Refit ApiException 的最佳重试策略？

Question

我正在使用 Refit 和 Polly 来调用 restful API 和我我想知道 Refits ApiException 的重试（如果有的话）策略应该是什么？

public static PolicyWrap MyRetryPolicy()
{
        // Try few times with little more time between... maybe the 
        // connection issue gets resolved
        var wireServerNetworkIssue = Policy.Handle<WebException>() 
                                    .WaitAndRetryAsync(new[] {
                                    TimeSpan.FromSeconds(1),
                                    TimeSpan.FromSeconds(2),
                                    TimeSpan.FromSeconds(4)});
        var policyList = new List<Policy>();

        // But if there is something wrong with the api
        // I should do what (if general)?
        var api = Policy.Handle<ApiException>()
                  .RetryAsync(1, onRetry: async (exception, i) =>
                  {
                       await Task.Run(() =>
                       {
                           // What would be normal to do here?
                           // Try again or do some circuit braking?
                       });
                  });

        policyList.Add(wireServerNetworkIssue);
        policyList.Add(api);

        return Policy.Wrap(policyList.ToArray());
}

然后我就这样使用它

try
{
    myApi = RestService.For<MyApi>("api base url");
    var policyWrapper = Policies.Policies.MyRetryPolicyWrapper();
    var response  = await policy.ExecuteAsync(() => myApi.SendReceiptAsync(receipt));
}
catch (ApiException apiEx)
{
  //Do something if the retry policy did´t fix it.
}
catch (WebException webEx)
{
  //Do something if the retry policy did´t fix it.
}

问题

ApiExceptions的正常重试策略是什么？你会只是电路制动还是在什么一般情况下你会做些什么来恢复？

答案可能是"it depends on what your service returns"，但我不得不问。

Answer 1

如果返回的 ApiException 包含有意义的 HttpStatusCode StatusCode properties, you could certainly choose which of those StatusCodes merit a retry; the Polly readme 建议：

int[] httpStatusCodesWorthRetrying = {408, 500, 502, 503, 504};

对于特定于 API 调用的 ApiException，只有了解那些特定于 API 的错误代表什么，才能指导是否重试它们。

如果您选择对某种类型的太多异常进行熔断，那应该通过将熔断器包装到您的 PolicyWrap, rather than within the onRetry delegate of the retry policy. Polly discusses 'Why circuit-break?' here, and links to a number of other circuit-breaker blog posts at the foot of the readme circuit-breaker section.

中来实现

Refit ApiException 的最佳重试策略？

Best retry policy for Refit ApiException?

c#

asp.net-web-api2

refit

polly