From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: violetc <58360096+s-yh-china@users.noreply.github.com>
Date: Sun, 14 Aug 2022 00:39:45 +0800
Subject: [PATCH] Multithreaded Tracker

This patch is Powered by Pufferfish(https://github.com/pufferfish-gg/Pufferfish)

diff --git a/src/main/java/top/leavesmc/leaves/LeavesConfig.java b/src/main/java/top/leavesmc/leaves/LeavesConfig.java
index d217994b16f2f749fe48fe0b895416e0ae02eee4..46233c5845cffb67d89f360c4dfdcc80abdf00c8 100644
--- a/src/main/java/top/leavesmc/leaves/LeavesConfig.java
+++ b/src/main/java/top/leavesmc/leaves/LeavesConfig.java
@@ -246,6 +246,20 @@ public final class LeavesConfig {
         dontSendUselessEntityPackets = getBoolean("settings.performance.dont-send-useless-entity-packets", dontSendUselessEntityPackets);
     }
 
+    public static boolean asyncEntityTracker = false;
+    private static boolean asyncEntityTrackerLock = false;
+    private static void asyncEntityTracker() {
+        if (!asyncEntityTrackerLock) {
+            asyncEntityTracker = getBoolean("settings.performance.async-entity-tracker", asyncEntityTracker);
+            asyncEntityTrackerLock = true;
+        }
+
+        if (asyncEntityTracker) {
+            asyncEntityTracker = false;
+            LeavesLogger.LOGGER.severe("Async EntityTracker is updating, it can't work");
+        }
+    }
+
     public static final class WorldConfig {
 
         public final String worldName;
diff --git a/src/main/java/top/leavesmc/leaves/tracker/MultithreadedTracker.java b/src/main/java/top/leavesmc/leaves/tracker/MultithreadedTracker.java
new file mode 100644
index 0000000000000000000000000000000000000000..559daa0150e395921d110efc63c477be0248ad25
--- /dev/null
+++ b/src/main/java/top/leavesmc/leaves/tracker/MultithreadedTracker.java
@@ -0,0 +1,125 @@
+package top.leavesmc.leaves.tracker;
+
+import com.google.common.util.concurrent.ThreadFactoryBuilder;
+import io.papermc.paper.util.maplist.IteratorSafeOrderedReferenceSet;
+import io.papermc.paper.world.ChunkEntitySlices;
+import net.minecraft.server.MinecraftServer;
+import net.minecraft.server.level.ChunkMap;
+import net.minecraft.world.entity.Entity;
+import net.minecraft.world.level.chunk.LevelChunk;
+
+import java.util.concurrent.ConcurrentLinkedQueue;
+import java.util.concurrent.Executor;
+import java.util.concurrent.Executors;
+import java.util.concurrent.atomic.AtomicInteger;
+
+// Powered by Pufferfish(https://github.com/pufferfish-gg/Pufferfish)
+public class MultithreadedTracker {
+
+    private static final int parallelism = Math.max(4, Runtime.getRuntime().availableProcessors());
+    private static final Executor trackerExecutor = Executors.newFixedThreadPool(parallelism, new ThreadFactoryBuilder()
+        .setNameFormat("puff-tracker-%d")
+        .setPriority(Thread.NORM_PRIORITY - 2)
+        .build());
+
+    private final IteratorSafeOrderedReferenceSet<LevelChunk> entityTickingChunks;
+    private final AtomicInteger taskIndex = new AtomicInteger();
+
+    private final ConcurrentLinkedQueue<Runnable> mainThreadTasks;
+    private final AtomicInteger finishedTasks = new AtomicInteger();
+
+    public MultithreadedTracker(IteratorSafeOrderedReferenceSet<LevelChunk> entityTickingChunks, ConcurrentLinkedQueue<Runnable> mainThreadTasks) {
+        this.entityTickingChunks = entityTickingChunks;
+        this.mainThreadTasks = mainThreadTasks;
+    }
+
+    public void tick() {
+        int iterator = this.entityTickingChunks.createRawIterator();
+
+        if (iterator == -1) {
+            return;
+        }
+
+        try {
+            this.taskIndex.set(iterator);
+            this.finishedTasks.set(0);
+
+            for (int i = 0; i < parallelism; i++) {
+                trackerExecutor.execute(this::run);
+            }
+
+            while (this.taskIndex.get() < this.entityTickingChunks.getListSize()) {
+                this.runMainThreadTasks();
+                this.handleTasks(5); // assist
+            }
+
+            while (this.finishedTasks.get() != parallelism) {
+                this.runMainThreadTasks();
+            }
+
+            this.runMainThreadTasks(); // finish any remaining tasks
+        } finally {
+            this.entityTickingChunks.finishRawIterator();
+        }
+    }
+
+    private void runMainThreadTasks() {
+        try {
+            Runnable task;
+            while ((task = this.mainThreadTasks.poll()) != null) {
+                task.run();
+            }
+        } catch (Throwable throwable) {
+            MinecraftServer.LOGGER.warn("Tasks failed while ticking track queue", throwable);
+        }
+    }
+
+    private void run() {
+        try {
+            while (handleTasks(10));
+        } finally {
+            this.finishedTasks.incrementAndGet();
+        }
+    }
+
+    private boolean handleTasks(int tasks) {
+        int index;
+        while ((index = this.taskIndex.getAndAdd(tasks)) < this.entityTickingChunks.getListSize()) {
+            for (int i = index; i < index + tasks && i < this.entityTickingChunks.getListSize(); i++) {
+                LevelChunk chunk = this.entityTickingChunks.rawGet(i);
+                if (chunk != null) {
+                    try {
+                        this.processChunk(chunk);
+                    } catch (Throwable throwable) {
+                        MinecraftServer.LOGGER.warn("Ticking tracker failed", throwable);
+                    }
+                }
+            }
+            return true;
+        }
+        return false;
+    }
+
+    private void processChunk(LevelChunk chunk) {
+        /* Updating DISABLE THIS
+        final ChunkEntitySlices entitySlices = chunk.level.entityManager.entitySliceManager.getChunk(chunk.locX, chunk.locZ);
+        if (entitySlices == null) {
+            return;
+        }
+
+        final Entity[] rawEntities = entitySlices.entities.getRawData();
+        final ChunkMap chunkMap = chunk.level.chunkSource.chunkMap;
+
+        for (int i = 0; i < rawEntities.length; i++) {
+            Entity entity = rawEntities[i];
+            if (entity != null) {
+                ChunkMap.TrackedEntity entityTracker = chunkMap.entityMap.get(entity.getId());
+                if (entityTracker != null) {
+                    entityTracker.updatePlayers(entityTracker.entity.getPlayersInTrackRange());
+                    this.mainThreadTasks.offer(entityTracker.serverEntity::sendChanges);
+                }
+            }
+        }
+         */
+    }
+}