任务。取消支持
考虑 this task> task.run 示例。它显示了如何通过取消支持创建任务。
我正在做类似的事情：
Task.Run(()=>{while (!token.IsCancellationRequested()) {...}}, token);
我的问题：
，因为我已经提到了取消令牌，为什么将其作为参数作为参数的目的。
我经常在示例中看到以下代码：
if（token.isCellationRequested）token.throwifcancellationRequelQulationRequequeldeRequrequreDeRequested（）;
此代码的目的是什么？为什么不只是返回该方法呢？
Consider this Task.Run example. It shows how to create a task with cancellation support.
I am doing something similar:
Task.Run(()=>{while (!token.IsCancellationRequested()) {...}}, token);
My questions:
Since I already have a reference to the cancellation token, why the purpose of passing it as a parameter to the
Task.Runinvocation?I often see the following code in examples:
if (token.IsCancellationRequested) token.ThrowIfCancellationRequested();
What's the purpose of this code? Why not just return from the method?
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如果将取消令牌传递给
task.run，如果在启动任务之前已取消令牌，它将永远不会开始为您节省资源（我的意思是不要创建线程等）。如果您只是从方法返回，任务的状态将不会为
取消，它将是rantococtertion。显然，这不是您期望的。另外，您可以将
operationCanceLedException用concellationToken作为参数，这将使task.status.statusbe取消，，但这是艰难而冗长的方式。token.throwifcancellationRequested是简洁的。您只需使用
token.throwifcancellationRequested（）;，无需检查token.iscancellationRequested即可。throwCancellationRequested方法已经这样做。If you pass the cancellation token to
Task.Run, if the token is cancelled before the Task is started, it will never be started saving you resources(I mean by not creating threads etc).If you just return from the method, the Task's Status will not be
Canceled, it will beRanToCompletion. Clearly this isn't what you'll expect.Alternatively you could throw
OperationCanceledExceptionwith theCancellationTokenas parameter, that will make theTask.Statusto beCanceled, but this is the hard and verbose way.token.ThrowIfCancellationRequestedis concise.You could simply use
token.ThrowIfCancellationRequested();, no need to check fortoken.IsCancellationRequested.ThrowIfCancellationRequestedmethod already does this.