From 5bfbfc5c8924c567cd57ca246396e7b8c02ff3a7 Mon Sep 17 00:00:00 2001
From: PJ Fanning <pjfanning@users.noreply.github.com>
Date: Fri, 8 Aug 2025 08:57:52 +0100
Subject: [PATCH] with Java 17 min - we can call Thread.onSpinWait directly
 (#2021)

---
 .sbt-java-formatter.conf                      |  1 -
 .../pekko/dispatch/affinity/OnSpinWait.java   | 44 -------------------
 .../dispatch/affinity/AffinityPool.scala      |  2 +-
 3 files changed, 1 insertion(+), 46 deletions(-)
 delete mode 100644 actor/src/main/java/org/apache/pekko/dispatch/affinity/OnSpinWait.java

diff --git a/.sbt-java-formatter.conf b/.sbt-java-formatter.conf
index 22dbb93843..c194cf733a 100644
--- a/.sbt-java-formatter.conf
+++ b/.sbt-java-formatter.conf
@@ -13,7 +13,6 @@ ignored-files = [
   "FlightAppModels.java",
 
   //pekko-actor
-  "OnSpinWait.java",
   "AbstractBoundedNodeQueue.java",
   "AbstractMessageDispatcher.java",
   "AbstractNodeQueue.java",
diff --git a/actor/src/main/java/org/apache/pekko/dispatch/affinity/OnSpinWait.java b/actor/src/main/java/org/apache/pekko/dispatch/affinity/OnSpinWait.java
deleted file mode 100644
index a1a6497dff..0000000000
--- a/actor/src/main/java/org/apache/pekko/dispatch/affinity/OnSpinWait.java
+++ /dev/null
@@ -1,44 +0,0 @@
-/*
- * Licensed to the Apache Software Foundation (ASF) under one or more
- * license agreements; and to You under the Apache License, version 2.0:
- *
- *   https://www.apache.org/licenses/LICENSE-2.0
- *
- * This file is part of the Apache Pekko project, which was derived from Akka.
- */
-
-/*
- * Copyright (C) 2009-2022 Lightbend Inc. <https://www.lightbend.com>
- */
-
-package org.apache.pekko.dispatch.affinity;
-
-import java.lang.invoke.MethodHandle;
-import java.lang.invoke.MethodHandles;
-import org.apache.pekko.annotation.InternalApi;
-import static java.lang.invoke.MethodType.methodType;
-
-/**
- * INTERNAL API
- */
-@InternalApi
-final class OnSpinWait {
-    private final static MethodHandle handle;
-
-    public final static void spinWait() throws Throwable {
-        handle.invoke(); // Will be inlined as an invokeExact since the callsite matches the MH definition of () -> void
-    }
-
-    static {
-        final MethodHandle noop = MethodHandles.constant(Object.class, null).asType(methodType(Void.TYPE));
-        MethodHandle impl;
-        try {
-          impl = MethodHandles.lookup().findStatic(Thread.class, "onSpinWait", methodType(Void.TYPE));
-        } catch (NoSuchMethodException nsme) {
-          impl = noop;
-        } catch (IllegalAccessException iae) {
-          impl = noop;
-        }
-        handle = impl;
-  };
-}
\ No newline at end of file
diff --git a/actor/src/main/scala/org/apache/pekko/dispatch/affinity/AffinityPool.scala b/actor/src/main/scala/org/apache/pekko/dispatch/affinity/AffinityPool.scala
index a1be4c479f..c34d39bc9d 100644
--- a/actor/src/main/scala/org/apache/pekko/dispatch/affinity/AffinityPool.scala
+++ b/actor/src/main/scala/org/apache/pekko/dispatch/affinity/AffinityPool.scala
@@ -85,7 +85,7 @@ private[affinity] object AffinityPool {
           idling = true
           transitionTo(Spinning)
         case Spinning =>
-          OnSpinWait.spinWait()
+          Thread.onSpinWait()
           turns += 1
           if (turns > maxSpins)
             transitionTo(Yielding)