From 3d3a3528bf37f07930cd275f3f629178b64039b3 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Johan=20Andr=C3=A9n?= <johan@markatta.com>
Date: Fri, 2 Sep 2016 16:40:38 +0200
Subject: [PATCH] Eliminated JVM crashing race on transport stop (#21337)

* Eliminated JVM crashing race on transport stop

* Fail explicitly if started more than once
---
 .../akka/remote/artery/ArteryTransport.scala  | 21 +++++++++++--------
 1 file changed, 12 insertions(+), 9 deletions(-)

diff --git a/akka-remote/src/main/scala/akka/remote/artery/ArteryTransport.scala b/akka-remote/src/main/scala/akka/remote/artery/ArteryTransport.scala
index 3aa3c6bfd6..16f82393c2 100644
--- a/akka-remote/src/main/scala/akka/remote/artery/ArteryTransport.scala
+++ b/akka-remote/src/main/scala/akka/remote/artery/ArteryTransport.scala
@@ -6,10 +6,9 @@ package akka.remote.artery
 import java.io.File
 import java.net.InetSocketAddress
 import java.nio.channels.{ DatagramChannel, FileChannel }
-
 import java.util.concurrent.CopyOnWriteArrayList
 import java.util.concurrent.TimeUnit
-import java.util.concurrent.atomic.AtomicLong
+import java.util.concurrent.atomic.{ AtomicLong, AtomicReference }
 
 import scala.annotation.tailrec
 import scala.collection.JavaConverters._
@@ -20,7 +19,6 @@ import scala.util.Failure
 import scala.util.Success
 import scala.util.Try
 import scala.util.control.NonFatal
-
 import akka.Done
 import akka.NotUsed
 import akka.actor._
@@ -276,7 +274,7 @@ private[remote] class ArteryTransport(_system: ExtendedActorSystem, _provider: R
   @volatile private[this] var materializer: Materializer = _
   @volatile private[this] var controlSubject: ControlMessageSubject = _
   @volatile private[this] var messageDispatcher: MessageDispatcher = _
-  @volatile private[this] var mediaDriver: Option[MediaDriver] = None
+  private[this] val mediaDriver = new AtomicReference[Option[MediaDriver]](None)
   @volatile private[this] var aeron: Aeron = _
   @volatile private[this] var aeronErrorLogTask: Cancellable = _
 
@@ -438,19 +436,24 @@ private[remote] class ArteryTransport(_system: ExtendedActorSystem, _provider: R
       log.debug("Started embedded media driver in directory [{}]", driver.aeronDirectoryName)
       topLevelFREvents.loFreq(Transport_MediaDriverStarted, driver.aeronDirectoryName().getBytes("US-ASCII"))
       Runtime.getRuntime.addShutdownHook(stopMediaDriverShutdownHook)
-      mediaDriver = Some(driver)
+      if (!mediaDriver.compareAndSet(None, Some(driver))) {
+        throw new IllegalStateException("media driver started more than once")
+      }
     }
   }
 
-  private def aeronDir: String = mediaDriver match {
+  private def aeronDir: String = mediaDriver.get match {
     case Some(driver) ⇒ driver.aeronDirectoryName
     case None         ⇒ settings.Advanced.AeronDirectoryName
   }
 
   private def stopMediaDriver(): Unit = {
-    mediaDriver.foreach { driver ⇒
+    // make sure we only close the driver once or we will crash the JVM
+    val maybeDriver = mediaDriver.getAndSet(None)
+    maybeDriver.foreach { driver ⇒
       // this is only for embedded media driver
       driver.close()
+
       try {
         if (settings.Advanced.DeleteAeronDirectory) {
           IoUtil.delete(new File(driver.aeronDirectoryName), false)
@@ -461,8 +464,8 @@ private[remote] class ArteryTransport(_system: ExtendedActorSystem, _provider: R
             "Couldn't delete Aeron embedded media driver files in [{}] due to [{}]",
             driver.aeronDirectoryName, e.getMessage)
       }
+      Try(Runtime.getRuntime.removeShutdownHook(stopMediaDriverShutdownHook))
     }
-    Try(Runtime.getRuntime.removeShutdownHook(stopMediaDriverShutdownHook))
   }
 
   // TODO: Add FR events
@@ -683,7 +686,7 @@ private[remote] class ArteryTransport(_system: ExtendedActorSystem, _provider: R
         topLevelFREvents.loFreq(Transport_AeronErrorLogTaskStopped, NoMetaData)
       }
       if (aeron != null) aeron.close()
-      if (mediaDriver.isDefined) {
+      if (mediaDriver.get.isDefined) {
         stopMediaDriver()
         topLevelFREvents.loFreq(Transport_MediaFileDeleted, NoMetaData)
       }