按需演员获取或创建 [英] on demand actor get or else create

问题描述

我可以用 actorOf 创建演员，并用 actorFor 查看他们.我现在想通过一些 id:String 获取一个演员，如果它不存在，我希望它被创建.像这样:

I can create actors with actorOf and look them with actorFor. I now want to get an actor by some id:String and if it doesnt exist, I want it to be created. Something like this:

  def getRCActor(id: String):ActorRef = {
    Logger.info("getting actor %s".format(id))
    var a = system.actorFor(id)
    if(a.isTerminated){
      Logger.info("actor is terminated, creating new one")
      return system.actorOf(Props[RC], id:String)
    }else{
      return a
    }
   }

但这不起作用，因为 isTerminated 总是正确的，我得到 actor name 1 is not unique! 第二次调用的异常.我想我在这里使用了错误的模式.有人可以帮助如何实现这一目标吗?我需要

But this doesn't work as isTerminated is always true and I get actor name 1 is not unique! exception for the second call. I guess I am using the wrong pattern here. Can someone help how to achieve this? I need

• 按需创建演员
• 按 id 查找演员，如果不存在则创建他们
• 继续破坏的能力，因为我不知道我是否会再次需要它

我应该为此使用调度程序还是路由器?

Should I use a Dispatcher or Router for this?

解决方案按照建议，我使用一个具体的主管，将可用的演员保存在地图中.可以要求提供他的一个孩子.

Solution As proposed I use a concrete Supervisor that holds the available actors in a map. It can be asked to provide one of his children.

class RCSupervisor extends Actor {

  implicit val timeout = Timeout(1 second)
  var as = Map.empty[String, ActorRef]

  def getRCActor(id: String) = as get id getOrElse {
    val c = context actorOf Props[RC]
    as += id -> c
    context watch c
    Logger.info("created actor")
    c
  }

  def receive = {

    case Find(id) => {
      sender ! getRCActor(id)
    }

    case Terminated(ref) => {
      Logger.info("actor terminated")
      as = as filterNot { case (_, v) => v == ref }
    }
  }
}

他的伴生对象

object RCSupervisor {

  // this is specific to Playframework (Play's default actor system)
  var supervisor = Akka.system.actorOf(Props[RCSupervisor])

  implicit val timeout = Timeout(1 second)

  def findA(id: String): ActorRef = {
    val f = (supervisor ? Find(id))
    Await.result(f, timeout.duration).asInstanceOf[ActorRef]
  }
  ...
}

推荐答案

我使用 akka 的时间并不长，但演员的创建者默认是他们的主管.因此，父母可以监听他们的终止；

I've not been using akka for that long, but the creator of the actors is by default their supervisor. Hence the parent can listen for their termination;

var as = Map.empty[String, ActorRef] 
def getRCActor(id: String) = as get id getOrElse {
  val c = context actorOf Props[RC]
  as += id -> c
  context watch c
  c
}

但显然你需要注意他们的终止；

But obviously you need to watch for their Termination;

def receive = {
  case Terminated(ref) => as = as filterNot { case (_, v) => v == ref }

这是一个解决方案吗?我必须说我没有完全理解你的意思 终止总是正确的 => 演员姓名 1 不是唯一的！"

Is that a solution? I must say I didn't completely understand what you meant by "terminated is always true => actor name 1 is not unique!"

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