英文:
continue Kotlin coroutine job after cancellation
问题
我希望在一个Kotlin协程被取消后做一点工作（在这个协程内部有一个延迟函数）。使用线程，我可以捕获InterruptedException并做一些工作，然后结束线程。但是使用Kotlin协程，在调用取消后，当执行到延迟函数时，它立即取消了作业。
我知道如果我在协程内部使用Thread.sleep，它会起作用。但是有没有更好的解决方案？我希望在取消后继续作业，而不是在作业被取消时运行一些代码。
英文:
I want to do a little word after a kotlin coroutine is cancelled. (I have a delay function inside this coroutine). by using threads, I can catch InterruptedException and do some work, then finish the thread. but with Kotlin coroutines, it cancels the job immediately after calling cancel, when execution reaches the delay function.
I know if I use Thread.sleep inside coroutine, it will do the job. but is there any better solution?
I want to continue job after cancellation, not run some code if job is canceled
答案1
得分: 1
使用 withContext(NonCancellable) { ... }。在此上下文中运行的代码不会对外部协程的取消做出反应。这意味着诸如 delay 这样的函数不会抛出 CancellationException。
您可以与 try/finally 结合使用，以在协程取消后运行挂起代码。
在此示例中，对 delay 的调用将延迟协程的终止，并且即使协程已被取消，也不会抛出 CancellationException。
try {
// 进行操作
} finally {
withContext(NonCancellable) {
delay(1000)
}
}
有关此机制的更多详细信息，请参阅Kotlin文档。如果您想要更多细节，我还写了一篇更长的文章，介绍了它的工作原理。
请注意，您无法“取消取消”协程。使用 try/finally 与 NonCancellable 结合主要用于运行清理任务。协程 Job 仍标记为已取消，并且协程仍应确保最终终止。
英文:
Use withContext(NonCancellable) { ... }. Code run inside this context won't react to cancellation of the outer coroutine. That means that functions like delay won't throw CancellationException.
You can use this in combination with try/finally to run suspending code after coroutine cancellation.
In this example, the call to delay will delay the termination of the coroutine, and won't throw a CancellationException, even if the coroutine has been cancelled.
try {
// do stuff
} finally {
withContext(NonCancellable) {
delay(1000)
}
}
This mechanism is described in more detail in the Kotlin docs. If you want even more detail, I've also written a longer article about how it works.
Note that you can't "un-cancel" the coroutine. Using try/finally in combination with NonCancellable is primarily intended for running cleanup tasks. The coroutine Job is still marked as cancelled, and the coroutine should still ensure that it eventually terminates.
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