From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Radiation_pi <pi1243039811@outlook.com>
Date: Mon, 25 Mar 2024 23:00:19 +0800
Subject: [PATCH] Virtual Thread for linear flusher


diff --git a/src/main/java/org/dreeam/leaf/config/modules/opt/VT4LinearFlusher.java b/src/main/java/org/dreeam/leaf/config/modules/opt/VT4LinearFlusher.java
new file mode 100644
index 0000000000000000000000000000000000000000..d4576c9930d12548d4302207f61a0eb8b1fa7b7a
--- /dev/null
+++ b/src/main/java/org/dreeam/leaf/config/modules/opt/VT4LinearFlusher.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 VT4LinearFlusher implements IConfigModule {
+
+    @Override
+    public EnumConfigCategory getCategory() {
+        return EnumConfigCategory.PERFORMANCE;
+    }
+
+    @Override
+    public String getBaseName() {
+        return "use_virtual_thread_for_linear_flusher";
+    }
+
+    @ConfigInfo(baseName = "enabled")
+    public static boolean enabled = false;
+
+    @Override
+    public void onLoaded(CommentedFileConfig config) {
+        config.setComment("performance.use_virtual_thread_for_linear_flusher", """
+                 Use the new Virtual Thread introduced in JDK 21 for Linear Region Flusher.
+                """);
+    }
+}
diff --git a/src/main/java/org/purpurmc/purpur/region/LinearRegionFileFlusher.java b/src/main/java/org/purpurmc/purpur/region/LinearRegionFileFlusher.java
index 0d3d9193e8d8f72141dc155840c5eed1a744761c..339157b5e5a81e3c1c5b54fbd9e3c53ea3f51716 100644
--- a/src/main/java/org/purpurmc/purpur/region/LinearRegionFileFlusher.java
+++ b/src/main/java/org/purpurmc/purpur/region/LinearRegionFileFlusher.java
@@ -4,9 +4,12 @@ import com.google.common.util.concurrent.ThreadFactoryBuilder;
 
 import java.util.Queue;
 import java.util.concurrent.*;
+import java.lang.reflect.InvocationTargetException;
+import java.lang.reflect.Method;
 
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
+import org.galemc.gale.virtualthread.VirtualThreadService;
 import org.purpurmc.purpur.PurpurConfig;
 import org.bukkit.Bukkit;
 
@@ -18,12 +21,28 @@ public class LinearRegionFileFlusher {
                     .setNameFormat("linear-flush-scheduler")
                     .build()
     );
-    private final ExecutorService executor = Executors.newFixedThreadPool(
-            PurpurConfig.linearFlushThreads,
-            new ThreadFactoryBuilder()
-                    .setNameFormat("linear-flusher-%d")
-                    .build()
-    );
+
+    private ExecutorService executor;
+
+    {
+        try {
+            if (VirtualThreadService.getJavaMajorVersion() >= VirtualThreadService.minimumJavaMajorVersionWithoutFeaturePreview && org.dreeam.leaf.config.modules.opt.VT4LinearFlusher.enabled) {
+                Method newThreadPerTaskExecutor = Executors.class.getMethod("newThreadPerTaskExecutor", ThreadFactory.class);
+
+                executor = (ExecutorService) newThreadPerTaskExecutor.invoke(null, VirtualThreadService.get().createFactory());
+            } else {
+                throw new UnsupportedOperationException();
+            }
+        } catch (NoSuchMethodException | IllegalAccessException | InvocationTargetException |
+                 UnsupportedOperationException e) {
+            LOGGER.error("Failed to create Virtual Thread executor! Fallback to default executor.");
+            executor = Executors.newFixedThreadPool(
+                    PurpurConfig.linearFlushThreads,
+                    new ThreadFactoryBuilder()
+                            .setNameFormat("linear-flusher-%d")
+                            .build());
+        }
+    }
 
     public LinearRegionFileFlusher() {
         Bukkit.getLogger().info("Using " + PurpurConfig.linearFlushThreads + " threads for linear region flushing.");