如何避免使用C＃事件处理程序重复while循环？

Question

In a Windows Forms application, i have a ComboBox element and need to run some code pieces periodically when ComboBox element changes.

The problem with code is, when ComboBox Text changes A to B or vice versa ,event handler triggers and previous while(true) loops are still running.

When event handler is triggered, needs to run one infinite loop.

private void comboBox_SelectedIndexChanged(object sender, EventArgs e)
{
    string status = comboBox.SelectedItem.ToString();

    Task.Run(async () =>
    {
        while (true)
        {
            // Running on ui thread
            datagrid.BeginInvoke((MethodInvoker)delegate
            {
                status = comboBox.SelectedItem.ToString();
            });

            if (status == "A")
            {
                Work();
            }

            else if (status == "B")
            {
                anotherWork();
            }
            else if (status == "C")
            {
                someWork();
                break;
            }

            await Task.Delay(3000);
        }
    });
}

Tried with ManualResetEvent, CancellationTokenSource, and bool check but none of them solved the problem.

What is the best practice to prevent repeated while loops?

Edit: Implemented timer already but wanted to while loop trick. I was doing bool check in a wrong way, Owen s answer is accepted.

Answer 1

Add a bool to check whether or not the loop is running:

private bool _loopRunning;

private void comboBox_SelectedIndexChanged(object sender, EventArgs e)
{
    if(_loopRunning)
    {
        return;
    }

    _loopRunning = true;

    string status = comboBox.SelectedItem.ToString();

    Task.Run(async () =>
    {
        // stuff

        _loopRunning = false;
    });
}