在akka.net actor中使用async/await是否安全？

Question

在下面的代码中,我使用.net提供的语法糖,async/await方法,但是请注意,这不是在akka中处理异步操作的好方法,我宁愿使用PipeTo().

public class AggregatorActor : ActorBase, IWithUnboundedStash
{
    #region Constructor
    public AggregatorActor(IActorSystemSettings settings, IAccountComponent component, LogSettings logSettings) : base(settings, logSettings)
    {
        _accountComponent = component;
        _settings = settings;
    }
    #endregion

    #region Public Methods

    public override void Listening()
    {

        ReceiveAsync<ProfilerMessages.ProfilerBase>(async x => await HandleMessage(x));
        ReceiveAsync<ProfilerMessages.TimeElasped>(async x => await HandleMessage(x));
    }
    public override async Task HandleMessage(object msg)
    {
        msg.Match().With<ProfilerMessages.GetSummary>(async x =>
        {
            _sender = Context.Sender;
            //Become busy. Stash
            Become(Busy);

            //Handle different request
            await HandleSummaryRequest(x.UserId, x.CasinoId, x.GamingServerId, x.AccountNumber, x.GroupName);
        });
        msg.Match().With<ProfilerMessages.RecurringCheck>(x =>
        {
            _logger.Info("Recurring Message");
            if (IsAllResponsesReceived())
            {
                BeginAggregate();
            }
        });
        msg.Match().With<ProfilerMessages.TimeElasped>(x =>
        {
            _logger.Info("Time Elapsed");
            BeginAggregate();
        });
    }
    private async Task HandleSummaryRequest(int userId, int casinoId, int gsid, string accountNumber, string groupName)
    {
        try
        {
            var accountMsg = new AccountMessages.GetAggregatedData(userId, accountNumber, casinoId, gsid);
            //AskPattern.AskAsync<AccountMessages.AccountResponseAll>(Context.Self, _accountActor, accountMsg, _settings.NumberOfMilliSecondsToWaitForResponse, (x) => { return x; });
            _accountActor.Tell(accountMsg);

            var contactMsg = new ContactMessages.GetAggregatedContactDetails(userId);
            //AskPattern.AskAsync<Messages.ContactMessages.ContactResponse>(Context.Self, _contactActor, contactMsg, _settings.NumberOfMilliSecondsToWaitForResponse, (x) => { return x; });
            _contactActor.Tell(contactMsg);

            var analyticMsg = new AnalyticsMessages.GetAggregatedAnalytics(userId, casinoId, gsid);
            //AskPattern.AskAsync<Messages.AnalyticsMessages.AnalyticsResponse>(Context.Self, _analyticsActor, analyticMsg, _settings.NumberOfMilliSecondsToWaitForResponse, (x) => { return x; });
            _analyticsActor.Tell(analyticMsg);

            var financialMsg = new FinancialMessages.GetAggregatedFinancialDetails(userId.ToString());
            //AskPattern.AskAsync<Messages.FinancialMessages.FinancialResponse>(Context.Self, _financialActor, financialMsg, _settings.NumberOfMilliSecondsToWaitForResponse, (x) => { return x; });
            _financialActor.Tell(financialMsg);

            var verificationMsg = VerificationMessages.GetAggregatedVerification.Instance(groupName, casinoId.ToString(), userId.ToString(), gsid);
            _verificationActor.Tell(verificationMsg);

            var riskMessage = RiskMessages.GeAggregatedRiskDetails.Instance(userId, accountNumber, groupName, casinoId, gsid);
            _riskActor.Tell(riskMessage);

            _cancelable = Context.System.Scheduler.ScheduleTellOnceCancelable(TimeSpan.FromMilliseconds(_settings.AggregatorTimeOut), Self, Messages.ProfilerMessages.TimeElasped.Instance(), Self);
            _cancelRecurring = Context.System.Scheduler.ScheduleTellRepeatedlyCancelable(_settings.RecurringResponseCheck, _settings.RecurringResponseCheck, Self, Messages.ProfilerMessages.RecurringCheck.Instance(), Self);
        }
        catch (Exception ex)
        {
            ExceptionHandler(ex);
        }
    }
    #endregion
}

正如您在示例代码中看到的,我正在使用async/await,并使用Akka.net提供的ReceiveAsync()方法.

如果我们不能在actor中使用async/await,那么ReceiveAsync()的目的是什么？

Answer 1

您可以在actor中使用async/await,但是这需要一些编排来暂停/恢复actor的邮箱,直到异步任务完成.这使得actor不可重入,这意味着它不会选择任何新消息,直到当前任务完成.要在actor中使用async/await,您可以:

1. 使用ReceiveAsync哪个可以采用异步处理程序.
2. 用ActorTaskScheduler.RunTask.包装你的异步方法调用.这在actor生命周期方法(如PreStart/ PostStop)的上下文中通常很有用.

请记住,如果使用默认的actor消息调度程序,这将起作用,但如果将actor配置为使用不同类型的调度程序,则无法保证它可以正常工作.

在演员中使用async/await也会产生性能下降,这与暂停/恢复机制和演员缺乏重入性有关.在许多商业案例中,这不是一个真正的问题,但有时可能是高性能/低延迟工作流程中的问题.