異步任務如何有條件地返回

Question

您好，我試圖有條件地返回一個異步方法任務。以下是我嘗試的方式。

public string DoMessage(MyObj obj) 
    { 
     string returnStatus = "Processing..."; 
     var storageAccount = CloudStorageAccount.DevelopmentStorageAccount; 
     var queueClient = storageAccount.CreateCloudQueueClient(); 

     var queue = queueClient.GetQueueReference(ConfigurationManager.AppSettings["QueueName"]); 
     if (queue.CreateIfNotExists())   { 
     } 

     var msg = CloudQueueMessageExtensions.Serialize(obj); 
     queue.AddMessage(msg); 

     //Task processTask = RunMessageProces(); 
     var t = Task.Run(() => RunMessageProces()); 
     t.Wait(); 
     return returnStatus; 
    } 

    private async Task<string> RunMessageProces() 
    { 
     statusProcess = "Your message successfully inserted in process queue."; 
     await Task.Run(() => { 
      lock (_oQueue) 
      { 
       if (flagProcessing == true) //return when queue processing alredy started 
       { 
        return statusProcess; //Error ..??? how to return 
       } 
       flagProcessing = true; //else start processing the queue till there are messages. 
      } 
     }); 
     statusProcess = ProcessMyMessage(); 
     return statusProcess; 
    } 

    private string ProcessMyMessage() {...} 

我失蹤了什麼？如何在有條件地返回字符串之間的異步方法裏面也存在等待鎖匿名塊（？）。我在任務中進行異步操作，因爲由於服務的暴露部分，「消息」同時充斥着大量呼叫。

Answer 1

我假設你問如何從任務訪問返回的值。

private async Task<string> RunMessageProces() 
    { 
     var statusProcess = "Your message successfully inserted in process queue."; 
     var retValue = await Task.Run(() => 
     { 
      lock (_oQueue) 
      { 
       if (flagProcessing == true) //return when queue processing alredy started 
       { 
        return "Error"; // or some such error indicator 
       } 
       flagProcessing = true; //else start processing the queue till there are messages. 
      } 
      return string.Empty; // return a string here too.... 
     }); 

     // if(retValue == "Error") { return "Error" } 
     statusProcess = ProcessMyMessage(); 
     return statusProcess; 
    }