Interface implemented by classes wishing to know the current number of pending and due threads awaiting processing.
Thread Queue Update(nDue Timers, nTotal Timers)
Call-back that fires each time a thread timer is processed, and the thread queue information changes.
The number of registered timers (including intervals) that are now ready to be processed.
The total number of registered timers and intervals — both overdue, and not yet requiring processing.