Polly-调用异步ExecuteAsync(和类似方法)时，请使用异步定义的策略 [英] Polly - Please use asynchronous-defined policies when calling asynchronous ExecuteAsync (and similar) methods

问题描述

在执行包含以下内容的包装策略时，出现上述异常:重试，断路器和隔板.

I am getting the above exception when executing a wrapped policy including: retry, circuit breaker and bulk head.

我有以下政策:

var sharedBulkhead = Policy.BulkheadAsync(
            maxParallelization: maxParallelizations, 
            maxQueuingActions: maxQueuingActions,
            onBulkheadRejectedAsync: (context) =>
            {
                Log.Info($"Bulk head rejected => Policy Wrap: {context.PolicyWrapKey}, Policy: {context.PolicyKey}, Endpoint: {context.OperationKey}");
                return TaskHelper.EmptyTask;
            }
        );

var retryPolicy = Policy.Handle<Exception>(e => (e is HttpRequestException)).WaitAndRetryAsync(
            retryCount: maxRetryCount,
            sleepDurationProvider: attempt => TimeSpan.FromSeconds(Math.Pow(2, attempt)),
            onRetryAsync: (exception, calculatedWaitDuration, retryCount, context) =>
            {
                Log.Error($"Retry => Count: {retryCount}, Wait duration: {calculatedWaitDuration}, Policy Wrap: {context.PolicyWrapKey}, Policy: {context.PolicyKey}, Endpoint: {context.OperationKey}, Exception: {exception}.");
                return TaskHelper.EmptyTask;
            });

            var circuitBreaker = Policy.Handle<Exception>(e => (e is HttpRequestException)).CircuitBreakerAsync(
            exceptionsAllowedBeforeBreaking: maxExceptionsBeforeBreaking, 
            durationOfBreak: TimeSpan.FromSeconds(circuitBreakDurationSeconds), 
            onBreak: (exception, timespan, context) =>
            {
                Log.Error($"Circuit broken => Policy Wrap: {context.PolicyWrapKey}, Policy: {context.PolicyKey}, Endpoint: {context.OperationKey}, Exception: {exception}");
            },
            onReset: (context) =>
            {
                Log.Info($"Circuit reset => Policy Wrap: {context.PolicyWrapKey}, Policy: {context.PolicyKey}, Endpoint: {context.OperationKey}");
            }
        );

var fallbackForCircuitBreaker = Policy<bool>
         .Handle<BrokenCircuitException>()
         .FallbackAsync(
             fallbackValue: false,
             onFallbackAsync: (b, context) =>
             {
                 Log.Error($"Operation attempted on broken circuit => Policy Wrap: {context.PolicyWrapKey}, Policy: {context.PolicyKey}, Endpoint: {context.OperationKey}");
                 return TaskHelper.EmptyTask;
             }
         );

var fallbackForAnyException = Policy<bool>
            .Handle<Exception>()
            .FallbackAsync(
                fallbackAction: (ct, context) => { return Task.FromResult(false); },
                onFallbackAsync: (e, context) =>
                {
                    Log.Error($"An unexpected error occured => Policy Wrap: {context.PolicyWrapKey}, Policy: {context.PolicyKey}, Endpoint: {context.OperationKey}");
                    return TaskHelper.EmptyTask;
                }
            );


var resilienceStrategy = Policy.WrapAsync(retryPolicy, circuitBreaker, sharedBulkhead);
        var policyWrap = fallbackForAnyException.WrapAsync(fallbackForCircuitBreaker.Wrap(resilienceStrategy));

我这样执行政策:

Task.Run(() =>
        {
            foreach (var changeMessage in changeMessages)
            {
                policyWrap.ExecuteAsync((context) => CallApi(changeMessage), new Context(endPoint));
            }
        });

这将产生上述异常:在调用异步ExecuteAsync(和类似方法)方法时，请使用异步定义的策略."在fallbackForAnyException中.我在做什么错了?

This is producing the said exception: "Please use asynchronous-defined policies when calling asynchronous ExecuteAsync (and similar) methods." inside the fallbackForAnyException. What am I doing wrong?

推荐答案

您在此处组合了同步和异步执行，因此出现了错误消息.这是由于最后一行代码:

You are combining synchronous and asynchronous execution here, hence the error message. This is because of the last line of code:

var policyWrap = fallbackForAnyException.WrapAsync(
    fallbackForCircuitBreaker.Wrap(resilienceStrategy));
                            //^^^^

请注意我突出显示的部分.相反，应该是:

Note the bit I've highlighted. That should instead be:

var policyWrap = fallbackForAnyException.WrapAsync(
    fallbackForCircuitBreaker.WrapAsync(resilienceStrategy));

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