Cancel Thread Sleep

Question

I have a simple Console application with 2 running threads.

The first thread is measuring some values, and the second thread looks for user input and performs some mouse movements.

while (true)
{
    if (Input.IsKeyDown(VC_L))
    {
        Mouse.Move(300, 500);
        Thread.Sleep(thread1_delay);
        Mouse.Move(670, 300);
        Thread.Sleep(thread1_delay);
        Mouse.Move(870, 700);
        Thread.Sleep(thread1_delay);
    }
}

The problem is I want to stop the second thread as soon as I get another key as input. But it's not working since the thread is still sleeping and doesn't react.

Answer 1

Just use a CancellationToken and be done with it

Propagates notification that operations should be canceled.

Example

public static async Task DoFunkyStuff(CancellationToken token)
{
   // a logical escape for the loop
   while (!token.IsCancellationRequested)
   {
      try
      {
         Console.WriteLine("Waiting");
         await Task.Delay(1000, token);
      }
      catch (OperationCanceledException e)
      {
         Console.WriteLine("Task Cancelled");
      }
   }
   Console.WriteLine("Finished");
}

Usage

static async Task Main(string[] args)
{

   var ts = new CancellationTokenSource();

   Console.WriteLine("Press key to cancel tasks");
   var task = DoFunkyStuff(ts.Token);

   // user input
   Console.ReadKey();

   Console.WriteLine("Cancelling token");

   // this is how to cancel
   ts.Cancel();

   // just to prove the task has been cancelled
   await task;

   // because i can
   Console.WriteLine("Elvis has left the building");
   Console.ReadKey();
}

Results

Press key to cancel tasks
Waiting
Waiting
Waiting
Waiting
Waiting
Cancelling token
Task Cancelled
Finished
Elvis has left the building

Answer 2

The second thread should check for a Boolean value when it wakes up. You should set this value to false when your condition is met. Now when the second thread wakes up it will complete it's execution.