子actor在失败时不会重新启动

Question

我有一个父演员是：

public sealed class PersistenceSupervisor : ReceiveActor
{

    protected override void PreStart()
    {
        base.PreStart();

        Become(Active);
    }

    protected override SupervisorStrategy SupervisorStrategy()
    {
        return new OneForOneStrategy(
            10,
            TimeSpan.FromSeconds(0),
            x =>
            {
                return Directive.Restart;
            });
    }

    private void Active(object message)
    {
        IInventorPersister inventorPersistor = new InventorPersister();
        IActorRef persister = Context.ActorOf(Props.Create<Persister>(inventorPersistor), "persisterActor");
        var task = persister.Ask(message);
        task.Wait();
        Sender.Tell(task.Result);
    }
}

还有用于测试目的的具有随机失败功能的子actor：

public sealed class Persister : ReceiveActor
{
    private readonly IInventorPersister inventorPersister;

    protected override void PreStart()
    {
        base.PreStart();

        Become(ActiveAsync);
    }

    private async void ActiveAsync(object message)
    {
        try
        {
            var savedSender = Context.Sender;
            Task persisting = Persist(message as CreatePublication);
            await persisting;
            savedSender.Tell("Success");
        }
        catch (Exception e)
        {
            throw new Exception(e.ToString());
        }
    }

    public Persister(IInventorPersister inventorPersister)        
    {
        this.inventorPersister = inventorPersister;
    }

    private async Task Persist(CreatePublication message)
    {
        RandomFailure.Fail();    
        // This function is to make an UPDATE query to db        
        await inventorPersister.Persist(message.PublicationNumber, message.Inventors);            
    }

    // Random failure for testing purpose
    private static class RandomFailure
    {
        private static readonly Random R = new Random();
        public static void Fail()
        {
            if (R.Next(0, 2) == 0)
            {
                throw new InvalidOperationException("Random failure");
            }
        }
    }
}

这个想法是重新启动子actor直到它成功。但是，当失败发生时，应用程序会立即停止并崩溃。我很感激任何帮助。非常感谢。

Answer 1

一些更一般的提示：

1. 您正在使用ReceiveActor，它希望通过actor 构造函数中的Receive/ReceiveAsync 方法提供消息处理程序。 Become(ActiveAsync) 由非类型化 Actor 而非 ReceiveActor 继承者使用。
2. 您处于活动状态的异步方法不会返回纯 void 的任务 - 很难预测系统将如何运行，何时会从此类方法引发异常。
3. 不要在actor的构造函数中使用Become，如果没有必要，不要使用PreStart方法。在actor初始化期间抛出的异常总是会导致actor被停止（即使它的监督策略是重新启动它）。

话虽如此，最简单的方法就是向您的演员提供ReceiveAsync 处理程序。

public sealed class Persister : ReceiveActor
{
    private readonly IInventorPersister inventorPersister;

    public Persister(IInventorPersister inventorPersister)
    {
        this.inventorPersister = inventorPersister;
        ReceiveAsync<CreatePublication>(async message =>
        {
            await Persist(message);
            Context.Sender.Tell("Success");
        });
    }
    private async Task Persist(CreatePublication message) { ... }

    ...
}