相关疑难解决方法(0)

目前我有这个要求:

await url
    .SetQueryParams(queryString)
    .SetClaimsToken()
    .GetJsonAsync<T>()

我现在想开始使用Polly(https://github.com/App-vNext/Polly)来处理重试并提供更好的用户体验.例如,由于网络连接不良,第一次尝试时不会"挂断"用户.这是我尝试使用的示例:

int[] httpStatusCodesWorthRetrying = { 408, 500, 502, 503, 504 };
Policy
    .Handle<HttpException>()
    .OrResult<HttpResponse>(r => httpStatusCodesWorthRetrying.Contains(r.StatusCode))
    .WaitAndRetryAsync(new[] {
                    TimeSpan.FromSeconds(1),
                    TimeSpan.FromSeconds(2),
                    TimeSpan.FromSeconds(3)
                })
    .ExecuteAsync( await url... )

但它需要HttpResponse是返回类型.正如你从我的Flurl例子中看到的那样,它正在返回T,即使它是一个HttpResponse.这T只是用于反序列化的类型StringContent.

第一个例子根本不起作用,因为我在PCL中使用它并且我无法获得对它的引用System.Web.所以我尝试了这个:

Policy
    .HandleResult(HttpStatusCode.InternalServerError)
    .OrResult(HttpStatusCode.BadGateway)
    .OrResult(HttpStatusCode.BadRequest)
    .WaitAndRetryAsync(new[] {
        TimeSpan.FromSeconds(1),
        TimeSpan.FromSeconds(2),
        TimeSpan.FromSeconds(3)
    })
    .ExecuteAsync(async () =>
    {
        await url...
    });

但是这个也不起作用,因为Polly期望HttpStatusCode作为回归类型.所以我的问题是:我如何告诉polly处理那些HttpStatusCode并仍允许我返回类型T？

如果 HTTP 调用失败，我在非常基本的场景中使用 Polly 进行指数退避：

protected override async Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
{
    return await HandleTransientHttpError()
        .Or<TimeoutException>()
        .WaitAndRetryAsync(4, retryAttempt => TimeSpan.FromSeconds(Math.Pow(3, retryAttempt)))
        .ExecuteAsync(async () => await base.SendAsync(request, cancellationToken).ConfigureAwait(false));
}

private static PolicyBuilder<HttpResponseMessage> HandleTransientHttpError()
{
    return Policy
        .HandleResult<HttpResponseMessage>(response => (int)response.StatusCode >= 500 || response.StatusCode == System.Net.HttpStatusCode.RequestTimeout)
        .Or<HttpRequestException>();
}

我有一个测试 API，它只是HttpListener在while(true). 目前，我正在尝试测试客户端在每次调用收到 500 时是否正确重试。

while (true)
{
    listener.Start();
    Console.WriteLine("Listening...");
    HttpListenerContext context = listener.GetContext();
    HttpListenerRequest request = context.Request;

    HttpListenerResponse response = context.Response;
    response.StatusCode = (int)HttpStatusCode.InternalServerError;

    //Thread.Sleep(1000 * 1); …