scala - Akka - 询问模式 - 组合结果

Question

我正在设计一个演员系统。centerActor 需要等待 actor1 和 actor2 的结果才能响应客户端。

在中心演员：

def receive: Receive ={
  case request => {
    implicit val timeout = Timeout(1.seconds)
    val ask1 = actor1 ? Update1.mapTo[Int]
    val ask2 = actor2 ? Update2.mapTo[String]
    val response =
      (for(x <- ask1; y <- ask2) yield Done).recover{case _ => FailReply}
    response pipeTo sender
  }
}

在这种设计中，我的发件人（客户端）无法接收Done消息。我不知道为什么。所以我在考虑第二种设计：

def receive: Receive = {
  implicit val timeout = Timeout(1.seconds)
  case request => {
    val ask1 = actor1 ? Update1.mapTo[Int]
    val ask2 = actor2 ? Update2.mapTo[String]
    val response =
      (for(x <- ask1; y <- ask2) yield Done).recover{case _ => FailReply})
    response pipeTo self
    context.become(waiting(sender))
  }
}

def waiting(s: ActorRef) = {

    case Done => 
         s ! Done
         unstashAll()
         context.unbecome()
    case FailReply => s ! FailReply
    case _ => stash()

}