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

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

4 files changed, 70 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.
diff --git a/test/files/jvm/t3470.check b/test/files/jvm/t3470.check
new file mode 100644
index 0000000000..94cb526756
--- /dev/null
+++ b/test/files/jvm/t3470.check
@@ -0,0 +1,3 @@
+A: started: 1
+A: started: 2
+A: started: 3
diff --git a/test/files/jvm/t3470.scala b/test/files/jvm/t3470.scala
new file mode 100644
index 0000000000..5e4242cdd7
--- /dev/null
+++ b/test/files/jvm/t3470.scala
@@ -0,0 +1,30 @@
+import scala.actors._
+
+object Test {
+
+  def expectActorState(a: Reactor[T] forSome { type T }, s: Actor.State.Value) {
+    var done = false
+    var i = 0
+    while (!done) {
+      i = i + 1
+      if (i == 10) { // only wait for 2 seconds total
+        println("FAIL ["+a+": expected "+s+"]")
+        done = true
+      }
+
+      Thread.sleep(200)
+      if (a.getState == s) // success
+        done = true
+    }
+  }
+
+  def main(args: Array[String]) {
+    val a = new Actor { var c = 0; def act() = { c += 1; println("A: started: " + c) } }
+    a.start()
+    expectActorState(a, Actor.State.Terminated)
+    a.restart()
+    expectActorState(a, Actor.State.Terminated)
+    a.restart()
+  }
+
+}