Improve async task handler (#203)

PATCHES.md

@@ -65,6 +65,7 @@ # Patches
 | server |  Implement bed explosion options      | William Blake Galbreath |  |
 | server |  Implement respawn anchor explosion options      | William Blake Galbreath |  |
 | server |  Improve Hopper Performance      | Aikar |  |
+| server |  Improve async task handler      | ishland |  |
 | server |  Item stuck sleep config      | tr7zw |  |
 | api |  Kill AnnotationTest      | tr7zw |  |
 | server |  Lagging threshold      | William Blake Galbreath |  |

patches/server/0051-Improve-async-task-handler.patch

@@ -0,0 +1,82 @@
+From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
+From: ishland <ishlandmc@yeah.net>
+Date: Sun, 20 Sep 2020 19:43:03 +0300
+Subject: [PATCH] Improve async task handler
+
+Replace ConcurrentLinkedQueue and LockSupport hacks to reduce execute times
+
+diff --git a/src/main/java/net/minecraft/server/IAsyncTaskHandler.java b/src/main/java/net/minecraft/server/IAsyncTaskHandler.java
+index 5df6be7e8d9b1295ed0700b3be90c3778fc7d77c..95aec7d4705a7a275fe7f5d6aec877dd7ad0f529 100644
+--- a/src/main/java/net/minecraft/server/IAsyncTaskHandler.java
++++ b/src/main/java/net/minecraft/server/IAsyncTaskHandler.java
+@@ -13,8 +13,9 @@ 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.LinkedBlockingDeque<R> d = new java.util.concurrent.LinkedBlockingDeque<>(); // Yatopia
+     private int e;
++    private R next = null; // Yatopia
+ 
+     protected IAsyncTaskHandler(String s) {
+         this.b = s;
+@@ -79,7 +80,7 @@ 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 - replaced by LinkedBlockingQueue
+     }
+ 
+     public void execute(Runnable runnable) {
+@@ -92,21 +93,30 @@ public abstract class IAsyncTaskHandler<R extends Runnable> implements Mailbox<R
+     }
+ 
+     public void executeAll() { // Paper - protected -> public
++        /* // Yatopia start - replaced logic
+         while (this.executeNext()) {
+             ;
+         }
++         */
++        while (!d.isEmpty()) {
++            if (next == null) queuePull();
++            if (!executeNext()) break;
++        }
++        // Yatopia end
+ 
+     }
+ 
+     protected boolean executeNext() {
+-        R r0 = this.d.peek(); // Paper - decompile fix
++        R r0 = next; // Paper - decompile fix // Yatopia - temp storage
++        if (next == null || !d.isEmpty()) queuePull(); // Yatopia - attempt to get from queue
+ 
+         if (r0 == null) {
+             return false;
+         } else if (this.e == 0 && !this.canExecute(r0)) {
+             return false;
+         } else {
+-            this.executeTask(this.d.remove()); // Paper - decompile fix
++            this.executeTask(r0); // Paper - decompile fix // Yatopia - replaced with r0
++            next = null; // Yatopia - clear temp for next task
+             return true;
+         }
+     }
+@@ -126,9 +136,17 @@ public abstract class IAsyncTaskHandler<R extends Runnable> implements Mailbox<R
+ 
+     }
+ 
++    protected final void queuePull() { bl(); } // Yatopia - OBFHELPER
+     protected void bl() {
++        /* // 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) {