能够处理一些其他的消息之前初始化一个演员 [英] Initializing an actor before being able to handle some other messages

问题描述

我有它创建另一个演员：

I have an actor which creates another one:

class MyActor1 extends Actor {
  val a2 = system actorOf Props(new MyActor(123))
}

第二男主角必须初始化（引导）本身，一旦它创建，仅在它必须能够做其他的工作。

The second actor must initialize (bootstrap) itself once it created and only after that it must be able to do other job.

class MyActor2(a: Int) extends Actor {
  //initialized (bootstrapped) itself, potentially a long operation 
  //how?
  val initValue = // get from a server

  //handle incoming messages
  def receive = {
    case "job1" => // do some job but after it's initialized (bootstrapped) itself
  }
}

所以 MyActor2 的第一件事要做的就是做初始化本身的一些工作。因为它是请求到服务器可能需要一些时间。它成功完成后，才，就必须成为能够通过来处理传入的短信接收。在此之前 - 它必须这样做。

So the very first thing MyActor2 must do is do some job of initializing itself. It might take some time because it's request to a server. Only after it finishes successfully, it must become able to handle incoming messages through receive. Before that - it must not do that.

当然，到服务器的请求必须是异步的（preferably，使用未来，而不是异步，的await 或其他高层次的东西，比如 AsyncHttpClient ）。我知道如何使用的未来，这不是一个问题，虽然。

Of course, a request to a server must be asynchronous (preferably, using Future, not async, await or other high level stuff like AsyncHttpClient). I know how to use Future, it's not a problem, though.

我如何保证？

P.S。我的猜测是，它必须首先发送一个消息给它本身。

p.s. My guess is that it must send a message to itself first.

推荐答案

您可以使用成为方法初始化后改变演员的行为：

You could use become method to change actor's behavior after initialization:

class MyActor2(a: Int) extends Actor {

  server ! GetInitializationData

  def initialize(d: InitializationData) = ???

  //handle incoming messages
  val initialized: Receive = {
    case "job1" => // do some job but after it's initialized (bootstrapped) itself
  }

  def receive = {
    case d @ InitializationData =>
      initialize(d)
      context become initialized
  }
}

请注意，这样的演员会在初始化之前丢弃所有消息。你会使用的 藏匿 ：

Note that such actor will drop all messages before initialization. You'll have to preserve these messages manually, for instance using Stash:

class MyActor2(a: Int) extends Actor with Stash {

  ...

  def receive = {
    case d @ InitializationData =>
      initialize(d)
      unstashAll()
      context become initialized
    case _ => stash()
  }
}

如果你不想使用 VAR 初始化，您可以创建使用初始化行为 InitializationData 是这样的：

If you don't want to use var for initialization you could create initialized behavior using InitializationData like this:

class MyActor2(a: Int) extends Actor {

  server ! GetInitializationData

  //handle incoming messages
  def initialized(intValue: Int, strValue: String): Receive = {
    case "job1" => // use `intValue` and `strValue` here
  }

  def receive = {
    case InitializationData(intValue, strValue) =>
      context become initialized(intValue, strValue)
  }
}

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