检查参与者的终止并避免向该参与者发送消息

Question

我希望避免给终止的参与者发送死信消息，并避免向该参与者发送消息

class PingActor extends Actor with ActorLogging {
  import PingActor._

  var counter = 0
  var sendMessages = true
  val pongActor = context.actorOf(PongActor.props, "pongActor")
  context.watch(pongActor)

  def receive = {
    case Terminated(pong) =>
      sendMessages = false


    case Initialize =>
        println("In PingActor - starting ping-pong")
      pongActor ! PingMessage("ping")
    case PongActor.PongMessage(text) =>
      println("In PingActor - received message: {}", text)
      counter += 1
      if (counter == 10 ) context.system.shutdown()
      else {
        context.actorSelection(pongActor.path) ! PingMessage("ping")
      }
  } 
}
class PongActor extends Actor with ActorLogging {
  import PongActor._
  var counter = 0

  def receive = {
    case PingActor.PingMessage(text) => 
      println(s"In PongActor - received message: $text counter = $counter \n reply with pong message")

      if (counter < 5) {
        counter = counter + 1
      }
      else
        {
          println("Oh crap , bye bye ")
          context.stop(self)
        }
      sender() ! PongMessage("pong")

  }

actorSelection没有像我预期的那样工作，从ping发送的最后一条消息仍然以一纸空文告终：

[信息][09/16/2016 00:47:46.237][MyActorSystem-Akka.Actor.Default-Dispatcher-4][Akka://MyActorSystem/User/PingActor/PongActor]从参与者[Akka://MyActorSystem/User/PingActor#1697177867]到参与者[Akka://MyActorSystem/User/PingActor/PongActor#524615423]的消息[com.example.PingActor$PingMessage]未传递。[1]遇到的一纸空文。可以通过配置设置'Akka.log-dead-letters'和'Akka.log-dead-letters-dhider-shutdown'关闭或调整此日志记录。

Answer 1

基于actors的异步特性，我认为您不能继续使用actorselection。我认为，一旦您收到terminated消息，您就可以确定该演员已经死亡。但是，当参与者死亡时，邮箱中等待处理的邮件可能仍然很少。您可以做的是让另一个参与者监听deadletter通道，如果该参与者收到了一条本来要发送给其他参与者的消息，则该参与者就会执行操作。