Common:

- Fix NPE with combat task pings. All combat task management is now done in player netty threads.

Bukkit:
- Disable paper plugin remapping
- Build a "lite" version that doesn't shade PacketEvents, allows multiple plugins to share PacketEvents or for you to update PacketEvents without rebuilding KnockbackSync

Fabric:
- Actually call onLoad() to init PE
- Explicitly prevent loading on Client

.github/workflows/build-gradle.yml

@@ -29,7 +29,7 @@ jobs:
       - name: Setup Gradle 8.10
         uses: gradle/actions/setup-gradle@v4
         with:
-          gradle-version: "8.10" # Quotes required to prevent YAML converting to number
+          gradle-version: "8.13" # Quotes required to prevent YAML converting to number
 
       - name: Generate build number
         id: buildnumber
@@ -53,39 +53,26 @@ jobs:
           # Ensure snapshot is set to false
           sed -i "s/val snapshot = .*/val snapshot = false/" build.gradle.kts
 
-      - name: Build with Gradle
-        run: gradle clean build -x test
+      - name: Build without PE shaded
+        run: gradle build -PshadePE=false -x test
         env:
           GITHUB_REPOSITORY: ${{ github.repository }}
 
-      - name: Rename shaded jar to overwrite non-shaded jar
-        run: mv bukkit/build/libs/knockbacksync-bukkit-${{ env.NEW_VERSION }}-all.jar bukkit/build/libs/knockbacksync-bukkit-${{ env.NEW_VERSION }}.jar
+      - name: Build with PE shaded Gradle
+        run: gradle build -PshadePE=true -x test
+        env:
+          GITHUB_REPOSITORY: ${{ github.repository }}
 
-      # Download PaperSpigot (Choose version for reproducibility
-      - name: Download PaperSpigot
-        run: |
-          mkdir -p paper-server/plugins
-          curl -o paperclip.jar https://api.papermc.io/v2/projects/paper/versions/1.21.1/builds/120/downloads/paper-1.21.1-120.jar 
-          mv paperclip.jar paper-server/
-
-      # Copy Plugin into Plugins Folder and Start Server
-      - name: Copy Plugin and Start Paper Server
-        run: |
-          cp bukkit/build/libs/knockbacksync-bukkit-${{ env.NEW_VERSION }}.jar paper-server/plugins/
-          cd paper-server
-          # Start the server to remap the plugin
-          timeout 60 java -Xms3G -Xmx3G -XX:+UseG1GC -XX:+ParallelRefProcEnabled -XX:MaxGCPauseMillis=200 -XX:+UnlockExperimentalVMOptions -XX:+DisableExplicitGC -XX:+AlwaysPreTouch -XX:G1NewSizePercent=30 -XX:G1MaxNewSizePercent=40 -XX:G1HeapRegionSize=8M -XX:G1ReservePercent=20 -XX:G1HeapWastePercent=5 -XX:G1MixedGCCountTarget=4 -XX:InitiatingHeapOccupancyPercent=15 -XX:G1MixedGCLiveThresholdPercent=90 -XX:G1RSetUpdatingPauseTimePercent=5 -XX:SurvivorRatio=32 -XX:+PerfDisableSharedMem -XX:MaxTenuringThreshold=1 -jar -Dcom.mojang.eula.agree=true paperclip.jar --nogui || true
-
-      # Get the Hashes of the Original and Remapped JARs
+      # Get the Hashes of the Original and Lite JARs
       - name: Calculate Hashes
         run: |
           # Calculate hash for the original JAR
-          ORIGINAL_HASH=$(sha256sum bukkit/build/libs/knockbacksync-bukkit-${{ env.NEW_VERSION }}.jar | awk '{print $1}')
-          echo "ORIGINAL_HASH=$ORIGINAL_HASH" >> $GITHUB_ENV
-          # Calculate hash for the remapped JAR
-          REMAPPED_HASH=$(sha256sum paper-server/plugins/.paper-remapped/knockbacksync-bukkit-${{ env.NEW_VERSION }}.jar | awk '{print $1}')
-          echo "REMAPPED_HASH=$REMAPPED_HASH" >> $GITHUB_ENV
-          # Calculate hash for the remapped JAR
+          BUKKIT_HASH=$(sha256sum bukkit/build/libs/knockbacksync-bukkit-${{ env.NEW_VERSION }}.jar | awk '{print $1}')
+          echo "BUKKIT_HASH=$BUKKIT_HASH" >> $GITHUB_ENV
+          # Calculate hash for the lite JAR
+          BUKKIT_LITE_HASH=$(sha256sum bukkit/build/libs/knockbacksync-bukkit-lite-${{ env.NEW_VERSION }}.jar | awk '{print $1}')
+          echo "BUKKIT_LITE_HASH=$BUKKIT_LITE_HASH" >> $GITHUB_ENV
+          # Calculate hash for the lite JAR
           FABRIC_HASH=$(sha256sum fabric/build/libs/knockbacksync-fabric-${{ env.NEW_VERSION }}.jar | awk '{print $1}')
           echo "FABRIC_HASH=$FABRIC_HASH" >> $GITHUB_ENV
 
@@ -111,8 +98,8 @@ jobs:
           }
           
           # Add new hashes if they don't exist
-          add_hash_if_new "${{ env.ORIGINAL_HASH }}"
-          add_hash_if_new "${{ env.REMAPPED_HASH }}"
+          add_hash_if_new "${{ env.BUKKIT_HASH }}"
+          add_hash_if_new "${{ env.BUKKIT_LITE_HASH }}"
           add_hash_if_new "${{ env.FABRIC_HASH }}"
           
           # Check if the file has changed
@@ -143,23 +130,25 @@ jobs:
           # Clean up
           rm dev-builds.txt.original
 
-      - name: Create artifacts directory
-        run: mkdir -p artifacts
-
-      - name: Copy bukkit artifact
-        run: cp bukkit/build/libs/knockbacksync-bukkit-${{ env.NEW_VERSION }}.jar artifacts/
-
-      - name: Copy fabric artifact
-        run: cp fabric/build/libs/knockbacksync-fabric-${{ env.NEW_VERSION }}.jar artifacts/
-
-      - name: Zip the artifacts
-        run: zip -r KnockbackSync-${{ env.NEW_VERSION }}.zip artifacts/*
-
-      - name: Upload artifacts zip
+      - name: Upload Bukkit Artifact
         uses: actions/upload-artifact@v4
         with:
-          name: KnockbackSync-${{ env.NEW_VERSION }}.zip
-          path: KnockbackSync-${{ env.NEW_VERSION }}.zip
+          name: knockbacksync-bukkit-${{ env.NEW_VERSION }}.jar
+          path: bukkit/build/libs/knockbacksync-bukkit-${{ env.NEW_VERSION }}.jar
+          retention-days: 90
+
+      - name: Upload Bukkit Lite Artifact
+        uses: actions/upload-artifact@v4
+        with:
+          name: knockbacksync-bukkit-lite-${{ env.NEW_VERSION }}.jar
+          path: bukkit/build/libs/knockbacksync-bukkit-lite-${{ env.NEW_VERSION }}.jar
+          retention-days: 90
+
+      - name: Upload Fabric Artifact
+        uses: actions/upload-artifact@v4
+        with:
+          name: knockbacksync-fabric-${{ env.NEW_VERSION }}.jar
+          path: fabric/build/libs/knockbacksync-fabric-${{ env.NEW_VERSION }}.jar
           retention-days: 90
 
       - uses: Kir-Antipov/mc-publish@v3.3
@@ -171,6 +160,7 @@ jobs:
 
           files: |
             bukkit/build/libs/knockbacksync-bukkit-${{ env.NEW_VERSION }}.jar
+            bukkit/build/libs/knockbacksync-bukkit-lite-${{ env.NEW_VERSION }}.jar
 
           name: KnockbackSync-${{ env.NEW_VERSION }}
           version: ${{ env.NEW_VERSION }}

build.gradle.kts

@@ -3,13 +3,17 @@ import java.io.ByteArrayOutputStream
 plugins {
     id("java")
     id("com.gradleup.shadow") version "8.3.3" apply false
-    id("fabric-loom") version "1.8-SNAPSHOT" apply false
+    id("fabric-loom") version "1.10.2" apply false
 }
 
 val fullVersion = "1.3.5"
 val snapshot = true
 val githubRepo = System.getenv("GITHUB_REPOSITORY") ?: project.findProperty("githubRepo").toString()
 
+extra["shadePE"] = project.findProperty("shadePE")?.toString()?.toBoolean()
+    ?: System.getenv("SHADE_PE")?.toBoolean()
+    ?: true
+
 allprojects {
     fun getVersionMeta(includeHash: Boolean): String {
         if (!snapshot) {

bukkit/build.gradle.kts

@@ -4,8 +4,10 @@ plugins {
     id("com.gradleup.shadow")
 }
 
+val shadePE: Boolean by rootProject.extra
+
 base {
-    archivesName.set("${rootProject.property("archives_base_name")}-bukkit")
+    archivesName.set("${rootProject.property("archives_base_name")}-bukkit${if (shadePE) "" else "-lite"}")
 }
 
 val shadeThisThing: Configuration by configurations.creating {
@@ -31,13 +33,17 @@ dependencies {
 
     compileOnly("org.spigotmc:spigot-api:1.18.2-R0.1-SNAPSHOT")
     compileOnly("org.geysermc.floodgate:api:2.0-SNAPSHOT")
+    compileOnly("io.netty:netty-all:4.1.72.Final")
 
     compileOnly("org.projectlombok:lombok:1.18.34")
     annotationProcessor("org.projectlombok:lombok:1.18.34")
 
     shadeThisThing(implementation("org.kohsuke:github-api:1.326")!!)
-    shadeThisThing(implementation("com.github.retrooper:packetevents-spigot:2.7.0-SNAPSHOT")!!)
-//    shadeThisThing(implementation("net.kyori:adventure-platform-bukkit:4.3.4")!!)
+    if (shadePE) {
+        shadeThisThing(implementation("com.github.retrooper:packetevents-spigot:2.7.0-SNAPSHOT")!!)
+    } else {
+        compileOnly("com.github.retrooper:packetevents-spigot:2.7.0-SNAPSHOT")
+    }
     shadeThisThing(implementation("org.incendo:cloud-paper:2.0.0-beta.10")!!)
     shadeThisThing(implementation("org.incendo:cloud-core:2.0.0")!!)
 
@@ -46,6 +52,13 @@ dependencies {
 }
 
 tasks.withType<ShadowJar> {
+    manifest {
+        attributes["paperweight-mappings-namespace"] = "mojang"
+    }
+
+    // Remove the -all suffix from the output JAR file name
+    archiveClassifier.set("")
+
     configurations = listOf(shadeThisThing)
     isEnableRelocation = false
     relocationPrefix = "${project.property("maven_group")}.${project.property("archives_base_name")}.shaded"
@@ -58,11 +71,14 @@ tasks.build {
 tasks.processResources {
     from(project(":common").sourceSets.main.get().resources)
     inputs.property("version", project.version)
+    inputs.property("shadePE", shadePE) // Add shadePE as an input to trigger reprocessing if it changes
     filteringCharset = "UTF-8"
 
+
     filesMatching("plugin.yml") {
         expand(
             "version" to project.version,
+            "depends" to if (shadePE) "[]" else listOf("packetevents")
         )
     }
 }

bukkit/src/main/resources/plugin.yml

@@ -5,6 +5,7 @@ api-version: '1.13' # We actually support 1.12.2, api-version was added later th
 authors: [ Caseload, Axionize ]
 description: Synchronizes player knockback for smoother gameplay.
 folia-supported: true
+depends: ${depends}
 permissions:
   knockbacksync.update:
     default: op

common/build.gradle.kts

@@ -2,17 +2,23 @@ plugins {
     id("com.github.gmazzo.buildconfig") version "3.1.0"
 }
 
+val shadePE: Boolean by rootProject.extra
+
 dependencies {
     // True compileOnly deps
     compileOnly("org.geysermc.floodgate:api:2.0-SNAPSHOT")
+    compileOnly("io.netty:netty-all:4.1.72.Final")
     compileOnly("org.projectlombok:lombok:1.18.34")
     annotationProcessor("org.projectlombok:lombok:1.18.34")
 
     // Shaded in or bundled by platform-specific code
-    implementation("com.github.retrooper:packetevents-api:2.7.0-SNAPSHOT")
+    if (shadePE) {
+        implementation("com.github.retrooper:packetevents-api:2.7.0-SNAPSHOT")
+    } else {
+        compileOnly("com.github.retrooper:packetevents-api:2.7.0-SNAPSHOT")
+    }
+
     implementation("org.yaml:snakeyaml:2.0")
-//    implementation("com.fasterxml.jackson.core:jackson-databind:2.17.2")
-//    implementation("com.fasterxml.jackson.dataformat:jackson-dataformat-yaml:2.17.2")
     implementation("org.kohsuke:github-api:1.326") {
         exclude(group = "commons-io", module = "commons-io")
         exclude(group = "org.apache.commons", module = "commons-lang3")

common/src/main/java/me/caseload/knockbacksync/listener/PlayerJoinQuitListener.java

@@ -25,9 +25,7 @@ public abstract class PlayerJoinQuitListener {
         if (playerData == null)
             return;
 
-        if (playerData.isInCombat())
-            playerData.quitCombat();
-
+        playerData.quitCombat(true);
         PlayerDataManager.removePlayerData(uuid);
     }
 }

common/src/main/java/me/caseload/knockbacksync/manager/CombatManager.java

@@ -8,17 +8,17 @@ import java.util.concurrent.ConcurrentHashMap;
 
 public class CombatManager {
 
-    private static final Set<UUID> combatPlayers = ConcurrentHashMap.newKeySet();
+    private static final Set<@NotNull UUID> combatPlayers = ConcurrentHashMap.newKeySet();
 
-    public static @NotNull Set<UUID> getPlayers() {
+    public static @NotNull Set<@NotNull UUID> getPlayers() {
         return combatPlayers;
     }
 
-    public static void addPlayer(UUID uuid) {
+    public static void addPlayer(@NotNull UUID uuid) {
         combatPlayers.add(uuid);
     }
 
-    public static void removePlayer(UUID uuid) {
+    public static void removePlayer(@NotNull UUID uuid) {
         combatPlayers.remove(uuid);
     }
 }

common/src/main/java/me/caseload/knockbacksync/player/PlayerData.java

@@ -23,6 +23,7 @@ import me.caseload.knockbacksync.event.events.ToggleOnOffEvent;
 import me.caseload.knockbacksync.manager.CombatManager;
 import me.caseload.knockbacksync.manager.ConfigManager;
 import me.caseload.knockbacksync.scheduler.AbstractTaskHandle;
+import me.caseload.knockbacksync.scheduler.NettyTaskHandle;
 import me.caseload.knockbacksync.util.MathUtil;
 import me.caseload.knockbacksync.util.data.Pair;
 import me.caseload.knockbacksync.world.PlatformWorld;
@@ -32,8 +33,10 @@ import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 
 import java.lang.reflect.Field;
+import io.netty.channel.Channel;
 import java.util.*;
 import java.util.concurrent.ConcurrentLinkedQueue;
+import java.util.concurrent.TimeUnit;
 
 @Getter
 public class PlayerData {
@@ -77,6 +80,7 @@ public class PlayerData {
     @Getter private final JitterCalculator jitterCalculator = new JitterCalculator();
     @Setter private double jitter;
     @Nullable private AbstractTaskHandle combatTask;
+    @NotNull private final Object combatTaskLock = new Object(); // Lock object for synchronization
     @Nullable @Setter private Double ping, previousPing;
     @Nullable @Setter private Double verticalVelocity;
     @Nullable @Setter private Integer lastDamageTicks;
@@ -292,28 +296,41 @@ public class PlayerData {
         return yAxis;
     }
 
-    public boolean isInCombat() {
-        return combatTask != null;
-    }
-
     public void updateCombat() {
-        if (isInCombat())
-            combatTask.cancel();
-
-        combatTask = newCombatTask();
-        CombatManager.addPlayer(uuid);
+        Channel channel = (Channel) user.getChannel();
+        channel.eventLoop().execute(() -> {
+            if (combatTask != null) {
+                combatTask.cancel();
+            }
+            combatTask = newCombatTask(channel);
+            CombatManager.addPlayer(uuid);
+        });
     }
 
-    public void quitCombat() {
-        if (combatTask != null) combatTask.cancel(); // rarely throws NPE without null check
-        combatTask = null;
-        CombatManager.removePlayer(uuid);
+    /**
+     * Cancels the combatTask quit task. This prevents quitCombat() from being called later against a new combat task
+     * Or against a player that has disconnected already
+     * @param async Whether we are already in the players netty thread
+     */
+    public void quitCombat(boolean async) {
+        Channel channel = (Channel) user.getChannel();
+        Runnable runnable = () -> {
+            if (combatTask != null) {
+                combatTask.cancel();
+                combatTask = null;
+            }
+            CombatManager.removePlayer(uuid);
+        };
+        if (async) {
+            channel.eventLoop().execute(runnable);
+        } else {
+            runnable.run();
+        }
     }
 
     @NotNull
-    private AbstractTaskHandle newCombatTask() {
-        return Base.INSTANCE.getScheduler().runTaskLaterAsynchronously(
-                this::quitCombat, Base.INSTANCE.getConfigManager().getCombatTimer());
+    private AbstractTaskHandle newCombatTask(Channel channel) {
+        return new NettyTaskHandle(channel.eventLoop().schedule(() -> quitCombat(false), convertTicksToMilliseconds(Base.INSTANCE.getConfigManager().getCombatTimer()), TimeUnit.MILLISECONDS));
     }
 
     public ClientVersion getClientVersion() {
@@ -360,4 +377,8 @@ public class PlayerData {
                 throw new IllegalStateException("Unknown ping_strategy: " + pingStrategy);
         }
     }
+
+    private long convertTicksToMilliseconds(long ticks) {
+        return ticks * 50;
+    }
 }

common/src/main/java/me/caseload/knockbacksync/scheduler/NettyTaskHandle.java

@@ -0,0 +1,22 @@
+package me.caseload.knockbacksync.scheduler;
+
+import io.netty.util.concurrent.ScheduledFuture;
+
+public class NettyTaskHandle implements AbstractTaskHandle {
+
+    private final ScheduledFuture scheduledFuture;
+
+    public NettyTaskHandle(ScheduledFuture<?> scheduledFuture) {
+        this.scheduledFuture = scheduledFuture;
+    }
+
+    @Override
+    public boolean getCancelled() {
+        return scheduledFuture.isCancelled();
+    }
+
+    @Override
+    public void cancel() {
+        scheduledFuture.cancel(true);
+    }
+}

fabric/build.gradle.kts

@@ -3,6 +3,8 @@ plugins {
     id("com.gradleup.shadow")
 }
 
+val shadePE: Boolean by rootProject.extra
+
 loom {
     accessWidenerPath = file("src/main/resources/knockbacksync.accesswidener")
 }
@@ -57,6 +59,7 @@ dependencies {
 
     compileOnly("org.geysermc.floodgate:api:2.0-SNAPSHOT")
     compileOnly("org.projectlombok:lombok:1.18.34")
+    compileOnly("io.netty:netty-all:4.1.72.Final")
     annotationProcessor("org.projectlombok:lombok:1.18.34")
 }
 

fabric/src/main/java/me/caseload/knockbacksync/FabricLoaderMod.java

@@ -1,5 +1,6 @@
 package me.caseload.knockbacksync;
 
+import net.fabricmc.api.EnvType;
 import net.fabricmc.api.ModInitializer;
 import net.fabricmc.fabric.api.event.lifecycle.v1.ServerLifecycleEvents;
 import net.fabricmc.loader.api.FabricLoader;
@@ -16,15 +17,23 @@ public class FabricLoaderMod implements PreLaunchEntrypoint, ModInitializer {
 
     @Override
     public void onPreLaunch() {
+        ensureServer();
         core.load();
     }
 
     @Override
     public void onInitialize() {
+        ensureServer();
         core.enable();
         ServerLifecycleEvents.SERVER_STOPPING.register((server) -> {
             core.scheduler.shutdown();
             core.statsManager.getMetrics().shutdown();
         });
     }
+
+    private void ensureServer() {
+        if (FabricLoader.getInstance().getEnvironmentType() == EnvType.CLIENT) {
+            throw new IllegalStateException("This mod can only be run on servers");
+        }
+    }
 }

fabric/src/main/resources/fabric.mod.json

@@ -10,6 +10,9 @@
   "icon": "assets/knockbacksync/icon.png",
   "environment": "*",
   "entrypoints": {
+    "preLaunch": [
+      "me.caseload.knockbacksync.FabricLoaderMod"
+    ],
     "main": [
       "me.caseload.knockbacksync.FabricLoaderMod"
     ]