From d0882858cdabbe8f0f40243899b79caa310f08e3 Mon Sep 17 00:00:00 2001
From: He-Pin <hepin1989@gmail.com>
Date: Sun, 19 Jan 2025 12:15:34 +0800
Subject: [PATCH] feat: Add LoadMetrics support for virtual thread executor.

---
 .../pekko/dispatch/VirtualThreadSupport.scala   | 17 +++++++++++++++++
 project/JdkOptions.scala                        |  2 ++
 2 files changed, 19 insertions(+)

diff --git a/actor/src/main/scala/org/apache/pekko/dispatch/VirtualThreadSupport.scala b/actor/src/main/scala/org/apache/pekko/dispatch/VirtualThreadSupport.scala
index 955cdc17102..430b3bfc451 100644
--- a/actor/src/main/scala/org/apache/pekko/dispatch/VirtualThreadSupport.scala
+++ b/actor/src/main/scala/org/apache/pekko/dispatch/VirtualThreadSupport.scala
@@ -73,6 +73,23 @@ private[dispatch] object VirtualThreadSupport {
     }
   }
 
+  /**
+   * Try to get the default scheduler of virtual thread.
+   */
+  def getVirtualThreadDefaultScheduler: ForkJoinPool =
+    try {
+      require(isSupported, "Virtual thread is not supported.")
+      val clazz = Class.forName("java.lang.VirtualThread")
+      val fieldName = "DEFAULT_SCHEDULER"
+      val field = clazz.getDeclaredField(fieldName)
+      field.setAccessible(true)
+      field.get(null).asInstanceOf[ForkJoinPool]
+    } catch {
+      case NonFatal(e) =>
+        // --add-opens java.base/java.lang=ALL-UNNAMED
+        throw new UnsupportedOperationException("Failed to create newThreadPerTaskExecutor.", e)
+    }
+
   /**
    * Try to get the default scheduler of virtual thread.
    */
diff --git a/project/JdkOptions.scala b/project/JdkOptions.scala
index 852a2bb82da..27fca13cbed 100644
--- a/project/JdkOptions.scala
+++ b/project/JdkOptions.scala
@@ -49,6 +49,8 @@ object JdkOptions extends AutoPlugin {
 
   lazy val versionSpecificJavaOptions =
     if (isJdk17orHigher) {
+      // for virtual threads
+      "--add-opens=java.base/java.lang=ALL-UNNAMED" ::
       // for aeron
       "--add-opens=java.base/sun.nio.ch=ALL-UNNAMED" ::
       // for LevelDB