被取消的任务

Question

此服务从两个位置获取令牌并将令牌作为标头附加到每个 HTTP 请求中。我不知道为什么，但我收到了这个错误。我正在处理异步，但这个任务仍然被取消。

public class TokenService : DelegatingHandler, IHostedService
    {
        public IConfiguration Configuration { get; }
        private Timer _timer;
        public IHttpClientFactory _clientFactory;
        protected HttpClient _client_SB;
        protected HttpClient _client_Opsman_SB;
        private readonly IServiceScopeFactory _scopeFactory;
        string connectionString = "";

        public TokenService(IConfiguration configuration, IHttpClientFactory clientFactory, IServiceScopeFactory scopeFactory)
        {
            Configuration = configuration;
            _clientFactory = clientFactory;
            _scopeFactory = scopeFactory;
            connectionString = Configuration.GetConnectionString("DefaultConnection");
            _client_SB = _clientFactory.CreateClient("TestEnv");
            _client_Opsman_SB = _clientFactory.CreateClient("OpsmanTestEnv");
        }

        public Task StartAsync(CancellationToken cancellationToken)
        {
            _timer = new Timer(GetAccessToken, null, 0, 3300000);
            _timer = new Timer(GetAccessTokenOpsMan, null, 0, 3300000);
            return Task.CompletedTask;
        }

        public Task StopAsync(CancellationToken cancellationToken)
        {
            //Timer does not have a stop. 
            _timer?.Change(Timeout.Infinite, 0);
            return Task.CompletedTask;
        }

        public async Task<Token> GetToken(Uri authenticationUrl, Dictionary<string, string> authenticationCredentials)
        {
            HttpClient client = new HttpClient();
            FormUrlEncodedContent content = new FormUrlEncodedContent(authenticationCredentials);
            HttpResponseMessage response = await client.PostAsync(authenticationUrl, content);

            if (response.StatusCode != System.Net.HttpStatusCode.OK)
            {
                string message = String.Format("POST failed. Received HTTP {0}", response.StatusCode);
                throw new ApplicationException(message);
            }

            string responseString = await response.Content.ReadAsStringAsync();
            Token token = JsonConvert.DeserializeObject<Token>(responseString);

            return token;
        }
        private void GetAccessToken(object state)
        {
            Dictionary<string, string> authenticationCredentials_sb = Configuration.GetSection("TestEnvironment:Credentials").GetChildren().Select(x => new KeyValuePair<string, string>(x.Key, x.Value)).ToDictionary(x => x.Key, x => x.Value);
            Token token_sb = GetToken(new Uri(Configuration["TestEnvironment:URL"]), authenticationCredentials_sb).Result;

            _client_SB.DefaultRequestHeaders.Add("Authorization", $"Bearer {token_sb.AccessToken}");
        }

        private void GetAccessTokenOpsMan(object state)
        {

            Dictionary<string, string> authenticationCredentials_opsman_sb = Configuration.GetSection("OpsManTestEnvironment:Credentials").GetChildren().Select(x => new KeyValuePair<string, string>(x.Key, x.Value)).ToDictionary(x => x.Key, x => x.Value);
            Token opsman_token_sb = GetToken(new Uri(Configuration["OpsManTestEnvironment:URL"]), authenticationCredentials_opsman_sb).Result;
            _client_Opsman_SB.DefaultRequestHeaders.Add("Authorization", $"Bearer {opsman_token_sb.AccessToken}");
        }
    }

未处理的异常：System.AggregateException：一个或多个错误 发生了。 （一个任务被取消了。）---> System.Threading.Tasks.TaskCanceledException：任务被取消。 --- 内部异常堆栈跟踪结束 --- 在 System.Threading.Tasks.Task`1.GetResultCore(Boolean waitCompletionNotification）在 ProjectEcho.Services.TestService.GetAccessTokenOpsMan(Object state) in c:\agent_Work09\73\s\Services\TestService.cs:第 73 行 System.Threading.ExecutionContext.RunInternal（ExecutionContext executionContext、ContextCallback 回调、对象状态） --- 从之前抛出异常的位置结束堆栈跟踪 --- 在 System.Threading.TimerQueueTimer.CallCallback() 处 System.Threading.TimerQueueTimer.Fire() 在 System.Threading.TimerQueue.FireNextTimers() }

Answer 1

您需要查看内部异常，您只是报告 AggregateException 但这只是真正的 INNER 异常的包装。

catch (AggregateException agg_ex)
{
   //just get first exception, it will contain the most relevant error.
   var ex = agg_ex.InnerExceptions[0];
}