如何写＆QUOT; awaitable＆QUOT;方法？ [英] How to write an "awaitable" method?

问题描述

我终于寻找到异步和放大器;等待的关键字，我有种搞定，但所有的例子我见过的.NET Framework中，例如，呼叫异步方法这一，这就要求 HttpClient.GetStringAsync（）。

I'm finally looking into the async & await keywords, which I kind of "get", but all the examples I've seen call async methods in the .Net framework, e.g. this one, which calls HttpClient.GetStringAsync().

什么我不是很清楚就是在这样的方法的推移，我会怎么写我自己的awaitable的方法。它是那样简单包裹code，我想在一个任务异步运行，并返回？

What I'm not so clear on is what goes on in such a method, and how I would write my own "awaitable" method. Is it as simple as wrapping the code that I want to run asynchronously in a Task and returning that?

推荐答案

这是因为

Task.Run(() => ExpensiveTask());

要使它成为一个awaitable方式：

To make it an awaitable method:

public Task ExpensiveTaskAsync()
{
    return Task.Run(() => ExpensiveTask());
}

这里最重要的是返回的任务。该方法甚至没有被异步标记。 （刚看了一点点进一步为它进入图片）

The important thing here is to return a task. The method doesn't even have to be marked async. (Just read a little bit further for it to come into the picture)

现在这可以被称为

async public void DoStuff()
{
    PrepareExpensiveTask();
    await ExpensiveTaskAsync();
    UseResultsOfExpensiveTask();
}

请注意，这里的方法签名说异步，因为该方法可以控制权返回给调用者，直到 ExpensiveTaskAsync（）回报。此外，在这种情况下，昂贵的装置，耗时，例如网络请求或类似。送过重计算到另一个线程，它通常是更好地使用旧的方法，即 System.ComponentModel.BackgroundWorker 的GUI应用程序或 System.Threading.Thread 。

Note that here the method signature says async, since the method may return control to the caller until ExpensiveTaskAsync() returns. Also, expensive in this case means time-consuming, like a web request or similar. To send off heavy computation to another thread, it is usually better to use the "old" approaches, i.e. System.ComponentModel.BackgroundWorker for GUI applications or System.Threading.Thread.

这篇关于如何写＆QUOT; awaitable＆QUOT;方法？的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！