Question

Consider the following code:

public class EventManager
{
  public Task<string> GetResponseAsync(string request)
  {
    CancellationTokenSource tokenSource = new CancellationTokenSource();

    return new Task<string>( () =>
    {
      // send the request
      this.Send(request);

      // wait for the response until I've been cancelled or I timed out.
      // this is important because I want to cancel my "wait" if either occur

      // WHAT CODE CAN I WRITE HERE TO SEE IF THIS TASK HAS TIMED OUT?
      // (see the example below)
      // 
      // Note that I'm not talking about cancellation
      // (tokenSource.Token.IsCancellationRequested)

      return response;
    }, tokenSource.Token);
  }
}


public static void Main()
{
  EventManager mgr = new EventManager();
  Task<string> responseTask = mgr.GetResponseAsync("ping");
  responseTask.Start();

  if (responseTask.Wait(2000))
  {
    Console.WriteLine("Got response: " + responseTask.Result);
  }
  else
  {
    Console.WriteLine("Didn't get a response in time");
  }
}

Answer 1

You can’t know if your Task timed out because it actually never times out in this sample. The Wait API will block on the Task completing or the specified time ellapsing. If the time ellapses nothing happens to the Task itself, the caller of Wait simply returns with false. The Task continues to run unchanged

If you want to communicate to the Task that you are no longer interested in it’s results the best way is to use cancellation.