Cannot stop the BackgroundWorker

Question

I know that this question has posted several times, but this situation is different. So supposed that I'm executing a method that need to iterate through several items (database rows), this require a lot of time.
Now in my BackgroundWorker I need in some case to stop the synchronization, in particular when the user press a button. What I did in the _DoWork event is this:

private void worker_DoWork(object sender, DoWorkEventArgs e)
{
    while (!worker.CancellationPending)
    {
        LongOperation();
    }
}

now the problem's that when I call worker.CancelAsync() the LongOperation() continue the execution but shouldn't! 'cause the while have the condition of CancellationPending. I saw in the net that this solution is thread-safe, so maybe am I doing something wrong?

Answer 1

All you need is the following structure

private void runButton_Click(object sender, EventArgs e)
{
    worker=new BackgroundWorker();

    worker.WorkerSupportsCancellation=true;
    worker.RunWorkerCompleted+=Bk_RunWorkerCompleted;
    worker.DoWork+=Bk_DoWork;
    worker.RunWorkerAsync();
}

private void cancelButton_Click(object sender, EventArgs e)
{
    worker.CancelAsync();
}

void ReallyReallyLongOperation(BackgroundWorker worker)
{
    ...within a loop
    if(worker.CancellationPending) 
    {
        return;
    }
}

private void Bk_DoWork(object sender, DoWorkEventArgs e)
{
    ReallyReallyLongOperation(worker);
    if(worker.CancellationPending)
    {
        e.Cancel = true;
    }
}

private void Bk_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
{
    if(!e.Cancelled)
    {
        ...
    }
}