Leaf/patches/server/0075-Virtual-Thread-for-async-scheduler.patch

From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: nostalfinals <yuu8583@proton.me>
Date: Tue, 12 Mar 2024 00:36:29 +0800
Subject: [PATCH] Virtual Thread for async scheduler


diff --git a/src/main/java/org/bukkit/craftbukkit/Main.java b/src/main/java/org/bukkit/craftbukkit/Main.java
index ee166ad76bd2c143e04e4bf6bd9991bc90ab99a5..13f3f8628143ffc22a2d2c2129ea4836b0a679d7 100644
--- a/src/main/java/org/bukkit/craftbukkit/Main.java
+++ b/src/main/java/org/bukkit/craftbukkit/Main.java
@@ -385,7 +385,6 @@ public class Main {
             tryPreloadClass("org.bukkit.craftbukkit.scheduler.CraftScheduler$1");
             tryPreloadClass("org.bukkit.craftbukkit.scheduler.CraftScheduler$2");
             tryPreloadClass("org.bukkit.craftbukkit.scheduler.CraftScheduler$3");
-            tryPreloadClass("org.bukkit.craftbukkit.scheduler.CraftScheduler$4");
             tryPreloadClass("org.slf4j.helpers.MessageFormatter");
             tryPreloadClass("org.slf4j.helpers.FormattingTuple");
             tryPreloadClass("org.slf4j.helpers.BasicMarker");
diff --git a/src/main/java/org/bukkit/craftbukkit/scheduler/CraftAsyncScheduler.java b/src/main/java/org/bukkit/craftbukkit/scheduler/CraftAsyncScheduler.java
index 9c1aff17aabd062640e3f451a2ef8c50a7c62f10..ba7784780a578350992be3e2cfcb9791aa805838 100644
--- a/src/main/java/org/bukkit/craftbukkit/scheduler/CraftAsyncScheduler.java
+++ b/src/main/java/org/bukkit/craftbukkit/scheduler/CraftAsyncScheduler.java
@@ -25,30 +25,55 @@ package org.bukkit.craftbukkit.scheduler;
 
 import com.destroystokyo.paper.ServerSchedulerReportingWrapper;
 import com.google.common.util.concurrent.ThreadFactoryBuilder;
+import org.apache.logging.log4j.LogManager;
+import org.apache.logging.log4j.Logger;
+import org.galemc.gale.virtualthread.VirtualThreadService;
 import org.bukkit.plugin.Plugin;
 
+import java.lang.reflect.Method;
 import java.util.ArrayList;
 import java.util.Iterator;
 import java.util.List;
 import java.util.concurrent.Executor;
 import java.util.concurrent.Executors;
 import java.util.concurrent.SynchronousQueue;
+import java.util.concurrent.ThreadFactory;
 import java.util.concurrent.ThreadPoolExecutor;
 import java.util.concurrent.TimeUnit;
 
 public class CraftAsyncScheduler extends CraftScheduler {
 
-    private final ThreadPoolExecutor executor = new ThreadPoolExecutor(
-            4, Integer.MAX_VALUE,30L, TimeUnit.SECONDS, new SynchronousQueue<>(),
-            new ThreadFactoryBuilder().setNameFormat("Craft Scheduler Thread - %1$d").setUncaughtExceptionHandler(new net.minecraft.DefaultUncaughtExceptionHandlerWithName(net.minecraft.server.MinecraftServer.LOGGER)).build()); // Paper
+    private final Logger LOGGER = LogManager.getLogger(getClass().getName()); // Leaf - Class logger
+    private Executor executor; // Leaf - use super class
     private final Executor management = Executors.newSingleThreadExecutor(new ThreadFactoryBuilder()
             .setNameFormat("Craft Async Scheduler Management Thread").setUncaughtExceptionHandler(new net.minecraft.DefaultUncaughtExceptionHandlerWithName(net.minecraft.server.MinecraftServer.LOGGER)).build()); // Paper
     private final List<CraftTask> temp = new ArrayList<>();
 
     CraftAsyncScheduler() {
         super(true);
-        executor.allowCoreThreadTimeOut(true);
-        executor.prestartAllCoreThreads();
+
+        // Leaf start - Ability to use Virtual Thread for async scheduler
+        if (VirtualThreadService.getJavaMajorVersion() >= VirtualThreadService.minimumJavaMajorVersionWithoutFeaturePreview && org.dreeam.leaf.config.modules.opt.VT4BukkitScheduler.enabled) {
+            try {
+                Method newThreadPerTaskExecutor = Executors.class.getMethod("newThreadPerTaskExecutor", ThreadFactory.class);
+
+                executor = (Executor) newThreadPerTaskExecutor.invoke(null, VirtualThreadService.get().createFactory());
+                //executor = Executors.newThreadPerTaskExecutor(Thread.ofVirtual().name("Craft Scheduler Thread - ", 0).factory()); // Leaf - When Minecraft using Java21
+                return;
+            } catch (Exception ignored) {
+                LOGGER.error("Failed to create Virtual Thread executor! Fallback to default executor.");
+            }
+        }
+
+        executor = new ThreadPoolExecutor(
+                4, Integer.MAX_VALUE, 30L, TimeUnit.SECONDS, new SynchronousQueue<>(),
+                new ThreadFactoryBuilder().setNameFormat("Craft Scheduler Thread - %1$d").setUncaughtExceptionHandler(new net.minecraft.DefaultUncaughtExceptionHandlerWithName(net.minecraft.server.MinecraftServer.LOGGER)).build());
+
+        var threadPoolExecutor = (ThreadPoolExecutor) executor;
+
+        threadPoolExecutor.allowCoreThreadTimeOut(true);
+        threadPoolExecutor.prestartAllCoreThreads();
+        // Leaf end
     }
 
     @Override
diff --git a/src/main/java/org/dreeam/leaf/config/modules/opt/VT4BukkitScheduler.java b/src/main/java/org/dreeam/leaf/config/modules/opt/VT4BukkitScheduler.java
new file mode 100644
index 0000000000000000000000000000000000000000..9add2256eea4de354f7e4ada10b4d0ccb32a60a1
--- /dev/null
+++ b/src/main/java/org/dreeam/leaf/config/modules/opt/VT4BukkitScheduler.java
@@ -0,0 +1,29 @@
+package org.dreeam.leaf.config.modules.opt;
+
+import com.electronwill.nightconfig.core.file.CommentedFileConfig;
+import org.dreeam.leaf.config.ConfigInfo;
+import org.dreeam.leaf.config.EnumConfigCategory;
+import org.dreeam.leaf.config.IConfigModule;
+
+public class VT4BukkitScheduler implements IConfigModule {
+
+    @Override
+    public EnumConfigCategory getCategory() {
+        return EnumConfigCategory.PERFORMANCE;
+    }
+
+    @Override
+    public String getBaseName() {
+        return "use_virtual_thread_for_async_scheduler";
+    }
+
+    @ConfigInfo(baseName = "enabled")
+    public static boolean enabled = false;
+
+    @Override
+    public void onLoaded(CommentedFileConfig config) {
+        config.setComment("performance.use_virtual_thread_for_async_scheduler", """
+                 Use the new Virtual Thread introduced in JDK 21 for CraftAsyncScheduler.
+                """);
+    }
+}