What's the best way to cancel a long operation?

Question

I have run into a problem that I'm not sure how to resolve. I have a method that contains a call from a service that populates a data table such as:

private void GetCases()
{
    try
    {
        //Setup our criteria
        Web_search_criteria myCriteria = new Web_search_criteria()
        {
            Keynum = 9, //Use Opening Date Key
            Range_start = "20100101", //01-01-2010
            Range_end = "20121223" //12-23-2013
        };


        //The myCases object is a datatable that is populated from the GetCasesDT() call.
        int status = db.server.GetCasesDT(myCriteria, ref myCases);
    }
    catch (Exception ex)
    {
        XtraMessageBox.Show("Unable to get data: " + ex.Message);
    }
}

So, as you can see, there isn't a way for me to grab just a few cases at a time - it just grabs it all.

Right now, I have this method being called in a BackgroundWorker's DoWork event, and I display another form with a marquee progress bar on it so the user will know that the system is actually doing something. On that form, I have a Cancel button that I subscribe to. Here is the code that does that:

    backgroundWorker1 = new BackgroundWorker() 
    { 
        WorkerSupportsCancellation = true,
        WorkerReportsProgress = true
    };

    //DoWork Event
    backgroundWorker1.DoWork += backgroundWorker1_DoWork;

    //Show the progress bar with subscription to event
    pb.btnCancel.Click += this.CancelBW;
    pb.Show();

    //Run the backgroundworker
    this.backgroundWorker1.RunWorkerAsync();

    //Don't lock up the application
    while (this.backgroundWorker1.IsBusy)
    {
        Application.DoEvents();
    }

I have tried to cancel the BackgroundWorker in the CancelBW event by using CancelAsync(), but then I read more and realize that doesn't work and would only work if I could break up that initial call so the BackgroundWorker could check on progress.

I have thought about using Thread instead of a BackgroundWorker, but have read that Aborting a thread will cause kittens to spontaneously combust.

So, what's the best way for me to handle this in which a user could cancel a long process?

What's the best way to cancel a long operation?

2 Answers