Question

我同时使用改装和 Polly 来调用restful API，我想知道Refits ApiException的重试（如果有的话）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());
}

然后我像这样使用它

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 的正常重试政策是什么？您是否只是制动电路或在一般情况下会采取什么措施来恢复？

答案可能是“这取决于你的服务回报”，但我只想问。

Answer 1

如果返回的ApiException包含有意义的HttpStatusCode StatusCode属性，您当然可以选择哪些StatusCodes值得重试; Polly readme建议：

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

对于所调用的API的ApiException，只知道这些特定于API的错误代表什么，可以指导是否重试它们。

如果您选择断断续续的某种类型的异常，应该通过将断路器包装到PolicyWrap而不是在重试策略的onRetry代表内来实现。 Polly讨论了为什么要断电？＆＃39; here，以及readme circuit-breaker section脚下许多其他断路器博客帖子的链接。

Refit ApiException的最佳重试策略？

1 个答案: