Question

I have an issue with the System.Timers.Timer object. I use the timer object to perform a task at regular intervals. In the timer constructor I call the method doing the work ( DoTimeCheck() ), to ensure that the task is run once at startup also. The work (at regular intervals) is done in a BackgroundWorker.

I call the timer with this:

 UpdaterTimer ut = UpdaterTimer.UpdaterTimerInstance;

My problem is that I need to delay the first run of the task with 3 minutes(the one that runs at application startup). Subsequent runs (Elapsed event) should run without delay. I thought of doing this by calling

System.Threading.Thread.Sleep(TimeToDelayFirstRunInMiliseconds);

but this fails, because it also hangs the UI of the app (main thread) making it unusable. How can I delay the first run of DoTimeCheck() without hanging the UI?
The code of the timer is below. If the issue is not presented in a clear manner please let me know and I will edit. Thank you in advance.

  public sealed class UpdaterTimer : Timer
{
    private static readonly UpdaterTimer _timer = new UpdaterTimer();
    public static UpdaterTimer UpdaterTimerInstance
    {
        get { return _timer; }
    }

    static UpdaterTimer()
    {
        _timer.AutoReset = true;
        _timer.Interval = Utils.TimeBetweenChecksInMiliseconds;
        _timer.Elapsed += new ElapsedEventHandler(_timer_Elapsed);
        _timer.Start();
        DoTimeCheck();

    }

    static void _timer_Elapsed(object sender, ElapsedEventArgs e)
    {
        DoTimeCheck();
    }

    private static void DoTimeCheck()
    {
        //... work here 
    }
}

Answer 1

One way of doing this would be to give the Timer Interval an initial value (e.g. 3 minutes). Then, in your Elapsed event handler, you could change the interval to your regular value which will be used from then on.

 _timer.Interval = Utils.InitialCheckInterval;

 static void _timer_Elapsed(object sender, ElapsedEventArgs e)
 {
     if (_timer.Interval == Utils.InitialCheckInterval)
     {
         _timer.Interval = Utils.RegularCheckInterval;
     }

     DoTimeCheck();
 }