如何在再次调用事件时中止之前的执行?

这样怎么样:

    private CancellationTokenSource cancellationTokenSource = new CancellationTokenSource();
    public async void OnMainThread()
    {
        cancellationTokenSource.Cancel();
        var newCts = new CancellationTokenSource();
        cancellationTokenSource = newCts;
        try
        {
            var result = await AsyncOp(newCts.Token);
            if (!newCts.IsCancellationRequested)
            {
                // Update UI
            }
        }
        catch (OperationCanceledException)
        {
            // Ignore
        }
    }

    public async Task<int> AsyncOp(CancellationToken cancel)
    {
        // Do the async work
        return 0;
    }