private WaitHandle notifyObject; // Who do notify when object disposed
//
// Private constructor - used to ensure all constructors initialise
// the object in the same way.
//
private Timer(TimerCallback callback, Object state)
{
//
// Validate the parameters.
//
if (callback == null)
{
throw new ArgumentNullException("callback");
}
//
// If this is the first timer constructed allocate resources
// for the timer thread and start it.
//
lock (typeof(Timer))
{
if (Timer.alarmClock == null)
{
if (!Thread.CanStartThreads())
{
throw new NotImplementedException();
}
Timer.alarmClock = new AlarmClock();
Timer.disposeQueue = new System.Collections.Queue();
Timer.now = Timer.UtcMilliseconds();
Timer.threadWakeup = new AutoResetEvent(false);
Timer.timerThread = new Thread(new ThreadStart(Timer.Run));
Timer.timerThread.IsBackground = true;
Timer.timerThread.Start();
}
}
//
// Initialize the timer state.
//
lock (this)
{
this.disposed = false;
this.alarm = Timer.alarmClock.CreateAlarm(
new AlarmClock.AlarmExpiredHandler(this.fireTimer));
this.callback = callback;
this.state = state;
}
}
//
// Advance the time in the Alarm object so it is the same as the
// real time.
//
private static void AdvanceTime(long timerPeriod)
{
long elapsed;
lock (typeof(Timer))
{
long was = Timer.now;
Timer.now = Timer.UtcMilliseconds();
elapsed = Timer.now - was;
}
// if elapsed is less then zero the system time might have been changed to the past.
// so dont sleep. This works well.
if (elapsed < 0)
{
elapsed = 0;
}
// if elapsed is greater then x*timerPeriod the system time might have been changed to the future.
// This is a workaround. but works.
else if (timerPeriod > 0 && elapsed > 10 * timerPeriod)
{
elapsed = 0;
}
Timer.alarmClock.Sleep(elapsed);
}