wpf - C# Threading/Async: Running a task in the background while UI is interactable

Question

After looking around on both Async/Await and Threading, I'm still unsure of the right way to apply it to my situation. No matter the variation that I try my UI still hangs because I don't seem to be calling my desired function asynchronously, additionally, I may in fact need threading for my solution.

What I'm trying to do: I have a WPF application on which there is a button that I would like to start an operation that still allows interaction with the program, through UI or otherwise. Once a condition is met that is determined outside of this function, the function should end. To me this sounds fairly standard but I have a feeling I'm misunderstanding something and I've implemented it incorrectly.

What I have right now:

private async void start_button_Click(object sender, RoutedEventArgs e)
{
    await StaticClass.MyFunction();
}

private void stop_button_Click(object sender, RoutedEventArgs e)
{
    StaticClass.stopFlag = true;
}

public static Task<int> myFunction()
{
    //Stuff Happens

    while(StaticClass.stopFlag == false)
        //Do Stuff

    //Stuff Happens

    return Task.FromResult(1) //I know this is bad, part of the reason I'm asking
}

I was hoping for some guidance on if I'm approaching this the right way and any insight on what I'm doing wrong.

Answer 1

You've definitely implemented it incorrectly. You're returning a Task<int>, but only once all the work has already been done.

It seems to me that you should probably just have a synchronous method:

private static void MyFunction()
{
    // Loop in here
}

Then start a task for it like this:

Task task = Task.Run((Action) MyFunction);

You can then await that task if you want - although in the example you've given, there's no point in doing so, as you're not doing anything after the await anyway.

I'd also agree with Reed that using a CancellationToken would be cleaner than a static flag somewhere else.