November 2020
Intermediate to advanced
226 pages
5h 34m
Chinese
Content preview from C#并发编程经典实例（第2版）
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94
｜
第
8
章
else
tcs.TrySetResult(result);
});
return
tcs.Task;
}
讨论
可以通过
TaskCompletionSource<T>
模式包装任意异步方法，即使这种方法是非官方的也可以。
首先创建
TaskCompletionSource<T>
实例，然后安排回调函数，这样
TaskCompletionSource<T>
能恰当地完成任务。接着，启动实际的异步操作。最后，返回附属于
TaskCompletionSource<T>
的
Task<T>
。
必须确保
TaskCompletionSource<T>
总能完成，这一点非常关键。尤其是要想清楚如何处理
错误，确保
TaskCompletionSource<T>
能妥善地完成。在上例中，因为异常显式传递至回调
函数，所以不需要
catch
块，但某些非官方模式可能需要在回调函数中捕获异常，并把它
们放到
TaskCompletionSource<T>
中。
参阅
8.1
节探讨用于
EAP
（
Operation
Async
和
Operation
Completed
）的
TAP
包装器。
8.2
节探讨用于
APM
（
Begin
Operation
和
End
Operation
）的
TAP
包装器。
8.4
异步包装并行代码
问题
假设想用
await
消耗
CPU
密集型并行处理。这种做法通常是可取的，这样
UI
线程就不会
阻塞，等待并行处理完成。
解决方案
Parallel
类型和
PLINQ
使用线程池执行并行处理。它们也会包含调用线程，将其作为并
行处理线程之一。因此，如果从 ...
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I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
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I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.