如何停止BackgroundWorker的DoWork处理程序仅包含一个（长时间运行）语句？

Question

I have a problem with a BackgroundWorker whose DoWork handler contains only one statement. Which means that I cannot check the CancellationPending flag:

private void BackgroundWorker_DoWork(object sender, DoWorkEventArgs e)
{
    CallTimeConsumerFunction();
}

How can I stop this BackgroundWorker ? Is there any work-around?

Answer 1

Looking at .NET 4's Task Parallel Library (TPL), which came after BackgroundWorker and is rather well-designed, can give you an idea how you should approach this.

Cancellation in the TPL is built on the idea of cooperative cancellation . This means that tasks are not forcibly stopped from the outside; instead they participate in the cancellation process by periodically checking whether cancellation has been requested and, if so, by gracefully aborting "from the inside".

I recommend you follow the TPL's example and implement cooperative cancellation. Like this comment states, inject cancellation logic into CallTimeConsumerFunction . For example:

void CallTimeConsumerFunction(Func<bool> shouldCancel)
{                          // ^^^^^^^^^^^^^^^^^^^^^^^
                           // add this; can be called to find out whether to abort or not
    … // possibly lengthy operation
    if (shouldCancel()) return;
    … // possibly lengthy operation
}

private void BackgroundWorker_DoWork(object sender, DoWorkEventArgs e)
{
    CallTimeConsumerFunction(shouldCancel: () => backgroundWorker.CancellationPending);
}                         // ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^