java – Akka：在演员系统之外回传？

发布时间：2020-12-15 00:49:06 所属栏目：Java 来源：网络整理

导读：我有以下驱动程序/主类封装我的Akka程序： // Groovy pseudo-codeclass FizzBuzz { ActorSystem actorSystem static void main(String[] args) { FizzBuzz d = new FizzBuzz() d.run() } void run() { Initialize initCmd = new Initialize() MasterActor ma

我有以下驱动程序/主类封装我的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
    }
}

以下ChickenCluckDetector演员：

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),它存在于actor系统之外？我可以提供一个关于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)
        }
    }
}

但我有一种感觉,这违反了Akka的最佳实践,可能导致各种基于并发的问题,特别是如果只有一个FizzBu??zz(有)非演员/驱动程序,以及一万个ChickenCluckDetector演员.想法？

解决方法

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,这个父母可以安全地保存对FizzBu??zz的引用,从他所有的孩子那里收到cluck并调用onCluck方法.

在演员之外获取消息的一个选择是询问.在Scala中有演员DSL(仅为完整性添加).但我相信你的例子中不需要这些.

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);
        }
    }

}

（编辑：李大同）

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