java - Akka:在 actor 系统之外进行通信？

Question

我有以下驱动程序/主类封装了我的 Akka 程序:

// Groovy pseudo-code
class FizzBuzz {
    ActorSystem actorSystem

    static void main(String[] args) {
        FizzBuzz d = new FizzBuzz()
        d.run()
    }

    void run() {
        Initialize initCmd = new Initialize()
        MasterActor master = actorSystem.get(...)

        // Tells the entire actor system to initialize itself and start doing stuff.
        // ChickenCluckDetector is an actor managed/supervised by MasterActor.
        master.tell(initCmd, ...)
    }

    // Called when a ChickenCluckDetector actor inside the actor system receives
    // a 'Cluck' message.
    void onChickenGoesCluck(Cluck cluck) {
        // Do something
    }
}

以及以下 ChickenCluckDetector 参与者:

class ChickenCluckDetector extends UntypedActor {
    @Override
    void onReceive(Object message) {
        if(message instanceof Cluck) {
            Cluck cluck = message as Cluck

            // Now, how to pass the message safely/properly to FizzBuzz#onCluck?
        }
    }
}

所以手头的问题是如何安全/正确地将 Cluck 消息传递给 FizzBu​​zz#onCluck(Cluck)，在外面 actor 系统？ 我可以 提供对ChickenCluckDetector 的FizzBu​​zz 引用，如下所示:

class ChickenCluckDetector extends UntypedActor {
    FizzBuzz fizzBuzz

    @Override
    void onReceive(Object message) {
        if(message instanceof Cluck) {
            Cluck cluck = message as Cluck

            fizzBuzz.onCluck(cluck)
        }
    }
}

但我觉得这违反了 Akka 的最佳实践，并可能导致各种基于并发的问题，特别是如果只有一个 FizzBu​​zz(存在)非 Actor /驱动程序，并且十个千 ChickenCluckDetector Actor 。想法？

Answer 1

if there's only one FizzBuzz (which there is) non-actor/driver, and ten thousand ChickenCluckDetector actors

那么最好为所有这些 ChickenCluckDetectors 创建一个共同的父级。然后，该父级可以安全地持有对 FizzBu​​zz 的引用，接收来自他所有子级的咯咯声并调用 onCluck 方法。

在 actors 之外获取消息的一个选项是询问。在 Scala 中有 actor DSL(添加只是为了完整性)。但我相信您的示例中不需要这些。

public class ChickenCluckMaster extends UntypedActor {

    private FizzBuzz fizzBuzz;

    public ChickenCluckMaster(FizzBuzz fizzBuzz) {
        this.fizzBuzz = fizzBuzz;
    }

    public void onReceive(Object message) throws Exception {
        if (message instanceOf CreateDetector) {
            getContext().actorOf(
                Props.create(ChickenCluckDetector.class, getSelf); // Create child
        } else if (message instanceof Cluck) {
            fizzBuzz.onCluck(cluck);
        } else {
            unhandled(message);
        }
    }

}

public class ChickenCluckDetector extends UntypedActor {

    private ActorRef master;

    public ChickenCluckDetector(ActorRef master) {
        this.master = master;
    }

    public void onReceive(Object message) throws Exception { 
        if (message instanceof Cluck) {
            Cluck cluck = (Cluck) message;
            master.tell(cluck, getSelf);
        } else {
            unhandled(message);
        }
    }

}