akka unstashAll() not replaying the messages

Question

I have this:

val receive = beforeLoadReceive // my default receive

override def preStart(): Unit = {
  doSomeLoadFromDB()
  unstashAll()
  context.become(connectedReceive)
  println("I also get to here..."
}

def connectedReceive: Receive = {
    case GetData =>
      println("for some reason i'm not getting to here after unstashAll why?")
      sender() ! "this is your data"
}

def beforeLoadReceive: Receive = {
    case GetData =>
      println(s"I get to here so it's stashed")
      stash()
}

so i'm using the stash() I see I get a message to there so its stashed, also I see afterwards that unstashAll() is called but I don't get the message in: connectedReceive any reason for that?

Answer 1

I'd recommend moving DB initialization and unstash/become code to a separate message (say InitDB) handler as preStart() is called before any message is processed. The code below works as expected:

object GetData
object InitDB

class ReporterActor extends Actor {
  val dbActor = context.system.actorOf(Props(new DbActor()))

  override def preStart(): Unit = {
    super.preStart()
    dbActor ! GetData
  }

  def receive = {
    case m: String => {
      println("Received: " + m)
      context.system.terminate()
    }
  }
}

class DbActor extends Actor with Stash {
  val receive = beforeLoadReceive // my default receive

  override def preStart(): Unit = {
    self ! InitDB
  }

  def connectedReceive: Receive = {
    case GetData =>
      println("for some reason i'm not getting to here after unstashAll why?")
      sender() ! "this is your data"
  }

  def beforeLoadReceive: Receive = {
    case InitDB =>
      // doSomeLoadFromDB()
      Thread.sleep(5000)
      context.become(connectedReceive)
      unstashAll()
      println("I also get to here...")

    case GetData =>
      println(s"I get to here so it's stashed")
      stash()
  }
}

val as = ActorSystem()
val actor = as.actorOf(Props(new ReporterActor()))

Await.result(as.whenTerminated, 10.seconds)

Output:

I get to here so it's stashed
I also get to here...
for some reason i'm not getting to here after unstashAll why?
Received: this is your data