From ca09f706eb4557bb35c9c6f71881e44b33fb217f Mon Sep 17 00:00:00 2001
From: Patrik Nordwall <patrik.nordwall@gmail.com>
Date: Wed, 25 Jan 2017 09:01:11 +0100
Subject: [PATCH] Change signature of addJvmShutdownHook

* because with Scala 2.12 it can't infer the right overload
* prefer the `() =>`, but here it's clear that it's a callback
* similar in ActorSystem.registerOnTermination
---
 .../src/main/scala/akka/actor/CoordinatedShutdown.scala     | 6 +++---
 akka-docs/rst/scala/code/docs/actor/ActorDocSpec.scala      | 2 +-
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/akka-actor/src/main/scala/akka/actor/CoordinatedShutdown.scala b/akka-actor/src/main/scala/akka/actor/CoordinatedShutdown.scala
index 472537317d..815a7ed729 100644
--- a/akka-actor/src/main/scala/akka/actor/CoordinatedShutdown.scala
+++ b/akka-actor/src/main/scala/akka/actor/CoordinatedShutdown.scala
@@ -377,14 +377,14 @@ final class CoordinatedShutdown private[akka] (
    * concurrently, but they are running before Akka internal shutdown
    * hooks, e.g. those shutting down Artery.
    */
-  @tailrec def addJvmShutdownHook(hook: () ⇒ Unit): Unit = {
+  @tailrec def addJvmShutdownHook[T](hook: ⇒ T): Unit = {
     if (!runStarted.get) {
       val currentLatch = _jvmHooksLatch.get
       val newLatch = new CountDownLatch(currentLatch.getCount.toInt + 1)
       if (_jvmHooksLatch.compareAndSet(currentLatch, newLatch)) {
         try Runtime.getRuntime.addShutdownHook(new Thread {
           override def run(): Unit = {
-            try hook() finally _jvmHooksLatch.get.countDown()
+            try hook finally _jvmHooksLatch.get.countDown()
           }
         }) catch {
           case e: IllegalStateException ⇒
@@ -404,6 +404,6 @@ final class CoordinatedShutdown private[akka] (
    * hooks, e.g. those shutting down Artery.
    */
   def addJvmShutdownHook(hook: Runnable): Unit =
-    addJvmShutdownHook(() ⇒ hook.run())
+    addJvmShutdownHook(hook.run())
 
 }
diff --git a/akka-docs/rst/scala/code/docs/actor/ActorDocSpec.scala b/akka-docs/rst/scala/code/docs/actor/ActorDocSpec.scala
index bcdd62620a..fbb45b7ff2 100644
--- a/akka-docs/rst/scala/code/docs/actor/ActorDocSpec.scala
+++ b/akka-docs/rst/scala/code/docs/actor/ActorDocSpec.scala
@@ -646,7 +646,7 @@ class ActorDocSpec extends AkkaSpec("""
     //#coordinated-shutdown-addTask
 
     //#coordinated-shutdown-jvm-hook
-    CoordinatedShutdown(system).addJvmShutdownHook { () =>
+    CoordinatedShutdown(system).addJvmShutdownHook {
       println("custom JVM shutdown hook...")
     }
     //#coordinated-shutdown-jvm-hook