C# Background Worker Question

Question

I have a background worker that does basically the following:

1. Find next available file and mark it as in process
2. Process the file and save the updated version as a new file
3. Mark the original as processed

The above steps will need to loop and continue processing while there are files to process.

I would like the Background Worker to be able to be stopped, and I see the WorkerSupportsCancellation setting, but how do I ensure that it can only stop between files, not while a file is being processed?

Answer 1

Set WorkerSupportsCancellation to true, and periodically check the CancellationPending property in the DoWork event handler.

The CancelAsync method only sets the CancellationPending property. It doesn't kill the thread; it's up to the worker to respond to the cancellation request.

eg:

private void myBackgroundWorker_DoWork(object sender, DoWorkEventArgs e)
{
    while( !myBackgroundWorker.CancellationPending )
    {
        // Process another file
    }
}

Answer 2

You have to check CancellationPending procepty of background worker at the end of file processing

    static void Main(string[] args)
            {
                BackgroundWorker bw = new BackgroundWorker();
                bw.DoWork += new DoWorkEventHandler(bw_DoWork);
                bw.WorkerSupportsCancellation = true;
                bw.RunWorkerAsync();
                Thread.Sleep(5000);
                bw.CancelAsync();
                Console.ReadLine();
            }

            static void bw_DoWork(object sender, DoWorkEventArgs e)
            {
                string[] files = new string[] {"", "" };
                foreach (string file in files)
                { 
                    if(((BackgroundWorker)sender).CancellationPending)
                    {
                        e.Cancel = true;
                        //set this code at the end of file processing
                        return;
                    }
                }
            }