From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: ishland <ishlandmc@yeah.net>
Date: Sun, 20 Sep 2020 00:05:44 +0800
Subject: [PATCH] Improve task performance

Replace ConcurrentLinkedQueue + LockSupport hack to reduce time
consumption of addTask(R)V

Co-authored-by: Mykyta Komarn <nkomarn@hotmail.com>

diff --git a/src/main/java/net/minecraft/server/IAsyncTaskHandler.java b/src/main/java/net/minecraft/server/IAsyncTaskHandler.java
index 27db247aa40e0516302c74b9bf00c631a8607af5..6f14c97fcc36c0717f72443d620c2383e102ba0f 100644
--- a/src/main/java/net/minecraft/server/IAsyncTaskHandler.java
+++ b/src/main/java/net/minecraft/server/IAsyncTaskHandler.java
@@ -13,9 +13,11 @@ public abstract class IAsyncTaskHandler<R extends Runnable> implements Mailbox<R
 
     private final String b;
     private static final Logger LOGGER = LogManager.getLogger();
-    private final Queue<R> d = Queues.newConcurrentLinkedQueue();
+    private final java.util.concurrent.BlockingDeque<R> d = new java.util.concurrent.LinkedBlockingDeque<>(); // Yatopia - improve task performance
     private int e;
 
+    private R next = null; // Yatopia - improve task performance - temp storage for next object
+
     protected IAsyncTaskHandler(String s) {
         this.b = s;
     }
@@ -79,7 +81,7 @@ public abstract class IAsyncTaskHandler<R extends Runnable> implements Mailbox<R
     public final void addTask(R r0) { a(r0); }; // Paper - OBFHELPER
     public void a(R r0) {
         this.d.add(r0);
-        LockSupport.unpark(this.getThread());
+        // LockSupport.unpark(this.getThread()); // Yatopia - improve task performance - replaced by LinkedBlockingQueue
     }
 
     public void execute(Runnable runnable) {
@@ -99,14 +101,18 @@ public abstract class IAsyncTaskHandler<R extends Runnable> implements Mailbox<R
     }
 
     protected boolean executeNext() {
-        R r0 = this.d.peek(); // Paper - decompile fix
+        if(next == null && !d.isEmpty()) bm(); // Yatopia - Improve task performance
 
-        if (r0 == null) {
+        if (next == null) { // Yatopia - Improve task performance
             return false;
-        } else if (this.e == 0 && !this.canExecute(r0)) {
+        } else if (this.e == 0 && !this.canExecute(next)) { // Yatopia - Improve task performance
             return false;
         } else {
-            this.executeTask(this.d.remove()); // Paper - decompile fix
+            // Yatopia start - Improve task performance
+            R r = next;
+            next = null;
+            this.executeTask(r); // Paper - decompile fix
+            // Yatopia end
             return true;
         }
     }
@@ -127,8 +133,17 @@ public abstract class IAsyncTaskHandler<R extends Runnable> implements Mailbox<R
     }
 
     protected void bm() {
+        // Yatopia start - replaced logic
+        /*
         Thread.yield();
         LockSupport.parkNanos("waiting for tasks", 100000L);
+        */
+        next = null;
+        try {
+            next = d.poll(100, java.util.concurrent.TimeUnit.MICROSECONDS);
+        } catch (InterruptedException ignored) {
+        }
+        // Yatopia end
     }
 
     protected void executeTask(R r0) {