#1320 - Implementing readResolve and writeReplace for the DeadLetterActorRef

akka-actor-tests/src/test/scala/akka/serialization/SerializeSpec.scala

@@ -7,6 +7,9 @@ package akka.serialization
 import akka.serialization.Serialization._
 import scala.reflect._
 import akka.testkit.AkkaSpec
+import akka.AkkaApplication
+import java.io.{ ObjectInputStream, ByteArrayInputStream, ByteArrayOutputStream, ObjectOutputStream }
+import akka.actor.DeadLetterActorRef
 
 object SerializeSpec {
   @BeanInfo
@@ -61,5 +64,20 @@ class SerializeSpec extends AkkaSpec {
         case Right(p)        ⇒ assert(p === r)
       }
     }
+
+    "serialize DeadLetterActorRef" in {
+      val outbuf = new ByteArrayOutputStream()
+      val out = new ObjectOutputStream(outbuf)
+      val a = new AkkaApplication()
+      out.writeObject(a.deadLetters)
+      out.flush()
+      out.close()
+
+      val in = new ObjectInputStream(new ByteArrayInputStream(outbuf.toByteArray))
+      Serialization.app.withValue(a) {
+        val deadLetters = in.readObject().asInstanceOf[DeadLetterActorRef]
+        deadLetters must be(a.deadLetters)
+      }
+    }
   }
 }

akka-actor/src/main/scala/akka/actor/ActorRef.scala

@@ -11,6 +11,7 @@ import java.lang.{ UnsupportedOperationException, IllegalStateException }
 import akka.AkkaApplication
 import akka.event.ActorEventBus
 import akka.serialization.Serialization
+import akka.actor.DeadLetterActorRef.SerializedDeadLetterActorRef
 
 /**
  * ActorRef is an immutable and serializable handle to an Actor.
@@ -350,6 +351,15 @@ trait MinimalActorRef extends ActorRef with ScalaActorRef {
 
 case class DeadLetter(message: Any, sender: ActorRef)
 
+object DeadLetterActorRef {
+  class SerializedDeadLetterActorRef extends Serializable { //TODO implement as Protobuf for performance?
+    @throws(classOf[java.io.ObjectStreamException])
+    private def readResolve(): AnyRef = Serialization.app.value.deadLetters
+  }
+
+  val serialized = new SerializedDeadLetterActorRef
+}
+
 class DeadLetterActorRef(val app: AkkaApplication) extends MinimalActorRef {
   val brokenPromise = new KeptPromise[Any](Left(new ActorKilledException("In DeadLetterActorRef, promises are always broken.")))(app.dispatcher)
   override val address: String = "akka:internal:DeadLetterActorRef"
@@ -358,7 +368,13 @@ class DeadLetterActorRef(val app: AkkaApplication) extends MinimalActorRef {
 
   protected[akka] override def postMessageToMailbox(message: Any, sender: ActorRef): Unit = app.eventHandler.notify(DeadLetter(message, sender))
 
-  def ?(message: Any)(implicit timeout: Timeout): Future[Any] = brokenPromise
+  def ?(message: Any)(implicit timeout: Timeout): Future[Any] = {
+    app.eventHandler.notify(DeadLetter(message, this))
+    brokenPromise
+  }
+
+  @throws(classOf[java.io.ObjectStreamException])
+  private def writeReplace(): AnyRef = DeadLetterActorRef.serialized
 }
 
 abstract class AskActorRef(protected val app: AkkaApplication)(timeout: Timeout = app.AkkaConfig.ActorTimeout, dispatcher: MessageDispatcher = app.dispatcher) extends MinimalActorRef {
@@ -373,9 +389,9 @@ abstract class AskActorRef(protected val app: AkkaApplication)(timeout: Timeout
   protected def whenDone(): Unit
 
   protected[akka] override def postMessageToMailbox(message: Any, sender: ActorRef): Unit = message match {
-    case akka.actor.Status.Success(r) ⇒ result.completeWithResult(r)
-    case akka.actor.Status.Failure(f) ⇒ result.completeWithException(f)
-    case other                        ⇒ result.completeWithResult(other)
+    case Status.Success(r) ⇒ result.completeWithResult(r)
+    case Status.Failure(f) ⇒ result.completeWithException(f)
+    case other             ⇒ result.completeWithResult(other)
   }
 
   protected[akka] override def sendSystemMessage(message: SystemMessage): Unit = message match {

akka-actor/src/main/scala/akka/actor/ActorRefProvider.scala

@@ -30,6 +30,7 @@ trait ActorRefProvider {
   private[akka] def evict(address: String): Boolean
 
   private[akka] def deserialize(actor: SerializedActorRef): Option[ActorRef]
+
   private[akka] def serialize(actor: ActorRef): AnyRef
 
   private[akka] def createDeathWatch(): DeathWatch