scala.actors: Fixed race in TimerThread

2 files changed, 9 insertions, 4 deletions

diff --git a/src/actors/scala/actors/Actor.scala b/src/actors/scala/actors/Actor.scala
index 55bfb662b9..df2ec1571b 100644
--- a/src/actors/scala/actors/Actor.scala
+++ b/src/actors/scala/actors/Actor.scala
@@ -329,6 +329,9 @@ trait Actor extends OutputChannel[Any] {
     if (shouldExit) exit()
     this.synchronized {
       tick()
+      // first, remove spurious TIMEOUT message from mailbox if any
+      val spurious = mailbox.extractFirst((m: Any) => m == TIMEOUT)
+
       val qel = mailbox.extractFirst((m: Any) => f.isDefinedAt(m))
       if (null eq qel) {
         if (msec == 0) {
@@ -392,6 +395,9 @@ trait Actor extends OutputChannel[Any] {
     Scheduler.pendReaction
     this.synchronized {
       tick()
+      // first, remove spurious TIMEOUT message from mailbox if any
+      val spurious = mailbox.extractFirst((m: Any) => m == TIMEOUT)
+
       val qel = mailbox.extractFirst((m: Any) => f.isDefinedAt(m))
       if (null eq qel) {
         waitingFor = f.isDefinedAt
@@ -504,6 +510,7 @@ trait Actor extends OutputChannel[Any] {
   private[actors] var isDetached = false
   private[actors] var isWaiting = false
 
+  // guarded by lock of this
   private[actors] def scheduleActor(f: PartialFunction[Any, Unit], msg: Any) =
     if ((f eq null) && (continuation eq null)) {
       // do nothing (timeout is handled instead)
diff --git a/src/actors/scala/actors/TimerThread.scala b/src/actors/scala/actors/TimerThread.scala
index 1c5a65959e..397c489414 100644
--- a/src/actors/scala/actors/TimerThread.scala
+++ b/src/actors/scala/actors/TimerThread.scala
@@ -70,8 +70,7 @@ object TimerThread extends AnyRef with Runnable {
         // process guys waiting for signal and empty list
         for (val wa <- lateList) {
           if (wa.valid) {
-            wa.actor.continuation = null
-            wa.actor.scheduleActor(wa.f, TIMEOUT)
+            wa.actor ! TIMEOUT
           }
         }
         lateList = Nil
@@ -90,8 +89,7 @@ object TimerThread extends AnyRef with Runnable {
   def requestTimeout(a: Actor, f: PartialFunction[Any, Unit], waitMillis: long): unit = synchronized {
     val wakeTime = now + waitMillis
     if (waitMillis <= 0) {
-      a.continuation = null
-      a.scheduleActor(f, TIMEOUT)
+      a ! TIMEOUT
       return
     }