Completion function for an event.
typedef void(* bps_event_completion_func)(bps_event_t *event);
An event may have a completion function that will be called by the system when the event is no longer used. A completion function may be used by the originator of the event to free dynamic resources associated with the event's payload. When an event's completion function is invoked, the event may safely be reused by the event's originator or bps_event_destroy() should be invoked. If NULL is set as an event's completion function, the event is destroyed internally. An event may be resubmitted to BPS from within the completion function by using bps_push_event() .