CODEWITHSUNDEEP
c#multithreadingwinformsbutton
Mead Alsorani
Mead Alsorani

Reputation: 51

Enable/Disable buttons while thread is working

I have a button that starts two threads

private void CrawdBtn_Click(object sender, EventArgs e)
{
    CrawdBtn.Enabled = false;
    t = new Thread(AddLinksToList);
    b = new Thread(EnqueueFromList);
    t.Start();
    b.Start();            
}

and there are another buttons to pause, Resume, Stop those threads My question is how can I disable (pause, Resume, Stop) buttons while the threads are working and re enable Crawl after the threads finished

Upvotes: 2

Views: 1301

Answers (2)

ad79h
ad79h

Reputation: 53

To solve your problem you can make a thread to check the ThreadState of thread t and thread b

private void btnstart_Click(object sender, EventArgs e)
{
  
    t = new Thread(AddLinksToList);
    b = new Thread(EnqueueFromList);


    t.Start();
    b.Start();
    if (threadchecker == null)//this if determines Whether it's the first time or not
    {
        threadchecker = new Thread(() => ChekingStateOfThreads());
        threadchecker.IsBackground = true;
        threadchecker.Start();
    }
}

Since the thread wants to check the ThreadState of those threads it should always run. and This is ChekingStateOfThreads

private void ChekingStateOfThreads()
{
    while (true)
    {
        Thread.Sleep(1000);
   
        if (t.ThreadState == ThreadState.Stopped)
        {
            this.Invoke(new Action(() =>
            {
                btnpause.Enabled = btnstart.Enabled = false;
                btnresume.Enabled = btnstop.Enabled = true;
            }));
        }
        else if (t.ThreadState == ThreadState.Running)
        {
            this.Invoke(new Action(() =>
            {
                btnstart.Enabled = btnresume.Enabled = false;
                btnpause.Enabled = btnstop.Enabled = true;
            }));
        }
        else if (t.ThreadState == ThreadState.Aborted)
        {
            this.Invoke(new Action(() =>
            {
                btnstart.Enabled = true;
                btnpause.Enabled = btnresume.Enabled = btnstop.Enabled = false;
            }));
        }
        else if (t.ThreadState == ThreadState.Suspended)
        {
            this.Invoke(new Action(() =>
            {
                btnpause.Enabled = btnstart.Enabled = false;
                btnresume.Enabled = btnstop.Enabled = true;
            }));
        }
    }
}

The concept of function is pretty simple. Each 1 second the thread is check the state of thread t.

See Why use Invoke on Controls in .net? to figure out why should we use INVOKE.

To abort the threadchecker just use the Form_closing Event

private void Form1_FormClosed(object sender, FormClosedEventArgs e)
{
    threadchecker.Abort();
}

Upvotes: 1

Theodor Zoulias
Theodor Zoulias

Reputation: 43748

Here is how you could start a Thread and have a way to await its completion:

public static Thread CreateAwaitableThread(Action action, out Task threadCompletion)
{
    var tcs = new TaskCompletionSource<bool>();
    threadCompletion = tcs.Task;
    return new Thread(() =>
    {
        try
        {
            action();
        }
        finally
        {
            tcs.SetResult(true);
        }
    });
}

This method returns the newly created Thread, and also a Task that will be completed when the Thread is completed. You could use it like this:

private async void CrawdBtn_Click(object sender, EventArgs e)
{
    CrawdBtn.Enabled = false;
    Thread t1 = CreateAwaitableThread(AddLinksToList, out var t1c);
    Thread t2 = CreateAwaitableThread(EnqueueFromList, out var t2c);
    t1.Start();
    t2.Start();
    await Task.WhenAll(t1c, t2c);
    CrawdBtn.Enabled = true;
}

In case of an exception the error will not be propagated through the Task. It is assumed that the delegates already include error handling logic. If not, an unhandled exception will occur as usual.

Upvotes: 1

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