How do I know whether a Task is canceled by a timeout or a manual trigger?

Question

Say I have the following Start and Cancel event handlers. How do I know who was the one who triggered the cancellation?

private CancellationTokenSource cts;
    private async void OnStartClick(object sender, RoutedEventArgs e)
    {
        try
        {
            cts = new CancellationTokenSource();
            cts.CancelAfter(5000);
            await Task.Delay(10000,cts.Token);

        }
        catch (TaskCanceledException taskCanceledException)
        {
            ??? How do i know who canceled the task here ???
        }
    }

    private void OnCancelClick(object sender, RoutedEventArgs e)
    {
        cts.Cancel();
        cts.Dispose();
    }

Answer 1

Store in a field whether the cancel-button was clicked or not:

bool hasUserCancelled = false;

And reset this field before you start:

        hasUserCancelled = false;
        cts = new CancellationTokenSource();
        cts.CancelAfter(5000);

Set it in the cancel-button click handler:

private void OnCancelClick(object sender, RoutedEventArgs e)
{
    hasUserCancelled = true;
    cts.Cancel();
    cts.Dispose();
}

The information that you wanted is now available in the catch:

    catch (TaskCanceledException taskCanceledException)
    {
        Debug.WriteLine(new { hasUserCancelled });
    }