C# 引发异常时，任务未处于错误状态

在以下示例中引发异常（假设engine.Send（…）引发异常），我似乎无法理解为什么我的任务没有处于错误状态：

但我似乎不知道如何将其集成到示例代码中。我是否在开始（）之前调用它？在等待（）之前

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我想让调用程序知道receiverTask抛出了一个异常并失败了。有什么指针吗？

如果我正确理解了这个上下文，您可以省去

.Start（）

而使用

.Wait（）

稍微不同一些。

（我不知道你的

引擎.Send（someObject）

方法是什么，所以我不得不假设。）

假设您的方法返回bool（这没关系，只是为了写下一些东西。

如果是同步的，则返回的任务可以是：

 Task<bool> receiverTask = Task<bool>.Run(async () =>
            await Task<bool>.FromResult(engine.Send(someObject)));

 Task<bool> receiverTask = Task.Run(async () =>
            await engine.Send(someObject));

但您也可以使用Try/Catch块：

 try
 {
    receiverTask.Wait();

    if (receiverTask.Status == TaskStatus.RanToCompletion)
       Console.WriteLine("Completed: {0}  Result: {1}", receiverTask.GetAwaiter().IsCompleted, receiverTask.Result);
 }
 catch (Exception)
 {
    receiverTask.ContinueWith(t =>
    {
       //With continuation
       if (receiverTask.IsFaulted)
          Console.WriteLine(receiverTask.Exception.InnerExceptions[0].Message);
    }, TaskContinuationOptions.OnlyOnFaulted);

       //or without
       //if (receiverTask.IsCanceled)
       //Console.WriteLine(receiverTask.Exception.InnerExceptions[0].Message);
 }

---

ContinueWith实际上在后台调用Start和Wait方法，因此您可以删除这两个调用并用ContinueWith方法替换它们。请选中ReceiveTask.Result.IsFaulted。该任务失败，而不是ReceiveTask。

 Task<bool> receiverTask = Task.Factory.StartNew(async delegate
 {
    bool _result = await Task<bool>.FromResult(engine.Send(someObject));
    return _result;
 }, TaskScheduler.Default).Unwrap();

 Task<bool> receiverTask = Task.Run(async () =>
            await engine.Send(someObject));

 Task<bool> receiverTask = Task.Factory.StartNew(async delegate
 {
    bool _result = await engine.Send(someObject);
    return _result;
 }, TaskScheduler.Current).Unwrap<bool>();

 receiverTask.ContinueWith(t =>
 {
    //Continue on faulted
    Console.WriteLine(receiverTask.GetAwaiter().IsCompleted);
    if (receiverTask.IsFaulted)
       Console.WriteLine(receiverTask.Exception.InnerExceptions[0].Message);
 }, TaskContinuationOptions.OnlyOnFaulted).Wait(0);

 receiverTask.ContinueWith(t =>
 {
    //Continue on canceled
    Console.WriteLine(receiverTask.GetAwaiter().IsCompleted);
    if (receiverTask.IsCanceled)
       Console.WriteLine(receiverTask.Exception.InnerExceptions[0].Message);
 }, TaskContinuationOptions.OnlyOnCanceled).Wait(0);

 receiverTask.ContinueWith(t =>
 {
    //Standard behaviour
    Console.WriteLine(receiverTask.GetAwaiter().IsCompleted);
    Console.WriteLine(receiverTask.Status.ToString());
 }, TaskContinuationOptions.None).Wait();

 //This writes only if no errors have been raised
 if (receiverTask.Status == TaskStatus.RanToCompletion)
    Console.WriteLine("Completed: {0}  Result: {1}", receiverTask.GetAwaiter().IsCompleted, receiverTask.Result);

 try
 {
    receiverTask.Wait();

    if (receiverTask.Status == TaskStatus.RanToCompletion)
       Console.WriteLine("Completed: {0}  Result: {1}", receiverTask.GetAwaiter().IsCompleted, receiverTask.Result);
 }
 catch (Exception)
 {
    receiverTask.ContinueWith(t =>
    {
       //With continuation
       if (receiverTask.IsFaulted)
          Console.WriteLine(receiverTask.Exception.InnerExceptions[0].Message);
    }, TaskContinuationOptions.OnlyOnFaulted);

       //or without
       //if (receiverTask.IsCanceled)
       //Console.WriteLine(receiverTask.Exception.InnerExceptions[0].Message);
 }