object's event processing loop to execute at most one handler.
run_one() function blocks until one handler has been
dispatched, or until the
has been stopped.
The number of handlers that were executed. A zero return value implies
object is stopped (the
stopped() function returns
Subsequent calls to
poll_one() will return immediately unless there is a
prior call to
run_one() function from a thread that is currently
calling one of
on the same
object may introduce the potential for deadlock. It is the caller's reponsibility
to avoid this.