Remove chunk unload queue

sources/src/main/java/io/akarin/server/mixin/cps/MixinChunkProviderServer.java

@@ -0,0 +1,79 @@
+package io.akarin.server.mixin.cps;
+
+import java.util.Iterator;
+
+import org.spigotmc.SlackActivityAccountant;
+import org.spongepowered.asm.mixin.Final;
+import org.spongepowered.asm.mixin.Mixin;
+import org.spongepowered.asm.mixin.Overwrite;
+import org.spongepowered.asm.mixin.Shadow;
+
+import it.unimi.dsi.fastutil.longs.Long2ObjectOpenHashMap;
+import net.minecraft.server.Chunk;
+import net.minecraft.server.ChunkProviderServer;
+import net.minecraft.server.IChunkLoader;
+import net.minecraft.server.WorldServer;
+
+@Mixin(value = ChunkProviderServer.class, remap = false)
+public class MixinChunkProviderServer {
+    @Shadow @Final public WorldServer world;
+    @Shadow public Long2ObjectOpenHashMap<Chunk> chunks;
+    
+    public int pendingUnloadChunks; // For keeping unload target-size features
+    
+    public void unload(Chunk chunk) {
+        if (this.world.worldProvider.c(chunk.locX, chunk.locZ)) {
+            // Akarin - avoid using the queue and simply check the unloaded flag during unloads
+            // this.unloadQueue.add(Long.valueOf(ChunkCoordIntPair.a(chunk.locX, chunk.locZ)));
+            pendingUnloadChunks++;
+            chunk.setShouldUnload(true); // PAIL: shouldUnload
+        }
+    }
+    
+    @Shadow public boolean unloadChunk(Chunk chunk, boolean save) { return true; }
+    @Shadow @Final private IChunkLoader chunkLoader;
+    @Shadow @Final private static double UNLOAD_QUEUE_RESIZE_FACTOR;
+    
+    @Overwrite
+    public boolean unloadChunks() {
+        if (!this.world.savingDisabled) {
+            SlackActivityAccountant activityAccountant = world.getMinecraftServer().slackActivityAccountant;
+            activityAccountant.startActivity(0.5);
+            
+            Iterator<Chunk> it = chunks.values().iterator();
+            long now = System.currentTimeMillis();
+            long unloadAfter = world.paperConfig.delayChunkUnloadsBy;
+            int targetSize = Math.min(pendingUnloadChunks - 100,  (int) (pendingUnloadChunks * UNLOAD_QUEUE_RESIZE_FACTOR)); // Paper - Make more aggressive
+            
+            for (int i = 0; i < chunks.size() && pendingUnloadChunks > targetSize; i++) { // CraftBukkit removes unload logic to its method, we must check index
+                Chunk chunk = it.next();
+                
+                if (chunk != null && chunk.isUnloading()) {
+                    if (unloadAfter > 0) {
+                        // We changed Paper's delay unload logic, the original behavior is just mark as unloading
+                        if (chunk.scheduledForUnload == null || now - chunk.scheduledForUnload < unloadAfter) {
+                            continue;
+                        }
+                        chunk.scheduledForUnload = null;
+                    }
+                    
+                    // If a plugin cancelled it, we shouldn't trying unload it for a while
+                    chunk.setShouldUnload(false); // Paper 
+                    
+                    if (!unloadChunk(chunk, true)) continue; // Event cancelled
+                    pendingUnloadChunks--;
+                    
+                    if (activityAccountant.activityTimeIsExhausted()) break;
+                }
+            }
+            activityAccountant.endActivity();
+            this.chunkLoader.b(); // PAIL: chunkTick
+        }
+        return false;
+    }
+    
+    @Overwrite
+    public String getName() {
+        return "ServerChunkCache: " + chunks.size(); // Akarin - remove unload queue
+    }
+}

sources/src/main/java/io/akarin/server/mixin/cps/MixinCraftWorld.java

@@ -0,0 +1,52 @@
+package io.akarin.server.mixin.cps;
+
+import java.util.Set;
+
+import org.bukkit.craftbukkit.CraftWorld;
+import org.spongepowered.asm.lib.Opcodes;
+import org.spongepowered.asm.mixin.Mixin;
+import org.spongepowered.asm.mixin.injection.At;
+import org.spongepowered.asm.mixin.injection.Redirect;
+import org.spongepowered.asm.mixin.injection.callback.CallbackInfo;
+import org.spongepowered.asm.mixin.injection.Inject;
+
+import net.minecraft.server.Chunk;
+import net.minecraft.server.PlayerChunk;
+
+@Mixin(value = CraftWorld.class, remap = false)
+public class MixinCraftWorld {
+    @Inject(method = "processChunkGC()V", at = @At(
+            value = "INVOKE",
+            target = "net/minecraft/server/ChunkProviderServer.unload(Lnet/minecraft/server/Chunk;)V"
+    ))
+    public void cancelUnloading(Chunk chunk, CallbackInfo ci) {
+        if (chunk.isUnloading()) ci.cancel();
+    }
+    
+    @Redirect(method = "processChunkGC()V", at = @At(
+            value = "INVOKE",
+            target = "java/util/Set.contains(Ljava/lang/Object;)Z",
+            opcode = Opcodes.INVOKEINTERFACE
+    ))
+    public boolean checkUnloading(Set<Long> set, Object chunkHash) {
+        return false;
+    }
+    
+    @Redirect(method = "regenerateChunk", at = @At(
+            value = "INVOKE",
+            target = "java/util/Set.remove(Ljava/lang/Object;)Z",
+            opcode = Opcodes.INVOKEINTERFACE
+    ))
+    public boolean regenChunk(Set<Long> set, Object chunkHash) {
+        return false;
+    }
+    
+    @Inject(method = "processChunkGC()V", at = @At(
+            value = "FIELD",
+            target = "net/minecraft/server/PlayerChunk.chunk:Lnet/minecraft/server/Chunk;",
+            opcode = Opcodes.PUTFIELD
+    ))
+    public void noUnload(PlayerChunk playerChunk, Chunk chunk, CallbackInfo ci) {
+        chunk.setShouldUnload(false);
+    }
+}