C# WPF Threading : How to Stop the newly created thread in a event function(Click on a button). without affecting the main thread

Question

Here in the below code I want to stop the thread which is created in StartInvokeExplorer function. Also the starter function in the StartInvokeExplorer is a keyhook function.

public  void InvokeExplorerStart_Click(object sender, RoutedEventArgs e)

{
            Automate.IsInvokeExplorerClicked = true;
            if (InvokeExplorer.Content.Equals("InvokeExplorerStart"))
            {
                InvokeExplorer.Content = "InvokeExplorerStop";
                StartInvokeExplorer();
                //InvokeExplorer.Dispatcher.BeginInvoke(new InvokeExplorerDelegate(StartInvokeExplorer));
            }
            else
            {
                InvokeExplorer.Content = "InvokeExplorerStart";
                StopInvokeExplorer();
            }            
        }  

public void StartInvokeExplorer()
        {
            if (XmlDataGrid.SelectedCells.Count > 0)
            {
                StartupCount = 1;
                thread = new Thread(() =>
                {
                    Starter(StartupCount);
                });
                thread.IsBackground = true;
                thread.Start();

 

            }
            else
            {
                MessageBox.Show("Please select the recorded row to fetch the new data ");
                InvokeExplorer.Content = "InvokeExplorerStart";
            }

        }


private void Starter(int cnt)
        {
            try
            {
                if (cnt > 0)
                {
                    Hook.GlobalEvents().MouseClick += (sender, e) =>
                    {
                       if (e.Button == MouseButtons.Left)
                        {
                            Automate.Show(e);
                        }                      
                    };
                    Hook.GlobalEvents().MouseDoubleClick += (sender, e) =>
                    {
                        Automate.IsDoubleClick = true;
                        Automate.Show(e);
                        Automate.IsDoubleClick = false;
                    };
                    System.Windows.Forms.Application.Run(new ApplicationContext());
                }
                else
                {
                    Hook.GlobalEvents().Dispose();
                }
            }
            catch (Exception ex)
            {
                ErrorLog.Log(ex);
            }
        }

Answer 1

As from what I have understand, you want to stop the running thread. This is how.

First, you need to create some stop logic. In your case, it would be some variable, like:

bool threadShouldRun;

and then inside your thread function, you should create a loop like:

void MyThreadFunc()
{
    while(threadShouldRun)
    {
        threadWork();
        Thread.Sleep(100);
    }
}

When you want to stop the thread, just set your threadShouldRun variable to false.

Sleep is needed here. Without this, thread may use 100% of processor core.

Answer 2

You can use an AutoResetEvent in conjunction with a CancellationToken . Something along the line of (code not tested)

CancellationTokenSource cts;
AutoResetEvent autoResetEvent;
Thread thread;

public void ThreadStart()
{
    cts = new CancellationTokenSource();
    autoResetEvent = new AutoResetEvent();

    thread = new Thread(new ParameterizedThreadStart(ThreadJob));
    thread.Start(cts.Token);
}

public void ThreadStop()
{
    cts?.Cancel();
    thread?.Join();

    cts?.Dispose();
    autoResetEvent?.Dispose();
}

public static void ThreadJob(object obj)
{
    var ct = (CancellationToken)obj;
    while (!ct.IsCancellationRequested)
    {
        if(WaitHandle.WaitAny(new[] { tc.WaitHandle, autoResetEvent}) == 1)
        {
            // Do your stuff
        }
    }
}

public void PerformJobInThread()
{
    autoResetEvent?.Set();
}

This way your thread will run until you call the ThreadStop method (actually, until you cancel your CancellationTokenSource) but you can still control when to "enable" it.