preStart挂钩：发送给演员本身的消息 [英] preStart hook: a message to the actor itself

问题描述

假设我覆盖了 preStart 钩子，并向 self 发送了一条消息：

Let's say I override the preStart hook and send a message to self:

Class SomeActor extends Actor {

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

  ...

}

我可以期望 SomeMessage 是队列中的第一条消息吗？

Can I expect that SomeMessage will be the first message in the queue?

推荐答案

否，由于actor的创建是异步发生的，因此有人可能在构造函数或 preStart 实际运行之前就已经将消息排队。如果您需要确保先处理此消息，则需要使用成为和隐藏：

No, since actor creation happens asynchronously someone might have enqueued a message before the constructor or preStart actually run. If you need to ensure processing of this message before any other then you’ll need to use become and stash:

self ! SomeMessage

def receive = initial

def initial: Receive = {
  case SomeMessage =>
    // do stuff
    unstashAll()
    context become initialized
  case _ => stash()
}

def initialized: Receive = {
  // your normal behavior
}

您需要混合使用 akka.actor.Stash 特性，并将此actor配置为使用 DequeBasedMailbox 。

You’ll need to mix in the akka.actor.Stash trait and configure this actor to use a DequeBasedMailbox.

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