异步一路下来？ [英] Async all the way down?

问题描述

试图了解新的异步/待机模式，我有一个问题，我无法找到答案，即我是否应该装饰我的方法与异步的，如果我打算打电话给其他异步功能的方法，或只是返回工作 s其中合适呢？

Trying to understand the new async/await pattern, I have one question which I can't find an answer to, namely if I should decorate my methods with async, if I intend to call those methods from other async functions, or just return Tasks where appropriate?

换句话说，这些类A，B或C的这是最好的，

In other words, which of these classes A, B or C is best, and why?

class A<T>
{
      public async Task<T> foo1() //Should be consumed
      {
          return await foo2();
      }

      public async Task<T> foo2() //Could be consumed
      {
          return await foo3();
      }

      private async Task<T> foo3() //Private
      {
          return await Task.Run(...);
      }
}

class B<T>
{
      public async Task<T> foo1() //Should be consumed
      {
          return await foo2();
      }

      public async Task<T> foo2() //Could be consumed
      {
          return await foo3();
      }

      private Task<T> foo3() //Private
      {
          return Task.Run(...);
      }
}

class C<T>
{
      public async Task<T> foo1() //Should be consumed
      {
          return await foo2();
      }

      public Task<T> foo2() //Could be consumed
      {
          return foo3();
      }

      private Task<T> foo3() //Private
      {
          return Task.Run(...);
      }
}

这似乎是多余的overdecorate方法，所以我很自然地倚向 C ，但在同一时间，感觉有点尴尬与任务＆LT工作; T＆GT ; ，除非您使用等待关键字

It seems redundant to overdecorate methods so I naturally lean toward C, but at the same time it feels somewhat awkward to work with Task<T> unless you use the await keyword.

推荐答案

这两个版本有效的工作是相同的，唯一不同的是，当你使用等待在这里，你会得到的性能损失（因为国家机器必须建立和延续将最有可能被使用）。

Both versions work effectively the same, the only difference is that when you use await here, you get some performance penalty (because the state machine must be set up and a continuation will most likely be used).

因此​​，可以归结为一个权衡：你想对你的方法，由于它是略少可读性的成本在某种程度上更有效率？或者，你愿意牺牲性能可读性？

So, it comes down to a tradeoff: Do you want your methods to be somewhat more efficient at the cost of being slightly less readable? Or are you willing to sacrifice performance for readability?

通常情况下，我会建议你先去为了提高可读性，如果分析告诉你，这是值得的只注重性能。但是，在这种情况下，我觉得在可读性的增加是很小的，所以我可能不会使用等待。

Usually, I would advise you to go for readability first and only focus on performance if profiling tells you it's worth it. But in this case, I think the increase in readability is small, so I would probably not use await.

另外请注意，您的类 C 仍然没有走得足够远： foo1（）也没有需要等待。

Also note that your class C still doesn't go far enough: foo1() also doesn't need await.

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