Addresses see #3470 by adding a method Reactor....

Addresses see #3470 by adding a method Reactor.restart. Review by rompf.

2 files changed, 37 insertions, 24 deletions

diff --git a/src/actors/scala/actors/Actor.scala b/src/actors/scala/actors/Actor.scala
index 988e7dda6c..8caa624f67 100644
--- a/src/actors/scala/actors/Actor.scala
+++ b/src/actors/scala/actors/Actor.scala
@@ -622,24 +622,22 @@ trait Actor extends AbstractActor with ReplyReactor with ActorCanReply with Inpu
     _state == Actor.State.Terminated
   }
 
-  override def start(): Actor = synchronized {
-    if (_state == Actor.State.New) {
-      _state = Actor.State.Runnable
-
-      // Reset various flags.
-      //
-      // Note that we do *not* reset `trapExit`. The reason is that
-      // users should be able to set the field in the constructor
-      // and before `act` is called.
-      exitReason = 'normal
-      shouldExit = false
+  // guarded by this
+  private[actors] override def dostart() {
+    // Reset various flags.
+    //
+    // Note that we do *not* reset `trapExit`. The reason is that
+    // users should be able to set the field in the constructor
+    // and before `act` is called.
+    exitReason = 'normal
+    shouldExit = false
 
-      scheduler newActor this
-      scheduler execute (new Reaction(this))
+    super.dostart()
+  }
 
-      this
-    } else
-      this
+  override def start(): Actor = synchronized {
+    super.start()
+    this
   }
 
   override def getState: Actor.State.Value = synchronized {
diff --git a/src/actors/scala/actors/Reactor.scala b/src/actors/scala/actors/Reactor.scala
index b5b9080c27..1c1dfdbd7a 100644
--- a/src/actors/scala/actors/Reactor.scala
+++ b/src/actors/scala/actors/Reactor.scala
@@ -215,17 +215,32 @@ trait Reactor[Msg >: Null] extends OutputChannel[Msg] with Combinators {
     scheduler executeFromActor makeReaction(null, handler, msg)
   }
 
+  // guarded by this
+  private[actors] def dostart() {
+    _state = Actor.State.Runnable
+    scheduler newActor this
+    scheduler execute makeReaction(() => act(), null, null)
+  }
+
   /**
-   * Starts this $actor.
+   * Starts this $actor. This method is idempotent.
    */
   def start(): Reactor[Msg] = synchronized {
-    if (_state == Actor.State.New) {
-      _state = Actor.State.Runnable
-      scheduler newActor this
-      scheduler execute makeReaction(() => act())
-      this
-    } else
-      this
+    if (_state == Actor.State.New)
+      dostart()
+    this
+  }
+
+  /**
+   * Restarts this $actor.
+   *
+   * @throws java.lang.IllegalStateException  if the $actor is not in state `Actor.State.Terminated`
+   */
+  def restart(): Unit = synchronized {
+    if (_state == Actor.State.Terminated)
+      dostart()
+    else
+      throw new IllegalStateException("restart only in state "+Actor.State.Terminated)
   }
 
   /** Returns the execution state of this $actor.