmp.size(); ++i) {
+    ASSERT_OK(statuses[i]);
+    ASSERT_TRUE(CheckUncompressableValue(key_uncmp[i], values[i].ToString()));
+  }
+  if (compression_enabled() && !has_compressed_cache()) {
+    expected_reads += (read_from_cache ? 3 : 3);
+  } else {
+    expected_reads += (read_from_cache ? 4 : 4);
+  }
+  ASSERT_EQ(env_->random_read_counter_.Read(), expected_reads);
+
+  keys.resize(5);
+  statuses.resize(5);
+  std::vector<int> key_tr{1, 2, 15, 16, 55};
+  for (size_t i = 0; i < key_tr.size(); ++i) {
+    key_data[i] = "a" + Key(key_tr[i]);
+    keys[i] = Slice(key_data[i]);
+    statuses[i] = Status::OK();
+    values[i].Reset();
+  }
+  dbfull()->MultiGet(ro, dbfull()->DefaultColumnFamily(), keys.size(),
+                     keys.data(), values.data(), statuses.data(), true);
+  for (size_t i = 0; i < key_tr.size(); ++i) {
+    ASSERT_OK(statuses[i]);
+    ASSERT_TRUE(CheckUncompressableValue(key_tr[i], values[i].ToString()));
+  }
+  if (compression_enabled() && !has_compressed_cache()) {
+    expected_reads += (read_from_cache ? 0 : 2);
+    ASSERT_EQ(env_->random_read_counter_.Read(), expected_reads);
+  } else {
+    if (has_uncompressed_cache()) {
+      expected_reads += (read_from_cache ? 0 : 3);
+      ASSERT_EQ(env_->random_read_counter_.Read(), expected_reads);
+    } else {
+      // A rare case, even we enable the block compression but some of data
+      // blocks are not compressed due to content. If user only enable the
+      // compressed cache, the uncompressed blocks will not tbe cached, and
+      // block reads will be triggered. The number of reads is related to
+      // the compression algorithm.
+      ASSERT_TRUE(env_->random_read_counter_.Read() >= expected_reads);
+    }
+  }
 }

 INSTANTIATE_TEST_CASE_P(
@@ -2045,48 +2124,81 @@ TEST_P(DBBasicTestWithTimestampWithParam, PutAndGet) {
      10 /*bits_per_key*/, false /*use_block_based_builder*/));
  bbto.whole_key_filtering = true;
  options.table_factory.reset(NewBlockBasedTableFactory(bbto));
-  DestroyAndReopen(options);
-  CreateAndReopenWithCF({"pikachu"}, options);
-  size_t num_cfs = handles_.size();
-  ASSERT_EQ(2, num_cfs);
-  std::vector<std::string> write_ts_strs(kNumTimestamps);
-  std::vector<std::string> read_ts_strs(kNumTimestamps);
-  std::vector<Slice> write_ts_list;
-  std::vector<Slice> read_ts_list;

-  for (size_t i = 0; i != kNumTimestamps; ++i) {
-    write_ts_list.emplace_back(EncodeTimestamp(i * 2, 0, &write_ts_strs[i]));
-    read_ts_list.emplace_back(EncodeTimestamp(1 + i * 2, 0, &read_ts_strs[i]));
-    const Slice& write_ts = write_ts_list.back();
-    WriteOptions wopts;
-    wopts.timestamp = &write_ts;
-    for (int cf = 0; cf != static_cast<int>(num_cfs); ++cf) {
-      for (size_t j = 0; j != (kNumKeysPerFile - 1) / kNumTimestamps; ++j) {
-        ASSERT_OK(Put(cf, "key" + std::to_string(j),
-                      "value_" + std::to_string(j) + "_" + std::to_string(i),
-                      wopts));
-      }
-      if (!memtable_only) {
-        ASSERT_OK(Flush(cf));
-      }
-    }
+  std::vector<CompressionType> compression_types;
+  compression_types.push_back(kNoCompression);
+  if (Zlib_Supported()) {
+    compression_types.push_back(kZlibCompression);
  }
-  const auto& verify_db_func = [&]() {
-    for (size_t i = 0; i != kNumTimestamps; ++i) {
-      ReadOptions ropts;
-      ropts.timestamp = &read_ts_list[i];
-      for (int cf = 0; cf != static_cast<int>(num_cfs); ++cf) {
-        ColumnFamilyHandle* cfh = handles_[cf];
-        for (size_t j = 0; j != (kNumKeysPerFile - 1) / kNumTimestamps; ++j) {
-          std::string value;
-          ASSERT_OK(db_->Get(ropts, cfh, "key" + std::to_string(j), &value));
-          ASSERT_EQ("value_" + std::to_string(j) + "_" + std::to_string(i),
-                    value);
+#if LZ4_VERSION_NUMBER >= 10400  // r124+
+  compression_types.push_back(kLZ4Compression);
+  compression_types.push_back(kLZ4HCCompression);
+#endif  // LZ4_VERSION_NUMBER >= 10400
+  if (ZSTD_Supported()) {
+    compression_types.push_back(kZSTD);
+  }
+
+  // Switch compression dictionary on/off to check key extraction
+  // correctness in kBuffered state
+  std::vector<uint32_t> max_dict_bytes_list = {0, 1 << 14};  // 0 or 16KB
+
+  for (auto compression_type : compression_types) {
+    for (uint32_t max_dict_bytes : max_dict_bytes_list) {
+      options.compression = compression_type;
+      options.compression_opts.max_dict_bytes = max_dict_bytes;
+      if (compression_type == kZSTD) {
+        options.compression_opts.zstd_max_train_bytes = max_dict_bytes;
+      }
+      options.target_file_size_base = 1 << 26;  // 64MB
+
+      DestroyAndReopen(options);
+      CreateAndReopenWithCF({"pikachu"}, options);
+      size_t num_cfs = handles_.size();
+      ASSERT_EQ(2, num_cfs);
+      std::vector<std::string> write_ts_strs(kNumTimestamps);
+      std::vector<std::string> read_ts_strs(kNumTimestamps);
+      std::vector<Slice> write_ts_list;
+      std::vector<Slice> read_ts_list;
+
+      for (size_t i = 0; i != kNumTimestamps; ++i) {
+        write_ts_list.emplace_back(
+            EncodeTimestamp(i * 2, 0, &write_ts_strs[i]));
+        read_ts_list.emplace_back(
+            EncodeTimestamp(1 + i * 2, 0, &read_ts_strs[i]));
+        const Slice& write_ts = write_ts_list.back();
+        WriteOptions wopts;
+        wopts.timestamp = &write_ts;
+        for (int cf = 0; cf != static_cast<int>(num_cfs); ++cf) {
+          for (size_t j = 0; j != (kNumKeysPerFile - 1) / kNumTimestamps; ++j) {
+            ASSERT_OK(Put(
+                cf, "key" + std::to_string(j),
+                "value_" + std::to_string(j) + "_" + std::to_string(i), wopts));
+          }
+          if (!memtable_only) {
+            ASSERT_OK(Flush(cf));
+          }
        }
      }
+      const auto& verify_db_func = [&]() {
+        for (size_t i = 0; i != kNumTimestamps; ++i) {
+          ReadOptions ropts;
+          ropts.timestamp = &read_ts_list[i];
+          for (int cf = 0; cf != static_cast<int>(num_cfs); ++cf) {
+            ColumnFamilyHandle* cfh = handles_[cf];
+            for (size_t j = 0; j != (kNumKeysPerFile - 1) / kNumTimestamps;
+                 ++j) {
+              std::string value;
+              ASSERT_OK(
+                  db_->Get(ropts, cfh, "key" + std::to_string(j), &value));
+              ASSERT_EQ("value_" + std::to_string(j) + "_" + std::to_string(i),
+                        value);
+            }
+          }
+        }
+      };
+      verify_db_func();
    }
-  };
-  verify_db_func();
+  }
 }

 INSTANTIATE_TEST_CASE_P(Timestamp, DBBasicTestWithTimestampWithParam,
@@ -10,6 +10,7 @@
 #include "cache/lru_cache.h"
 #include "db/db_test_util.h"
 #include "port/stack_trace.h"
+#include "util/compression.h"

 namespace rocksdb {

@@ -685,16 +686,18 @@ TEST_F(DBBlockCacheTest, CacheCompressionDict) {

  // Try all the available libraries that support dictionary compression
  std::vector<CompressionType> compression_types;
-#ifdef ZLIB
-  compression_types.push_back(kZlibCompression);
-#endif  // ZLIB
-#if LZ4_VERSION_NUMBER >= 10400
-  compression_types.push_back(kLZ4Compression);
-  compression_types.push_back(kLZ4HCCompression);
-#endif  // LZ4_VERSION_NUMBER >= 10400
-#if ZSTD_VERSION_NUMBER >= 500
-  compression_types.push_back(kZSTD);
-#endif  // ZSTD_VERSION_NUMBER >= 500
+  if (Zlib_Supported()) {
+    compression_types.push_back(kZlibCompression);
+  }
+  if (LZ4_Supported()) {
+    compression_types.push_back(kLZ4Compression);
+    compression_types.push_back(kLZ4HCCompression);
+  }
+  if (ZSTD_Supported()) {
+    compression_types.push_back(kZSTD);
+  } else if (ZSTDNotFinal_Supported()) {
+    compression_types.push_back(kZSTDNotFinalCompression);
+  }
  Random rnd(301);
  for (auto compression_type : compression_types) {
    Options options = CurrentOptions();
@@ -1503,6 +1503,37 @@ TEST_F(DBCompactionTest, DISABLED_ManualPartialFill) {
  }
 }

+TEST_F(DBCompactionTest, ManualCompactionWithUnorderedWrite) {
+  rocksdb::SyncPoint::GetInstance()->LoadDependency(
+      {{"DBImpl::WriteImpl:UnorderedWriteAfterWriteWAL",
+        "DBCompactionTest::ManualCompactionWithUnorderedWrite:WaitWriteWAL"},
+       {"DBImpl::WaitForPendingWrites:BeforeBlock",
+        "DBImpl::WriteImpl:BeforeUnorderedWriteMemtable"}});
+
+  Options options = CurrentOptions();
+  options.unordered_write = true;
+  DestroyAndReopen(options);
+  Put("foo", "v1");
+  ASSERT_OK(Flush());
+
+  Put("bar", "v1");
+  rocksdb::SyncPoint::GetInstance()->EnableProcessing();
+  port::Thread writer([&]() { Put("foo", "v2"); });
+
+  TEST_SYNC_POINT(
+      "DBCompactionTest::ManualCompactionWithUnorderedWrite:WaitWriteWAL");
+  ASSERT_OK(db_->CompactRange(CompactRangeOptions(), nullptr, nullptr));
+
+  writer.join();
+  ASSERT_EQ(Get("foo"), "v2");
+
+  SyncPoint::GetInstance()->DisableProcessing();
+  SyncPoint::GetInstance()->ClearAllCallBacks();
+
+  Reopen(options);
+  ASSERT_EQ(Get("foo"), "v2");
+}
+
 TEST_F(DBCompactionTest, DeleteFileRange) {
  Options options = CurrentOptions();
  options.write_buffer_size = 10 * 1024 * 1024;
@@ -3657,71 +3688,103 @@ TEST_F(DBCompactionTest, LevelPeriodicCompaction) {
  const int kNumLevelFiles = 2;
  const int kValueSize = 100;

-  Options options = CurrentOptions();
-  options.periodic_compaction_seconds = 48 * 60 * 60;  // 2 days
-  options.max_open_files = -1;       // needed for ttl compaction
-  env_->time_elapse_only_sleep_ = false;
-  options.env = env_;
+  for (bool if_restart : {false, true}) {
+    for (bool if_open_all_files : {false, true}) {
+      Options options = CurrentOptions();
+      options.periodic_compaction_seconds = 48 * 60 * 60;  // 2 days
+      if (if_open_all_files) {
+        options.max_open_files = -1;  // needed for ttl compaction
+      } else {
+        options.max_open_files = 20;
+      }
+      // RocksDB sanitize max open files to at least 20. Modify it back.
+      rocksdb::SyncPoint::GetInstance()->SetCallBack(
+          "SanitizeOptions::AfterChangeMaxOpenFiles", [&](void* arg) {
+            int* max_open_files = static_cast<int*>(arg);
+            *max_open_files = 0;
+          });
+      // In the case where all files are opened and doing DB restart
+      // forcing the file creation time in manifest file to be 0 to
+      // simulate the case of reading from an old version.
+      rocksdb::SyncPoint::GetInstance()->SetCallBack(
+          "VersionEdit::EncodeTo:VarintFileCreationTime", [&](void* arg) {
+            if (if_restart && if_open_all_files) {
+              std::string* encoded_fieled = static_cast<std::string*>(arg);
+              *encoded_fieled = "";
+              PutVarint64(encoded_fieled, 0);
+            }
+          });

-  env_->addon_time_.store(0);
-  DestroyAndReopen(options);
+      env_->time_elapse_only_sleep_ = false;
+      options.env = env_;

-  int periodic_compactions = 0;
-  rocksdb::SyncPoint::GetInstance()->SetCallBack(
-      "LevelCompactionPicker::PickCompaction:Return", [&](void* arg) {
-        Compaction* compaction = reinterpret_cast<Compaction*>(arg);
-        auto compaction_reason = compaction->compaction_reason();
-        if (compaction_reason == CompactionReason::kPeriodicCompaction) {
-          periodic_compactions++;
+      env_->addon_time_.store(0);
+      DestroyAndReopen(options);
+
+      int periodic_compactions = 0;
+      rocksdb::SyncPoint::GetInstance()->SetCallBack(
+          "LevelCompactionPicker::PickCompaction:Return", [&](void* arg) {
+            Compaction* compaction = reinterpret_cast<Compaction*>(arg);
+            auto compaction_reason = compaction->compaction_reason();
+            if (compaction_reason == CompactionReason::kPeriodicCompaction) {
+              periodic_compactions++;
+            }
+          });
+      rocksdb::SyncPoint::GetInstance()->EnableProcessing();
+
+      Random rnd(301);
+      for (int i = 0; i < kNumLevelFiles; ++i) {
+        for (int j = 0; j < kNumKeysPerFile; ++j) {
+          ASSERT_OK(Put(Key(i * kNumKeysPerFile + j),
+                        RandomString(&rnd, kValueSize)));
        }
-      });
-  rocksdb::SyncPoint::GetInstance()->EnableProcessing();
+        Flush();
+      }
+      dbfull()->TEST_WaitForCompact();

-  Random rnd(301);
-  for (int i = 0; i < kNumLevelFiles; ++i) {
-    for (int j = 0; j < kNumKeysPerFile; ++j) {
-      ASSERT_OK(
-          Put(Key(i * kNumKeysPerFile + j), RandomString(&rnd, kValueSize)));
+      ASSERT_EQ("2", FilesPerLevel());
+      ASSERT_EQ(0, periodic_compactions);
+
+      // Add 50 hours and do a write
+      env_->addon_time_.fetch_add(50 * 60 * 60);
+      ASSERT_OK(Put("a", "1"));
+      Flush();
+      dbfull()->TEST_WaitForCompact();
+      // Assert that the files stay in the same level
+      ASSERT_EQ("3", FilesPerLevel());
+      // The two old files go through the periodic compaction process
+      ASSERT_EQ(2, periodic_compactions);
+
+      MoveFilesToLevel(1);
+      ASSERT_EQ("0,3", FilesPerLevel());
+
+      // Add another 50 hours and do another write
+      env_->addon_time_.fetch_add(50 * 60 * 60);
+      ASSERT_OK(Put("b", "2"));
+      if (if_restart) {
+        Reopen(options);
+      } else {
+        Flush();
+      }
+      dbfull()->TEST_WaitForCompact();
+      ASSERT_EQ("1,3", FilesPerLevel());
+      // The three old files now go through the periodic compaction process. 2
+      // + 3.
+      ASSERT_EQ(5, periodic_compactions);
+
+      // Add another 50 hours and do another write
+      env_->addon_time_.fetch_add(50 * 60 * 60);
+      ASSERT_OK(Put("c", "3"));
+      Flush();
+      dbfull()->TEST_WaitForCompact();
+      ASSERT_EQ("2,3", FilesPerLevel());
+      // The four old files now go through the periodic compaction process. 5
+      // + 4.
+      ASSERT_EQ(9, periodic_compactions);
+
+      rocksdb::SyncPoint::GetInstance()->DisableProcessing();
    }
-    Flush();
  }
-  dbfull()->TEST_WaitForCompact();
-
-  ASSERT_EQ("2", FilesPerLevel());
-  ASSERT_EQ(0, periodic_compactions);
-
-  // Add 50 hours and do a write
-  env_->addon_time_.fetch_add(50 * 60 * 60);
-  ASSERT_OK(Put("a", "1"));
-  Flush();
-  dbfull()->TEST_WaitForCompact();
-  // Assert that the files stay in the same level
-  ASSERT_EQ("3", FilesPerLevel());
-  // The two old files go through the periodic compaction process
-  ASSERT_EQ(2, periodic_compactions);
-
-  MoveFilesToLevel(1);
-  ASSERT_EQ("0,3", FilesPerLevel());
-
-  // Add another 50 hours and do another write
-  env_->addon_time_.fetch_add(50 * 60 * 60);
-  ASSERT_OK(Put("b", "2"));
-  Flush();
-  dbfull()->TEST_WaitForCompact();
-  ASSERT_EQ("1,3", FilesPerLevel());
-  // The three old files now go through the periodic compaction process. 2 + 3.
-  ASSERT_EQ(5, periodic_compactions);
-
-  // Add another 50 hours and do another write
-  env_->addon_time_.fetch_add(50 * 60 * 60);
-  ASSERT_OK(Put("c", "3"));
-  Flush();
-  dbfull()->TEST_WaitForCompact();
-  ASSERT_EQ("2,3", FilesPerLevel());
-  // The four old files now go through the periodic compaction process. 5 + 4.
-  ASSERT_EQ(9, periodic_compactions);
-
-  rocksdb::SyncPoint::GetInstance()->DisableProcessing();
 }

 TEST_F(DBCompactionTest, LevelPeriodicCompactionWithOldDB) {
@@ -3734,7 +3797,6 @@ TEST_F(DBCompactionTest, LevelPeriodicCompactionWithOldDB) {
  const int kValueSize = 100;

  Options options = CurrentOptions();
-  options.max_open_files = -1;  // needed for ttl compaction
  env_->time_elapse_only_sleep_ = false;
  options.env = env_;

@@ -102,7 +102,7 @@ Status DBImpl::GetLiveFiles(std::vector<std::string>& ret,
        TEST_SYNC_POINT("DBImpl::GetLiveFiles:1");
        TEST_SYNC_POINT("DBImpl::GetLiveFiles:2");
        mutex_.Lock();
-        cfd->Unref();
+        cfd->UnrefAndTryDelete();
        if (!status.ok()) {
          break;
        }
@@ -212,6 +212,30 @@ TEST_F(DBFlushTest, ManualFlushWithMinWriteBufferNumberToMerge) {
  t.join();
 }

+TEST_F(DBFlushTest, ScheduleOnlyOneBgThread) {
+  Options options = CurrentOptions();
+  Reopen(options);
+  SyncPoint::GetInstance()->DisableProcessing();
+  SyncPoint::GetInstance()->ClearAllCallBacks();
+  int called = 0;
+  SyncPoint::GetInstance()->SetCallBack(
+      "DBImpl::MaybeScheduleFlushOrCompaction:AfterSchedule:0", [&](void* arg) {
+        ASSERT_NE(nullptr, arg);
+        auto unscheduled_flushes = *reinterpret_cast<int*>(arg);
+        ASSERT_EQ(0, unscheduled_flushes);
+        ++called;
+      });
+  SyncPoint::GetInstance()->EnableProcessing();
+
+  ASSERT_OK(Put("a", "foo"));
+  FlushOptions flush_opts;
+  ASSERT_OK(dbfull()->Flush(flush_opts));
+  ASSERT_EQ(1, called);
+
+  SyncPoint::GetInstance()->DisableProcessing();
+  SyncPoint::GetInstance()->ClearAllCallBacks();
+}
+
 TEST_P(DBFlushDirectIOTest, DirectIO) {
  Options options;
  options.create_if_missing = true;
@@ -52,6 +52,7 @@
 #include "db/version_set.h"
 #include "db/write_batch_internal.h"
 #include "db/write_callback.h"
+#include "env/composite_env_wrapper.h"
 #include "file/file_util.h"
 #include "file/filename.h"
 #include "file/random_access_file_reader.h"
@@ -102,6 +103,7 @@
 #include "util/string_util.h"

 namespace rocksdb {
+
 const std::string kDefaultColumnFamilyName("default");
 const std::string kPersistentStatsColumnFamilyName(
    "___rocksdb_stats_history___");
@@ -141,16 +143,15 @@ void DumpSupportInfo(Logger* logger) {
  ROCKS_LOG_HEADER(logger, "Fast CRC32 supported: %s",
                   crc32c::IsFastCrc32Supported().c_str());
 }
-
-int64_t kDefaultLowPriThrottledRate = 2 * 1024 * 1024;
 }  // namespace

 DBImpl::DBImpl(const DBOptions& options, const std::string& dbname,
               const bool seq_per_batch, const bool batch_per_txn)
-    : env_(options.env),
-      dbname_(dbname),
+    : dbname_(dbname),
      own_info_log_(options.info_log == nullptr),
      initial_db_options_(SanitizeOptions(dbname, options)),
+      env_(initial_db_options_.env),
+      fs_(initial_db_options_.file_system),
      immutable_db_options_(initial_db_options_),
      mutable_db_options_(initial_db_options_),
      stats_(immutable_db_options_.statistics.get()),
@@ -158,9 +159,9 @@ DBImpl::DBImpl(const DBOptions& options, const std::string& dbname,
             immutable_db_options_.use_adaptive_mutex),
      default_cf_handle_(nullptr),
      max_total_in_memory_state_(0),
-      env_options_(BuildDBOptions(immutable_db_options_, mutable_db_options_)),
-      env_options_for_compaction_(env_->OptimizeForCompactionTableWrite(
-          env_options_, immutable_db_options_)),
+      file_options_(BuildDBOptions(immutable_db_options_, mutable_db_options_)),
+      file_options_for_compaction_(fs_->OptimizeForCompactionTableWrite(
+          file_options_, immutable_db_options_)),
      seq_per_batch_(seq_per_batch),
      batch_per_txn_(batch_per_txn),
      db_lock_(nullptr),
@@ -178,11 +179,6 @@ DBImpl::DBImpl(const DBOptions& options, const std::string& dbname,
      write_thread_(immutable_db_options_),
      nonmem_write_thread_(immutable_db_options_),
      write_controller_(mutable_db_options_.delayed_write_rate),
-      // Use delayed_write_rate as a base line to determine the initial
-      // low pri write rate limit. It may be adjusted later.
-      low_pri_write_rate_limiter_(NewGenericRateLimiter(std::min(
-          static_cast<int64_t>(mutable_db_options_.delayed_write_rate / 8),
-          kDefaultLowPriThrottledRate))),
      last_batch_group_size_(0),
      unscheduled_flushes_(0),
      unscheduled_compactions_(0),
@@ -201,7 +197,7 @@ DBImpl::DBImpl(const DBOptions& options, const std::string& dbname,
      unable_to_release_oldest_log_(false),
      num_running_ingest_file_(0),
 #ifndef ROCKSDB_LITE
-      wal_manager_(immutable_db_options_, env_options_, seq_per_batch),
+      wal_manager_(immutable_db_options_, file_options_, seq_per_batch),
 #endif  // ROCKSDB_LITE
      event_logger_(immutable_db_options_.info_log.get()),
      bg_work_paused_(0),
@@ -247,7 +243,7 @@ DBImpl::DBImpl(const DBOptions& options, const std::string& dbname,
  co.metadata_charge_policy = kDontChargeCacheMetadata;
  table_cache_ = NewLRUCache(co);

-  versions_.reset(new VersionSet(dbname_, &immutable_db_options_, env_options_,
+  versions_.reset(new VersionSet(dbname_, &immutable_db_options_, file_options_,
                                 table_cache_.get(), write_buffer_manager_,
                                 &write_controller_, &block_cache_tracer_));
  column_family_memtables_.reset(
@@ -337,7 +333,7 @@ Status DBImpl::ResumeImpl() {
        mutex_.Unlock();
        s = FlushMemTable(cfd, flush_opts, FlushReason::kErrorRecovery);
        mutex_.Lock();
-        cfd->Unref();
+        cfd->UnrefAndTryDelete();
        if (!s.ok()) {
          break;
        }
@@ -425,7 +421,7 @@ void DBImpl::CancelAllBackgroundWork(bool wait) {
          mutex_.Unlock();
          FlushMemTable(cfd, FlushOptions(), FlushReason::kShutDown);
          mutex_.Lock();
-          cfd->Unref();
+          cfd->UnrefAndTryDelete();
        }
      }
    }
@@ -482,17 +478,12 @@ Status DBImpl::CloseHelper() {
  while (!flush_queue_.empty()) {
    const FlushRequest& flush_req = PopFirstFromFlushQueue();
    for (const auto& iter : flush_req) {
-      ColumnFamilyData* cfd = iter.first;
-      if (cfd->Unref()) {
-        delete cfd;
-      }
+      iter.first->UnrefAndTryDelete();
    }
  }
  while (!compaction_queue_.empty()) {
    auto cfd = PopFirstFromCompactionQueue();
-    if (cfd->Unref()) {
-      delete cfd;
-    }
+    cfd->UnrefAndTryDelete();
  }

  if (default_cf_handle_ != nullptr || persist_stats_cf_handle_ != nullptr) {
@@ -599,6 +590,7 @@ Status DBImpl::CloseHelper() {
      ret = s;
    }
  }
+
  if (ret.IsAborted()) {
    // Reserve IsAborted() error for those where users didn't release
    // certain resource and they can release them and come back and
@@ -879,7 +871,7 @@ Status DBImpl::TablesRangeTombstoneSummary(ColumnFamilyHandle* column_family,
          column_family);
  ColumnFamilyData* cfd = cfh->cfd();

-  SuperVersion* super_version = cfd->GetReferencedSuperVersion(&mutex_);
+  SuperVersion* super_version = cfd->GetReferencedSuperVersion(this);
  Version* version = super_version->current;

  Status s =
@@ -895,7 +887,6 @@ void DBImpl::ScheduleBgLogWriterClose(JobContext* job_context) {
      AddToLogsToFreeQueue(l);
    }
    job_context->logs_to_free.clear();
-    SchedulePurge();
  }
 }

@@ -1060,14 +1051,14 @@ Status DBImpl::SetDBOptions(
      wal_changed = mutable_db_options_.wal_bytes_per_sync !=
                    new_options.wal_bytes_per_sync;
      mutable_db_options_ = new_options;
-      env_options_for_compaction_ = EnvOptions(new_db_options);
-      env_options_for_compaction_ = env_->OptimizeForCompactionTableWrite(
-          env_options_for_compaction_, immutable_db_options_);
-      versions_->ChangeEnvOptions(mutable_db_options_);
+      file_options_for_compaction_ = FileOptions(new_db_options);
+      file_options_for_compaction_ = fs_->OptimizeForCompactionTableWrite(
+          file_options_for_compaction_, immutable_db_options_);
+      versions_->ChangeFileOptions(mutable_db_options_);
      //TODO(xiez): clarify why apply optimize for read to write options
-      env_options_for_compaction_ = env_->OptimizeForCompactionTableRead(
-          env_options_for_compaction_, immutable_db_options_);
-      env_options_for_compaction_.compaction_readahead_size =
+      file_options_for_compaction_ = fs_->OptimizeForCompactionTableRead(
+          file_options_for_compaction_, immutable_db_options_);
+      file_options_for_compaction_.compaction_readahead_size =
          mutable_db_options_.compaction_readahead_size;
      WriteThread::Writer w;
      write_thread_.EnterUnbatched(&w, &mutex_);
@@ -1322,19 +1313,34 @@ void DBImpl::BackgroundCallPurge() {
    delete log_writer;
    mutex_.Lock();
  }
-  for (const auto& file : purge_files_) {
-    const PurgeFileInfo& purge_file = file.second;
+  while (!superversions_to_free_queue_.empty()) {
+    assert(!superversions_to_free_queue_.empty());
+    SuperVersion* sv = superversions_to_free_queue_.front();
+    superversions_to_free_queue_.pop_front();
+    mutex_.Unlock();
+    delete sv;
+    mutex_.Lock();
+  }
+
+  // Can't use iterator to go over purge_files_ because inside the loop we're
+  // unlocking the mutex that protects purge_files_.
+  while (!purge_files_.empty()) {
+    auto it = purge_files_.begin();
+    // Need to make a copy of the PurgeFilesInfo before unlocking the mutex.
+    PurgeFileInfo purge_file = it->second;
+
    const std::string& fname = purge_file.fname;
    const std::string& dir_to_sync = purge_file.dir_to_sync;
    FileType type = purge_file.type;
    uint64_t number = purge_file.number;
    int job_id = purge_file.job_id;

+    purge_files_.erase(it);
+
    mutex_.Unlock();
    DeleteObsoleteFileImpl(job_id, fname, dir_to_sync, type, number);
    mutex_.Lock();
  }
-  purge_files_.clear();

  bg_purge_scheduled_--;

@@ -1374,10 +1380,14 @@ static void CleanupIteratorState(void* arg1, void* /*arg2*/) {
    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();
    }
    state->mu->Unlock();

-    delete state->super_version;
+    if (!state->background_purge) {
+      delete state->super_version;
+    }
    if (job_context.HaveSomethingToDelete()) {
      if (state->background_purge) {
        // PurgeObsoleteFiles here does not delete files. Instead, it adds the
@@ -1434,7 +1444,7 @@ InternalIterator* DBImpl::NewInternalIterator(const ReadOptions& read_options,
  if (s.ok()) {
    // Collect iterators for files in L0 - Ln
    if (read_options.read_tier != kMemtableTier) {
-      super_version->current->AddIterators(read_options, env_options_,
+      super_version->current->AddIterators(read_options, file_options_,
                                           &merge_iter_builder, range_del_agg);
    }
    internal_iter = merge_iter_builder.Finish();
@@ -2452,7 +2462,7 @@ Iterator* DBImpl::NewIterator(const ReadOptions& read_options,
    result = nullptr;

 #else
-    SuperVersion* sv = cfd->GetReferencedSuperVersion(&mutex_);
+    SuperVersion* sv = cfd->GetReferencedSuperVersion(this);
    auto iter = new ForwardIterator(this, read_options, cfd, sv);
    result = NewDBIterator(
        env_, read_options, *cfd->ioptions(), sv->mutable_cf_options,
@@ -2478,7 +2488,7 @@ ArenaWrappedDBIter* DBImpl::NewIteratorImpl(const ReadOptions& read_options,
                                            ReadCallback* read_callback,
                                            bool allow_blob,
                                            bool allow_refresh) {
-  SuperVersion* sv = cfd->GetReferencedSuperVersion(&mutex_);
+  SuperVersion* sv = cfd->GetReferencedSuperVersion(this);

  // Try to generate a DB iterator tree in continuous memory area to be
  // cache friendly. Here is an example of result:
@@ -2557,7 +2567,7 @@ Status DBImpl::NewIterators(
 #else
    for (auto cfh : column_families) {
      auto cfd = reinterpret_cast<ColumnFamilyHandleImpl*>(cfh)->cfd();
-      SuperVersion* sv = cfd->GetReferencedSuperVersion(&mutex_);
+      SuperVersion* sv = cfd->GetReferencedSuperVersion(this);
      auto iter = new ForwardIterator(this, read_options, cfd, sv);
      iterators->push_back(NewDBIterator(
          env_, read_options, *cfd->ioptions(), sv->mutable_cf_options,
@@ -2729,6 +2739,15 @@ const std::string& DBImpl::GetName() const { return dbname_; }

 Env* DBImpl::GetEnv() const { return env_; }

+FileSystem* DB::GetFileSystem() const {
+  static LegacyFileSystemWrapper fs_wrap(GetEnv());
+  return &fs_wrap;
+}
+
+FileSystem* DBImpl::GetFileSystem() const {
+  return immutable_db_options_.fs.get();
+}
+
 Options DBImpl::GetOptions(ColumnFamilyHandle* column_family) const {
  InstrumentedMutexLock l(&mutex_);
  auto cfh = reinterpret_cast<ColumnFamilyHandleImpl*>(column_family);
@@ -2884,7 +2903,7 @@ bool DBImpl::GetAggregatedIntProperty(const Slice& property,

 SuperVersion* DBImpl::GetAndRefSuperVersion(ColumnFamilyData* cfd) {
  // TODO(ljin): consider using GetReferencedSuperVersion() directly
-  return cfd->GetThreadLocalSuperVersion(&mutex_);
+  return cfd->GetThreadLocalSuperVersion(this);
 }

 // REQUIRED: this function should only be called on the write thread or if the
@@ -2902,11 +2921,19 @@ SuperVersion* DBImpl::GetAndRefSuperVersion(uint32_t column_family_id) {
 void DBImpl::CleanupSuperVersion(SuperVersion* sv) {
  // Release SuperVersion
  if (sv->Unref()) {
+    bool defer_purge =
+            immutable_db_options().avoid_unnecessary_blocking_io;
    {
      InstrumentedMutexLock l(&mutex_);
      sv->Cleanup();
+      if (defer_purge) {
+        AddSuperVersionsToFreeQueue(sv);
+        SchedulePurge();
+      }
+    }
+    if (!defer_purge) {
+      delete sv;
    }
-    delete sv;
    RecordTick(stats_, NUMBER_SUPERVERSION_CLEANUPS);
  }
  RecordTick(stats_, NUMBER_SUPERVERSION_RELEASES);
@@ -3301,12 +3328,12 @@ Status DBImpl::GetDbIdentity(std::string& identity) const {

 Status DBImpl::GetDbIdentityFromIdentityFile(std::string* identity) const {
  std::string idfilename = IdentityFileName(dbname_);
-  const EnvOptions soptions;
+  const FileOptions soptions;
  std::unique_ptr<SequentialFileReader> id_file_reader;
  Status s;
  {
-    std::unique_ptr<SequentialFile> idfile;
-    s = env_->NewSequentialFile(idfilename, &idfile, soptions);
+    std::unique_ptr<FSSequentialFile> idfile;
+    s = fs_->NewSequentialFile(idfilename, soptions, &idfile, nullptr);
    if (!s.ok()) {
      return s;
    }
@@ -3315,7 +3342,7 @@ Status DBImpl::GetDbIdentityFromIdentityFile(std::string* identity) const {
  }

  uint64_t file_size;
-  s = env_->GetFileSize(idfilename, &file_size);
+  s = fs_->GetFileSize(idfilename, IOOptions(), &file_size, nullptr);
  if (!s.ok()) {
    return s;
  }
@@ -3389,7 +3416,12 @@ Status DBImpl::Close() {
 Status DB::ListColumnFamilies(const DBOptions& db_options,
                              const std::string& name,
                              std::vector<std::string>* column_families) {
-  return VersionSet::ListColumnFamilies(column_families, name, db_options.env);
+  FileSystem* fs = db_options.file_system.get();
+  LegacyFileSystemWrapper legacy_fs(db_options.env);
+  if (!fs) {
+    fs = &legacy_fs;
+  }
+  return VersionSet::ListColumnFamilies(column_families, name, fs);
 }

 Snapshot::~Snapshot() {}
@@ -3554,8 +3586,8 @@ Status DBImpl::WriteOptionsFile(bool need_mutex_lock,

  std::string file_name =
      TempOptionsFileName(GetName(), versions_->NewFileNumber());
-  Status s =
-      PersistRocksDBOptions(db_options, cf_names, cf_opts, file_name, GetEnv());
+  Status s = PersistRocksDBOptions(db_options, cf_names, cf_opts, file_name,
+                                   GetFileSystem());

  if (s.ok()) {
    s = RenameTempFileToOptionsFile(file_name);
@@ -3899,7 +3931,7 @@ Status DBImpl::IngestExternalFiles(
  for (const auto& arg : args) {
    auto* cfd = static_cast<ColumnFamilyHandleImpl*>(arg.column_family)->cfd();
    ingestion_jobs.emplace_back(
-        env_, versions_.get(), cfd, immutable_db_options_, env_options_,
+        env_, versions_.get(), cfd, immutable_db_options_, file_options_,
        &snapshots_, arg.options, &directories_, &event_logger_);
  }
  std::vector<std::pair<bool, Status>> exec_results;
@@ -3912,7 +3944,7 @@ Status DBImpl::IngestExternalFiles(
    start_file_number += args[i - 1].external_files.size();
    auto* cfd =
        static_cast<ColumnFamilyHandleImpl*>(args[i].column_family)->cfd();
-    SuperVersion* super_version = cfd->GetReferencedSuperVersion(&mutex_);
+    SuperVersion* super_version = cfd->GetReferencedSuperVersion(this);
    exec_results[i].second = ingestion_jobs[i].Prepare(
        args[i].external_files, start_file_number, super_version);
    exec_results[i].first = true;
@@ -3923,7 +3955,7 @@ Status DBImpl::IngestExternalFiles(
  {
    auto* cfd =
        static_cast<ColumnFamilyHandleImpl*>(args[0].column_family)->cfd();
-    SuperVersion* super_version = cfd->GetReferencedSuperVersion(&mutex_);
+    SuperVersion* super_version = cfd->GetReferencedSuperVersion(this);
    exec_results[0].second = ingestion_jobs[0].Prepare(
        args[0].external_files, next_file_number, super_version);
    exec_results[0].first = true;
@@ -3965,6 +3997,13 @@ Status DBImpl::IngestExternalFiles(
      nonmem_write_thread_.EnterUnbatched(&nonmem_w, &mutex_);
    }

+    // When unordered_write is enabled, the keys are writing to memtable in an
+    // unordered way. If the ingestion job checks memtable key range before the
+    // key landing in memtable, the ingestion job may skip the necessary
+    // memtable flush.
+    // So wait here to ensure there is no pending write to memtable.
+    WaitForPendingWrites();
+
    num_running_ingest_file_ += static_cast<int>(num_cfs);
    TEST_SYNC_POINT("DBImpl::IngestExternalFile:AfterIncIngestFileCounter");

@@ -4156,7 +4195,7 @@ Status DBImpl::CreateColumnFamilyWithImport(
  auto cfh = reinterpret_cast<ColumnFamilyHandleImpl*>(*handle);
  auto cfd = cfh->cfd();
  ImportColumnFamilyJob import_job(env_, versions_.get(), cfd,
-                                   immutable_db_options_, env_options_,
+                                   immutable_db_options_, file_options_,
                                   import_options, metadata.files);

  SuperVersionContext dummy_sv_ctx(/* create_superversion */ true);
@@ -4192,7 +4231,7 @@ Status DBImpl::CreateColumnFamilyWithImport(
  dummy_sv_ctx.Clean();

  if (status.ok()) {
-    SuperVersion* sv = cfd->GetReferencedSuperVersion(&mutex_);
+    SuperVersion* sv = cfd->GetReferencedSuperVersion(this);
    status = import_job.Prepare(next_file_number, sv);
    CleanupSuperVersion(sv);
  }
@@ -4269,7 +4308,7 @@ Status DBImpl::VerifyChecksum(const ReadOptions& read_options) {
  }
  std::vector<SuperVersion*> sv_list;
  for (auto cfd : cfd_list) {
-    sv_list.push_back(cfd->GetReferencedSuperVersion(&mutex_));
+    sv_list.push_back(cfd->GetReferencedSuperVersion(this));
  }
  for (auto& sv : sv_list) {
    VersionStorageInfo* vstorage = sv->current->storage_info();
@@ -4286,7 +4325,7 @@ Status DBImpl::VerifyChecksum(const ReadOptions& read_options) {
        const auto& fd = vstorage->LevelFilesBrief(i).files[j].fd;
        std::string fname = TableFileName(cfd->ioptions()->cf_paths,
                                          fd.GetNumber(), fd.GetPathId());
-        s = rocksdb::VerifySstFileChecksum(opts, env_options_, read_options,
+        s = rocksdb::VerifySstFileChecksum(opts, file_options_, read_options,
                                           fname);
      }
    }
@@ -4294,16 +4333,25 @@ Status DBImpl::VerifyChecksum(const ReadOptions& read_options) {
      break;
    }
  }
+  bool defer_purge =
+          immutable_db_options().avoid_unnecessary_blocking_io;
  {
    InstrumentedMutexLock l(&mutex_);
    for (auto sv : sv_list) {
      if (sv && sv->Unref()) {
        sv->Cleanup();
-        delete sv;
+        if (defer_purge) {
+          AddSuperVersionsToFreeQueue(sv);
+        } else {
+          delete sv;
+        }
      }
    }
+    if (defer_purge) {
+      SchedulePurge();
+    }
    for (auto cfd : cfd_list) {
-      cfd->Unref();
+      cfd->UnrefAndTryDelete();
    }
  }
  return s;
@@ -306,6 +306,7 @@ class DBImpl : public DB {
      ColumnFamilyHandle* column_family) override;
  virtual const std::string& GetName() const override;
  virtual Env* GetEnv() const override;
+  virtual FileSystem* GetFileSystem() const override;
  using DB::GetOptions;
  virtual Options GetOptions(ColumnFamilyHandle* column_family) const override;
  using DB::GetDBOptions;
@@ -798,6 +799,10 @@ class DBImpl : public DB {
    logs_to_free_queue_.push_back(log_writer);
  }

+  void AddSuperVersionsToFreeQueue(SuperVersion* sv) {
+    superversions_to_free_queue_.push_back(sv);
+  }
+
  void SetSnapshotChecker(SnapshotChecker* snapshot_checker);

  // Fill JobContext with snapshot information needed by flush and compaction.
@@ -941,13 +946,14 @@ class DBImpl : public DB {
 #endif  // NDEBUG

 protected:
-  Env* const env_;
  const std::string dbname_;
  std::string db_id_;
  std::unique_ptr<VersionSet> versions_;
  // Flag to check whether we allocated and own the info log file
  bool own_info_log_;
  const DBOptions initial_db_options_;
+  Env* const env_;
+  std::shared_ptr<FileSystem> fs_;
  const ImmutableDBOptions immutable_db_options_;
  MutableDBOptions mutable_db_options_;
  Statistics* stats_;
@@ -975,10 +981,10 @@ class DBImpl : public DB {
  bool single_column_family_mode_;

  // The options to access storage files
-  const EnvOptions env_options_;
+  const FileOptions file_options_;

  // Additonal options for compaction and flush
-  EnvOptions env_options_for_compaction_;
+  FileOptions file_options_for_compaction_;

  std::unique_ptr<ColumnFamilyMemTablesImpl> column_family_memtables_;

@@ -1109,6 +1115,8 @@ class DBImpl : public DB {
      bool read_only = false, bool error_if_log_file_exist = false,
      bool error_if_data_exists_in_logs = false);

+  virtual bool OwnTablesAndLogs() const { return true; }
+
 private:
  friend class DB;
  friend class ErrorHandler;
@@ -1193,7 +1201,7 @@ class DBImpl : public DB {
  };

  // PurgeFileInfo is a structure to hold information of files to be deleted in
-  // purge_queue_
+  // purge_files_
  struct PurgeFileInfo {
    std::string fname;
    std::string dir_to_sync;
@@ -1414,6 +1422,7 @@ class DBImpl : public DB {

  inline void WaitForPendingWrites() {
    mutex_.AssertHeld();
+    TEST_SYNC_POINT("DBImpl::WaitForPendingWrites:BeforeBlock");
    // In case of pipelined write is enabled, wait for all pending memtable
    // writers.
    if (immutable_db_options_.enable_pipelined_write) {
@@ -1829,8 +1838,6 @@ class DBImpl : public DB {

  WriteController write_controller_;

-  std::unique_ptr<RateLimiter> low_pri_write_rate_limiter_;
-
  // Size of the last batch group. In slowdown mode, next write needs to
  // sleep if it uses up the quota.
  // Note: This is to protect memtable and compaction. If the batch only writes
@@ -1888,6 +1895,7 @@ class DBImpl : public DB {

  // A queue to store log writers to close
  std::deque<log::Writer*> logs_to_free_queue_;
+  std::deque<SuperVersion*> superversions_to_free_queue_;
  int unscheduled_flushes_;
  int unscheduled_compactions_;

@@ -148,7 +148,7 @@ Status DBImpl::FlushMemTableToOutputFile(

  FlushJob flush_job(
      dbname_, cfd, immutable_db_options_, mutable_cf_options,
-      nullptr /* memtable_id */, env_options_for_compaction_, versions_.get(),
+      nullptr /* memtable_id */, file_options_for_compaction_, versions_.get(),
      &mutex_, &shutting_down_, snapshot_seqs, earliest_write_conflict_snapshot,
      snapshot_checker, job_context, log_buffer, directories_.GetDbDir(),
      GetDataDir(cfd, 0U),
@@ -332,7 +332,7 @@ Status DBImpl::AtomicFlushMemTablesToOutputFiles(
    const uint64_t* max_memtable_id = &(bg_flush_args[i].max_memtable_id_);
    jobs.emplace_back(new FlushJob(
        dbname_, cfd, immutable_db_options_, mutable_cf_options,
-        max_memtable_id, env_options_for_compaction_, versions_.get(), &mutex_,
+        max_memtable_id, file_options_for_compaction_, versions_.get(), &mutex_,
        &shutting_down_, snapshot_seqs, earliest_write_conflict_snapshot,
        snapshot_checker, job_context, log_buffer, directories_.GetDbDir(),
        data_dir, GetCompressionFlush(*cfd->ioptions(), mutable_cf_options),
@@ -659,7 +659,7 @@ Status DBImpl::CompactRange(const CompactRangeOptions& options,
    // one/both sides of the interval are unbounded. But it requires more
    // changes to RangesOverlapWithMemtables.
    Range range(*begin, *end);
-    SuperVersion* super_version = cfd->GetReferencedSuperVersion(&mutex_);
+    SuperVersion* super_version = cfd->GetReferencedSuperVersion(this);
    cfd->RangesOverlapWithMemtables({range}, super_version, &flush_needed);
    CleanupSuperVersion(super_version);
  }
@@ -968,7 +968,7 @@ Status DBImpl::CompactFilesImpl(
  CompactionJobStats compaction_job_stats;
  CompactionJob compaction_job(
      job_context->job_id, c.get(), immutable_db_options_,
-      env_options_for_compaction_, versions_.get(), &shutting_down_,
+      file_options_for_compaction_, versions_.get(), &shutting_down_,
      preserve_deletes_seqnum_.load(), log_buffer, directories_.GetDbDir(),
      GetDataDir(c->column_family_data(), c->output_path_id()), stats_, &mutex_,
      &error_handler_, snapshot_seqs, earliest_write_conflict_snapshot,
@@ -1257,7 +1257,7 @@ Status DBImpl::ReFitLevel(ColumnFamilyData* cfd, int level, int target_level) {
                   f->fd.GetFileSize(), f->smallest, f->largest,
                   f->fd.smallest_seqno, f->fd.largest_seqno,
                   f->marked_for_compaction, f->oldest_blob_file_number,
-                   f->oldest_ancester_time);
+                   f->oldest_ancester_time, f->file_creation_time);
    }
    ROCKS_LOG_DEBUG(immutable_db_options_.info_log,
                    "[%s] Apply version edit:\n%s", cfd->GetName().c_str(),
@@ -1540,6 +1540,7 @@ Status DBImpl::FlushMemTable(ColumnFamilyData* cfd,
        nonmem_write_thread_.EnterUnbatched(&nonmem_w, &mutex_);
      }
    }
+    WaitForPendingWrites();

    if (!cfd->mem()->IsEmpty() || !cached_recoverable_state_empty_.load()) {
      s = SwitchMemtable(cfd, &context);
@@ -1617,19 +1618,16 @@ Status DBImpl::FlushMemTable(ColumnFamilyData* cfd,
    }
    s = WaitForFlushMemTables(cfds, flush_memtable_ids,
                              (flush_reason == FlushReason::kErrorRecovery));
+    InstrumentedMutexLock lock_guard(&mutex_);
    for (auto* tmp_cfd : cfds) {
-      if (tmp_cfd->Unref()) {
-        // Only one thread can reach here.
-        InstrumentedMutexLock lock_guard(&mutex_);
-        delete tmp_cfd;
-      }
+      tmp_cfd->UnrefAndTryDelete();
    }
  }
-  TEST_SYNC_POINT("FlushMemTableFinished");
+  TEST_SYNC_POINT("DBImpl::FlushMemTable:FlushMemTableFinished");
  return s;
 }

-// Flush all elments in 'column_family_datas'
+// Flush all elements in 'column_family_datas'
 // and atomically record the result to the MANIFEST.
 Status DBImpl::AtomicFlushMemTables(
    const autovector<ColumnFamilyData*>& column_family_datas,
@@ -1665,6 +1663,7 @@ Status DBImpl::AtomicFlushMemTables(
        nonmem_write_thread_.EnterUnbatched(&nonmem_w, &mutex_);
      }
    }
+    WaitForPendingWrites();

    for (auto cfd : column_family_datas) {
      if (cfd->IsDropped()) {
@@ -1681,7 +1680,7 @@ Status DBImpl::AtomicFlushMemTables(
      }
      cfd->Ref();
      s = SwitchMemtable(cfd, &context);
-      cfd->Unref();
+      cfd->UnrefAndTryDelete();
      if (!s.ok()) {
        break;
      }
@@ -1721,12 +1720,9 @@ Status DBImpl::AtomicFlushMemTables(
    }
    s = WaitForFlushMemTables(cfds, flush_memtable_ids,
                              (flush_reason == FlushReason::kErrorRecovery));
+    InstrumentedMutexLock lock_guard(&mutex_);
    for (auto* cfd : cfds) {
-      if (cfd->Unref()) {
-        // Only one thread can reach here.
-        InstrumentedMutexLock lock_guard(&mutex_);
-        delete cfd;
-      }
+      cfd->UnrefAndTryDelete();
    }
  }
  return s;
@@ -1918,6 +1914,10 @@ void DBImpl::MaybeScheduleFlushOrCompaction() {
    fta->thread_pri_ = Env::Priority::HIGH;
    env_->Schedule(&DBImpl::BGWorkFlush, fta, Env::Priority::HIGH, this,
                   &DBImpl::UnscheduleFlushCallback);
+    --unscheduled_flushes_;
+    TEST_SYNC_POINT_CALLBACK(
+        "DBImpl::MaybeScheduleFlushOrCompaction:AfterSchedule:0",
+        &unscheduled_flushes_);
  }

  // special case -- if high-pri (flush) thread pool is empty, then schedule
@@ -1932,6 +1932,7 @@ void DBImpl::MaybeScheduleFlushOrCompaction() {
      fta->thread_pri_ = Env::Priority::LOW;
      env_->Schedule(&DBImpl::BGWorkFlush, fta, Env::Priority::LOW, this,
                     &DBImpl::UnscheduleFlushCallback);
+      --unscheduled_flushes_;
    }
  }

@@ -2015,8 +2016,6 @@ ColumnFamilyData* DBImpl::PopFirstFromCompactionQueue() {
 DBImpl::FlushRequest DBImpl::PopFirstFromFlushQueue() {
  assert(!flush_queue_.empty());
  FlushRequest flush_req = flush_queue_.front();
-  assert(unscheduled_flushes_ >= static_cast<int>(flush_req.size()));
-  unscheduled_flushes_ -= static_cast<int>(flush_req.size());
  flush_queue_.pop_front();
  // TODO: need to unset flush reason?
  return flush_req;
@@ -2058,7 +2057,7 @@ void DBImpl::SchedulePendingFlush(const FlushRequest& flush_req,
    cfd->Ref();
    cfd->SetFlushReason(flush_reason);
  }
-  unscheduled_flushes_ += static_cast<int>(flush_req.size());
+  ++unscheduled_flushes_;
  flush_queue_.push_back(flush_req);
 }

@@ -2204,16 +2203,13 @@ Status DBImpl::BackgroundFlush(bool* made_progress, JobContext* job_context,
    *reason = bg_flush_args[0].cfd_->GetFlushReason();
    for (auto& arg : bg_flush_args) {
      ColumnFamilyData* cfd = arg.cfd_;
-      if (cfd->Unref()) {
-        delete cfd;
+      if (cfd->UnrefAndTryDelete()) {
        arg.cfd_ = nullptr;
      }
    }
  }
  for (auto cfd : column_families_not_to_flush) {
-    if (cfd->Unref()) {
-      delete cfd;
-    }
+    cfd->UnrefAndTryDelete();
  }
  return status;
 }
@@ -2542,10 +2538,9 @@ Status DBImpl::BackgroundCompaction(bool* made_progress,
    // reference).
    // This will all happen under a mutex so we don't have to be afraid of
    // somebody else deleting it.
-    if (cfd->Unref()) {
+    if (cfd->UnrefAndTryDelete()) {
      // This was the last reference of the column family, so no need to
      // compact.
-      delete cfd;
      return Status::OK();
    }

@@ -2672,7 +2667,8 @@ Status DBImpl::BackgroundCompaction(bool* made_progress,
                           f->fd.GetPathId(), f->fd.GetFileSize(), f->smallest,
                           f->largest, f->fd.smallest_seqno,
                           f->fd.largest_seqno, f->marked_for_compaction,
-                           f->oldest_blob_file_number, f->oldest_ancester_time);
+                           f->oldest_blob_file_number, f->oldest_ancester_time,
+                           f->file_creation_time);

        ROCKS_LOG_BUFFER(
            log_buffer,
@@ -2751,7 +2747,7 @@ Status DBImpl::BackgroundCompaction(bool* made_progress,
    assert(is_snapshot_supported_ || snapshots_.empty());
    CompactionJob compaction_job(
        job_context->job_id, c.get(), immutable_db_options_,
-        env_options_for_compaction_, versions_.get(), &shutting_down_,
+        file_options_for_compaction_, versions_.get(), &shutting_down_,
        preserve_deletes_seqnum_.load(), log_buffer, directories_.GetDbDir(),
        GetDataDir(c->column_family_data(), c->output_path_id()), stats_,
        &mutex_, &error_handler_, snapshot_seqs,
@@ -129,7 +129,7 @@ Status DBImpl::PromoteL0(ColumnFamilyHandle* column_family, int target_level) {
                   f->fd.GetFileSize(), f->smallest, f->largest,
                   f->fd.smallest_seqno, f->fd.largest_seqno,
                   f->marked_for_compaction, f->oldest_blob_file_number,
-                   f->oldest_ancester_time);
+                   f->oldest_ancester_time, f->file_creation_time);
    }

    status = versions_->LogAndApply(cfd, *cfd->GetLatestMutableCFOptions(),
@@ -385,6 +385,7 @@ void DBImpl::PurgeObsoleteFiles(JobContext& state, bool schedule_only) {
    w->Close();
  }

+  bool own_files = OwnTablesAndLogs();
  std::unordered_set<uint64_t> files_to_del;
  for (const auto& candidate_file : candidate_files) {
    const std::string& to_delete = candidate_file.file_name;
@@ -484,6 +485,12 @@ void DBImpl::PurgeObsoleteFiles(JobContext& state, bool schedule_only) {
    }
 #endif  // !ROCKSDB_LITE

+    // If I do not own these files, e.g. secondary instance with max_open_files
+    // = -1, then no need to delete or schedule delete these files since they
+    // will be removed by their owner, e.g. the primary instance.
+    if (!own_files) {
+      continue;
+    }
    Status file_deletion_status;
    if (schedule_only) {
      InstrumentedMutexLock guard_lock(&mutex_);
@@ -495,7 +502,6 @@ void DBImpl::PurgeObsoleteFiles(JobContext& state, bool schedule_only) {

  {
    // After purging obsolete files, remove them from files_grabbed_for_purge_.
-    // Use a temporary vector to perform bulk deletion via swap.
    InstrumentedMutexLock guard_lock(&mutex_);
    autovector<uint64_t> to_be_removed;
    for (auto fn : files_grabbed_for_purge_) {
@@ -12,6 +12,7 @@

 #include "db/builder.h"
 #include "db/error_handler.h"
+#include "env/composite_env_wrapper.h"
 #include "file/read_write_util.h"
 #include "file/sst_file_manager_impl.h"
 #include "file/writable_file_writer.h"
@@ -34,6 +35,18 @@ Options SanitizeOptions(const std::string& dbname, const Options& src) {
 DBOptions SanitizeOptions(const std::string& dbname, const DBOptions& src) {
  DBOptions result(src);

+  if (result.file_system == nullptr) {
+    if (result.env == Env::Default()) {
+      result.file_system = FileSystem::Default();
+    } else {
+      result.file_system.reset(new LegacyFileSystemWrapper(result.env));
+    }
+  } else {
+    if (result.env == nullptr) {
+      result.env = Env::Default();
+    }
+  }
+
  // result.max_open_files means an "infinite" open files.
  if (result.max_open_files != -1) {
    int max_max_open_files = port::GetMaxOpenFiles();
@@ -254,16 +267,16 @@ Status DBImpl::NewDB() {
  ROCKS_LOG_INFO(immutable_db_options_.info_log, "Creating manifest 1 \n");
  const std::string manifest = DescriptorFileName(dbname_, 1);
  {
-    std::unique_ptr<WritableFile> file;
-    EnvOptions env_options = env_->OptimizeForManifestWrite(env_options_);
-    s = NewWritableFile(env_, manifest, &file, env_options);
+    std::unique_ptr<FSWritableFile> file;
+    FileOptions file_options = fs_->OptimizeForManifestWrite(file_options_);
+    s = NewWritableFile(fs_.get(), manifest, &file, file_options);
    if (!s.ok()) {
      return s;
    }
    file->SetPreallocationBlockSize(
        immutable_db_options_.manifest_preallocation_size);
    std::unique_ptr<WritableFileWriter> file_writer(new WritableFileWriter(
-        std::move(file), manifest, env_options, env_, nullptr /* stats */,
+        std::move(file), manifest, file_options, env_, nullptr /* stats */,
        immutable_db_options_.listeners));
    log::Writer log(std::move(file_writer), 0, false);
    std::string record;
@@ -277,7 +290,7 @@ Status DBImpl::NewDB() {
    // Make "CURRENT" file that points to the new manifest file.
    s = SetCurrentFile(env_, dbname_, 1, directories_.GetDbDir());
  } else {
-    env_->DeleteFile(manifest);
+    fs_->DeleteFile(manifest, IOOptions(), nullptr);
  }
  return s;
 }
@@ -350,7 +363,8 @@ Status DBImpl::Recover(
      return s;
    }

-    s = env_->FileExists(CurrentFileName(dbname_));
+    std::string current_fname = CurrentFileName(dbname_);
+    s = env_->FileExists(current_fname);
    if (s.IsNotFound()) {
      if (immutable_db_options_.create_if_missing) {
        // Has to be called only after Identity File creation is successful
@@ -363,7 +377,7 @@ Status DBImpl::Recover(
        }
      } else {
        return Status::InvalidArgument(
-            dbname_, "does not exist (create_if_missing is false)");
+            current_fname, "does not exist (create_if_missing is false)");
      }
    } else if (s.ok()) {
      if (immutable_db_options_.error_if_exists) {
@@ -375,20 +389,20 @@ Status DBImpl::Recover(
      assert(s.IsIOError());
      return s;
    }
-    // Verify compatibility of env_options_ and filesystem
+    // Verify compatibility of file_options_ and filesystem
    {
-      std::unique_ptr<RandomAccessFile> idfile;
-      EnvOptions customized_env(env_options_);
-      customized_env.use_direct_reads |=
+      std::unique_ptr<FSRandomAccessFile> idfile;
+      FileOptions customized_fs(file_options_);
+      customized_fs.use_direct_reads |=
          immutable_db_options_.use_direct_io_for_flush_and_compaction;
-      s = env_->NewRandomAccessFile(CurrentFileName(dbname_), &idfile,
-                                    customized_env);
+      s = fs_->NewRandomAccessFile(current_fname, customized_fs, &idfile,
+                                   nullptr);
      if (!s.ok()) {
        std::string error_str = s.ToString();
        // Check if unsupported Direct I/O is the root cause
-        customized_env.use_direct_reads = false;
-        s = env_->NewRandomAccessFile(CurrentFileName(dbname_), &idfile,
-                                      customized_env);
+        customized_fs.use_direct_reads = false;
+        s = fs_->NewRandomAccessFile(current_fname, customized_fs, &idfile,
+                                     nullptr);
        if (s.ok()) {
          return Status::InvalidArgument(
              "Direct I/O is not supported by the specified DB.");
@@ -408,7 +422,7 @@ Status DBImpl::Recover(
  // the very first time.
  if (db_id_.empty()) {
    // Check for the IDENTITY file and create it if not there.
-    s = env_->FileExists(IdentityFileName(dbname_));
+    s = fs_->FileExists(IdentityFileName(dbname_), IOOptions(), nullptr);
    // Typically Identity file is created in NewDB() and for some reason if
    // it is no longer available then at this point DB ID is not in Identity
    // file or Manifest.
@@ -748,9 +762,10 @@ Status DBImpl::RecoverLogFiles(const std::vector<uint64_t>& log_numbers,

    std::unique_ptr<SequentialFileReader> file_reader;
    {
-      std::unique_ptr<SequentialFile> file;
-      status = env_->NewSequentialFile(fname, &file,
-                                       env_->OptimizeForLogRead(env_options_));
+      std::unique_ptr<FSSequentialFile> file;
+      status = fs_->NewSequentialFile(fname,
+                                      fs_->OptimizeForLogRead(file_options_),
+                                      &file, nullptr);
      if (!status.ok()) {
        MaybeIgnoreError(&status);
        if (!status.ok()) {
@@ -920,7 +935,7 @@ Status DBImpl::RecoverLogFiles(const std::vector<uint64_t>& log_numbers,
        ColumnFamilyData* cfd;

        while ((cfd = flush_scheduler_.TakeNextColumnFamily()) != nullptr) {
-          cfd->Unref();
+          cfd->UnrefAndTryDelete();
          // If this asserts, it means that InsertInto failed in
          // filtering updates to already-flushed column families
          assert(cfd->GetLogNumber() <= log_number);
@@ -1119,17 +1134,18 @@ Status DBImpl::RestoreAliveLogFiles(const std::vector<uint64_t>& log_numbers) {
    // preallocated space are not needed anymore. It is likely only the last
    // log has such preallocated space, so we only truncate for the last log.
    if (log_number == log_numbers.back()) {
-      std::unique_ptr<WritableFile> last_log;
-      Status truncate_status = env_->ReopenWritableFile(
-          fname, &last_log,
-          env_->OptimizeForLogWrite(
-              env_options_,
-              BuildDBOptions(immutable_db_options_, mutable_db_options_)));
+      std::unique_ptr<FSWritableFile> last_log;
+      Status truncate_status = fs_->ReopenWritableFile(
+          fname,
+          fs_->OptimizeForLogWrite(
+              file_options_,
+              BuildDBOptions(immutable_db_options_, mutable_db_options_)),
+          &last_log, nullptr);
      if (truncate_status.ok()) {
-        truncate_status = last_log->Truncate(log.size);
+        truncate_status = last_log->Truncate(log.size, IOOptions(), nullptr);
      }
      if (truncate_status.ok()) {
-        truncate_status = last_log->Close();
+        truncate_status = last_log->Close(IOOptions(), nullptr);
      }
      // Not a critical error if fail to truncate.
      if (!truncate_status.ok()) {
@@ -1196,8 +1212,8 @@ Status DBImpl::WriteLevel0TableForRecovery(int job_id, ColumnFamilyData* cfd,
        range_del_iters.emplace_back(range_del_iter);
      }
      s = BuildTable(
-          dbname_, env_, *cfd->ioptions(), mutable_cf_options,
-          env_options_for_compaction_, cfd->table_cache(), iter.get(),
+          dbname_, env_, fs_.get(), *cfd->ioptions(), mutable_cf_options,
+          file_options_for_compaction_, cfd->table_cache(), iter.get(),
          std::move(range_del_iters), &meta, cfd->internal_comparator(),
          cfd->int_tbl_prop_collector_factories(), cfd->GetID(), cfd->GetName(),
          snapshot_seqs, earliest_write_conflict_snapshot, snapshot_checker,
@@ -1226,7 +1242,7 @@ Status DBImpl::WriteLevel0TableForRecovery(int job_id, ColumnFamilyData* cfd,
                  meta.fd.GetFileSize(), meta.smallest, meta.largest,
                  meta.fd.smallest_seqno, meta.fd.largest_seqno,
                  meta.marked_for_compaction, meta.oldest_blob_file_number,
-                  meta.oldest_ancester_time);
+                  meta.oldest_ancester_time, meta.file_creation_time);
  }

  InternalStats::CompactionStats stats(CompactionReason::kFlush, 1);
@@ -1280,12 +1296,12 @@ Status DB::Open(const DBOptions& db_options, const std::string& dbname,
 Status DBImpl::CreateWAL(uint64_t log_file_num, uint64_t recycle_log_number,
                         size_t preallocate_block_size, log::Writer** new_log) {
  Status s;
-  std::unique_ptr<WritableFile> lfile;
+  std::unique_ptr<FSWritableFile> lfile;

  DBOptions db_options =
      BuildDBOptions(immutable_db_options_, mutable_db_options_);
-  EnvOptions opt_env_options =
-      env_->OptimizeForLogWrite(env_options_, db_options);
+  FileOptions opt_file_options =
+      fs_->OptimizeForLogWrite(file_options_, db_options);
  std::string log_fname =
      LogFileName(immutable_db_options_.wal_dir, log_file_num);

@@ -1295,10 +1311,10 @@ Status DBImpl::CreateWAL(uint64_t log_file_num, uint64_t recycle_log_number,
                   recycle_log_number);
    std::string old_log_fname =
        LogFileName(immutable_db_options_.wal_dir, recycle_log_number);
-    s = env_->ReuseWritableFile(log_fname, old_log_fname, &lfile,
-                                opt_env_options);
+    s = fs_->ReuseWritableFile(log_fname, old_log_fname, opt_file_options,
+                               &lfile, /*dbg=*/nullptr);
  } else {
-    s = NewWritableFile(env_, log_fname, &lfile, opt_env_options);
+    s = NewWritableFile(fs_.get(), log_fname, &lfile, opt_file_options);
  }

  if (s.ok()) {
@@ -1307,7 +1323,7 @@ Status DBImpl::CreateWAL(uint64_t log_file_num, uint64_t recycle_log_number,

    const auto& listeners = immutable_db_options_.listeners;
    std::unique_ptr<WritableFileWriter> file_writer(
-        new WritableFileWriter(std::move(lfile), log_fname, opt_env_options,
+        new WritableFileWriter(std::move(lfile), log_fname, opt_file_options,
                               env_, nullptr /* stats */, listeners));
    *new_log = new log::Writer(std::move(file_writer), log_file_num,
                               immutable_db_options_.recycle_log_file_num > 0,
@@ -11,6 +11,7 @@
 #include "db/merge_context.h"
 #include "logging/auto_roll_logger.h"
 #include "monitoring/perf_context_imp.h"
+#include "util/cast_util.h"

 namespace rocksdb {

@@ -143,9 +144,10 @@ Status DBImplSecondary::MaybeInitLogReader(

    std::unique_ptr<SequentialFileReader> file_reader;
    {
-      std::unique_ptr<SequentialFile> file;
-      Status status = env_->NewSequentialFile(
-          fname, &file, env_->OptimizeForLogRead(env_options_));
+      std::unique_ptr<FSSequentialFile> file;
+      Status status = fs_->NewSequentialFile(
+          fname, fs_->OptimizeForLogRead(file_options_), &file,
+          nullptr);
      if (!status.ok()) {
        *log_reader = nullptr;
        return status;
@@ -405,7 +407,7 @@ ArenaWrappedDBIter* DBImplSecondary::NewIteratorImpl(
    const ReadOptions& read_options, ColumnFamilyData* cfd,
    SequenceNumber snapshot, ReadCallback* read_callback) {
  assert(nullptr != cfd);
-  SuperVersion* super_version = cfd->GetReferencedSuperVersion(&mutex_);
+  SuperVersion* super_version = cfd->GetReferencedSuperVersion(this);
  auto db_iter = NewArenaWrappedDbIterator(
      env_, read_options, *cfd->ioptions(), super_version->mutable_cf_options,
      snapshot,
@@ -497,45 +499,61 @@ Status DBImplSecondary::TryCatchUpWithPrimary() {
  // read the manifest and apply new changes to the secondary instance
  std::unordered_set<ColumnFamilyData*> cfds_changed;
  JobContext job_context(0, true /*create_superversion*/);
-  InstrumentedMutexLock lock_guard(&mutex_);
-  s = static_cast<ReactiveVersionSet*>(versions_.get())
-          ->ReadAndApply(&mutex_, &manifest_reader_, &cfds_changed);
+  {
+    InstrumentedMutexLock lock_guard(&mutex_);
+    s = static_cast_with_check<ReactiveVersionSet>(versions_.get())
+            ->ReadAndApply(&mutex_, &manifest_reader_, &cfds_changed);

-  ROCKS_LOG_INFO(immutable_db_options_.info_log, "Last sequence is %" PRIu64,
-                 static_cast<uint64_t>(versions_->LastSequence()));
-  for (ColumnFamilyData* cfd : cfds_changed) {
-    if (cfd->IsDropped()) {
-      ROCKS_LOG_DEBUG(immutable_db_options_.info_log, "[%s] is dropped\n",
-                      cfd->GetName().c_str());
-      continue;
+    ROCKS_LOG_INFO(immutable_db_options_.info_log, "Last sequence is %" PRIu64,
+                   static_cast<uint64_t>(versions_->LastSequence()));
+    for (ColumnFamilyData* cfd : cfds_changed) {
+      if (cfd->IsDropped()) {
+        ROCKS_LOG_DEBUG(immutable_db_options_.info_log, "[%s] is dropped\n",
+                        cfd->GetName().c_str());
+        continue;
+      }
+      VersionStorageInfo::LevelSummaryStorage tmp;
+      ROCKS_LOG_DEBUG(immutable_db_options_.info_log,
+                      "[%s] Level summary: %s\n", cfd->GetName().c_str(),
+                      cfd->current()->storage_info()->LevelSummary(&tmp));
    }
-    VersionStorageInfo::LevelSummaryStorage tmp;
-    ROCKS_LOG_DEBUG(immutable_db_options_.info_log, "[%s] Level summary: %s\n",
-                    cfd->GetName().c_str(),
-                    cfd->current()->storage_info()->LevelSummary(&tmp));
-  }

-  // list wal_dir to discover new WALs and apply new changes to the secondary
-  // instance
-  if (s.ok()) {
-    s = FindAndRecoverLogFiles(&cfds_changed, &job_context);
-  }
-  if (s.IsPathNotFound()) {
-    ROCKS_LOG_INFO(immutable_db_options_.info_log,
-                   "Secondary tries to read WAL, but WAL file(s) have already "
-                   "been purged by primary.");
-    s = Status::OK();
-  }
-  if (s.ok()) {
-    for (auto cfd : cfds_changed) {
-      cfd->imm()->RemoveOldMemTables(cfd->GetLogNumber(),
-                                     &job_context.memtables_to_free);
-      auto& sv_context = job_context.superversion_contexts.back();
-      cfd->InstallSuperVersion(&sv_context, &mutex_);
-      sv_context.NewSuperVersion();
+    // list wal_dir to discover new WALs and apply new changes to the secondary
+    // instance
+    if (s.ok()) {
+      s = FindAndRecoverLogFiles(&cfds_changed, &job_context);
+    }
+    if (s.IsPathNotFound()) {
+      ROCKS_LOG_INFO(
+          immutable_db_options_.info_log,
+          "Secondary tries to read WAL, but WAL file(s) have already "
+          "been purged by primary.");
+      s = Status::OK();
+    }
+    if (s.ok()) {
+      for (auto cfd : cfds_changed) {
+        cfd->imm()->RemoveOldMemTables(cfd->GetLogNumber(),
+                                       &job_context.memtables_to_free);
+        auto& sv_context = job_context.superversion_contexts.back();
+        cfd->InstallSuperVersion(&sv_context, &mutex_);
+        sv_context.NewSuperVersion();
+      }
    }
-    job_context.Clean();
  }
+  job_context.Clean();
+
+  // Cleanup unused, obsolete files.
+  JobContext purge_files_job_context(0);
+  {
+    InstrumentedMutexLock lock_guard(&mutex_);
+    // Currently, secondary instance does not own the database files, thus it
+    // is unnecessary for the secondary to force full scan.
+    FindObsoleteFiles(&purge_files_job_context, /*force=*/false);
+  }
+  if (purge_files_job_context.HaveSomethingToDelete()) {
+    PurgeObsoleteFiles(purge_files_job_context);
+  }
+  purge_files_job_context.Clean();
  return s;
 }

@@ -583,7 +601,7 @@ Status DB::OpenAsSecondary(
  handles->clear();
  DBImplSecondary* impl = new DBImplSecondary(tmp_opts, dbname);
  impl->versions_.reset(new ReactiveVersionSet(
-      dbname, &impl->immutable_db_options_, impl->env_options_,
+      dbname, &impl->immutable_db_options_, impl->file_options_,
      impl->table_cache_.get(), impl->write_buffer_manager_,
      &impl->write_controller_));
  impl->column_family_memtables_.reset(
@@ -172,6 +172,24 @@ class DBImplSecondary : public DBImpl {
    return Status::NotSupported("Not supported operation in secondary mode.");
  }

+  using DBImpl::SetDBOptions;
+  Status SetDBOptions(const std::unordered_map<std::string, std::string>&
+                      /*options_map*/) override {
+    // Currently not supported because changing certain options may cause
+    // flush/compaction.
+    return Status::NotSupported("Not supported operation in secondary mode.");
+  }
+
+  using DBImpl::SetOptions;
+  Status SetOptions(
+      ColumnFamilyHandle* /*cfd*/,
+      const std::unordered_map<std::string, std::string>& /*options_map*/)
+      override {
+    // Currently not supported because changing certain options may cause
+    // flush/compaction and/or write to MANIFEST.
+    return Status::NotSupported("Not supported operation in secondary mode.");
+  }
+
  using DBImpl::SyncWAL;
  Status SyncWAL() override {
    return Status::NotSupported("Not supported operation in secondary mode.");
@@ -269,6 +287,14 @@ class DBImplSecondary : public DBImpl {
    return s;
  }

+  bool OwnTablesAndLogs() const override {
+    // Currently, the secondary instance does not own the database files. It
+    // simply opens the files of the primary instance and tracks their file
+    // descriptors until they become obsolete. In the future, the secondary may
+    // create links to database files. OwnTablesAndLogs will return true then.
+    return false;
+  }
+
 private:
  friend class DB;

@@ -131,6 +131,7 @@ Status DBImpl::WriteImpl(const WriteOptions& write_options,
                              log_used, log_ref, &seq, sub_batch_cnt,
                              pre_release_callback, kDoAssignOrder,
                              kDoPublishLastSeq, disable_memtable);
+    TEST_SYNC_POINT("DBImpl::WriteImpl:UnorderedWriteAfterWriteWAL");
    if (!status.ok()) {
      return status;
    }
@@ -138,6 +139,7 @@ Status DBImpl::WriteImpl(const WriteOptions& write_options,
      *seq_used = seq;
    }
    if (!disable_memtable) {
+      TEST_SYNC_POINT("DBImpl::WriteImpl:BeforeUnorderedWriteMemtable");
      status = UnorderedWriteMemtable(write_options, my_batch, callback,
                                      log_ref, seq, sub_batch_cnt);
    }
@@ -1254,7 +1256,7 @@ Status DBImpl::SwitchWAL(WriteContext* write_context) {
  for (const auto cfd : cfds) {
    cfd->Ref();
    status = SwitchMemtable(cfd, write_context);
-    cfd->Unref();
+    cfd->UnrefAndTryDelete();
    if (!status.ok()) {
      break;
    }
@@ -1333,7 +1335,7 @@ Status DBImpl::HandleWriteBufferFull(WriteContext* write_context) {
    }
    cfd->Ref();
    status = SwitchMemtable(cfd, write_context);
-    cfd->Unref();
+    cfd->UnrefAndTryDelete();
    if (!status.ok()) {
      break;
    }
@@ -1516,15 +1518,16 @@ Status DBImpl::TrimMemtableHistory(WriteContext* context) {
  for (auto& cfd : cfds) {
    autovector<MemTable*> to_delete;
    cfd->imm()->TrimHistory(&to_delete, cfd->mem()->ApproximateMemoryUsage());
-    for (auto m : to_delete) {
-      delete m;
+    if (!to_delete.empty()) {
+      for (auto m : to_delete) {
+        delete m;
+      }
+      context->superversion_context.NewSuperVersion();
+      assert(context->superversion_context.new_superversion.get() != nullptr);
+      cfd->InstallSuperVersion(&context->superversion_context, &mutex_);
    }
-    context->superversion_context.NewSuperVersion();
-    assert(context->superversion_context.new_superversion.get() != nullptr);
-    cfd->InstallSuperVersion(&context->superversion_context, &mutex_);

-    if (cfd->Unref()) {
-      delete cfd;
+    if (cfd->UnrefAndTryDelete()) {
      cfd = nullptr;
    }
  }
@@ -1556,8 +1559,7 @@ Status DBImpl::ScheduleFlushes(WriteContext* context) {
    if (!cfd->mem()->IsEmpty()) {
      status = SwitchMemtable(cfd, context);
    }
-    if (cfd->Unref()) {
-      delete cfd;
+    if (cfd->UnrefAndTryDelete()) {
      cfd = nullptr;
    }
    if (!status.ok()) {
@@ -195,6 +195,90 @@ TEST_F(DBSecondaryTest, OpenAsSecondary) {
  verify_db_func("new_foo_value", "new_bar_value");
 }

+namespace {
+class TraceFileEnv : public EnvWrapper {
+ public:
+  explicit TraceFileEnv(Env* _target) : EnvWrapper(_target) {}
+  Status NewRandomAccessFile(const std::string& f,
+                             std::unique_ptr<RandomAccessFile>* r,
+                             const EnvOptions& env_options) override {
+    class TracedRandomAccessFile : public RandomAccessFile {
+     public:
+      TracedRandomAccessFile(std::unique_ptr<RandomAccessFile>&& target,
+                             std::atomic<int>& counter)
+          : target_(std::move(target)), files_closed_(counter) {}
+      ~TracedRandomAccessFile() override {
+        files_closed_.fetch_add(1, std::memory_order_relaxed);
+      }
+      Status Read(uint64_t offset, size_t n, Slice* result,
+                  char* scratch) const override {
+        return target_->Read(offset, n, result, scratch);
+      }
+
+     private:
+      std::unique_ptr<RandomAccessFile> target_;
+      std::atomic<int>& files_closed_;
+    };
+    Status s = target()->NewRandomAccessFile(f, r, env_options);
+    if (s.ok()) {
+      r->reset(new TracedRandomAccessFile(std::move(*r), files_closed_));
+    }
+    return s;
+  }
+
+  int files_closed() const {
+    return files_closed_.load(std::memory_order_relaxed);
+  }
+
+ private:
+  std::atomic<int> files_closed_{0};
+};
+}  // namespace
+
+TEST_F(DBSecondaryTest, SecondaryCloseFiles) {
+  Options options;
+  options.env = env_;
+  options.max_open_files = 1;
+  options.disable_auto_compactions = true;
+  Reopen(options);
+  Options options1;
+  std::unique_ptr<Env> traced_env(new TraceFileEnv(env_));
+  options1.env = traced_env.get();
+  OpenSecondary(options1);
+
+  static const auto verify_db = [&]() {
+    std::unique_ptr<Iterator> iter1(dbfull()->NewIterator(ReadOptions()));
+    std::unique_ptr<Iterator> iter2(db_secondary_->NewIterator(ReadOptions()));
+    for (iter1->SeekToFirst(), iter2->SeekToFirst();
+         iter1->Valid() && iter2->Valid(); iter1->Next(), iter2->Next()) {
+      ASSERT_EQ(iter1->key(), iter2->key());
+      ASSERT_EQ(iter1->value(), iter2->value());
+    }
+    ASSERT_FALSE(iter1->Valid());
+    ASSERT_FALSE(iter2->Valid());
+  };
+
+  ASSERT_OK(Put("a", "value"));
+  ASSERT_OK(Put("c", "value"));
+  ASSERT_OK(Flush());
+  ASSERT_OK(db_secondary_->TryCatchUpWithPrimary());
+  verify_db();
+
+  ASSERT_OK(Put("b", "value"));
+  ASSERT_OK(Put("d", "value"));
+  ASSERT_OK(Flush());
+  ASSERT_OK(db_secondary_->TryCatchUpWithPrimary());
+  verify_db();
+
+  ASSERT_OK(dbfull()->CompactRange(CompactRangeOptions(), nullptr, nullptr));
+  ASSERT_OK(db_secondary_->TryCatchUpWithPrimary());
+  ASSERT_EQ(2, static_cast<TraceFileEnv*>(traced_env.get())->files_closed());
+
+  Status s = db_secondary_->SetDBOptions({{"max_open_files", "-1"}});
+  ASSERT_TRUE(s.IsNotSupported());
+  CloseSecondary();
+}
+
 TEST_F(DBSecondaryTest, OpenAsSecondaryWALTailing) {
  Options options;
  options.env = env_;
@@ -804,6 +804,50 @@ TEST_P(DBIteratorTest, IteratorPinsRef) {
  } while (ChangeCompactOptions());
 }

+TEST_P(DBIteratorTest, IteratorDeleteAfterCfDelete) {
+  CreateAndReopenWithCF({"pikachu"}, CurrentOptions());
+
+  Put(1, "foo", "delete-cf-then-delete-iter");
+  Put(1, "hello", "value2");
+
+  ColumnFamilyHandle* cf = handles_[1];
+  ReadOptions ro;
+
+  auto* iter = db_->NewIterator(ro, cf);
+  iter->SeekToFirst();
+  ASSERT_EQ(IterStatus(iter), "foo->delete-cf-then-delete-iter");
+
+  // delete CF handle
+  db_->DestroyColumnFamilyHandle(cf);
+  handles_.erase(std::begin(handles_) + 1);
+
+  // delete Iterator after CF handle is deleted
+  iter->Next();
+  ASSERT_EQ(IterStatus(iter), "hello->value2");
+  delete iter;
+}
+
+TEST_P(DBIteratorTest, IteratorDeleteAfterCfDrop) {
+  CreateAndReopenWithCF({"pikachu"}, CurrentOptions());
+
+  Put(1, "foo", "drop-cf-then-delete-iter");
+
+  ReadOptions ro;
+  ColumnFamilyHandle* cf = handles_[1];
+
+  auto* iter = db_->NewIterator(ro, cf);
+  iter->SeekToFirst();
+  ASSERT_EQ(IterStatus(iter), "foo->drop-cf-then-delete-iter");
+
+  // drop and delete CF
+  db_->DropColumnFamily(cf);
+  db_->DestroyColumnFamilyHandle(cf);
+  handles_.erase(std::begin(handles_) + 1);
+
+  // delete Iterator after CF handle is dropped
+  delete iter;
+}
+
 // SetOptions not defined in ROCKSDB LITE
 #ifndef ROCKSDB_LITE
 TEST_P(DBIteratorTest, DBIteratorBoundTest) {
@@ -1297,19 +1341,19 @@ class DBIteratorTestForPinnedData : public DBIteratorTest {

      // Insert data to true_data map and to DB
      true_data[k] = v;
-      if (rnd.OneIn(static_cast<int>(100.0 / merge_percentage))) {
+      if (rnd.PercentTrue(merge_percentage)) {
        ASSERT_OK(db_->Merge(WriteOptions(), k, v));
      } else {
        ASSERT_OK(Put(k, v));
      }

      // Pick random keys to be used to test Seek()
-      if (rnd.OneIn(static_cast<int>(100.0 / seeks_percentage))) {
+      if (rnd.PercentTrue(seeks_percentage)) {
        random_keys.push_back(k);
      }

      // Delete some random keys
-      if (rnd.OneIn(static_cast<int>(100.0 / delete_percentage))) {
+      if (rnd.PercentTrue(delete_percentage)) {
        deleted_keys.push_back(k);
        true_data.erase(k);
        ASSERT_OK(Delete(k));
@@ -1867,7 +1911,7 @@ TEST_P(DBIteratorTest, IterPrevKeyCrossingBlocksRandomized) {
  // make sure that we dont merge them while flushing but actually
  // merge them in the read path
  for (int i = 0; i < kNumKeys; i++) {
-    if (rnd.OneIn(static_cast<int>(100.0 / kNoMergeOpPercentage))) {
+    if (rnd.PercentTrue(kNoMergeOpPercentage)) {
      // Dont give merge operations for some keys
      continue;
    }
@@ -1883,7 +1927,7 @@ TEST_P(DBIteratorTest, IterPrevKeyCrossingBlocksRandomized) {
  ASSERT_OK(Flush());

  for (int i = 0; i < kNumKeys; i++) {
-    if (rnd.OneIn(static_cast<int>(100.0 / kDeletePercentage))) {
+    if (rnd.PercentTrue(kDeletePercentage)) {
      gen_key = Key(i);

      ASSERT_OK(Delete(gen_key));
@@ -150,6 +150,8 @@ TEST_F(DBMergeOperatorTest, MergeErrorOnWrite) {
  options.create_if_missing = true;
  options.merge_operator.reset(new TestPutOperator());
  options.max_successive_merges = 3;
+  // allow_concurrent_memtable_write is incompatible with max_successive_merges
+  options.allow_concurrent_memtable_write = false;
  options.env = env_;
  Reopen(options);
  ASSERT_OK(Merge("k1", "v1"));
@@ -1427,6 +1427,47 @@ TEST_F(DBRangeDelTest, SnapshotPreventsDroppedKeys) {
  db_->ReleaseSnapshot(snapshot);
 }

+TEST_F(DBRangeDelTest, SnapshotPreventsDroppedKeysInImmMemTables) {
+  const int kFileBytes = 1 << 20;
+
+  Options options = CurrentOptions();
+  options.compression = kNoCompression;
+  options.disable_auto_compactions = true;
+  options.target_file_size_base = kFileBytes;
+  Reopen(options);
+
+  // block flush thread -> pin immtables in memory
+  SyncPoint::GetInstance()->DisableProcessing();
+  SyncPoint::GetInstance()->LoadDependency({
+      {"SnapshotPreventsDroppedKeysInImmMemTables:AfterNewIterator",
+       "DBImpl::BGWorkFlush"},
+  });
+  SyncPoint::GetInstance()->EnableProcessing();
+
+  ASSERT_OK(Put(Key(0), "a"));
+  std::unique_ptr<const Snapshot, std::function<void(const Snapshot*)>>
+      snapshot(db_->GetSnapshot(),
+               [this](const Snapshot* s) { db_->ReleaseSnapshot(s); });
+
+  ASSERT_OK(db_->DeleteRange(WriteOptions(), db_->DefaultColumnFamily(), Key(0),
+                             Key(10)));
+
+  ASSERT_OK(dbfull()->TEST_SwitchMemtable());
+
+  ReadOptions read_opts;
+  read_opts.snapshot = snapshot.get();
+  std::unique_ptr<Iterator> iter(db_->NewIterator(read_opts));
+
+  TEST_SYNC_POINT("SnapshotPreventsDroppedKeysInImmMemTables:AfterNewIterator");
+
+  iter->SeekToFirst();
+  ASSERT_TRUE(iter->Valid());
+  ASSERT_EQ(Key(0), iter->key());
+
+  iter->Next();
+  ASSERT_FALSE(iter->Valid());
+}
+
 TEST_F(DBRangeDelTest, RangeTombstoneWrittenToMinimalSsts) {
  // Adapted from
  // https://github.com/cockroachdb/cockroach/blob/de8b3ea603dd1592d9dc26443c2cc92c356fbc2f/pkg/storage/engine/rocksdb_test.go#L1267-L1398.
@@ -1022,7 +1022,8 @@ TEST_F(DBTest, FailMoreDbPaths) {

 void CheckColumnFamilyMeta(
    const ColumnFamilyMetaData& cf_meta,
-    const std::vector<std::vector<FileMetaData>>& files_by_level) {
+    const std::vector<std::vector<FileMetaData>>& files_by_level,
+    uint64_t start_time, uint64_t end_time) {
  ASSERT_EQ(cf_meta.name, kDefaultColumnFamilyName);
  ASSERT_EQ(cf_meta.levels.size(), files_by_level.size());

@@ -1060,6 +1061,14 @@ void CheckColumnFamilyMeta(
                file_meta_from_files.largest.user_key().ToString());
      ASSERT_EQ(file_meta_from_cf.oldest_blob_file_number,
                file_meta_from_files.oldest_blob_file_number);
+      ASSERT_EQ(file_meta_from_cf.oldest_ancester_time,
+                file_meta_from_files.oldest_ancester_time);
+      ASSERT_EQ(file_meta_from_cf.file_creation_time,
+                file_meta_from_files.file_creation_time);
+      ASSERT_GE(file_meta_from_cf.file_creation_time, start_time);
+      ASSERT_LE(file_meta_from_cf.file_creation_time, end_time);
+      ASSERT_GE(file_meta_from_cf.oldest_ancester_time, start_time);
+      ASSERT_LE(file_meta_from_cf.oldest_ancester_time, end_time);
    }

    ASSERT_EQ(level_meta_from_cf.size, level_size);
@@ -1113,6 +1122,11 @@ TEST_F(DBTest, MetaDataTest) {
  Options options = CurrentOptions();
  options.create_if_missing = true;
  options.disable_auto_compactions = true;
+
+  int64_t temp_time = 0;
+  options.env->GetCurrentTime(&temp_time);
+  uint64_t start_time = static_cast<uint64_t>(temp_time);
+
  DestroyAndReopen(options);

  Random rnd(301);
@@ -1139,9 +1153,12 @@ TEST_F(DBTest, MetaDataTest) {
  std::vector<std::vector<FileMetaData>> files_by_level;
  dbfull()->TEST_GetFilesMetaData(db_->DefaultColumnFamily(), &files_by_level);

+  options.env->GetCurrentTime(&temp_time);
+  uint64_t end_time = static_cast<uint64_t>(temp_time);
+
  ColumnFamilyMetaData cf_meta;
  db_->GetColumnFamilyMetaData(&cf_meta);
-  CheckColumnFamilyMeta(cf_meta, files_by_level);
+  CheckColumnFamilyMeta(cf_meta, files_by_level, start_time, end_time);

  std::vector<LiveFileMetaData> live_file_meta;
  db_->GetLiveFilesMetaData(&live_file_meta);
@@ -1688,6 +1705,7 @@ TEST_F(DBTest, Snapshot) {
    ASSERT_EQ(1U, GetNumSnapshots());
    uint64_t time_snap1 = GetTimeOldestSnapshots();
    ASSERT_GT(time_snap1, 0U);
+    ASSERT_EQ(GetSequenceOldestSnapshots(), s1->GetSequenceNumber());
    Put(0, "foo", "0v2");
    Put(1, "foo", "1v2");

@@ -1696,6 +1714,7 @@ TEST_F(DBTest, Snapshot) {
    const Snapshot* s2 = db_->GetSnapshot();
    ASSERT_EQ(2U, GetNumSnapshots());
    ASSERT_EQ(time_snap1, GetTimeOldestSnapshots());
+    ASSERT_EQ(GetSequenceOldestSnapshots(), s1->GetSequenceNumber());
    Put(0, "foo", "0v3");
    Put(1, "foo", "1v3");

@@ -1703,6 +1722,7 @@ TEST_F(DBTest, Snapshot) {
      ManagedSnapshot s3(db_);
      ASSERT_EQ(3U, GetNumSnapshots());
      ASSERT_EQ(time_snap1, GetTimeOldestSnapshots());
+      ASSERT_EQ(GetSequenceOldestSnapshots(), s1->GetSequenceNumber());

      Put(0, "foo", "0v4");
      Put(1, "foo", "1v4");
@@ -1718,6 +1738,7 @@ TEST_F(DBTest, Snapshot) {

    ASSERT_EQ(2U, GetNumSnapshots());
    ASSERT_EQ(time_snap1, GetTimeOldestSnapshots());
+    ASSERT_EQ(GetSequenceOldestSnapshots(), s1->GetSequenceNumber());
    ASSERT_EQ("0v1", Get(0, "foo", s1));
    ASSERT_EQ("1v1", Get(1, "foo", s1));
    ASSERT_EQ("0v2", Get(0, "foo", s2));
@@ -1732,9 +1753,11 @@ TEST_F(DBTest, Snapshot) {
    ASSERT_EQ("1v4", Get(1, "foo"));
    ASSERT_EQ(1U, GetNumSnapshots());
    ASSERT_LT(time_snap1, GetTimeOldestSnapshots());
+    ASSERT_EQ(GetSequenceOldestSnapshots(), s2->GetSequenceNumber());

    db_->ReleaseSnapshot(s2);
    ASSERT_EQ(0U, GetNumSnapshots());
+    ASSERT_EQ(GetSequenceOldestSnapshots(), 0);
    ASSERT_EQ("0v4", Get(0, "foo"));
    ASSERT_EQ("1v4", Get(1, "foo"));
  } while (ChangeOptions());
@@ -6420,6 +6443,12 @@ TEST_F(DBTest, CreationTimeOfOldestFile) {
          }
        }
      });
+  // Set file creation time in manifest all to 0.
+  rocksdb::SyncPoint::GetInstance()->SetCallBack(
+      "FileMetaData::FileMetaData", [&](void* arg) {
+        FileMetaData* meta = static_cast<FileMetaData*>(arg);
+        meta->file_creation_time = 0;
+      });
  rocksdb::SyncPoint::GetInstance()->EnableProcessing();

  Random rnd(301);
@@ -6431,7 +6460,7 @@ TEST_F(DBTest, CreationTimeOfOldestFile) {
    Flush();
  }

-  // At this point there should be 2 files, oen with file_creation_time = 0 and
+  // At this point there should be 2 files, one with file_creation_time = 0 and
  // the other non-zero. GetCreationTimeOfOldestFile API should return 0.
  uint64_t creation_time;
  Status s1 = dbfull()->GetCreationTimeOfOldestFile(&creation_time);
@@ -153,6 +153,8 @@ TEST_F(DBTest2, MaxSuccessiveMergesChangeWithDBRecovery) {
  options.create_if_missing = true;
  options.statistics = rocksdb::CreateDBStatistics();
  options.max_successive_merges = 3;
+  // allow_concurrent_memtable_write is incompatible with max_successive_merges
+  options.allow_concurrent_memtable_write = false;
  options.merge_operator = MergeOperators::CreatePutOperator();
  options.disable_auto_compactions = true;
  DestroyAndReopen(options);
@@ -4210,6 +4212,62 @@ TEST_F(DBTest2, SeekFileRangeDeleteTail) {
  }
  db_->ReleaseSnapshot(s1);
 }
+
+TEST_F(DBTest2, BackgroundPurgeTest) {
+  Options options = CurrentOptions();
+  options.write_buffer_manager = std::make_shared<rocksdb::WriteBufferManager>(1 << 20);
+  options.avoid_unnecessary_blocking_io = true;
+  DestroyAndReopen(options);
+  size_t base_value = options.write_buffer_manager->memory_usage();
+
+  ASSERT_OK(Put("a", "a"));
+  Iterator* iter = db_->NewIterator(ReadOptions());
+  ASSERT_OK(Flush());
+  size_t value = options.write_buffer_manager->memory_usage();
+  ASSERT_GT(value, base_value);
+
+  db_->GetEnv()->SetBackgroundThreads(1, Env::Priority::HIGH);
+  test::SleepingBackgroundTask sleeping_task_after;
+  db_->GetEnv()->Schedule(&test::SleepingBackgroundTask::DoSleepTask,
+                          &sleeping_task_after, Env::Priority::HIGH);
+  delete iter;
+
+  Env::Default()->SleepForMicroseconds(100000);
+  value = options.write_buffer_manager->memory_usage();
+  ASSERT_GT(value, base_value);
+
+  sleeping_task_after.WakeUp();
+  sleeping_task_after.WaitUntilDone();
+
+  test::SleepingBackgroundTask sleeping_task_after2;
+  db_->GetEnv()->Schedule(&test::SleepingBackgroundTask::DoSleepTask,
+                          &sleeping_task_after2, Env::Priority::HIGH);
+  sleeping_task_after2.WakeUp();
+  sleeping_task_after2.WaitUntilDone();
+
+  value = options.write_buffer_manager->memory_usage();
+  ASSERT_EQ(base_value, value);
+}
+
+TEST_F(DBTest2, SwitchMemtableRaceWithNewManifest) {
+  Options options = CurrentOptions();
+  DestroyAndReopen(options);
+  options.max_manifest_file_size = 10;
+  options.create_if_missing = true;
+  CreateAndReopenWithCF({"pikachu"}, options);
+  ASSERT_EQ(2, handles_.size());
+
+  ASSERT_OK(Put("foo", "value"));
+  const int kL0Files = options.level0_file_num_compaction_trigger;
+  for (int i = 0; i < kL0Files; ++i) {
+    ASSERT_OK(Put(/*cf=*/1, "a", std::to_string(i)));
+    ASSERT_OK(Flush(/*cf=*/1));
+  }
+
+  port::Thread thread([&]() { ASSERT_OK(Flush()); });
+  ASSERT_OK(dbfull()->TEST_WaitForCompact());
+  thread.join();
+}
 }  // namespace rocksdb

 #ifdef ROCKSDB_UNITTESTS_WITH_CUSTOM_OBJECTS_FROM_STATIC_LIBS
@@ -53,9 +53,9 @@ DBTestBase::DBTestBase(const std::string path)
 #ifndef ROCKSDB_LITE
  const char* test_env_uri = getenv("TEST_ENV_URI");
  if (test_env_uri) {
-    Status s = ObjectRegistry::NewInstance()->NewSharedObject(test_env_uri,
-                                                              &env_guard_);
-    base_env = env_guard_.get();
+    Env* test_env = nullptr;
+    Status s = Env::LoadEnv(test_env_uri, &test_env, &env_guard_);
+    base_env = test_env;
    EXPECT_OK(s);
    EXPECT_NE(Env::Default(), base_env);
  }
@@ -867,6 +867,13 @@ uint64_t DBTestBase::GetTimeOldestSnapshots() {
  return int_num;
 }

+uint64_t DBTestBase::GetSequenceOldestSnapshots() {
+  uint64_t int_num;
+  EXPECT_TRUE(
+      dbfull()->GetIntProperty("rocksdb.oldest-snapshot-sequence", &int_num));
+  return int_num;
+}
+
 // Return a string that contains all key,value pairs in order,
 // formatted like "(k1->v1)(k2->v2)".
 std::string DBTestBase::Contents(int cf) {
@@ -860,6 +860,8 @@ class DBTestBase : public testing::Test {

  uint64_t GetTimeOldestSnapshots();

+  uint64_t GetSequenceOldestSnapshots();
+
  // Return a string that contains all key,value pairs in order,
  // formatted like "(k1->v1)(k2->v2)".
  std::string Contents(int cf = 0);
@@ -1753,13 +1753,14 @@ TEST_P(DBTestUniversalCompaction, RecalculateScoreAfterPicking) {
  // scheduling more; otherwise, other CFs/DBs may be delayed unnecessarily.
  const int kNumFilesTrigger = 8;
  Options options = CurrentOptions();
+  options.memtable_factory.reset(
+      new SpecialSkipListFactory(KNumKeysByGenerateNewFile - 1));
  options.compaction_options_universal.max_merge_width = kNumFilesTrigger / 2;
  options.compaction_options_universal.max_size_amplification_percent =
      static_cast<unsigned int>(-1);
  options.compaction_style = kCompactionStyleUniversal;
  options.level0_file_num_compaction_trigger = kNumFilesTrigger;
  options.num_levels = num_levels_;
-  options.write_buffer_size = 100 << 10;  // 100KB
  Reopen(options);

  std::atomic<int> num_compactions_attempted(0);
@@ -8,6 +8,7 @@
 // found in the LICENSE file. See the AUTHORS file for names of contributors.

 #include "db/db_test_util.h"
+#include "env/composite_env_wrapper.h"
 #include "options/options_helper.h"
 #include "port/port.h"
 #include "port/stack_trace.h"
@@ -902,8 +903,8 @@ class RecoveryTestHelper {
      std::string fname = LogFileName(test->dbname_, current_log_number);
      std::unique_ptr<WritableFile> file;
      ASSERT_OK(db_options.env->NewWritableFile(fname, &file, env_options));
-      std::unique_ptr<WritableFileWriter> file_writer(
-          new WritableFileWriter(std::move(file), fname, env_options));
+      std::unique_ptr<WritableFileWriter> file_writer(new WritableFileWriter(
+          NewLegacyWritableFileWrapper(std::move(file)), fname, env_options));
      current_log_writer.reset(
          new log::Writer(std::move(file_writer), current_log_number,
                          db_options.recycle_log_file_num > 0));
@@ -183,7 +183,8 @@ TEST_F(DBErrorHandlingTest, CompactionWriteError) {
      );
  listener->EnableAutoRecovery(false);
  rocksdb::SyncPoint::GetInstance()->LoadDependency(
-      {{"FlushMemTableFinished", "BackgroundCallCompaction:0"}});
+      {{"DBImpl::FlushMemTable:FlushMemTableFinished",
+        "BackgroundCallCompaction:0"}});
  rocksdb::SyncPoint::GetInstance()->SetCallBack(
      "BackgroundCallCompaction:0", [&](void *) {
      fault_env->SetFilesystemActive(false, Status::NoSpace("Out of space"));
@@ -219,7 +220,8 @@ TEST_F(DBErrorHandlingTest, CorruptionError) {
  ASSERT_EQ(s, Status::OK());

  rocksdb::SyncPoint::GetInstance()->LoadDependency(
-      {{"FlushMemTableFinished", "BackgroundCallCompaction:0"}});
+      {{"DBImpl::FlushMemTable:FlushMemTableFinished",
+        "BackgroundCallCompaction:0"}});
  rocksdb::SyncPoint::GetInstance()->SetCallBack(
      "BackgroundCallCompaction:0", [&](void *) {
      fault_env->SetFilesystemActive(false, Status::Corruption("Corruption"));
@@ -101,14 +101,15 @@ Status ExternalSstFileIngestionJob::Prepare(
        TableFileName(cfd_->ioptions()->cf_paths, f.fd.GetNumber(),
                      f.fd.GetPathId());
    if (ingestion_options_.move_files) {
-      status = env_->LinkFile(path_outside_db, path_inside_db);
+      status =
+          fs_->LinkFile(path_outside_db, path_inside_db, IOOptions(), nullptr);
      if (status.ok()) {
        // It is unsafe to assume application had sync the file and file
        // directory before ingest the file. For integrity of RocksDB we need
        // to sync the file.
-        std::unique_ptr<WritableFile> file_to_sync;
-        status = env_->ReopenWritableFile(path_inside_db, &file_to_sync,
-                                          env_options_);
+        std::unique_ptr<FSWritableFile> file_to_sync;
+        status = fs_->ReopenWritableFile(path_inside_db, env_options_,
+                                         &file_to_sync, nullptr);
        if (status.ok()) {
          TEST_SYNC_POINT(
              "ExternalSstFileIngestionJob::BeforeSyncIngestedFile");
@@ -133,7 +134,7 @@ Status ExternalSstFileIngestionJob::Prepare(
      TEST_SYNC_POINT_CALLBACK("ExternalSstFileIngestionJob::Prepare:CopyFile",
                               nullptr);
      // CopyFile also sync the new file.
-      status = CopyFile(env_, path_outside_db, path_inside_db, 0,
+      status = CopyFile(fs_, path_outside_db, path_inside_db, 0,
                        db_options_.use_fsync);
    }
    TEST_SYNC_POINT("ExternalSstFileIngestionJob::Prepare:FileAdded");
@@ -246,16 +247,19 @@ Status ExternalSstFileIngestionJob::Run() {

    // We use the import time as the ancester time. This is the time the data
    // is written to the database.
-    uint64_t oldest_ancester_time = 0;
    int64_t temp_current_time = 0;
+    uint64_t current_time = kUnknownFileCreationTime;
+    uint64_t oldest_ancester_time = kUnknownOldestAncesterTime;
    if (env_->GetCurrentTime(&temp_current_time).ok()) {
-      oldest_ancester_time = static_cast<uint64_t>(temp_current_time);
+      current_time = oldest_ancester_time =
+          static_cast<uint64_t>(temp_current_time);
    }

    edit_.AddFile(f.picked_level, f.fd.GetNumber(), f.fd.GetPathId(),
                  f.fd.GetFileSize(), f.smallest_internal_key,
                  f.largest_internal_key, f.assigned_seqno, f.assigned_seqno,
-                  false, kInvalidBlobFileNumber, oldest_ancester_time);
+                  false, kInvalidBlobFileNumber, oldest_ancester_time,
+                  current_time);
  }
  return status;
 }
@@ -357,17 +361,19 @@ Status ExternalSstFileIngestionJob::GetIngestedFileInfo(
  file_to_ingest->external_file_path = external_file;

  // Get external file size
-  Status status = env_->GetFileSize(external_file, &file_to_ingest->file_size);
+  Status status = fs_->GetFileSize(external_file, IOOptions(),
+                                   &file_to_ingest->file_size, nullptr);
  if (!status.ok()) {
    return status;
  }

  // Create TableReader for external file
  std::unique_ptr<TableReader> table_reader;
-  std::unique_ptr<RandomAccessFile> sst_file;
+  std::unique_ptr<FSRandomAccessFile> sst_file;
  std::unique_ptr<RandomAccessFileReader> sst_file_reader;

-  status = env_->NewRandomAccessFile(external_file, &sst_file, env_options_);
+  status = fs_->NewRandomAccessFile(external_file, env_options_,
+                                    &sst_file, nullptr);
  if (!status.ok()) {
    return status;
  }
@@ -648,13 +654,15 @@ Status ExternalSstFileIngestionJob::AssignGlobalSeqnoForIngestedFile(
    // Determine if we can write global_seqno to a given offset of file.
    // If the file system does not support random write, then we should not.
    // Otherwise we should.
-    std::unique_ptr<RandomRWFile> rwfile;
-    Status status = env_->NewRandomRWFile(file_to_ingest->internal_file_path,
-                                          &rwfile, env_options_);
+    std::unique_ptr<FSRandomRWFile> rwfile;
+    Status status =
+        fs_->NewRandomRWFile(file_to_ingest->internal_file_path, env_options_,
+                             &rwfile, nullptr);
    if (status.ok()) {
      std::string seqno_val;
      PutFixed64(&seqno_val, seqno);
-      status = rwfile->Write(file_to_ingest->global_seqno_offset, seqno_val);
+      status = rwfile->Write(file_to_ingest->global_seqno_offset, seqno_val,
+                             IOOptions(), nullptr);
      if (status.ok()) {
        TEST_SYNC_POINT("ExternalSstFileIngestionJob::BeforeSyncGlobalSeqno");
        status = SyncIngestedFile(rwfile.get());
@@ -712,9 +720,9 @@ template <typename TWritableFile>
 Status ExternalSstFileIngestionJob::SyncIngestedFile(TWritableFile* file) {
  assert(file != nullptr);
  if (db_options_.use_fsync) {
-    return file->Fsync();
+    return file->Fsync(IOOptions(), nullptr);
  } else {
-    return file->Sync();
+    return file->Sync(IOOptions(), nullptr);
  }
 }

@@ -74,6 +74,7 @@ class ExternalSstFileIngestionJob {
      const IngestExternalFileOptions& ingestion_options,
      Directories* directories, EventLogger* event_logger)
      : env_(env),
+        fs_(db_options.fs.get()),
        versions_(versions),
        cfd_(cfd),
        db_options_(db_options),
@@ -158,6 +159,7 @@ class ExternalSstFileIngestionJob {
  Status SyncIngestedFile(TWritableFile* file);

  Env* env_;
+  FileSystem* fs_;
  VersionSet* versions_;
  ColumnFamilyData* cfd_;
  const ImmutableDBOptions& db_options_;
@@ -1700,6 +1700,35 @@ TEST_F(ExternalSSTFileTest, SstFileWriterNonSharedKeys) {
  ASSERT_OK(DeprecatedAddFile({file_path}));
 }

+TEST_F(ExternalSSTFileTest, WithUnorderedWrite) {
+  SyncPoint::GetInstance()->DisableProcessing();
+  SyncPoint::GetInstance()->LoadDependency(
+      {{"DBImpl::WriteImpl:UnorderedWriteAfterWriteWAL",
+        "ExternalSSTFileTest::WithUnorderedWrite:WaitWriteWAL"},
+       {"DBImpl::WaitForPendingWrites:BeforeBlock",
+        "DBImpl::WriteImpl:BeforeUnorderedWriteMemtable"}});
+  SyncPoint::GetInstance()->SetCallBack(
+      "DBImpl::IngestExternalFile:NeedFlush", [&](void* need_flush) {
+        ASSERT_TRUE(*reinterpret_cast<bool*>(need_flush));
+      });
+
+  Options options = CurrentOptions();
+  options.unordered_write = true;
+  DestroyAndReopen(options);
+  Put("foo", "v1");
+  SyncPoint::GetInstance()->EnableProcessing();
+  port::Thread writer([&]() { Put("bar", "v2"); });
+
+  TEST_SYNC_POINT("ExternalSSTFileTest::WithUnorderedWrite:WaitWriteWAL");
+  ASSERT_OK(GenerateAndAddExternalFile(options, {{"bar", "v3"}}, -1,
+                                       true /* allow_global_seqno */));
+  ASSERT_EQ(Get("bar"), "v3");
+
+  writer.join();
+  SyncPoint::GetInstance()->DisableProcessing();
+  SyncPoint::GetInstance()->ClearAllCallBacks();
+}
+
 TEST_P(ExternalSSTFileTest, IngestFileWithGlobalSeqnoRandomized) {
  Options options = CurrentOptions();
  options.IncreaseParallelism(20);
@@ -86,7 +86,7 @@ FlushJob::FlushJob(const std::string& dbname, ColumnFamilyData* cfd,
                   const ImmutableDBOptions& db_options,
                   const MutableCFOptions& mutable_cf_options,
                   const uint64_t* max_memtable_id,
-                   const EnvOptions& env_options, VersionSet* versions,
+                   const FileOptions& file_options, VersionSet* versions,
                   InstrumentedMutex* db_mutex,
                   std::atomic<bool>* shutting_down,
                   std::vector<SequenceNumber> existing_snapshots,
@@ -103,7 +103,7 @@ FlushJob::FlushJob(const std::string& dbname, ColumnFamilyData* cfd,
      db_options_(db_options),
      mutable_cf_options_(mutable_cf_options),
      max_memtable_id_(max_memtable_id),
-      env_options_(env_options),
+      file_options_(file_options),
      versions_(versions),
      db_mutex_(db_mutex),
      shutting_down_(shutting_down),
@@ -249,7 +249,8 @@ Status FlushJob::Run(LogsWithPrepTracker* prep_tracker,
  }
  RecordFlushIOStats();

-  auto stream = event_logger_->LogToBuffer(log_buffer_);
+  // When measure_io_stats_ is true, the default 512 bytes is not enough.
+  auto stream = event_logger_->LogToBuffer(log_buffer_, 1024);
  stream << "job" << job_context_->job_id << "event"
         << "flush_finished";
  stream << "output_compression"
@@ -368,10 +369,11 @@ Status FlushJob::WriteLevel0Table() {
      // It's not clear whether oldest_key_time is always available. In case
      // it is not available, use current_time.
      meta_.oldest_ancester_time = std::min(current_time, oldest_key_time);
+      meta_.file_creation_time = current_time;

      s = BuildTable(
-          dbname_, db_options_.env, *cfd_->ioptions(), mutable_cf_options_,
-          env_options_, cfd_->table_cache(), iter.get(),
+          dbname_, db_options_.env, db_options_.fs.get(), *cfd_->ioptions(),
+          mutable_cf_options_, file_options_, cfd_->table_cache(), iter.get(),
          std::move(range_del_iters), &meta_, cfd_->internal_comparator(),
          cfd_->int_tbl_prop_collector_factories(), cfd_->GetID(),
          cfd_->GetName(), existing_snapshots_,
@@ -413,7 +415,7 @@ Status FlushJob::WriteLevel0Table() {
                   meta_.fd.GetFileSize(), meta_.smallest, meta_.largest,
                   meta_.fd.smallest_seqno, meta_.fd.largest_seqno,
                   meta_.marked_for_compaction, meta_.oldest_blob_file_number,
-                   meta_.oldest_ancester_time);
+                   meta_.oldest_ancester_time, meta_.file_creation_time);
  }
 #ifndef ROCKSDB_LITE
  // Piggyback FlushJobInfo on the first first flushed memtable.
@@ -61,7 +61,7 @@ class FlushJob {
  FlushJob(const std::string& dbname, ColumnFamilyData* cfd,
           const ImmutableDBOptions& db_options,
           const MutableCFOptions& mutable_cf_options,
-           const uint64_t* max_memtable_id, const EnvOptions& env_options,
+           const uint64_t* max_memtable_id, const FileOptions& file_options,
           VersionSet* versions, InstrumentedMutex* db_mutex,
           std::atomic<bool>* shutting_down,
           std::vector<SequenceNumber> existing_snapshots,
@@ -108,7 +108,7 @@ class FlushJob {
  // equal to *max_memtable_id_ will be selected for flush. If null, then all
  // memtables in the column family will be selected.
  const uint64_t* max_memtable_id_;
-  const EnvOptions env_options_;
+  const FileOptions file_options_;
  VersionSet* versions_;
  InstrumentedMutex* db_mutex_;
  std::atomic<bool>* shutting_down_;
@@ -30,16 +30,13 @@ class FlushJobTest : public testing::Test {
 public:
  FlushJobTest()
      : env_(Env::Default()),
+        fs_(std::make_shared<LegacyFileSystemWrapper>(env_)),
        dbname_(test::PerThreadDBPath("flush_job_test")),
        options_(),
        db_options_(options_),
        column_family_names_({kDefaultColumnFamilyName, "foo", "bar"}),
        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)),
        shutting_down_(false),
        mock_table_factory_(new mock::MockTableFactory()) {
    EXPECT_OK(env_->CreateDirIfMissing(dbname_));
@@ -54,6 +51,12 @@ class FlushJobTest : public testing::Test {
      column_families.emplace_back(cf_name, cf_options_);
    }

+    db_options_.env = env_;
+    db_options_.fs = fs_;
+    versions_.reset(new VersionSet(dbname_, &db_options_, env_options_,
+                                   table_cache_.get(), &write_buffer_manager_,
+                                   &write_controller_,
+                                   /*block_cache_tracer=*/nullptr));
    EXPECT_OK(versions_->Recover(column_families, false));
  }

@@ -88,8 +91,8 @@ class FlushJobTest : public testing::Test {
    Status s = env_->NewWritableFile(
        manifest, &file, env_->OptimizeForManifestWrite(env_options_));
    ASSERT_OK(s);
-    std::unique_ptr<WritableFileWriter> file_writer(
-        new WritableFileWriter(std::move(file), manifest, EnvOptions()));
+    std::unique_ptr<WritableFileWriter> file_writer(new WritableFileWriter(
+        NewLegacyWritableFileWrapper(std::move(file)), manifest, EnvOptions()));
    {
      log::Writer log(std::move(file_writer), 0, false);
      std::string record;
@@ -109,6 +112,7 @@ class FlushJobTest : public testing::Test {
  }

  Env* env_;
+  std::shared_ptr<FileSystem> fs_;
  std::string dbname_;
  EnvOptions env_options_;
  Options options_;
@@ -60,9 +60,7 @@ ColumnFamilyData* FlushScheduler::TakeNextColumnFamily() {
    }

    // no longer relevant, retry
-    if (cfd->Unref()) {
-      delete cfd;
-    }
+    cfd->UnrefAndTryDelete();
  }
 }

@@ -80,9 +78,7 @@ bool FlushScheduler::Empty() {
 void FlushScheduler::Clear() {
  ColumnFamilyData* cfd;
  while ((cfd = TakeNextColumnFamily()) != nullptr) {
-    if (cfd->Unref()) {
-      delete cfd;
-    }
+    cfd->UnrefAndTryDelete();
  }
  assert(head_.load(std::memory_order_relaxed) == nullptr);
 }
@@ -239,9 +239,13 @@ void ForwardIterator::SVCleanup(DBImpl* db, SuperVersion* sv,
    db->FindObsoleteFiles(&job_context, false, true);
    if (background_purge_on_iterator_cleanup) {
      db->ScheduleBgLogWriterClose(&job_context);
+      db->AddSuperVersionsToFreeQueue(sv);
+      db->SchedulePurge();
    }
    db->mutex_.Unlock();
-    delete sv;
+    if (!background_purge_on_iterator_cleanup) {
+      delete sv;
+    }
    if (job_context.HaveSomethingToDelete()) {
      db->PurgeObsoleteFiles(job_context, background_purge_on_iterator_cleanup);
    }
@@ -614,7 +618,7 @@ void ForwardIterator::RebuildIterators(bool refresh_sv) {
  Cleanup(refresh_sv);
  if (refresh_sv) {
    // New
-    sv_ = cfd_->GetReferencedSuperVersion(&(db_->mutex_));
+    sv_ = cfd_->GetReferencedSuperVersion(db_);
  }
  ReadRangeDelAggregator range_del_agg(&cfd_->internal_comparator(),
                                       kMaxSequenceNumber /* upper_bound */);
@@ -668,7 +672,7 @@ void ForwardIterator::RebuildIterators(bool refresh_sv) {
 void ForwardIterator::RenewIterators() {
  SuperVersion* svnew;
  assert(sv_);
-  svnew = cfd_->GetReferencedSuperVersion(&(db_->mutex_));
+  svnew = cfd_->GetReferencedSuperVersion(db_);

  if (mutable_iter_ != nullptr) {
    DeleteIterator(mutable_iter_, true /* is_arena */);
@@ -92,14 +92,15 @@ Status ImportColumnFamilyJob::Prepare(uint64_t next_file_number,
        cfd_->ioptions()->cf_paths, f.fd.GetNumber(), f.fd.GetPathId());

    if (hardlink_files) {
-      status = env_->LinkFile(path_outside_db, path_inside_db);
+      status =
+          fs_->LinkFile(path_outside_db, path_inside_db, IOOptions(), nullptr);
      if (status.IsNotSupported()) {
        // Original file is on a different FS, use copy instead of hard linking
        hardlink_files = false;
      }
    }
    if (!hardlink_files) {
-      status = CopyFile(env_, path_outside_db, path_inside_db, 0,
+      status = CopyFile(fs_, path_outside_db, path_inside_db, 0,
                        db_options_.use_fsync);
    }
    if (!status.ok()) {
@@ -115,7 +116,8 @@ Status ImportColumnFamilyJob::Prepare(uint64_t next_file_number,
      if (f.internal_file_path.empty()) {
        break;
      }
-      const auto s = env_->DeleteFile(f.internal_file_path);
+      const auto s =
+          fs_->DeleteFile(f.internal_file_path, IOOptions(), nullptr);
      if (!s.ok()) {
        ROCKS_LOG_WARN(db_options_.info_log,
                       "AddFile() clean up for file %s failed : %s",
@@ -135,10 +137,12 @@ Status ImportColumnFamilyJob::Run() {

  // We use the import time as the ancester time. This is the time the data
  // is written to the database.
-  uint64_t oldest_ancester_time = 0;
  int64_t temp_current_time = 0;
+  uint64_t oldest_ancester_time = kUnknownOldestAncesterTime;
+  uint64_t current_time = kUnknownOldestAncesterTime;
  if (env_->GetCurrentTime(&temp_current_time).ok()) {
-    oldest_ancester_time = static_cast<uint64_t>(temp_current_time);
+    current_time = oldest_ancester_time =
+        static_cast<uint64_t>(temp_current_time);
  }

  for (size_t i = 0; i < files_to_import_.size(); ++i) {
@@ -149,7 +153,7 @@ Status ImportColumnFamilyJob::Run() {
                  f.fd.GetFileSize(), f.smallest_internal_key,
                  f.largest_internal_key, file_metadata.smallest_seqno,
                  file_metadata.largest_seqno, false, kInvalidBlobFileNumber,
-                  oldest_ancester_time);
+                  oldest_ancester_time, current_time);

    // If incoming sequence number is higher, update local sequence number.
    if (file_metadata.largest_seqno > versions_->LastSequence()) {
@@ -166,7 +170,8 @@ void ImportColumnFamilyJob::Cleanup(const Status& status) {
  if (!status.ok()) {
    // We failed to add files to the database remove all the files we copied.
    for (const auto& f : files_to_import_) {
-      const auto s = env_->DeleteFile(f.internal_file_path);
+      const auto s =
+          fs_->DeleteFile(f.internal_file_path, IOOptions(), nullptr);
      if (!s.ok()) {
        ROCKS_LOG_WARN(db_options_.info_log,
                       "AddFile() clean up for file %s failed : %s",
@@ -176,7 +181,8 @@ void ImportColumnFamilyJob::Cleanup(const Status& status) {
  } else if (status.ok() && import_options_.move_files) {
    // The files were moved and added successfully, remove original file links
    for (IngestedFileInfo& f : files_to_import_) {
-      const auto s = env_->DeleteFile(f.external_file_path);
+      const auto s =
+          fs_->DeleteFile(f.external_file_path, IOOptions(), nullptr);
      if (!s.ok()) {
        ROCKS_LOG_WARN(
            db_options_.info_log,
@@ -194,17 +200,19 @@ Status ImportColumnFamilyJob::GetIngestedFileInfo(
  file_to_import->external_file_path = external_file;

  // Get external file size
-  auto status = env_->GetFileSize(external_file, &file_to_import->file_size);
+  Status status = fs_->GetFileSize(external_file, IOOptions(),
+                                   &file_to_import->file_size, nullptr);
  if (!status.ok()) {
    return status;
  }

  // Create TableReader for external file
  std::unique_ptr<TableReader> table_reader;
-  std::unique_ptr<RandomAccessFile> sst_file;
+  std::unique_ptr<FSRandomAccessFile> sst_file;
  std::unique_ptr<RandomAccessFileReader> sst_file_reader;

-  status = env_->NewRandomAccessFile(external_file, &sst_file, env_options_);
+  status = fs_->NewRandomAccessFile(external_file, env_options_,
+                                    &sst_file, nullptr);
  if (!status.ok()) {
    return status;
  }
@@ -29,6 +29,7 @@ class ImportColumnFamilyJob {
        versions_(versions),
        cfd_(cfd),
        db_options_(db_options),
+        fs_(db_options_.fs.get()),
        env_options_(env_options),
        import_options_(import_options),
        metadata_(metadata) {}
@@ -60,6 +61,7 @@ class ImportColumnFamilyJob {
  VersionSet* versions_;
  ColumnFamilyData* cfd_;
  const ImmutableDBOptions& db_options_;
+  FileSystem* fs_;
  const EnvOptions& env_options_;
  autovector<IngestedFileInfo> files_to_import_;
  VersionEdit edit_;
@@ -231,6 +231,7 @@ static const std::string is_file_deletions_enabled =
    "is-file-deletions-enabled";
 static const std::string num_snapshots = "num-snapshots";
 static const std::string oldest_snapshot_time = "oldest-snapshot-time";
+static const std::string oldest_snapshot_sequence = "oldest-snapshot-sequence";
 static const std::string num_live_versions = "num-live-versions";
 static const std::string current_version_number =
    "current-super-version-number";
@@ -309,6 +310,8 @@ const std::string DB::Properties::kNumSnapshots =
    rocksdb_prefix + num_snapshots;
 const std::string DB::Properties::kOldestSnapshotTime =
    rocksdb_prefix + oldest_snapshot_time;
+const std::string DB::Properties::kOldestSnapshotSequence =
+    rocksdb_prefix + oldest_snapshot_sequence;
 const std::string DB::Properties::kNumLiveVersions =
    rocksdb_prefix + num_live_versions;
 const std::string DB::Properties::kCurrentSuperVersionNumber =
@@ -427,6 +430,9 @@ const std::unordered_map<std::string, DBPropertyInfo>
        {DB::Properties::kOldestSnapshotTime,
         {false, nullptr, &InternalStats::HandleOldestSnapshotTime, nullptr,
          nullptr}},
+        {DB::Properties::kOldestSnapshotSequence,
+         {false, nullptr, &InternalStats::HandleOldestSnapshotSequence, nullptr,
+          nullptr}},
        {DB::Properties::kNumLiveVersions,
         {false, nullptr, &InternalStats::HandleNumLiveVersions, nullptr,
          nullptr}},
@@ -772,6 +778,12 @@ bool InternalStats::HandleOldestSnapshotTime(uint64_t* value, DBImpl* db,
  return true;
 }

+bool InternalStats::HandleOldestSnapshotSequence(uint64_t* value, DBImpl* db,
+                                                 Version* /*version*/) {
+  *value = static_cast<uint64_t>(db->snapshots().GetOldestSnapshotSequence());
+  return true;
+}
+
 bool InternalStats::HandleNumLiveVersions(uint64_t* value, DBImpl* /*db*/,
                                          Version* /*version*/) {
  *value = cfd_->GetNumLiveVersions();
@@ -553,6 +553,8 @@ class InternalStats {
  bool HandleEstimateNumKeys(uint64_t* value, DBImpl* db, Version* version);
  bool HandleNumSnapshots(uint64_t* value, DBImpl* db, Version* version);
  bool HandleOldestSnapshotTime(uint64_t* value, DBImpl* db, Version* version);
+  bool HandleOldestSnapshotSequence(uint64_t* value, DBImpl* db,
+                                    Version* version);
  bool HandleNumLiveVersions(uint64_t* value, DBImpl* db, Version* version);
  bool HandleCurrentSuperVersionNumber(uint64_t* value, DBImpl* db,
                                       Version* version);
@@ -9,6 +9,7 @@

 #include "db/log_reader.h"
 #include "db/log_writer.h"
+#include "env/composite_env_wrapper.h"
 #include "file/sequence_file_reader.h"
 #include "file/writable_file_writer.h"
 #include "rocksdb/env.h"
@@ -120,6 +121,13 @@ class LogTest : public ::testing::TestWithParam<std::tuple<int, bool>> {
    }
  };

+  inline StringSource* GetStringSourceFromLegacyReader(
+      SequentialFileReader* reader) {
+    LegacySequentialFileWrapper* file =
+        static_cast<LegacySequentialFileWrapper*>(reader->file());
+    return static_cast<StringSource*>(file->target());
+  }
+
  class ReportCollector : public Reader::Reporter {
   public:
    size_t dropped_bytes_;
@@ -133,21 +141,19 @@ class LogTest : public ::testing::TestWithParam<std::tuple<int, bool>> {
  };

  std::string& dest_contents() {
-    auto dest =
-      dynamic_cast<test::StringSink*>(writer_.file()->writable_file());
+    auto dest = test::GetStringSinkFromLegacyWriter(writer_.file());
    assert(dest);
    return dest->contents_;
  }

  const std::string& dest_contents() const {
-    auto dest =
-      dynamic_cast<const test::StringSink*>(writer_.file()->writable_file());
+    auto dest = test::GetStringSinkFromLegacyWriter(writer_.file());
    assert(dest);
    return dest->contents_;
  }

  void reset_source_contents() {
-    auto src = dynamic_cast<StringSource*>(reader_->file()->file());
+    auto src = GetStringSourceFromLegacyReader(reader_->file());
    assert(src);
    src->contents_ = dest_contents();
  }
@@ -214,8 +220,7 @@ class LogTest : public ::testing::TestWithParam<std::tuple<int, bool>> {
  }

  void ShrinkSize(int bytes) {
-    auto dest =
-      dynamic_cast<test::StringSink*>(writer_.file()->writable_file());
+    auto dest = test::GetStringSinkFromLegacyWriter(writer_.file());
    assert(dest);
    dest->Drop(bytes);
  }
@@ -230,7 +235,7 @@ class LogTest : public ::testing::TestWithParam<std::tuple<int, bool>> {
  }

  void ForceError(size_t position = 0) {
-    auto src = dynamic_cast<StringSource*>(reader_->file()->file());
+    auto src = GetStringSourceFromLegacyReader(reader_->file());
    src->force_error_ = true;
    src->force_error_position_ = position;
  }
@@ -244,13 +249,13 @@ class LogTest : public ::testing::TestWithParam<std::tuple<int, bool>> {
  }

  void ForceEOF(size_t position = 0) {
-    auto src = dynamic_cast<StringSource*>(reader_->file()->file());
+    auto src = GetStringSourceFromLegacyReader(reader_->file());
    src->force_eof_ = true;
    src->force_eof_position_ = position;
  }

  void UnmarkEOF() {
-    auto src = dynamic_cast<StringSource*>(reader_->file()->file());
+    auto src = GetStringSourceFromLegacyReader(reader_->file());
    src->returned_partial_ = false;
    reader_->UnmarkEOF();
  }
@@ -752,8 +757,9 @@ class RetriableLogTest : public ::testing::TestWithParam<int> {
      s = env_->NewWritableFile(log_file_, &writable_file, env_options_);
    }
    if (s.ok()) {
-      writer_.reset(new WritableFileWriter(std::move(writable_file), log_file_,
-                                           env_options_));
+      writer_.reset(new WritableFileWriter(
+          NewLegacyWritableFileWrapper(std::move(writable_file)), log_file_,
+          env_options_));
      assert(writer_ != nullptr);
    }
    std::unique_ptr<SequentialFile> seq_file;
@@ -761,7 +767,8 @@ class RetriableLogTest : public ::testing::TestWithParam<int> {
      s = env_->NewSequentialFile(log_file_, &seq_file, env_options_);
    }
    if (s.ok()) {
-      reader_.reset(new SequentialFileReader(std::move(seq_file), log_file_));
+      reader_.reset(new SequentialFileReader(
+          NewLegacySequentialFileWrapper(seq_file), log_file_));
      assert(reader_ != nullptr);
      log_reader_.reset(new FragmentBufferedReader(
          nullptr, std::move(reader_), &report_, true /* checksum */,
@@ -772,8 +779,7 @@ class RetriableLogTest : public ::testing::TestWithParam<int> {
  }

  std::string contents() {
-    auto file =
-        dynamic_cast<test::StringSink*>(log_writer_->file()->writable_file());
+    auto file = test::GetStringSinkFromLegacyWriter(log_writer_->file());
    assert(file != nullptr);
    return file->contents_;
  }
@@ -138,7 +138,7 @@ class MemTable {

  // As a cheap version of `ApproximateMemoryUsage()`, this function doens't
  // require external synchronization. The value may be less accurate though
-  size_t ApproximateMemoryUsageFast() {
+  size_t ApproximateMemoryUsageFast() const {
    return approximate_memory_usage_.load(std::memory_order_relaxed);
  }

@@ -186,11 +186,14 @@ Status MemTableListVersion::AddRangeTombstoneIterators(
    const ReadOptions& read_opts, Arena* /*arena*/,
    RangeDelAggregator* range_del_agg) {
  assert(range_del_agg != nullptr);
+  // Except for snapshot read, using kMaxSequenceNumber is OK because these
+  // are immutable memtables.
+  SequenceNumber read_seq = read_opts.snapshot != nullptr
+                                ? read_opts.snapshot->GetSequenceNumber()
+                                : kMaxSequenceNumber;
  for (auto& m : memlist_) {
-    // Using kMaxSequenceNumber is OK because these are immutable memtables.
    std::unique_ptr<FragmentedRangeTombstoneIterator> range_del_iter(
-        m->NewRangeTombstoneIterator(read_opts,
-                                     kMaxSequenceNumber /* read_seq */));
+        m->NewRangeTombstoneIterator(read_opts, read_seq));
    range_del_agg->AddTombstones(std::move(range_del_iter));
  }
  return Status::OK();
@@ -277,7 +280,7 @@ void MemTableListVersion::Remove(MemTable* m,
 }

 // return the total memory usage assuming the oldest flushed memtable is dropped
-size_t MemTableListVersion::ApproximateMemoryUsageExcludingLast() {
+size_t MemTableListVersion::ApproximateMemoryUsageExcludingLast() const {
  size_t total_memtable_size = 0;
  for (auto& memtable : memlist_) {
    total_memtable_size += memtable->ApproximateMemoryUsage();
@@ -500,7 +503,7 @@ Status MemTableList::TryInstallMemtableFlushResults(
                           cfd->GetName().c_str(), m->file_number_, mem_id);
          assert(m->file_number_ > 0);
          current_->Remove(m, to_delete);
-          UpdateMemoryUsageExcludingLast();
+          UpdateCachedValuesFromMemTableListVersion();
          ResetTrimHistoryNeeded();
          ++mem_id;
        }
@@ -541,14 +544,14 @@ void MemTableList::Add(MemTable* m, autovector<MemTable*>* to_delete) {
  if (num_flush_not_started_ == 1) {
    imm_flush_needed.store(true, std::memory_order_release);
  }
-  UpdateMemoryUsageExcludingLast();
+  UpdateCachedValuesFromMemTableListVersion();
  ResetTrimHistoryNeeded();
 }

 void MemTableList::TrimHistory(autovector<MemTable*>* to_delete, size_t usage) {
  InstallNewVersion();
  current_->TrimHistory(to_delete, usage);
-  UpdateMemoryUsageExcludingLast();
+  UpdateCachedValuesFromMemTableListVersion();
  ResetTrimHistoryNeeded();
 }

@@ -563,18 +566,25 @@ size_t MemTableList::ApproximateUnflushedMemTablesMemoryUsage() {

 size_t MemTableList::ApproximateMemoryUsage() { return current_memory_usage_; }

-size_t MemTableList::ApproximateMemoryUsageExcludingLast() {
-  size_t usage =
+size_t MemTableList::ApproximateMemoryUsageExcludingLast() const {
+  const size_t usage =
      current_memory_usage_excluding_last_.load(std::memory_order_relaxed);
  return usage;
 }

-// Update current_memory_usage_excluding_last_, need to call whenever state
-// changes for MemtableListVersion (whenever InstallNewVersion() is called)
-void MemTableList::UpdateMemoryUsageExcludingLast() {
-  size_t total_memtable_size = current_->ApproximateMemoryUsageExcludingLast();
+bool MemTableList::HasHistory() const {
+  const bool has_history = current_has_history_.load(std::memory_order_relaxed);
+  return has_history;
+}
+
+void MemTableList::UpdateCachedValuesFromMemTableListVersion() {
+  const size_t total_memtable_size =
+      current_->ApproximateMemoryUsageExcludingLast();
  current_memory_usage_excluding_last_.store(total_memtable_size,
                                             std::memory_order_relaxed);
+
+  const bool has_history = current_->HasHistory();
+  current_has_history_.store(has_history, std::memory_order_relaxed);
 }

 uint64_t MemTableList::ApproximateOldestKeyTime() const {
@@ -704,7 +714,7 @@ Status InstallMemtableAtomicFlushResults(
                         cfds[i]->GetName().c_str(), m->GetFileNumber(),
                         mem_id);
        imm->current_->Remove(m, to_delete);
-        imm->UpdateMemoryUsageExcludingLast();
+        imm->UpdateCachedValuesFromMemTableListVersion();
        imm->ResetTrimHistoryNeeded();
      }
    }
@@ -754,7 +764,7 @@ void MemTableList::RemoveOldMemTables(uint64_t log_number,
    }
  }

-  UpdateMemoryUsageExcludingLast();
+  UpdateCachedValuesFromMemTableListVersion();
  ResetTrimHistoryNeeded();
 }

@@ -162,7 +162,11 @@ class MemTableListVersion {
  // excluding the last MemTable in memlist_history_. The reason for excluding
  // the last MemTable is to see if dropping the last MemTable will keep total
  // memory usage above or equal to max_write_buffer_size_to_maintain_
-  size_t ApproximateMemoryUsageExcludingLast();
+  size_t ApproximateMemoryUsageExcludingLast() const;
+
+  // Whether this version contains flushed memtables that are only kept around
+  // for transaction conflict checking.
+  bool HasHistory() const { return !memlist_history_.empty(); }

  bool MemtableLimitExceeded(size_t usage);

@@ -211,7 +215,8 @@ class MemTableList {
        commit_in_progress_(false),
        flush_requested_(false),
        current_memory_usage_(0),
-        current_memory_usage_excluding_last_(0) {
+        current_memory_usage_excluding_last_(0),
+        current_has_history_(false) {
    current_->Ref();
  }

@@ -266,11 +271,16 @@ class MemTableList {
  // Returns an estimate of the number of bytes of data in use.
  size_t ApproximateMemoryUsage();

-  // Returns the cached current_memory_usage_excluding_last_ value
-  size_t ApproximateMemoryUsageExcludingLast();
+  // Returns the cached current_memory_usage_excluding_last_ value.
+  size_t ApproximateMemoryUsageExcludingLast() const;

-  // Update current_memory_usage_excluding_last_ from MemtableListVersion
-  void UpdateMemoryUsageExcludingLast();
+  // Returns the cached current_has_history_ value.
+  bool HasHistory() const;
+
+  // Updates current_memory_usage_excluding_last_ and current_has_history_
+  // from MemTableListVersion. Must be called whenever InstallNewVersion is
+  // called.
+  void UpdateCachedValuesFromMemTableListVersion();

  // `usage` is the current size of the mutable Memtable. When
  // max_write_buffer_size_to_maintain is used, total size of mutable and
@@ -388,7 +398,11 @@ class MemTableList {
  // The current memory usage.
  size_t current_memory_usage_;

+  // Cached value of current_->ApproximateMemoryUsageExcludingLast().
  std::atomic<size_t> current_memory_usage_excluding_last_;
+
+  // Cached value of current_->HasHistory().
+  std::atomic<bool> current_has_history_;
 };

 // Installs memtable atomic flush results.
@@ -92,6 +92,7 @@ class MemTableListTest : public testing::Test {
    CreateDB();
    // Create a mock VersionSet
    DBOptions db_options;
+    db_options.file_system = FileSystem::Default();
    ImmutableDBOptions immutable_db_options(db_options);
    EnvOptions env_options;
    std::shared_ptr<Cache> table_cache(NewLRUCache(50000, 16));
@@ -138,6 +139,8 @@ class MemTableListTest : public testing::Test {
    CreateDB();
    // Create a mock VersionSet
    DBOptions db_options;
+    db_options.file_system.reset(new LegacyFileSystemWrapper(db_options.env));
+
    ImmutableDBOptions immutable_db_options(db_options);
    EnvOptions env_options;
    std::shared_ptr<Cache> table_cache(NewLRUCache(50000, 16));
@@ -78,6 +78,9 @@ std::shared_ptr<DB> OpenDb(const std::string& dbname, const bool ttl = false,
  options.create_if_missing = true;
  options.merge_operator = std::make_shared<CountMergeOperator>();
  options.max_successive_merges = max_successive_merges;
+  if (max_successive_merges > 0) {
+    options.allow_concurrent_memtable_write = false;
+  }
  Status s;
  DestroyDB(dbname, Options());
 // DBWithTTL is not supported in ROCKSDB_LITE
@@ -71,6 +71,7 @@
 #include "db/table_cache.h"
 #include "db/version_edit.h"
 #include "db/write_batch_internal.h"
+#include "env/composite_env_wrapper.h"
 #include "file/filename.h"
 #include "file/writable_file_writer.h"
 #include "options/cf_options.h"
@@ -348,8 +349,8 @@ class Repairer {
    if (!status.ok()) {
      return status;
    }
-    std::unique_ptr<SequentialFileReader> lfile_reader(
-        new SequentialFileReader(std::move(lfile), logname));
+    std::unique_ptr<SequentialFileReader> lfile_reader(new SequentialFileReader(
+        NewLegacySequentialFileWrapper(lfile), logname));

    // Create the log reader.
    LogReporter reporter;
@@ -421,17 +422,19 @@ class Repairer {
      if (range_del_iter != nullptr) {
        range_del_iters.emplace_back(range_del_iter);
      }
+
+      LegacyFileSystemWrapper fs(env_);
      status = BuildTable(
-          dbname_, env_, *cfd->ioptions(), *cfd->GetLatestMutableCFOptions(),
-          env_options_, table_cache_, iter.get(), std::move(range_del_iters),
-          &meta, cfd->internal_comparator(),
-          cfd->int_tbl_prop_collector_factories(), cfd->GetID(), cfd->GetName(),
-          {}, kMaxSequenceNumber, snapshot_checker, kNoCompression,
-          0 /* sample_for_compression */, CompressionOptions(), false,
-          nullptr /* internal_stats */, TableFileCreationReason::kRecovery,
-          nullptr /* event_logger */, 0 /* job_id */, Env::IO_HIGH,
-          nullptr /* table_properties */, -1 /* level */, current_time,
-          write_hint);
+          dbname_, env_, &fs, *cfd->ioptions(),
+          *cfd->GetLatestMutableCFOptions(), env_options_, table_cache_,
+          iter.get(), std::move(range_del_iters), &meta,
+          cfd->internal_comparator(), cfd->int_tbl_prop_collector_factories(),
+          cfd->GetID(), cfd->GetName(), {}, kMaxSequenceNumber,
+          snapshot_checker, kNoCompression, 0 /* sample_for_compression */,
+          CompressionOptions(), false, nullptr /* internal_stats */,
+          TableFileCreationReason::kRecovery, nullptr /* event_logger */,
+          0 /* job_id */, Env::IO_HIGH, nullptr /* table_properties */,
+          -1 /* level */, current_time, write_hint);
      ROCKS_LOG_INFO(db_options_.info_log,
                     "Log #%" PRIu64 ": %d ops saved to Table #%" PRIu64 " %s",
                     log, counter, meta.fd.GetNumber(),
@@ -577,13 +580,13 @@ class Repairer {

      // TODO(opt): separate out into multiple levels
      for (const auto* table : cf_id_and_tables.second) {
-        edit.AddFile(0, table->meta.fd.GetNumber(), table->meta.fd.GetPathId(),
-                     table->meta.fd.GetFileSize(), table->meta.smallest,
-                     table->meta.largest, table->meta.fd.smallest_seqno,
-                     table->meta.fd.largest_seqno,
-                     table->meta.marked_for_compaction,
-                     table->meta.oldest_blob_file_number,
-                     table->meta.oldest_ancester_time);
+        edit.AddFile(
+            0, table->meta.fd.GetNumber(), table->meta.fd.GetPathId(),
+            table->meta.fd.GetFileSize(), table->meta.smallest,
+            table->meta.largest, table->meta.fd.smallest_seqno,
+            table->meta.fd.largest_seqno, table->meta.marked_for_compaction,
+            table->meta.oldest_blob_file_number,
+            table->meta.oldest_ancester_time, table->meta.file_creation_time);
      }
      assert(next_file_number_ > 0);
      vset_.MarkFileNumberUsed(next_file_number_ - 1);
@@ -667,8 +670,14 @@ Status RepairDB(const std::string& dbname, const DBOptions& db_options,
 }

 Status RepairDB(const std::string& dbname, const Options& options) {
-  DBOptions db_options(options);
-  ColumnFamilyOptions cf_options(options);
+  Options opts(options);
+  if (opts.file_system == nullptr) {
+    opts.file_system.reset(new LegacyFileSystemWrapper(opts.env));
+    ;
+  }
+
+  DBOptions db_options(opts);
+  ColumnFamilyOptions cf_options(opts);
  Repairer repairer(dbname, db_options,
                    {}, cf_options /* default_cf_opts */,
                    cf_options /* unknown_cf_opts */,
@@ -74,7 +74,9 @@ TEST_F(RepairTest, CorruptManifest) {

  Close();
  ASSERT_OK(env_->FileExists(manifest_path));
-  CreateFile(env_, manifest_path, "blah", false /* use_fsync */);
+
+  LegacyFileSystemWrapper fs(env_);
+  CreateFile(&fs, manifest_path, "blah", false /* use_fsync */);
  ASSERT_OK(RepairDB(dbname_, CurrentOptions()));
  Reopen(CurrentOptions());

@@ -153,7 +155,9 @@ TEST_F(RepairTest, CorruptSst) {
  Flush();
  auto sst_path = GetFirstSstPath();
  ASSERT_FALSE(sst_path.empty());
-  CreateFile(env_, sst_path, "blah", false /* use_fsync */);
+
+  LegacyFileSystemWrapper fs(env_);
+  CreateFile(&fs, sst_path, "blah", false /* use_fsync */);

  Close();
  ASSERT_OK(RepairDB(dbname_, CurrentOptions()));
@@ -148,6 +148,14 @@ class SnapshotList {
    }
  }

+  int64_t GetOldestSnapshotSequence() const {
+    if (empty()) {
+      return 0;
+    } else {
+      return oldest()->GetSequenceNumber();
+    }
+  }
+
  uint64_t count() const { return count_; }

 private:
@@ -63,10 +63,10 @@ void AppendVarint64(IterKey* key, uint64_t v) {
 }  // namespace

 TableCache::TableCache(const ImmutableCFOptions& ioptions,
-                       const EnvOptions& env_options, Cache* const cache,
+                       const FileOptions& file_options, Cache* const cache,
                       BlockCacheTracer* const block_cache_tracer)
    : ioptions_(ioptions),
-      env_options_(env_options),
+      file_options_(file_options),
      cache_(cache),
      immortal_tables_(false),
      block_cache_tracer_(block_cache_tracer) {
@@ -89,7 +89,7 @@ void TableCache::ReleaseHandle(Cache::Handle* handle) {
 }

 Status TableCache::GetTableReader(
-    const EnvOptions& env_options,
+    const FileOptions& file_options,
    const InternalKeyComparator& internal_comparator, const FileDescriptor& fd,
    bool sequential_mode, bool record_read_stats, HistogramImpl* file_read_hist,
    std::unique_ptr<TableReader>* table_reader,
@@ -97,13 +97,14 @@ Status TableCache::GetTableReader(
    bool prefetch_index_and_filter_in_cache) {
  std::string fname =
      TableFileName(ioptions_.cf_paths, fd.GetNumber(), fd.GetPathId());
-  std::unique_ptr<RandomAccessFile> file;
-  Status s = ioptions_.env->NewRandomAccessFile(fname, &file, env_options);
+  std::unique_ptr<FSRandomAccessFile> file;
+  Status s = ioptions_.fs->NewRandomAccessFile(fname, file_options, &file,
+                                               nullptr);

  RecordTick(ioptions_.statistics, NO_FILE_OPENS);
  if (s.ok()) {
    if (!sequential_mode && ioptions_.advise_random_on_open) {
-      file->Hint(RandomAccessFile::RANDOM);
+      file->Hint(FSRandomAccessFile::kRandom);
    }
    StopWatch sw(ioptions_.env, ioptions_.statistics, TABLE_OPEN_IO_MICROS);
    std::unique_ptr<RandomAccessFileReader> file_reader(
@@ -112,7 +113,7 @@ Status TableCache::GetTableReader(
            record_read_stats ? ioptions_.statistics : nullptr, SST_READ_MICROS,
            file_read_hist, ioptions_.rate_limiter, ioptions_.listeners));
    s = ioptions_.table_factory->NewTableReader(
-        TableReaderOptions(ioptions_, prefix_extractor, env_options,
+        TableReaderOptions(ioptions_, prefix_extractor, file_options,
                           internal_comparator, skip_filters, immortal_tables_,
                           level, fd.largest_seqno, block_cache_tracer_),
        std::move(file_reader), fd.GetFileSize(), table_reader,
@@ -129,7 +130,7 @@ void TableCache::EraseHandle(const FileDescriptor& fd, Cache::Handle* handle) {
  cache_->Erase(key);
 }

-Status TableCache::FindTable(const EnvOptions& env_options,
+Status TableCache::FindTable(const FileOptions& file_options,
                             const InternalKeyComparator& internal_comparator,
                             const FileDescriptor& fd, Cache::Handle** handle,
                             const SliceTransform* prefix_extractor,
@@ -150,7 +151,7 @@ Status TableCache::FindTable(const EnvOptions& env_options,
      return Status::Incomplete("Table not found in table_cache, no_io is set");
    }
    std::unique_ptr<TableReader> table_reader;
-    s = GetTableReader(env_options, internal_comparator, fd,
+    s = GetTableReader(file_options, internal_comparator, fd,
                       false /* sequential mode */, record_read_stats,
                       file_read_hist, &table_reader, prefix_extractor,
                       skip_filters, level, prefetch_index_and_filter_in_cache);
@@ -172,7 +173,7 @@ Status TableCache::FindTable(const EnvOptions& env_options,
 }

 InternalIterator* TableCache::NewIterator(
-    const ReadOptions& options, const EnvOptions& env_options,
+    const ReadOptions& options, const FileOptions& file_options,
    const InternalKeyComparator& icomparator, const FileMetaData& file_meta,
    RangeDelAggregator* range_del_agg, const SliceTransform* prefix_extractor,
    TableReader** table_reader_ptr, HistogramImpl* file_read_hist,
@@ -191,7 +192,7 @@ InternalIterator* TableCache::NewIterator(
  auto& fd = file_meta.fd;
  table_reader = fd.table_reader;
  if (table_reader == nullptr) {
-    s = FindTable(env_options, icomparator, fd, &handle, prefix_extractor,
+    s = FindTable(file_options, icomparator, fd, &handle, prefix_extractor,
                  options.read_tier == kBlockCacheTier /* no_io */,
                  !for_compaction /* record_read_stats */, file_read_hist,
                  skip_filters, level);
@@ -206,8 +207,8 @@ InternalIterator* TableCache::NewIterator(
      result = NewEmptyInternalIterator<Slice>(arena);
    } else {
      result = table_reader->NewIterator(options, prefix_extractor, arena,
-                                         skip_filters, caller,
-                                         env_options.compaction_readahead_size);
+                                   skip_filters, caller,
+                                   file_options.compaction_readahead_size);
    }
    if (handle != nullptr) {
      result->RegisterCleanup(&UnrefEntry, cache_, handle);
@@ -264,7 +265,7 @@ Status TableCache::GetRangeTombstoneIterator(
  TableReader* t = fd.table_reader;
  Cache::Handle* handle = nullptr;
  if (t == nullptr) {
-    s = FindTable(env_options_, internal_comparator, fd, &handle);
+    s = FindTable(file_options_, internal_comparator, fd, &handle);
    if (s.ok()) {
      t = GetTableReaderFromHandle(handle);
    }
@@ -381,7 +382,7 @@ Status TableCache::Get(const ReadOptions& options,
  if (!done && s.ok()) {
    if (t == nullptr) {
      s = FindTable(
-          env_options_, internal_comparator, fd, &handle, prefix_extractor,
+          file_options_, internal_comparator, fd, &handle, prefix_extractor,
          options.read_tier == kBlockCacheTier /* no_io */,
          true /* record_read_stats */, file_read_hist, skip_filters, level);
      if (s.ok()) {
@@ -481,7 +482,7 @@ Status TableCache::MultiGet(const ReadOptions& options,
  if (s.ok() && !table_range.empty()) {
    if (t == nullptr) {
      s = FindTable(
-          env_options_, internal_comparator, fd, &handle, prefix_extractor,
+          file_options_, internal_comparator, fd, &handle, prefix_extractor,
          options.read_tier == kBlockCacheTier /* no_io */,
          true /* record_read_stats */, file_read_hist, skip_filters, level);
      if (s.ok()) {
@@ -551,7 +552,7 @@ Status TableCache::MultiGet(const ReadOptions& options,
 }

 Status TableCache::GetTableProperties(
-    const EnvOptions& env_options,
+    const FileOptions& file_options,
    const InternalKeyComparator& internal_comparator, const FileDescriptor& fd,
    std::shared_ptr<const TableProperties>* properties,
    const SliceTransform* prefix_extractor, bool no_io) {
@@ -565,7 +566,7 @@ Status TableCache::GetTableProperties(
  }

  Cache::Handle* table_handle = nullptr;
-  s = FindTable(env_options, internal_comparator, fd, &table_handle,
+  s = FindTable(file_options, internal_comparator, fd, &table_handle,
                prefix_extractor, no_io);
  if (!s.ok()) {
    return s;
@@ -578,7 +579,7 @@ Status TableCache::GetTableProperties(
 }

 size_t TableCache::GetMemoryUsageByTableReader(
-    const EnvOptions& env_options,
+    const FileOptions& file_options,
    const InternalKeyComparator& internal_comparator, const FileDescriptor& fd,
    const SliceTransform* prefix_extractor) {
  Status s;
@@ -589,7 +590,7 @@ size_t TableCache::GetMemoryUsageByTableReader(
  }

  Cache::Handle* table_handle = nullptr;
-  s = FindTable(env_options, internal_comparator, fd, &table_handle,
+  s = FindTable(file_options, internal_comparator, fd, &table_handle,
                prefix_extractor, true);
  if (!s.ok()) {
    return 0;
@@ -614,7 +615,7 @@ uint64_t TableCache::ApproximateOffsetOf(
  Cache::Handle* table_handle = nullptr;
  if (table_reader == nullptr) {
    const bool for_compaction = (caller == TableReaderCaller::kCompaction);
-    Status s = FindTable(env_options_, internal_comparator, fd, &table_handle,
+    Status s = FindTable(file_options_, internal_comparator, fd, &table_handle,
                         prefix_extractor, false /* no_io */,
                         !for_compaction /* record_read_stats */);
    if (s.ok()) {
@@ -641,7 +642,7 @@ uint64_t TableCache::ApproximateSize(
  Cache::Handle* table_handle = nullptr;
  if (table_reader == nullptr) {
    const bool for_compaction = (caller == TableReaderCaller::kCompaction);
-    Status s = FindTable(env_options_, internal_comparator, fd, &table_handle,
+    Status s = FindTable(file_options_, internal_comparator, fd, &table_handle,
                         prefix_extractor, false /* no_io */,
                         !for_compaction /* record_read_stats */);
    if (s.ok()) {
@@ -49,7 +49,7 @@ class HistogramImpl;
 class TableCache {
 public:
  TableCache(const ImmutableCFOptions& ioptions,
-             const EnvOptions& storage_options, Cache* cache,
+             const FileOptions& storage_options, Cache* cache,
             BlockCacheTracer* const block_cache_tracer);
  ~TableCache();

@@ -67,7 +67,7 @@ class TableCache {
  // @param skip_filters Disables loading/accessing the filter block
  // @param level The level this table is at, -1 for "not set / don't know"
  InternalIterator* NewIterator(
-      const ReadOptions& options, const EnvOptions& toptions,
+      const ReadOptions& options, const FileOptions& toptions,
      const InternalKeyComparator& internal_comparator,
      const FileMetaData& file_meta, RangeDelAggregator* range_del_agg,
      const SliceTransform* prefix_extractor, TableReader** table_reader_ptr,
@@ -128,7 +128,7 @@ class TableCache {
  // Find table reader
  // @param skip_filters Disables loading/accessing the filter block
  // @param level == -1 means not specified
-  Status FindTable(const EnvOptions& toptions,
+  Status FindTable(const FileOptions& toptions,
                   const InternalKeyComparator& internal_comparator,
                   const FileDescriptor& file_fd, Cache::Handle**,
                   const SliceTransform* prefix_extractor = nullptr,
@@ -146,7 +146,7 @@ class TableCache {
  // @returns: `properties` will be reset on success. Please note that we will
  //            return Status::Incomplete() if table is not present in cache and
  //            we set `no_io` to be true.
-  Status GetTableProperties(const EnvOptions& toptions,
+  Status GetTableProperties(const FileOptions& toptions,
                            const InternalKeyComparator& internal_comparator,
                            const FileDescriptor& file_meta,
                            std::shared_ptr<const TableProperties>* properties,
@@ -156,7 +156,7 @@ class TableCache {
  // Return total memory usage of the table reader of the file.
  // 0 if table reader of the file is not loaded.
  size_t GetMemoryUsageByTableReader(
-      const EnvOptions& toptions,
+      const FileOptions& toptions,
      const InternalKeyComparator& internal_comparator,
      const FileDescriptor& fd,
      const SliceTransform* prefix_extractor = nullptr);
@@ -193,7 +193,7 @@ class TableCache {

 private:
  // Build a table reader
-  Status GetTableReader(const EnvOptions& env_options,
+  Status GetTableReader(const FileOptions& file_options,
                        const InternalKeyComparator& internal_comparator,
                        const FileDescriptor& fd, bool sequential_mode,
                        bool record_read_stats, HistogramImpl* file_read_hist,
@@ -216,7 +216,7 @@ class TableCache {
                       size_t prefix_size, GetContext* get_context);

  const ImmutableCFOptions& ioptions_;
-  const EnvOptions& env_options_;
+  const FileOptions& file_options_;
  Cache* const cache_;
  std::string row_cache_id_;
  bool immortal_tables_;
@@ -12,6 +12,7 @@
 #include "db/db_impl/db_impl.h"
 #include "db/dbformat.h"
 #include "db/table_properties_collector.h"
+#include "env/composite_env_wrapper.h"
 #include "file/sequence_file_reader.h"
 #include "file/writable_file_writer.h"
 #include "options/cf_options.h"
@@ -48,7 +49,8 @@ void MakeBuilder(const Options& options, const ImmutableCFOptions& ioptions,
                 std::unique_ptr<TableBuilder>* builder) {
  std::unique_ptr<WritableFile> wf(new test::StringSink);
  writable->reset(
-      new WritableFileWriter(std::move(wf), "" /* don't care */, EnvOptions()));
+      new WritableFileWriter(NewLegacyWritableFileWrapper(std::move(wf)),
+                             "" /* don't care */, EnvOptions()));
  int unknown_level = -1;
  builder->reset(NewTableBuilder(
      ioptions, moptions, internal_comparator, int_tbl_prop_collector_factories,
@@ -282,8 +284,9 @@ void TestCustomizedTablePropertiesCollector(
  writer->Flush();

  // -- Step 2: Read properties
-  test::StringSink* fwf =
-      static_cast<test::StringSink*>(writer->writable_file());
+  LegacyWritableFileWrapper* file =
+      static_cast<LegacyWritableFileWrapper*>(writer->writable_file());
+  test::StringSink* fwf = static_cast<test::StringSink*>(file->target());
  std::unique_ptr<RandomAccessFileReader> fake_file_reader(
      test::GetRandomAccessFileReader(
          new test::StringSource(fwf->contents())));
@@ -422,8 +425,9 @@ void TestInternalKeyPropertiesCollector(
    ASSERT_OK(builder->Finish());
    writable->Flush();

-    test::StringSink* fwf =
-        static_cast<test::StringSink*>(writable->writable_file());
+    LegacyWritableFileWrapper* file =
+        static_cast<LegacyWritableFileWrapper*>(writable->writable_file());
+    test::StringSink* fwf = static_cast<test::StringSink*>(file->target());
    std::unique_ptr<RandomAccessFileReader> reader(
        test::GetRandomAccessFileReader(
            new test::StringSource(fwf->contents())));
@@ -42,22 +42,23 @@ TransactionLogIteratorImpl::TransactionLogIteratorImpl(
 Status TransactionLogIteratorImpl::OpenLogFile(
    const LogFile* log_file,
    std::unique_ptr<SequentialFileReader>* file_reader) {
-  Env* env = options_->env;
-  std::unique_ptr<SequentialFile> file;
+  FileSystem* fs = options_->fs.get();
+  std::unique_ptr<FSSequentialFile> file;
  std::string fname;
  Status s;
-  EnvOptions optimized_env_options = env->OptimizeForLogRead(soptions_);
+  EnvOptions optimized_env_options = fs->OptimizeForLogRead(soptions_);
  if (log_file->Type() == kArchivedLogFile) {
    fname = ArchivedLogFileName(dir_, log_file->LogNumber());
-    s = env->NewSequentialFile(fname, &file, optimized_env_options);
+    s = fs->NewSequentialFile(fname, optimized_env_options, &file, nullptr);
  } else {
    fname = LogFileName(dir_, log_file->LogNumber());
-    s = env->NewSequentialFile(fname, &file, optimized_env_options);
+    s = fs->NewSequentialFile(fname, optimized_env_options, &file, nullptr);
    if (!s.ok()) {
      //  If cannot open file in DB directory.
      //  Try the archive dir, as it could have moved in the meanwhile.
      fname = ArchivedLogFileName(dir_, log_file->LogNumber());
-      s = env->NewSequentialFile(fname, &file, optimized_env_options);
+      s = fs->NewSequentialFile(fname, optimized_env_options,
+                                &file, nullptr);
    }
  }
  if (s.ok()) {
@@ -34,10 +34,7 @@ ColumnFamilyData* TrimHistoryScheduler::TakeNextColumnFamily() {
      // success
      return cfd;
    }
-    if (cfd->Unref()) {
-      // no longer relevant, retry
-      delete cfd;
-    }
+    cfd->UnrefAndTryDelete();
  }
 }

@@ -49,9 +46,7 @@ bool TrimHistoryScheduler::Empty() {
 void TrimHistoryScheduler::Clear() {
  ColumnFamilyData* cfd;
  while ((cfd = TakeNextColumnFamily()) != nullptr) {
-    if (cfd->Unref()) {
-      delete cfd;
-    }
+    cfd->UnrefAndTryDelete();
  }
  assert(Empty());
 }
@@ -83,7 +83,7 @@ class VersionBuilder::Rep {
    std::unordered_map<uint64_t, FileMetaData*> added_files;
  };

-  const EnvOptions& env_options_;
+  const FileOptions& file_options_;
  Logger* info_log_;
  TableCache* table_cache_;
  VersionStorageInfo* base_vstorage_;
@@ -101,9 +101,10 @@ class VersionBuilder::Rep {
  FileComparator level_nonzero_cmp_;

 public:
-  Rep(const EnvOptions& env_options, Logger* info_log, TableCache* table_cache,
+  Rep(const FileOptions& file_options, Logger* info_log,
+      TableCache* table_cache,
      VersionStorageInfo* base_vstorage)
-      : env_options_(env_options),
+      : file_options_(file_options),
        info_log_(info_log),
        table_cache_(table_cache),
        base_vstorage_(base_vstorage),
@@ -461,7 +462,7 @@ class VersionBuilder::Rep {
        auto* file_meta = files_meta[file_idx].first;
        int level = files_meta[file_idx].second;
        statuses[file_idx] = table_cache_->FindTable(
-            env_options_, *(base_vstorage_->InternalComparator()),
+            file_options_, *(base_vstorage_->InternalComparator()),
            file_meta->fd, &file_meta->table_reader_handle, prefix_extractor,
            false /*no_io */, true /* record_read_stats */,
            internal_stats->GetFileReadHist(level), false, level,
@@ -500,11 +501,11 @@ class VersionBuilder::Rep {
  }
 };

-VersionBuilder::VersionBuilder(const EnvOptions& env_options,
+VersionBuilder::VersionBuilder(const FileOptions& file_options,
                               TableCache* table_cache,
                               VersionStorageInfo* base_vstorage,
                               Logger* info_log)
-    : rep_(new Rep(env_options, info_log, table_cache, base_vstorage)) {}
+    : rep_(new Rep(file_options, info_log, table_cache, base_vstorage)) {}

 VersionBuilder::~VersionBuilder() { delete rep_; }

@@ -8,7 +8,7 @@
 // found in the LICENSE file. See the AUTHORS file for names of contributors.
 //
 #pragma once
-#include "rocksdb/env.h"
+#include "rocksdb/file_system.h"
 #include "rocksdb/slice_transform.h"

 namespace rocksdb {
@@ -24,7 +24,7 @@ class InternalStats;
 // Versions that contain full copies of the intermediate state.
 class VersionBuilder {
 public:
-  VersionBuilder(const EnvOptions& env_options, TableCache* table_cache,
+  VersionBuilder(const FileOptions& file_options, TableCache* table_cache,
                 VersionStorageInfo* base_vstorage, Logger* info_log = nullptr);
  ~VersionBuilder();
  Status CheckConsistency(VersionStorageInfo* vstorage);
@@ -63,7 +63,7 @@ class VersionBuilderTest : public testing::Test {
        file_number, path_id, file_size, GetInternalKey(smallest, smallest_seq),
        GetInternalKey(largest, largest_seq), smallest_seqno, largest_seqno,
        /* marked_for_compact */ false, kInvalidBlobFileNumber,
-        kUnknownOldestAncesterTime);
+        kUnknownOldestAncesterTime, kUnknownFileCreationTime);
    f->compensated_file_size = file_size;
    f->num_entries = num_entries;
    f->num_deletions = num_deletions;
@@ -114,7 +114,8 @@ TEST_F(VersionBuilderTest, ApplyAndSaveTo) {
  VersionEdit version_edit;
  version_edit.AddFile(2, 666, 0, 100U, GetInternalKey("301"),
                       GetInternalKey("350"), 200, 200, false,
-                       kInvalidBlobFileNumber, kUnknownOldestAncesterTime);
+                       kInvalidBlobFileNumber, kUnknownOldestAncesterTime,
+                       kUnknownFileCreationTime);
  version_edit.DeleteFile(3, 27U);

  EnvOptions env_options;
@@ -149,7 +150,8 @@ TEST_F(VersionBuilderTest, ApplyAndSaveToDynamic) {
  VersionEdit version_edit;
  version_edit.AddFile(3, 666, 0, 100U, GetInternalKey("301"),
                       GetInternalKey("350"), 200, 200, false,
-                       kInvalidBlobFileNumber, kUnknownOldestAncesterTime);
+                       kInvalidBlobFileNumber, kUnknownOldestAncesterTime,
+                       kUnknownFileCreationTime);
  version_edit.DeleteFile(0, 1U);
  version_edit.DeleteFile(0, 88U);

@@ -187,7 +189,8 @@ TEST_F(VersionBuilderTest, ApplyAndSaveToDynamic2) {
  VersionEdit version_edit;
  version_edit.AddFile(4, 666, 0, 100U, GetInternalKey("301"),
                       GetInternalKey("350"), 200, 200, false,
-                       kInvalidBlobFileNumber, kUnknownOldestAncesterTime);
+                       kInvalidBlobFileNumber, kUnknownOldestAncesterTime,
+                       kUnknownFileCreationTime);
  version_edit.DeleteFile(0, 1U);
  version_edit.DeleteFile(0, 88U);
  version_edit.DeleteFile(4, 6U);
@@ -216,19 +219,24 @@ TEST_F(VersionBuilderTest, ApplyMultipleAndSaveTo) {
  VersionEdit version_edit;
  version_edit.AddFile(2, 666, 0, 100U, GetInternalKey("301"),
                       GetInternalKey("350"), 200, 200, false,
-                       kInvalidBlobFileNumber, kUnknownOldestAncesterTime);
+                       kInvalidBlobFileNumber, kUnknownOldestAncesterTime,
+                       kUnknownFileCreationTime);
  version_edit.AddFile(2, 676, 0, 100U, GetInternalKey("401"),
                       GetInternalKey("450"), 200, 200, false,
-                       kInvalidBlobFileNumber, kUnknownOldestAncesterTime);
+                       kInvalidBlobFileNumber, kUnknownOldestAncesterTime,
+                       kUnknownFileCreationTime);
  version_edit.AddFile(2, 636, 0, 100U, GetInternalKey("601"),
                       GetInternalKey("650"), 200, 200, false,
-                       kInvalidBlobFileNumber, kUnknownOldestAncesterTime);
+                       kInvalidBlobFileNumber, kUnknownOldestAncesterTime,
+                       kUnknownFileCreationTime);
  version_edit.AddFile(2, 616, 0, 100U, GetInternalKey("501"),
                       GetInternalKey("550"), 200, 200, false,
-                       kInvalidBlobFileNumber, kUnknownOldestAncesterTime);
+                       kInvalidBlobFileNumber, kUnknownOldestAncesterTime,
+                       kUnknownFileCreationTime);
  version_edit.AddFile(2, 606, 0, 100U, GetInternalKey("701"),
                       GetInternalKey("750"), 200, 200, false,
-                       kInvalidBlobFileNumber, kUnknownOldestAncesterTime);
+                       kInvalidBlobFileNumber, kUnknownOldestAncesterTime,
+                       kUnknownFileCreationTime);

  EnvOptions env_options;

@@ -255,30 +263,37 @@ TEST_F(VersionBuilderTest, ApplyDeleteAndSaveTo) {
  VersionEdit version_edit;
  version_edit.AddFile(2, 666, 0, 100U, GetInternalKey("301"),
                       GetInternalKey("350"), 200, 200, false,
-                       kInvalidBlobFileNumber, kUnknownOldestAncesterTime);
+                       kInvalidBlobFileNumber, kUnknownOldestAncesterTime,
+                       kUnknownFileCreationTime);
  version_edit.AddFile(2, 676, 0, 100U, GetInternalKey("401"),
                       GetInternalKey("450"), 200, 200, false,
-                       kInvalidBlobFileNumber, kUnknownOldestAncesterTime);
+                       kInvalidBlobFileNumber, kUnknownOldestAncesterTime,
+                       kUnknownFileCreationTime);
  version_edit.AddFile(2, 636, 0, 100U, GetInternalKey("601"),
                       GetInternalKey("650"), 200, 200, false,
-                       kInvalidBlobFileNumber, kUnknownOldestAncesterTime);
+                       kInvalidBlobFileNumber, kUnknownOldestAncesterTime,
+                       kUnknownFileCreationTime);
  version_edit.AddFile(2, 616, 0, 100U, GetInternalKey("501"),
                       GetInternalKey("550"), 200, 200, false,
-                       kInvalidBlobFileNumber, kUnknownOldestAncesterTime);
+                       kInvalidBlobFileNumber, kUnknownOldestAncesterTime,
+                       kUnknownFileCreationTime);
  version_edit.AddFile(2, 606, 0, 100U, GetInternalKey("701"),
                       GetInternalKey("750"), 200, 200, false,
-                       kInvalidBlobFileNumber, kUnknownOldestAncesterTime);
+                       kInvalidBlobFileNumber, kUnknownOldestAncesterTime,
+                       kUnknownFileCreationTime);
  version_builder.Apply(&version_edit);

  VersionEdit version_edit2;
  version_edit.AddFile(2, 808, 0, 100U, GetInternalKey("901"),
                       GetInternalKey("950"), 200, 200, false,
-                       kInvalidBlobFileNumber, kUnknownOldestAncesterTime);
+                       kInvalidBlobFileNumber, kUnknownOldestAncesterTime,
+                       kUnknownFileCreationTime);
  version_edit2.DeleteFile(2, 616);
  version_edit2.DeleteFile(2, 636);
  version_edit.AddFile(2, 806, 0, 100U, GetInternalKey("801"),
                       GetInternalKey("850"), 200, 200, false,
-                       kInvalidBlobFileNumber, kUnknownOldestAncesterTime);
+                       kInvalidBlobFileNumber, kUnknownOldestAncesterTime,
+                       kUnknownFileCreationTime);
  version_builder.Apply(&version_edit2);

  version_builder.SaveTo(&new_vstorage);
@@ -62,6 +62,7 @@ enum CustomTag : uint32_t {
  kMinLogNumberToKeepHack = 3,
  kOldestBlobFileNumber = 4,
  kOldestAncesterTime = 5,
+  kFileCreationTime = 6,
  kPathId = 65,
 };
 // If this bit for the custom tag is set, opening DB should fail if
@@ -217,6 +218,14 @@ bool VersionEdit::EncodeTo(std::string* dst) const {
    TEST_SYNC_POINT_CALLBACK("VersionEdit::EncodeTo:VarintOldestAncesterTime",
                             &varint_oldest_ancester_time);
    PutLengthPrefixedSlice(dst, Slice(varint_oldest_ancester_time));
+
+    PutVarint32(dst, CustomTag::kFileCreationTime);
+    std::string varint_file_creation_time;
+    PutVarint64(&varint_file_creation_time, f.file_creation_time);
+    TEST_SYNC_POINT_CALLBACK("VersionEdit::EncodeTo:VarintFileCreationTime",
+                             &varint_file_creation_time);
+    PutLengthPrefixedSlice(dst, Slice(varint_file_creation_time));
+
    if (f.fd.GetPathId() != 0) {
      PutVarint32(dst, CustomTag::kPathId);
      char p = static_cast<char>(f.fd.GetPathId());
@@ -335,6 +344,11 @@ const char* VersionEdit::DecodeNewFile4From(Slice* input) {
            return "invalid oldest ancester time";
          }
          break;
+        case kFileCreationTime:
+          if (!GetVarint64(&field, &f.file_creation_time)) {
+            return "invalid file creation time";
+          }
+          break;
        case kNeedCompaction:
          if (field.size() != 1) {
            return "need_compaction field wrong size";
@@ -660,6 +674,8 @@ std::string VersionEdit::DebugString(bool hex_key) const {
    }
    r.append(" oldest_ancester_time:");
    AppendNumberTo(&r, f.oldest_ancester_time);
+    r.append(" file_creation_time:");
+    AppendNumberTo(&r, f.file_creation_time);
  }
  r.append("\n  ColumnFamily: ");
  AppendNumberTo(&r, column_family_);
@@ -26,6 +26,7 @@ class VersionSet;
 constexpr uint64_t kFileNumberMask = 0x3FFFFFFFFFFFFFFF;
 constexpr uint64_t kInvalidBlobFileNumber = 0;
 constexpr uint64_t kUnknownOldestAncesterTime = 0;
+constexpr uint64_t kUnknownFileCreationTime = 0;

 extern uint64_t PackFileNumberAndPathId(uint64_t number, uint64_t path_id);

@@ -128,7 +129,10 @@ struct FileMetaData {
  // in turn be outputs for compact older SST files. We track the memtable
  // flush timestamp for the oldest SST file that eventaully contribute data
  // to this file. 0 means the information is not available.
-  uint64_t oldest_ancester_time = 0;
+  uint64_t oldest_ancester_time = kUnknownOldestAncesterTime;
+
+  // Unix time when the SST file is created.
+  uint64_t file_creation_time = kUnknownFileCreationTime;

  FileMetaData() = default;

@@ -136,13 +140,17 @@ struct FileMetaData {
               const InternalKey& smallest_key, const InternalKey& largest_key,
               const SequenceNumber& smallest_seq,
               const SequenceNumber& largest_seq, bool marked_for_compact,
-               uint64_t oldest_blob_file, uint64_t _oldest_ancester_time)
+               uint64_t oldest_blob_file, uint64_t _oldest_ancester_time,
+               uint64_t _file_creation_time)
      : fd(file, file_path_id, file_size, smallest_seq, largest_seq),
        smallest(smallest_key),
        largest(largest_key),
        marked_for_compaction(marked_for_compact),
        oldest_blob_file_number(oldest_blob_file),
-        oldest_ancester_time(_oldest_ancester_time) {}
+        oldest_ancester_time(_oldest_ancester_time),
+        file_creation_time(_file_creation_time) {
+    TEST_SYNC_POINT_CALLBACK("FileMetaData::FileMetaData", this);
+  }

  // REQUIRED: Keys must be given to the function in sorted order (it expects
  // the last key to be the largest).
@@ -168,13 +176,23 @@ struct FileMetaData {
  // if table reader is already pinned.
  // 0 means the information is not available.
  uint64_t TryGetOldestAncesterTime() {
-    if (oldest_ancester_time != 0) {
+    if (oldest_ancester_time != kUnknownOldestAncesterTime) {
      return oldest_ancester_time;
    } else if (fd.table_reader != nullptr &&
               fd.table_reader->GetTableProperties() != nullptr) {
      return fd.table_reader->GetTableProperties()->creation_time;
    }
-    return 0;
+    return kUnknownOldestAncesterTime;
+  }
+
+  uint64_t TryGetFileCreationTime() {
+    if (file_creation_time != kUnknownFileCreationTime) {
+      return file_creation_time;
+    } else if (fd.table_reader != nullptr &&
+               fd.table_reader->GetTableProperties() != nullptr) {
+      return fd.table_reader->GetTableProperties()->file_creation_time;
+    }
+    return kUnknownFileCreationTime;
  }
 };

@@ -277,14 +295,14 @@ class VersionEdit {
               uint64_t file_size, const InternalKey& smallest,
               const InternalKey& largest, const SequenceNumber& smallest_seqno,
               const SequenceNumber& largest_seqno, bool marked_for_compaction,
-               uint64_t oldest_blob_file_number,
-               uint64_t oldest_ancester_time) {
+               uint64_t oldest_blob_file_number, uint64_t oldest_ancester_time,
+               uint64_t file_creation_time) {
    assert(smallest_seqno <= largest_seqno);
    new_files_.emplace_back(
-        level,
-        FileMetaData(file, file_path_id, file_size, smallest, largest,
-                     smallest_seqno, largest_seqno, marked_for_compaction,
-                     oldest_blob_file_number, oldest_ancester_time));
+        level, FileMetaData(file, file_path_id, file_size, smallest, largest,
+                            smallest_seqno, largest_seqno,
+                            marked_for_compaction, oldest_blob_file_number,
+                            oldest_ancester_time, file_creation_time));
  }

  void AddFile(int level, const FileMetaData& f) {
@@ -37,7 +37,7 @@ TEST_F(VersionEditTest, EncodeDecode) {
                 InternalKey("foo", kBig + 500 + i, kTypeValue),
                 InternalKey("zoo", kBig + 600 + i, kTypeDeletion),
                 kBig + 500 + i, kBig + 600 + i, false, kInvalidBlobFileNumber,
-                 888);
+                 888, 678);
    edit.DeleteFile(4, kBig + 700 + i);
  }

@@ -55,17 +55,19 @@ TEST_F(VersionEditTest, EncodeDecodeNewFile4) {
  edit.AddFile(3, 300, 3, 100, InternalKey("foo", kBig + 500, kTypeValue),
               InternalKey("zoo", kBig + 600, kTypeDeletion), kBig + 500,
               kBig + 600, true, kInvalidBlobFileNumber,
-               kUnknownOldestAncesterTime);
+               kUnknownOldestAncesterTime, kUnknownFileCreationTime);
  edit.AddFile(4, 301, 3, 100, InternalKey("foo", kBig + 501, kTypeValue),
               InternalKey("zoo", kBig + 601, kTypeDeletion), kBig + 501,
               kBig + 601, false, kInvalidBlobFileNumber,
-               kUnknownOldestAncesterTime);
+               kUnknownOldestAncesterTime, kUnknownFileCreationTime);
  edit.AddFile(5, 302, 0, 100, InternalKey("foo", kBig + 502, kTypeValue),
               InternalKey("zoo", kBig + 602, kTypeDeletion), kBig + 502,
-               kBig + 602, true, kInvalidBlobFileNumber, 666);
+               kBig + 602, true, kInvalidBlobFileNumber, 666, 888);
  edit.AddFile(5, 303, 0, 100, InternalKey("foo", kBig + 503, kTypeBlobIndex),
               InternalKey("zoo", kBig + 603, kTypeBlobIndex), kBig + 503,
-               kBig + 603, true, 1001, kUnknownOldestAncesterTime);
+               kBig + 603, true, 1001, kUnknownOldestAncesterTime,
+               kUnknownFileCreationTime);
+  ;

  edit.DeleteFile(4, 700);

@@ -104,10 +106,10 @@ TEST_F(VersionEditTest, ForwardCompatibleNewFile4) {
  edit.AddFile(3, 300, 3, 100, InternalKey("foo", kBig + 500, kTypeValue),
               InternalKey("zoo", kBig + 600, kTypeDeletion), kBig + 500,
               kBig + 600, true, kInvalidBlobFileNumber,
-               kUnknownOldestAncesterTime);
+               kUnknownOldestAncesterTime, kUnknownFileCreationTime);
  edit.AddFile(4, 301, 3, 100, InternalKey("foo", kBig + 501, kTypeValue),
               InternalKey("zoo", kBig + 601, kTypeDeletion), kBig + 501,
-               kBig + 601, false, kInvalidBlobFileNumber, 686);
+               kBig + 601, false, kInvalidBlobFileNumber, 686, 868);
  edit.DeleteFile(4, 700);

  edit.SetComparatorName("foo");
@@ -154,7 +156,7 @@ TEST_F(VersionEditTest, NewFile4NotSupportedField) {
  edit.AddFile(3, 300, 3, 100, InternalKey("foo", kBig + 500, kTypeValue),
               InternalKey("zoo", kBig + 600, kTypeDeletion), kBig + 500,
               kBig + 600, true, kInvalidBlobFileNumber,
-               kUnknownOldestAncesterTime);
+               kUnknownOldestAncesterTime, kUnknownFileCreationTime);

  edit.SetComparatorName("foo");
  edit.SetLogNumber(kBig + 100);
@@ -182,7 +184,8 @@ TEST_F(VersionEditTest, NewFile4NotSupportedField) {
 TEST_F(VersionEditTest, EncodeEmptyFile) {
  VersionEdit edit;
  edit.AddFile(0, 0, 0, 0, InternalKey(), InternalKey(), 0, 0, false,
-               kInvalidBlobFileNumber, kUnknownOldestAncesterTime);
+               kInvalidBlobFileNumber, kUnknownOldestAncesterTime,
+               kUnknownFileCreationTime);
  std::string buffer;
  ASSERT_TRUE(!edit.EncodeTo(&buffer));
 }
@@ -853,7 +853,7 @@ namespace {
 class LevelIterator final : public InternalIterator {
 public:
  LevelIterator(TableCache* table_cache, const ReadOptions& read_options,
-                const EnvOptions& env_options,
+                const FileOptions& file_options,
                const InternalKeyComparator& icomparator,
                const LevelFilesBrief* flevel,
                const SliceTransform* prefix_extractor, bool should_sample,
@@ -863,7 +863,7 @@ class LevelIterator final : public InternalIterator {
                    compaction_boundaries = nullptr)
      : table_cache_(table_cache),
        read_options_(read_options),
-        env_options_(env_options),
+        file_options_(file_options),
        icomparator_(icomparator),
        user_comparator_(icomparator.user_comparator()),
        flevel_(flevel),
@@ -975,7 +975,7 @@ class LevelIterator final : public InternalIterator {
    }
    CheckMayBeOutOfLowerBound();
    return table_cache_->NewIterator(
-        read_options_, env_options_, icomparator_, *file_meta.file_metadata,
+        read_options_, file_options_, icomparator_, *file_meta.file_metadata,
        range_del_agg_, prefix_extractor_,
        nullptr /* don't need reference to table */, file_read_hist_, caller_,
        /*arena=*/nullptr, skip_filters_, level_, smallest_compaction_key,
@@ -998,7 +998,7 @@ class LevelIterator final : public InternalIterator {

  TableCache* table_cache_;
  const ReadOptions read_options_;
-  const EnvOptions& env_options_;
+  const FileOptions& file_options_;
  const InternalKeyComparator& icomparator_;
  const UserComparatorWrapper user_comparator_;
  const LevelFilesBrief* flevel_;
@@ -1206,7 +1206,7 @@ class BaseReferencedVersionBuilder {
 public:
  explicit BaseReferencedVersionBuilder(ColumnFamilyData* cfd)
      : version_builder_(new VersionBuilder(
-            cfd->current()->version_set()->env_options(), cfd->table_cache(),
+            cfd->current()->version_set()->file_options(), cfd->table_cache(),
            cfd->current()->storage_info(), cfd->ioptions()->info_log)),
        version_(cfd->current()) {
    version_->Ref();
@@ -1227,7 +1227,7 @@ Status Version::GetTableProperties(std::shared_ptr<const TableProperties>* tp,
  auto table_cache = cfd_->table_cache();
  auto ioptions = cfd_->ioptions();
  Status s = table_cache->GetTableProperties(
-      env_options_, cfd_->internal_comparator(), file_meta->fd, tp,
+      file_options_, cfd_->internal_comparator(), file_meta->fd, tp,
      mutable_cf_options_.prefix_extractor.get(), true /* no io */);
  if (s.ok()) {
    return s;
@@ -1241,7 +1241,7 @@ Status Version::GetTableProperties(std::shared_ptr<const TableProperties>* tp,

  // 2. Table is not present in table cache, we'll read the table properties
  // directly from the properties block in the file.
-  std::unique_ptr<RandomAccessFile> file;
+  std::unique_ptr<FSRandomAccessFile> file;
  std::string file_name;
  if (fname != nullptr) {
    file_name = *fname;
@@ -1250,7 +1250,8 @@ Status Version::GetTableProperties(std::shared_ptr<const TableProperties>* tp,
      TableFileName(ioptions->cf_paths, file_meta->fd.GetNumber(),
                    file_meta->fd.GetPathId());
  }
-  s = ioptions->env->NewRandomAccessFile(file_name, &file, env_options_);
+  s = ioptions->fs->NewRandomAccessFile(file_name, file_options_, &file,
+                                        nullptr);
  if (!s.ok()) {
    return s;
  }
@@ -1420,7 +1421,7 @@ size_t Version::GetMemoryUsageByTableReaders() {
  for (auto& file_level : storage_info_.level_files_brief_) {
    for (size_t i = 0; i < file_level.num_files; i++) {
      total_usage += cfd_->table_cache()->GetMemoryUsageByTableReader(
-          env_options_, cfd_->internal_comparator(), file_level.files[i].fd,
+          file_options_, cfd_->internal_comparator(), file_level.files[i].fd,
          mutable_cf_options_.prefix_extractor.get());
    }
  }
@@ -1459,7 +1460,8 @@ void Version::GetColumnFamilyMetaData(ColumnFamilyMetaData* cf_meta) {
          file->fd.largest_seqno, file->smallest.user_key().ToString(),
          file->largest.user_key().ToString(),
          file->stats.num_reads_sampled.load(std::memory_order_relaxed),
-          file->being_compacted, file->oldest_blob_file_number});
+          file->being_compacted, file->oldest_blob_file_number,
+          file->TryGetOldestAncesterTime(), file->TryGetFileCreationTime()});
      files.back().num_entries = file->num_entries;
      files.back().num_deletions = file->num_deletions;
      level_size += file->fd.GetFileSize();
@@ -1485,10 +1487,9 @@ void Version::GetCreationTimeOfOldestFile(uint64_t* creation_time) {
  for (int level = 0; level < storage_info_.num_non_empty_levels_; level++) {
    for (FileMetaData* meta : storage_info_.LevelFiles(level)) {
      assert(meta->fd.table_reader != nullptr);
-      uint64_t file_creation_time =
-          meta->fd.table_reader->GetTableProperties()->file_creation_time;
-      if (file_creation_time == 0) {
-        *creation_time = file_creation_time;
+      uint64_t file_creation_time = meta->TryGetFileCreationTime();
+      if (file_creation_time == kUnknownFileCreationTime) {
+        *creation_time = 0;
        return;
      }
      if (file_creation_time < oldest_time) {
@@ -1547,7 +1548,7 @@ double VersionStorageInfo::GetEstimatedCompressionRatioAtLevel(
 }

 void Version::AddIterators(const ReadOptions& read_options,
-                           const EnvOptions& soptions,
+                           const FileOptions& soptions,
                           MergeIteratorBuilder* merge_iter_builder,
                           RangeDelAggregator* range_del_agg) {
  assert(storage_info_.finalized_);
@@ -1559,7 +1560,7 @@ void Version::AddIterators(const ReadOptions& read_options,
 }

 void Version::AddIteratorsForLevel(const ReadOptions& read_options,
-                                   const EnvOptions& soptions,
+                                   const FileOptions& soptions,
                                   MergeIteratorBuilder* merge_iter_builder,
                                   int level,
                                   RangeDelAggregator* range_del_agg) {
@@ -1614,7 +1615,7 @@ void Version::AddIteratorsForLevel(const ReadOptions& read_options,
 }

 Status Version::OverlapWithLevelIterator(const ReadOptions& read_options,
-                                         const EnvOptions& env_options,
+                                         const FileOptions& file_options,
                                         const Slice& smallest_user_key,
                                         const Slice& largest_user_key,
                                         int level, bool* overlap) {
@@ -1638,7 +1639,7 @@ Status Version::OverlapWithLevelIterator(const ReadOptions& read_options,
        continue;
      }
      ScopedArenaIterator iter(cfd_->table_cache()->NewIterator(
-          read_options, env_options, cfd_->internal_comparator(),
+          read_options, file_options, cfd_->internal_comparator(),
          *file->file_metadata, &range_del_agg,
          mutable_cf_options_.prefix_extractor.get(), nullptr,
          cfd_->internal_stats()->GetFileReadHist(0),
@@ -1655,7 +1656,7 @@ Status Version::OverlapWithLevelIterator(const ReadOptions& read_options,
  } else if (storage_info_.LevelFilesBrief(level).num_files > 0) {
    auto mem = arena.AllocateAligned(sizeof(LevelIterator));
    ScopedArenaIterator iter(new (mem) LevelIterator(
-        cfd_->table_cache(), read_options, env_options,
+        cfd_->table_cache(), read_options, file_options,
        cfd_->internal_comparator(), &storage_info_.LevelFilesBrief(level),
        mutable_cf_options_.prefix_extractor.get(), should_sample_file_read(),
        cfd_->internal_stats()->GetFileReadHist(level),
@@ -1719,7 +1720,7 @@ VersionStorageInfo::VersionStorageInfo(
 }

 Version::Version(ColumnFamilyData* column_family_data, VersionSet* vset,
-                 const EnvOptions& env_opt,
+                 const FileOptions& file_opt,
                 const MutableCFOptions mutable_cf_options,
                 uint64_t version_number)
    : env_(vset->env_),
@@ -1744,7 +1745,7 @@ Version::Version(ColumnFamilyData* column_family_data, VersionSet* vset,
      next_(this),
      prev_(this),
      refs_(0),
-      env_options_(env_opt),
+      file_options_(file_opt),
      mutable_cf_options_(mutable_cf_options),
      version_number_(version_number) {}

@@ -2501,8 +2502,7 @@ void VersionStorageInfo::ComputeExpiredTtlFiles(
 void VersionStorageInfo::ComputeFilesMarkedForPeriodicCompaction(
    const ImmutableCFOptions& ioptions,
    const uint64_t periodic_compaction_seconds) {
-  assert(periodic_compaction_seconds > 0 &&
-      periodic_compaction_seconds < port::kMaxUint64);
+  assert(periodic_compaction_seconds > 0);

  files_marked_for_periodic_compaction_.clear();

@@ -2513,8 +2513,8 @@ void VersionStorageInfo::ComputeFilesMarkedForPeriodicCompaction(
  }
  const uint64_t current_time = static_cast<uint64_t>(temp_current_time);

-  // If periodic_compaction_seconds > current_time, no file possibly qualifies
-  // periodic compaction.
+  // If periodic_compaction_seconds is larger than current time, periodic
+  // compaction can't possibly be triggered.
  if (periodic_compaction_seconds > current_time) {
    return;
  }
@@ -2524,20 +2524,18 @@ void VersionStorageInfo::ComputeFilesMarkedForPeriodicCompaction(

  for (int level = 0; level < num_levels(); level++) {
    for (auto f : files_[level]) {
-      if (!f->being_compacted && f->fd.table_reader != nullptr &&
-          f->fd.table_reader->GetTableProperties() != nullptr) {
+      if (!f->being_compacted) {
        // Compute a file's modification time in the following order:
        // 1. Use file_creation_time table property if it is > 0.
        // 2. Use creation_time table property if it is > 0.
        // 3. Use file's mtime metadata if the above two table properties are 0.
        // Don't consider the file at all if the modification time cannot be
        // correctly determined based on the above conditions.
-        uint64_t file_modification_time =
-            f->fd.table_reader->GetTableProperties()->file_creation_time;
-        if (file_modification_time == 0) {
+        uint64_t file_modification_time = f->TryGetFileCreationTime();
+        if (file_modification_time == kUnknownFileCreationTime) {
          file_modification_time = f->TryGetOldestAncesterTime();
        }
-        if (file_modification_time == 0) {
+        if (file_modification_time == kUnknownOldestAncesterTime) {
          auto file_path = TableFileName(ioptions.cf_paths, f->fd.GetNumber(),
                                         f->fd.GetPathId());
          status = ioptions.env->GetFileModificationTime(
@@ -3512,7 +3510,7 @@ void AtomicGroupReadBuffer::Clear() {

 VersionSet::VersionSet(const std::string& dbname,
                       const ImmutableDBOptions* _db_options,
-                       const EnvOptions& storage_options, Cache* table_cache,
+                       const FileOptions& storage_options, Cache* table_cache,
                       WriteBufferManager* write_buffer_manager,
                       WriteController* write_controller,
                       BlockCacheTracer* const block_cache_tracer)
@@ -3520,6 +3518,7 @@ VersionSet::VersionSet(const std::string& dbname,
          dbname, _db_options, storage_options, table_cache,
          write_buffer_manager, write_controller, block_cache_tracer)),
      env_(_db_options->env),
+      fs_(_db_options->fs.get()),
      dbname_(dbname),
      db_options_(_db_options),
      next_file_number_(2),
@@ -3532,7 +3531,7 @@ VersionSet::VersionSet(const std::string& dbname,
      prev_log_number_(0),
      current_version_number_(0),
      manifest_file_size_(0),
-      env_options_(storage_options),
+      file_options_(storage_options),
      block_cache_tracer_(block_cache_tracer) {}

 VersionSet::~VersionSet() {
@@ -3658,7 +3657,7 @@ Status VersionSet::ProcessManifestWrites(
        }
      }
      if (version == nullptr) {
-        version = new Version(last_writer->cfd, this, env_options_,
+        version = new Version(last_writer->cfd, this, file_options_,
                              last_writer->mutable_cf_options,
                              current_version_number_++);
        versions.push_back(version);
@@ -3754,6 +3753,10 @@ Status VersionSet::ProcessManifestWrites(
    pending_manifest_file_number_ = manifest_file_number_;
  }

+  // Local cached copy of state variable(s). WriteCurrentStateToManifest()
+  // reads its content after releasing db mutex to avoid race with
+  // SwitchMemtable().
+  std::unordered_map<uint32_t, MutableCFState> curr_state;
  if (new_descriptor_log) {
    // if we are writing out new snapshot make sure to persist max column
    // family.
@@ -3761,10 +3764,14 @@ Status VersionSet::ProcessManifestWrites(
      first_writer.edit_list.front()->SetMaxColumnFamily(
          column_family_set_->GetMaxColumnFamily());
    }
+    for (const auto* cfd : *column_family_set_) {
+      assert(curr_state.find(cfd->GetID()) == curr_state.end());
+      curr_state[cfd->GetID()] = {cfd->GetLogNumber()};
+    }
  }

  {
-    EnvOptions opt_env_opts = env_->OptimizeForManifestWrite(env_options_);
+    FileOptions opt_file_opts = fs_->OptimizeForManifestWrite(file_options_);
    mu->Unlock();

    TEST_SYNC_POINT("VersionSet::LogAndApply:WriteManifest");
@@ -3791,19 +3798,19 @@ Status VersionSet::ProcessManifestWrites(
                     pending_manifest_file_number_);
      std::string descriptor_fname =
          DescriptorFileName(dbname_, pending_manifest_file_number_);
-      std::unique_ptr<WritableFile> descriptor_file;
-      s = NewWritableFile(env_, descriptor_fname, &descriptor_file,
-                          opt_env_opts);
+      std::unique_ptr<FSWritableFile> descriptor_file;
+      s = NewWritableFile(fs_, descriptor_fname, &descriptor_file,
+                          opt_file_opts);
      if (s.ok()) {
        descriptor_file->SetPreallocationBlockSize(
            db_options_->manifest_preallocation_size);

        std::unique_ptr<WritableFileWriter> file_writer(new WritableFileWriter(
-            std::move(descriptor_file), descriptor_fname, opt_env_opts, env_,
+            std::move(descriptor_file), descriptor_fname, opt_file_opts, env_,
            nullptr, db_options_->listeners));
        descriptor_log_.reset(
            new log::Writer(std::move(file_writer), 0, false));
-        s = WriteCurrentStateToManifest(descriptor_log_.get());
+        s = WriteCurrentStateToManifest(curr_state, descriptor_log_.get());
      }
    }

@@ -3891,9 +3898,7 @@ Status VersionSet::ProcessManifestWrites(
    } else if (first_writer.edit_list.front()->is_column_family_drop_) {
      assert(batch_edits.size() == 1);
      first_writer.cfd->SetDropped();
-      if (first_writer.cfd->Unref()) {
-        delete first_writer.cfd;
-      }
+      first_writer.cfd->UnrefAndTryDelete();
    } else {
      // Each version in versions corresponds to a column family.
      // For each column family, update its log number indicating that logs
@@ -4171,8 +4176,7 @@ Status VersionSet::ApplyOneVersionEditToBuilder(
      builders.erase(builder);
      cfd = column_family_set_->GetColumnFamily(edit.column_family_);
      assert(cfd != nullptr);
-      if (cfd->Unref()) {
-        delete cfd;
+      if (cfd->UnrefAndTryDelete()) {
        cfd = nullptr;
      } else {
        // who else can have reference to cfd!?
@@ -4257,15 +4261,16 @@ Status VersionSet::ExtractInfoFromVersionEdit(
  return Status::OK();
 }

-Status VersionSet::GetCurrentManifestPath(const std::string& dbname, Env* env,
+Status VersionSet::GetCurrentManifestPath(const std::string& dbname,
+                                          FileSystem* fs,
                                          std::string* manifest_path,
                                          uint64_t* manifest_file_number) {
-  assert(env != nullptr);
+  assert(fs != nullptr);
  assert(manifest_path != nullptr);
  assert(manifest_file_number != nullptr);

  std::string fname;
-  Status s = ReadFileToString(env, CurrentFileName(dbname), &fname);
+  Status s = ReadFileToString(fs, CurrentFileName(dbname), &fname);
  if (!s.ok()) {
    return s;
  }
@@ -4367,7 +4372,7 @@ Status VersionSet::Recover(

  // Read "CURRENT" file, which contains a pointer to the current manifest file
  std::string manifest_path;
-  Status s = GetCurrentManifestPath(dbname_, env_, &manifest_path,
+  Status s = GetCurrentManifestPath(dbname_, fs_, &manifest_path,
                                    &manifest_file_number_);
  if (!s.ok()) {
    return s;
@@ -4378,9 +4383,10 @@ Status VersionSet::Recover(

  std::unique_ptr<SequentialFileReader> manifest_file_reader;
  {
-    std::unique_ptr<SequentialFile> manifest_file;
-    s = env_->NewSequentialFile(manifest_path, &manifest_file,
-                                env_->OptimizeForManifestRead(env_options_));
+    std::unique_ptr<FSSequentialFile> manifest_file;
+    s = fs_->NewSequentialFile(manifest_path,
+                               fs_->OptimizeForManifestRead(file_options_),
+                               &manifest_file, nullptr);
    if (!s.ok()) {
      return s;
    }
@@ -4389,7 +4395,8 @@ Status VersionSet::Recover(
                                 db_options_->log_readahead_size));
  }
  uint64_t current_manifest_file_size;
-  s = env_->GetFileSize(manifest_path, &current_manifest_file_size);
+  s = fs_->GetFileSize(manifest_path, IOOptions(), &current_manifest_file_size,
+                       nullptr);
  if (!s.ok()) {
    return s;
  }
@@ -4496,7 +4503,7 @@ Status VersionSet::Recover(
          true /* is_initial_load */,
          cfd->GetLatestMutableCFOptions()->prefix_extractor.get());

-      Version* v = new Version(cfd, this, env_options_,
+      Version* v = new Version(cfd, this, file_options_,
                               *cfd->GetLatestMutableCFOptions(),
                               current_version_number_++);
      builder->SaveTo(v->storage_info());
@@ -4541,23 +4548,24 @@ Status VersionSet::Recover(
 }

 Status VersionSet::ListColumnFamilies(std::vector<std::string>* column_families,
-                                      const std::string& dbname, Env* env) {
+                                      const std::string& dbname,
+                                      FileSystem* fs) {
  // these are just for performance reasons, not correcntes,
  // so we're fine using the defaults
-  EnvOptions soptions;
+  FileOptions soptions;
  // Read "CURRENT" file, which contains a pointer to the current manifest file
  std::string manifest_path;
  uint64_t manifest_file_number;
-  Status s = GetCurrentManifestPath(dbname, env, &manifest_path,
-                                    &manifest_file_number);
+  Status s =
+      GetCurrentManifestPath(dbname, fs, &manifest_path, &manifest_file_number);
  if (!s.ok()) {
    return s;
  }

  std::unique_ptr<SequentialFileReader> file_reader;
  {
-    std::unique_ptr<SequentialFile> file;
-    s = env->NewSequentialFile(manifest_path, &file, soptions);
+    std::unique_ptr<FSSequentialFile> file;
+    s = fs->NewSequentialFile(manifest_path, soptions, &file, nullptr);
    if (!s.ok()) {
      return s;
  }
@@ -4611,7 +4619,7 @@ Status VersionSet::ListColumnFamilies(std::vector<std::string>* column_families,
 #ifndef ROCKSDB_LITE
 Status VersionSet::ReduceNumberOfLevels(const std::string& dbname,
                                        const Options* options,
-                                        const EnvOptions& env_options,
+                                        const FileOptions& file_options,
                                        int new_levels) {
  if (new_levels <= 1) {
    return Status::InvalidArgument(
@@ -4624,7 +4632,7 @@ Status VersionSet::ReduceNumberOfLevels(const std::string& dbname,
                                        options->table_cache_numshardbits));
  WriteController wc(options->delayed_write_rate);
  WriteBufferManager wb(options->db_write_buffer_size);
-  VersionSet versions(dbname, &db_options, env_options, tc.get(), &wb, &wc,
+  VersionSet versions(dbname, &db_options, file_options, tc.get(), &wb, &wc,
                      /*block_cache_tracer=*/nullptr);
  Status status;

@@ -4700,9 +4708,11 @@ Status VersionSet::DumpManifest(Options& options, std::string& dscname,
  std::unique_ptr<SequentialFileReader> file_reader;
  Status s;
  {
-    std::unique_ptr<SequentialFile> file;
-    s = options.env->NewSequentialFile(
-        dscname, &file, env_->OptimizeForManifestRead(env_options_));
+    std::unique_ptr<FSSequentialFile> file;
+    s = options.file_system->NewSequentialFile(
+        dscname,
+        options.file_system->OptimizeForManifestRead(file_options_), &file,
+        nullptr);
    if (!s.ok()) {
      return s;
    }
@@ -4784,8 +4794,7 @@ Status VersionSet::DumpManifest(Options& options, std::string& dscname,
        comparators.erase(edit.column_family_);
        cfd = column_family_set_->GetColumnFamily(edit.column_family_);
        assert(cfd != nullptr);
-        cfd->Unref();
-        delete cfd;
+        cfd->UnrefAndTryDelete();
        cfd = nullptr;
      } else {
        if (!cf_in_builders) {
@@ -4863,7 +4872,7 @@ Status VersionSet::DumpManifest(Options& options, std::string& dscname,
      assert(builders_iter != builders.end());
      auto builder = builders_iter->second->version_builder();

-      Version* v = new Version(cfd, this, env_options_,
+      Version* v = new Version(cfd, this, file_options_,
                               *cfd->GetLatestMutableCFOptions(),
                               current_version_number_++);
      builder->SaveTo(v->storage_info());
@@ -4917,7 +4926,9 @@ void VersionSet::MarkMinLogNumberToKeep2PC(uint64_t number) {
  }
 }

-Status VersionSet::WriteCurrentStateToManifest(log::Writer* log) {
+Status VersionSet::WriteCurrentStateToManifest(
+    const std::unordered_map<uint32_t, MutableCFState>& curr_state,
+    log::Writer* log) {
  // TODO: Break up into multiple records to reduce memory usage on recovery?

  // WARNING: This method doesn't hold a mutex!!
@@ -4980,10 +4991,13 @@ Status VersionSet::WriteCurrentStateToManifest(log::Writer* log) {
                       f->fd.GetFileSize(), f->smallest, f->largest,
                       f->fd.smallest_seqno, f->fd.largest_seqno,
                       f->marked_for_compaction, f->oldest_blob_file_number,
-                       f->oldest_ancester_time);
+                       f->oldest_ancester_time, f->file_creation_time);
        }
      }
-      edit.SetLogNumber(cfd->GetLogNumber());
+      const auto iter = curr_state.find(cfd->GetID());
+      assert(iter != curr_state.end());
+      uint64_t log_number = iter->second.log_number;
+      edit.SetLogNumber(log_number);
      std::string record;
      if (!edit.EncodeTo(&record)) {
        return Status::Corruption(
@@ -5240,7 +5254,7 @@ void VersionSet::AddLiveFiles(std::vector<FileDescriptor>* live_list) {

 InternalIterator* VersionSet::MakeInputIterator(
    const Compaction* c, RangeDelAggregator* range_del_agg,
-    const EnvOptions& env_options_compactions) {
+    const FileOptions& file_options_compactions) {
  auto cfd = c->column_family_data();
  ReadOptions read_options;
  read_options.verify_checksums = true;
@@ -5265,7 +5279,8 @@ InternalIterator* VersionSet::MakeInputIterator(
        const LevelFilesBrief* flevel = c->input_levels(which);
        for (size_t i = 0; i < flevel->num_files; i++) {
          list[num++] = cfd->table_cache()->NewIterator(
-              read_options, env_options_compactions, cfd->internal_comparator(),
+              read_options, file_options_compactions,
+              cfd->internal_comparator(),
              *flevel->files[i].file_metadata, range_del_agg,
              c->mutable_cf_options()->prefix_extractor.get(),
              /*table_reader_ptr=*/nullptr,
@@ -5278,7 +5293,7 @@ InternalIterator* VersionSet::MakeInputIterator(
      } else {
        // Create concatenating iterator for the files from this level
        list[num++] = new LevelIterator(
-            cfd->table_cache(), read_options, env_options_compactions,
+            cfd->table_cache(), read_options, file_options_compactions,
            cfd->internal_comparator(), c->input_levels(which),
            c->mutable_cf_options()->prefix_extractor.get(),
            /*should_sample=*/false,
@@ -5431,7 +5446,7 @@ ColumnFamilyData* VersionSet::CreateColumnFamily(

  MutableCFOptions dummy_cf_options;
  Version* dummy_versions =
-      new Version(nullptr, this, env_options_, dummy_cf_options);
+      new Version(nullptr, this, file_options_, dummy_cf_options);
  // Ref() dummy version once so that later we can call Unref() to delete it
  // by avoiding calling "delete" explicitly (~Version is private)
  dummy_versions->Ref();
@@ -5439,7 +5454,7 @@ ColumnFamilyData* VersionSet::CreateColumnFamily(
      edit->column_family_name_, edit->column_family_, dummy_versions,
      cf_options);

-  Version* v = new Version(new_cfd, this, env_options_,
+  Version* v = new Version(new_cfd, this, file_options_,
                           *new_cfd->GetLatestMutableCFOptions(),
                           current_version_number_++);

@@ -5483,11 +5498,11 @@ uint64_t VersionSet::GetTotalSstFilesSize(Version* dummy_versions) {

 ReactiveVersionSet::ReactiveVersionSet(const std::string& dbname,
                                       const ImmutableDBOptions* _db_options,
-                                       const EnvOptions& _env_options,
+                                       const FileOptions& _file_options,
                                       Cache* table_cache,
                                       WriteBufferManager* write_buffer_manager,
                                       WriteController* write_controller)
-    : VersionSet(dbname, _db_options, _env_options, table_cache,
+    : VersionSet(dbname, _db_options, _file_options, table_cache,
                 write_buffer_manager, write_controller,
                 /*block_cache_tracer=*/nullptr),
      number_of_edits_to_skip_(0) {}
@@ -5618,7 +5633,7 @@ Status ReactiveVersionSet::Recover(
      assert(builders_iter != builders.end());
      auto* builder = builders_iter->second->version_builder();

-      Version* v = new Version(cfd, this, env_options_,
+      Version* v = new Version(cfd, this, file_options_,
                               *cfd->GetLatestMutableCFOptions(),
                               current_version_number_++);
      builder->SaveTo(v->storage_info());
@@ -5811,8 +5826,7 @@ Status ReactiveVersionSet::ApplyOneVersionEditToBuilder(
    // secondary instance. (Is it possible that the ref count for cfd is 0 but
    // the ref count for its versions is higher than 0?)
    cfd->SetDropped();
-    if (cfd->Unref()) {
-      delete cfd;
+    if (cfd->UnrefAndTryDelete()) {
      cfd = nullptr;
    }
    active_version_builders_.erase(builder_iter);
@@ -5839,7 +5853,7 @@ Status ReactiveVersionSet::ApplyOneVersionEditToBuilder(
        &s);

    if (s.ok()) {
-      auto version = new Version(cfd, this, env_options_,
+      auto version = new Version(cfd, this, file_options_,
                                 *cfd->GetLatestMutableCFOptions(),
                                 current_version_number_++);
      builder->SaveTo(version->storage_info());
@@ -5882,9 +5896,9 @@ Status ReactiveVersionSet::MaybeSwitchManifest(
  Status s;
  do {
    std::string manifest_path;
-    s = GetCurrentManifestPath(dbname_, env_, &manifest_path,
+    s = GetCurrentManifestPath(dbname_, fs_, &manifest_path,
                               &manifest_file_number_);
-    std::unique_ptr<SequentialFile> manifest_file;
+    std::unique_ptr<FSSequentialFile> manifest_file;
    if (s.ok()) {
      if (nullptr == manifest_reader->get() ||
          manifest_reader->get()->file()->file_name() != manifest_path) {
@@ -5894,9 +5908,9 @@ Status ReactiveVersionSet::MaybeSwitchManifest(
        TEST_SYNC_POINT(
            "ReactiveVersionSet::MaybeSwitchManifest:"
            "AfterGetCurrentManifestPath:1");
-        s = env_->NewSequentialFile(
-            manifest_path, &manifest_file,
-            env_->OptimizeForManifestRead(env_options_));
+        s = fs_->NewSequentialFile(manifest_path,
+                                   env_->OptimizeForManifestRead(file_options_),
+                                   &manifest_file, nullptr);
      } else {
        // No need to switch manifest.
        break;
@@ -559,15 +559,15 @@ class Version {
  // Append to *iters a sequence of iterators that will
  // yield the contents of this Version when merged together.
  // REQUIRES: This version has been saved (see VersionSet::SaveTo)
-  void AddIterators(const ReadOptions&, const EnvOptions& soptions,
+  void AddIterators(const ReadOptions&, const FileOptions& soptions,
                    MergeIteratorBuilder* merger_iter_builder,
                    RangeDelAggregator* range_del_agg);

-  void AddIteratorsForLevel(const ReadOptions&, const EnvOptions& soptions,
+  void AddIteratorsForLevel(const ReadOptions&, const FileOptions& soptions,
                            MergeIteratorBuilder* merger_iter_builder,
                            int level, RangeDelAggregator* range_del_agg);

-  Status OverlapWithLevelIterator(const ReadOptions&, const EnvOptions&,
+  Status OverlapWithLevelIterator(const ReadOptions&, const FileOptions&,
                                  const Slice& smallest_user_key,
                                  const Slice& largest_user_key,
                                  int level, bool* overlap);
@@ -684,6 +684,7 @@ class Version {

 private:
  Env* env_;
+  FileSystem* fs_;
  friend class ReactiveVersionSet;
  friend class VersionSet;

@@ -729,14 +730,14 @@ class Version {
  Version* next_;               // Next version in linked list
  Version* prev_;               // Previous version in linked list
  int refs_;                    // Number of live refs to this version
-  const EnvOptions env_options_;
+  const FileOptions file_options_;
  const MutableCFOptions mutable_cf_options_;

  // A version number that uniquely represents this version. This is
  // used for debugging and logging purposes only.
  uint64_t version_number_;

-  Version(ColumnFamilyData* cfd, VersionSet* vset, const EnvOptions& env_opt,
+  Version(ColumnFamilyData* cfd, VersionSet* vset, const FileOptions& file_opt,
          MutableCFOptions mutable_cf_options, uint64_t version_number = 0);

  ~Version();
@@ -801,7 +802,7 @@ class AtomicGroupReadBuffer {
 class VersionSet {
 public:
  VersionSet(const std::string& dbname, const ImmutableDBOptions* db_options,
-             const EnvOptions& env_options, Cache* table_cache,
+             const FileOptions& file_options, Cache* table_cache,
             WriteBufferManager* write_buffer_manager,
             WriteController* write_controller,
             BlockCacheTracer* const block_cache_tracer);
@@ -863,7 +864,8 @@ class VersionSet {
      bool new_descriptor_log = false,
      const ColumnFamilyOptions* new_cf_options = nullptr);

-  static Status GetCurrentManifestPath(const std::string& dbname, Env* env,
+  static Status GetCurrentManifestPath(const std::string& dbname,
+                                       FileSystem* fs,
                                       std::string* manifest_filename,
                                       uint64_t* manifest_file_number);

@@ -876,7 +878,7 @@ class VersionSet {
  // Reads a manifest file and returns a list of column families in
  // column_families.
  static Status ListColumnFamilies(std::vector<std::string>* column_families,
-                                   const std::string& dbname, Env* env);
+                                   const std::string& dbname, FileSystem* fs);

 #ifndef ROCKSDB_LITE
  // Try to reduce the number of levels. This call is valid when
@@ -890,7 +892,7 @@ class VersionSet {
  // among [4-6] contains files.
  static Status ReduceNumberOfLevels(const std::string& dbname,
                                     const Options* options,
-                                     const EnvOptions& env_options,
+                                     const FileOptions& file_options,
                                     int new_levels);

  // printf contents (for debugging)
@@ -1004,7 +1006,7 @@ class VersionSet {
  // The caller should delete the iterator when no longer needed.
  InternalIterator* MakeInputIterator(
      const Compaction* c, RangeDelAggregator* range_del_agg,
-      const EnvOptions& env_options_compactions);
+      const FileOptions& file_options_compactions);

  // Add all files listed in any live version to *live.
  void AddLiveFiles(std::vector<FileDescriptor>* live_list);
@@ -1037,9 +1039,9 @@ class VersionSet {
                        uint64_t min_pending_output);

  ColumnFamilySet* GetColumnFamilySet() { return column_family_set_.get(); }
-  const EnvOptions& env_options() { return env_options_; }
-  void ChangeEnvOptions(const MutableDBOptions& new_options) {
-    env_options_.writable_file_max_buffer_size =
+  const FileOptions& file_options() { return file_options_; }
+  void ChangeFileOptions(const MutableDBOptions& new_options) {
+    file_options_.writable_file_max_buffer_size =
        new_options.writable_file_max_buffer_size;
  }

@@ -1073,8 +1075,14 @@ class VersionSet {
                           const Slice& start, const Slice& end,
                           TableReaderCaller caller);

+  struct MutableCFState {
+    uint64_t log_number;
+  };
+
  // Save current contents to *log
-  Status WriteCurrentStateToManifest(log::Writer* log);
+  Status WriteCurrentStateToManifest(
+      const std::unordered_map<uint32_t, MutableCFState>& curr_state,
+      log::Writer* log);

  void AppendVersion(ColumnFamilyData* column_family_data, Version* v);

@@ -1106,6 +1114,7 @@ class VersionSet {
  std::unique_ptr<ColumnFamilySet> column_family_set_;

  Env* const env_;
+  FileSystem* const fs_;
  const std::string dbname_;
  std::string db_id_;
  const ImmutableDBOptions* const db_options_;
@@ -1150,7 +1159,7 @@ class VersionSet {
  std::vector<std::string> obsolete_manifests_;

  // env options for all reads and writes except compactions
-  EnvOptions env_options_;
+  FileOptions file_options_;

  BlockCacheTracer* const block_cache_tracer_;

@@ -1174,7 +1183,7 @@ class ReactiveVersionSet : public VersionSet {
 public:
  ReactiveVersionSet(const std::string& dbname,
                     const ImmutableDBOptions* _db_options,
-                     const EnvOptions& _env_options, Cache* table_cache,
+                     const FileOptions& _file_options, Cache* table_cache,
                     WriteBufferManager* write_buffer_manager,
                     WriteController* write_controller);

@@ -40,7 +40,7 @@ class GenerateLevelFilesBriefTest : public testing::Test {
        InternalKey(smallest, smallest_seq, kTypeValue),
        InternalKey(largest, largest_seq, kTypeValue), smallest_seq,
        largest_seq, /* marked_for_compact */ false, kInvalidBlobFileNumber,
-        kUnknownOldestAncesterTime);
+        kUnknownOldestAncesterTime, kUnknownFileCreationTime);
    files_.push_back(f);
  }

@@ -135,7 +135,7 @@ class VersionStorageInfoTest : public testing::Test {
        file_number, 0, file_size, GetInternalKey(smallest, 0),
        GetInternalKey(largest, 0), /* smallest_seq */ 0, /* largest_seq */ 0,
        /* marked_for_compact */ false, kInvalidBlobFileNumber,
-        kUnknownOldestAncesterTime);
+        kUnknownOldestAncesterTime, kUnknownFileCreationTime);
    f->compensated_file_size = file_size;
    vstorage_.AddFile(level, f);
  }
@@ -146,7 +146,8 @@ class VersionStorageInfoTest : public testing::Test {
    FileMetaData* f = new FileMetaData(
        file_number, 0, file_size, smallest, largest, /* smallest_seq */ 0,
        /* largest_seq */ 0, /* marked_for_compact */ false,
-        kInvalidBlobFileNumber, kUnknownOldestAncesterTime);
+        kInvalidBlobFileNumber, kUnknownOldestAncesterTime,
+        kUnknownFileCreationTime);
    f->compensated_file_size = file_size;
    vstorage_.AddFile(level, f);
  }
@@ -609,21 +610,25 @@ class VersionSetTestBase {

  VersionSetTestBase()
      : env_(Env::Default()),
+        fs_(std::make_shared<LegacyFileSystemWrapper>(env_)),
        dbname_(test::PerThreadDBPath("version_set_test")),
        db_options_(),
        mutable_cf_options_(cf_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)),
-        reactive_versions_(std::make_shared<ReactiveVersionSet>(
-            dbname_, &db_options_, env_options_, table_cache_.get(),
-            &write_buffer_manager_, &write_controller_)),
        shutting_down_(false),
        mock_table_factory_(std::make_shared<mock::MockTableFactory>()) {
    EXPECT_OK(env_->CreateDirIfMissing(dbname_));
+
+    db_options_.env = env_;
+    db_options_.fs = fs_;
+    versions_.reset(new VersionSet(dbname_, &db_options_, env_options_,
+                                   table_cache_.get(), &write_buffer_manager_,
+                                   &write_controller_,
+                                   /*block_cache_tracer=*/nullptr)),
+        reactive_versions_ = std::make_shared<ReactiveVersionSet>(
+            dbname_, &db_options_, env_options_, table_cache_.get(),
+            &write_buffer_manager_, &write_controller_);
    db_options_.db_paths.emplace_back(dbname_,
                                      std::numeric_limits<uint64_t>::max());
  }
@@ -668,8 +673,8 @@ class VersionSetTestBase {
    Status s = env_->NewWritableFile(
        manifest, &file, env_->OptimizeForManifestWrite(env_options_));
    ASSERT_OK(s);
-    std::unique_ptr<WritableFileWriter> file_writer(
-        new WritableFileWriter(std::move(file), manifest, env_options_));
+    std::unique_ptr<WritableFileWriter> file_writer(new WritableFileWriter(
+        NewLegacyWritableFileWrapper(std::move(file)), manifest, env_options_));
    {
      log_writer->reset(new log::Writer(std::move(file_writer), 0, false));
      std::string record;
@@ -708,6 +713,7 @@ class VersionSetTestBase {
  }

  Env* env_;
+  std::shared_ptr<FileSystem> fs_;
  const std::string dbname_;
  EnvOptions env_options_;
  ImmutableDBOptions db_options_;
@@ -120,7 +120,7 @@ Status WalManager::GetUpdatesSince(
    return s;
  }
  iter->reset(new TransactionLogIteratorImpl(
-      db_options_.wal_dir, &db_options_, read_options, env_options_, seq,
+      db_options_.wal_dir, &db_options_, read_options, file_options_, seq,
      std::move(wal_files), version_set, seq_per_batch_));
  return (*iter)->status();
 }
@@ -464,9 +464,10 @@ Status WalManager::ReadFirstLine(const std::string& fname,
    }
  };

-  std::unique_ptr<SequentialFile> file;
-  Status status = env_->NewSequentialFile(
-      fname, &file, env_->OptimizeForLogRead(env_options_));
+  std::unique_ptr<FSSequentialFile> file;
+  Status status = fs_->NewSequentialFile(fname,
+                                         fs_->OptimizeForLogRead(file_options_),
+                                         &file, nullptr);
  std::unique_ptr<SequentialFileReader> file_reader(
      new SequentialFileReader(std::move(file), fname));

@@ -36,10 +36,11 @@ namespace rocksdb {
 class WalManager {
 public:
  WalManager(const ImmutableDBOptions& db_options,
-             const EnvOptions& env_options, const bool seq_per_batch = false)
+             const FileOptions& file_options, const bool seq_per_batch = false)
      : db_options_(db_options),
-        env_options_(env_options),
+        file_options_(file_options),
        env_(db_options.env),
+        fs_(db_options.fs.get()),
        purge_wal_files_last_run_(0),
        seq_per_batch_(seq_per_batch),
        wal_in_db_path_(IsWalDirSameAsDBPath(&db_options)) {}
@@ -88,8 +89,9 @@ class WalManager {

  // ------- state from DBImpl ------
  const ImmutableDBOptions& db_options_;
-  const EnvOptions& env_options_;
+  const FileOptions file_options_;
  Env* env_;
+  FileSystem* fs_;

  // ------- WalManager state -------
  // cache for ReadFirstRecord() calls
@@ -47,6 +47,8 @@ class WalManagerTest : public testing::Test {
                                      std::numeric_limits<uint64_t>::max());
    db_options_.wal_dir = dbname_;
    db_options_.env = env_.get();
+    fs_.reset(new LegacyFileSystemWrapper(env_.get()));
+    db_options_.fs = fs_;

    versions_.reset(new VersionSet(dbname_, &db_options_, env_options_,
                                   table_cache_.get(), &write_buffer_manager_,
@@ -79,8 +81,8 @@ class WalManagerTest : public testing::Test {
    std::string fname = ArchivedLogFileName(dbname_, current_log_number_);
    std::unique_ptr<WritableFile> file;
    ASSERT_OK(env_->NewWritableFile(fname, &file, env_options_));
-    std::unique_ptr<WritableFileWriter> file_writer(
-        new WritableFileWriter(std::move(file), fname, env_options_));
+    std::unique_ptr<WritableFileWriter> file_writer(new WritableFileWriter(
+        NewLegacyWritableFileWrapper(std::move(file)), fname, env_options_));
    current_log_writer_.reset(new log::Writer(std::move(file_writer), 0, false));
  }

@@ -111,6 +113,7 @@ class WalManagerTest : public testing::Test {
  WriteBufferManager write_buffer_manager_;
  std::unique_ptr<VersionSet> versions_;
  std::unique_ptr<WalManager> wal_manager_;
+  std::shared_ptr<LegacyFileSystemWrapper> fs_;

  std::unique_ptr<log::Writer> current_log_writer_;
  uint64_t current_log_number_;
@@ -130,8 +133,8 @@ TEST_F(WalManagerTest, ReadFirstRecordCache) {
      wal_manager_->TEST_ReadFirstRecord(kAliveLogFile, 1 /* number */, &s));
  ASSERT_EQ(s, 0U);

-  std::unique_ptr<WritableFileWriter> file_writer(
-      new WritableFileWriter(std::move(file), path, EnvOptions()));
+  std::unique_ptr<WritableFileWriter> file_writer(new WritableFileWriter(
+      NewLegacyWritableFileWrapper(std::move(file)), path, EnvOptions()));
  log::Writer writer(std::move(file_writer), 1,
                     db_options_.recycle_log_file_num > 0);
  WriteBatch batch;
@@ -1784,14 +1784,28 @@ class MemTableInserter : public WriteBatch::Handler {
    // check if memtable_list size exceeds max_write_buffer_size_to_maintain
    if (trim_history_scheduler_ != nullptr) {
      auto* cfd = cf_mems_->current();
-      assert(cfd != nullptr);
-      if (cfd->ioptions()->max_write_buffer_size_to_maintain > 0 &&
-          cfd->mem()->ApproximateMemoryUsageFast() +
-                  cfd->imm()->ApproximateMemoryUsageExcludingLast() >=
-              static_cast<size_t>(
-                  cfd->ioptions()->max_write_buffer_size_to_maintain) &&
-          cfd->imm()->MarkTrimHistoryNeeded()) {
-        trim_history_scheduler_->ScheduleWork(cfd);
+
+      assert(cfd);
+      assert(cfd->ioptions());
+
+      const size_t size_to_maintain = static_cast<size_t>(
+          cfd->ioptions()->max_write_buffer_size_to_maintain);
+
+      if (size_to_maintain > 0) {
+        MemTableList* const imm = cfd->imm();
+        assert(imm);
+
+        if (imm->HasHistory()) {
+          const MemTable* const mem = cfd->mem();
+          assert(mem);
+
+          if (mem->ApproximateMemoryUsageFast() +
+                      imm->ApproximateMemoryUsageExcludingLast() >=
+                  size_to_maintain &&
+              imm->MarkTrimHistoryNeeded()) {
+            trim_history_scheduler_->ScheduleWork(cfd);
+          }
+        }
      }
    }
  }
@@ -0,0 +1,14 @@
+add_executable(db_stress${ARTIFACT_SUFFIX}
+  db_stress.cc
+  db_stress_tool.cc
+  batched_ops_stress.cc
+  cf_consistency_stress.cc
+  db_stress_common.cc
+  db_stress_driver.cc
+  db_stress_test_base.cc
+  db_stress_shared_state.cc
+  db_stress_gflags.cc
+  db_stress_tool.cc
+  no_batched_ops_stress.cc)
+target_link_libraries(db_stress${ARTIFACT_SUFFIX} ${ROCKSDB_LIB})
+list(APPEND tool_deps db_stress)