//
// Unregisters the registered take.
//
public bool Unregister()
{
//
// If the unregister is being called from the callback method,
// we just set the *onlyOnce* to *true* and return.
//
if (cbtid == Thread.CurrentThread.ManagedThreadId)
{
executeOnce = true;
return(true);
}
//
// If the take is registered, we try to unregister it, and return
// only after the wait is actually unregistered.
// If the take was already unregistered or an unregister is taking
// place, this method returns false.
//
StSpinWait spinner = new StSpinWait();
StParker pk = new StParker(0);
StParker oldState;
do
{
if ((oldState = state) == INACTIVE)
{
return(false);
}
if (oldState == ACTIVE)
{
if (Interlocked.CompareExchange <StParker>(ref state, pk, ACTIVE) == ACTIVE)
{
break;
}
}
else if (!(oldState is SentinelParker))
{
return(false);
}
spinner.SpinOnce();
} while (true);
//
// Try to cancel the callback parker. If we succeed, call the unpark
// with status cancelled. Otherwise, a callback is taking place and
// we must wait until its completion.
//
if (cbparker.TryCancel())
{
cbparker.Unpark(StParkStatus.TakeCancelled);
}
else
{
pk.Park(BUSY_SPINS, StCancelArgs.None);
}
//
// Set the registered take object to inactive and return success.
//
state = INACTIVE;
return(true);
}
//
// Sets the timer.
//
public bool Set(int dueTime, int period, WaitOrTimerCallback callback, object cbState)
{
//
// If the timer is being set from the user callback function,
// we just save the new settings and return success.
//
if (cbtid == Thread.CurrentThread.ManagedThreadId)
{
this.dueTime = dueTime;
this.period = period;
useDueTime = true;
this.callback = callback;
this.cbState = cbState;
return(true);
}
//
// The timer is being set externally. So, we must first cancel the
// timer. If the timer is already being set or cancelled, we return
// failure.
//
StSpinWait spinner = new StSpinWait();
StParker pk = new StParker(0);
StParker oldState;
do
{
if ((oldState = state) == INACTIVE)
{
if (Interlocked.CompareExchange <StParker>(ref state, SETTING,
INACTIVE) == INACTIVE)
{
goto SetTimer;
}
}
else if (oldState == ACTIVE)
{
if (Interlocked.CompareExchange <StParker>(ref state, pk, ACTIVE) == ACTIVE)
{
break;
}
}
else if (!(oldState is SentinelParker))
{
return(false);
}
spinner.SpinOnce();
} while (true);
//
// Try to cancel the timer's callback parker. If succeed,
// call the unpark method; otherwise, the timer callback is
// taking place, so we must synchronize with its end.
//
if (cbparker.TryCancel())
{
cbparker.Unpark(StParkStatus.TimerCancelled);
}
else
{
pk.Park(100, StCancelArgs.None);
}
//
// Here, we know that the timer is cancelled and no one else
// is trying to set or cancel the timer.
// So, set the timer state to *our busy state* and start it with
// the new settings.
//
state = SETTING;
SetTimer:
this.dueTime = dueTime;
this.period = period;
useDueTime = false;
this.callback = callback;
this.cbState = cbState;
StNotificationEvent nev = tmrEvent as StNotificationEvent;
if (nev != null)
{
nev.Reset();
}
else
{
((StSynchronizationEvent)tmrEvent).Reset();
}
//
// Initialize the timer's parker, set the timer state to ACTIVE
// and enable the unpark callback.
//
cbparker.Reset();
state = ACTIVE;
int ws = cbparker.EnableCallback(dueTime, timer);
if (ws != StParkStatus.Pending)
{
//
// If the timer already fired or cancelled, call the unpark
// callback inline.
//
TimerCallback(ws);
}
return(true);
}
