如何取消并发繁重的任务？

Question

我有一个重型过程的任务在那个体内运行.另外,我们无法访问此方法的主体(繁重的过程),我们必须等到完成该过程.

现在我的问题是,如何在不中断任务的情况下取消,以便我不检查任何值？

我的代码是这样的:

private CancellationTokenSource CTS = new CancellationTokenSource();


public void CallMyMethod(CancellationTokenSource cts)
{
    //
    // Several methods they call each other. And pass tokens to each other.
    MyProcess(cts);
}


private void MyProcess(CancellationTokenSource cts)
{
    CancellationToken token = cts.Token;

    Task.Run(() =>
    {
        token.ThrowIfCancellationRequested(); // Work just when ThrowIfCancellationRequested called. and check that again

        if (token.IsCancellationRequested) // Must be checked every time, and after the investigation not work.
            return;

        // My long time process
        HeavyProcess();  // We have no access to the body of this method

    }, token);
}


private void CancelProcess()
{
    try
    {
        //
        // I want to cancel Now, Just Now not after HeavyProcess completion or checking token again!
        //
        CTS.Cancel();
        CTS.Token.ThrowIfCancellationRequested();
    }
    catch 
    { }
}

在运行之后我可以取消繁重的过程吗？

Answer 1

如果你无法控制长时间运行的方法,那么合作取消就不会起作用.您可以做的是将繁重的作业卸载到不同的进程,并在后台线程中监视进程:

private void MyProcess(CancellationTokenSource cts)
{
    cts.Token.ThrowIfCancellationRequested(); 

    // Move the heavy work to a different process
    var process = Process.Start(new ProcessStartInfo { /*  */ });

    // Register to the cancellation, where if the process is still
    // running, kill it.
    cts.Token.Register(() => 
    {
        if (!process.HasExited)
        {
            process.Kill();
        }
    });
}

现在,当您取消时,您将调用我们终止进程的回调:

private void CancelProcess()
{
    CTS.Cancel();
}