任务链没有TaskCompletionSource？ [英] Task chaining without TaskCompletionSource?

问题描述

我把一些异步/的await code到链式任务，这样我就可以在公布的框架中使用它。该的await code看起来像这样

I'm converting some async/await code to chained tasks, so I can use it in the released framework. The await code looks like this

public async Task<TraumMessage> Get() {
  var message = await Invoke("GET");
  var memorized = await message.Memorize();
  return memorized;
}

其中，

Task<TraumMessage> Invoke(string verb) {}
Task<TraumMessage> Memorize() {}

我希望链调用和背诵来返回由生产任务背诵，但导致任务＆LT;任务＆LT; TraumMessage＆GT; 。我已经结束了该解决方案是一个 TaskCompletionSource＆LT; TraumMessage＆GT; 我的信号：

I was hoping to chain Invoke and Memorize to return the task produced by Memorize, but that results in a Task<Task<TraumMessage>. The solution i've ended up is a TaskCompletionSource<TraumMessage> as my signal:

public Task<TraumMessage> Get() {
  var completion = new TaskCompletionSource<TraumMessage>();
  Invoke("GET").ContinueWith( t1 => {
     if(t1.IsFaulted) {
       completion.SetException(t1.Exception);
       return;
     }
     t1.Result.Memorize().ContinueWith( t2 => {
       if(t2.IsFaulted) {
         completion.SetException(t2.Exception);
         return;
       }
       completion.SetResult(t2.Result);
     });
  });
  return completion.Task;
}

有没有办法做到这一点，而不 TaskCompletionSource ？

推荐答案

我认为这是pretty大有作为你想要什么的唯一方式。链接不同的任务一起不被延续API的支持，因此你不得不求助于使用 TaskCompletionSource 一样，你必须协调工作。

I think that's pretty much the only way to accomplish what you want. Chaining disparate Tasks together isn't supported by the continuation APIs, so you have to resort to using a TaskCompletionSource like you have to coordinate the work.

我没有这台机器上安装了CTP异步，但你为什么不看看在code用反编译（或ILDASM，如果你知道如何阅读IL），看看它在做什么。我敢打赌，它非常类似于您TCS code在幕后的东西。

I don't have the Async CTP installed on this machine, but why don't you take a look at the code with a decompiler (or ILDASM if you know how to read IL) to see what it's doing. I bet it does something very similar to your TCS code under the covers.

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