scala - Akka确保毒丸被消耗

Question

我想要一个在 Akka actor 处理 PoisonPill 时完成的 future 。

我试过:

一些引用？毒丸

但这永远不会完成。我认为你只能使用 '!'并不是 '？'。有什么想法吗？

Answer 1

如果您想要监视某个子 actor 的生命周期，您可以简单地 watch 该 actor 并根据您的逻辑处理 Terminated 消息。例如:

class MyActor extends Actor {

  import context._ // to avoid writing context everywhere

  val child = actorOf(Props(new ChildActor)) // ChildActor is the type of the actor you are monitoring, the child
  watch(child) // subscribe to the Terminated message of the child

  override def receive: Receive = {
    case "kill" ⇒ child ! PoisonPill // kill the child. You could also use context.stop(child)
    case Terminated(`child`) ⇒ println("child died") // handle the termination of the child. Use back-ticks to make child a stable identifier
    case _ ⇒ println("meh") // who cares
  }
}

现在，如果你想要一个显式的 Future，我脑海中浮现的第一件事就是传递一个 Promise 给你想要观看的 Actor ，并覆盖 postStop 完成 promise 。它看起来像这样:

class MyActor(p: Promise[Unit]) extends Actor { // receive the Promise to complete

  override def receive: Receive = {
    case _ ⇒ println("meh") // who cares
  }

  override def postStop(): Unit = { // after stopped
    p.tryComplete(Success(())) // complete the promise
  }
}

object Main {
  def main(args: Array[String]) {
    val system = ActorSystem("test")
    val p = Promise[Unit]()
    val f = p.future // get the future from the promise
    val a = system.actorOf(Props(new MyActor(p))) // send the promise to the actor you want to watch

    f onSuccess { // register a callback when the future completes
      case _ ⇒ println("actor died")
    }

    a ! "foo"
    a ! PoisonPill
  }
}

希望对您有所帮助。干杯!