如何在Polly中创建策略以支持http响应重试后标头

Question

我正在尝试创建Polly策略来支持http response retry-after header

 var retryAfterPolicy = Policy
               .HandleResult<HttpResponseMessage>(r => r?.Headers?.RetryAfter != null)
               .WaitAndRetryAsync(retryCount: retryAttemptsBeforeBreaking,
                                    sleepDurationProvider: (count, response, context) => GetServerWaitDuration(response)
                );

上面的代码给我错误，

  

“ PolicyBuilder”不包含“ WaitAndRetryAsync”的定义，最佳扩展方法重载“ RetrySyntaxAsync.WaitAndRetryAsync（PolicyBuilder，int，Func）”要求接收者的类型为“ PolicyBuilder”

如何支持这一点，我还必须将其与其他政策（例如circuitBreakerPolicy）一起包装？

Answer 1

按如下所示更新您的代码，它应该可以工作

            var retryAfterPolicy = Policy
             .HandleResult<HttpResponseMessage>(r => r => r?.Headers?.RetryAfter != null)
             .WaitAndRetryAsync(3, i => TimeSpan.FromSeconds(2), (result, timeSpan, retryCount, context) =>
                          {
                           _logger.LogCritical($"Request failed with {result.Result.StatusCode}. Waiting {timeSpan} before next retry. Retry attempt {retryCount}");
                          });