xamarin - 使用 Refit 在 Xamarin 中请求开始失败

Question

在短时间内发出大量网络请求后，我们的响应中不断收到“任务已取消”错误，一旦我们开始收到这些错误，在错误停止后发出的任何请求也会返回相同的错误，直到我们重新启动应用程序。我们使用 anAuthenticatedHttpClientHandler来处理请求中的身份验证令牌：

public class AuthenticatedHttpClientHandler : HttpClientHandler
{
    private readonly IReauthService _reauthService;

    public AuthenticatedHttpClientHandler(IReauthService reauthService)
    {
        _reauthService = reauthService;
    }

    protected override async Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
    {
        Debug.WriteLine("Url: " + request.RequestUri);

        var auth = request.Headers.Authorization;

        if (auth != null)
        {
            string token = await _reauthService.GetToken();

            request.Headers.Authorization = new AuthenticationHeaderValue(auth.Scheme, token);
        }

        try
        {
            //Error occurs on this line
            HttpResponseMessage resp = await base.SendAsync(request, cancellationToken).ConfigureAwait(false);

            return resp;
        }
        catch (Exception e)
        {
            //this.GetLogger().LogToDebugConsole("FAILED: " + request.Method + " " + request.RequestUri);
            //this.GetLogger().LogToDebugConsole("Reason: " + e.Message);
            //this.GetLogger().LogToDebugConsole("Stacktrace: " + e.StackTrace);

            Crashes.TrackError(e);

            throw new RequestFailedException(e);
        }
    }
}

我们像这样使用它：

container.RegisterSingleton(() =>
        {
            var handler = container.Resolve<AuthenticatedHttpClientHandler>();

            HttpClient client = new HttpClient(handler)
            {
                BaseAddress = new Uri(UrlConfig.MobileApiBaseUrl + UrlConfig.Version),
                Timeout = TimeSpan.FromSeconds(30)
            };

            var service = RestService.For<IMobileApiClient>(client);
            return service;
        });

30 秒超时不是问题，因为我们所有的请求都在 2 秒以下，我们可以一致地重现错误。

HttpClient每次调用都使用一个实例。我们也使用 MvvmCross，而且这个问题似乎只出现在 iOS 上。我们尝试在项目设置中更改 HttpClientImplementation，并HttpClient在每次调用中使用新实例，但均未奏效。

完整的堆栈跟踪：

==========A task was canceled.==========
==========  at System.Net.Http.MonoWebRequestHandler.SendAsync (System.Net.Http.HttpRequestMessage request, System.Threading.CancellationToken cancellationToken) [0x004ac] in /Library/Frameworks/Xamarin.iOS.framework/Versions/Current/src/Xamarin.iOS/mcs/class/System.Net.Http/MonoWebRequestHandler.cs:507 
at CustomerApp.Core.Networking.LoggingAuthenticatedHttpClientHandler.SendAsync (System.Net.Http.HttpRequestMessage request, System.Threading.CancellationToken cancellationToken) [0x0059f] in /Users/user/VSProjects/CustomerApp/CustomerApp.Core/Networking/AuthenticatedHttpClientHandler.cs:38 ==========

构建设置：