+ #!+sb-doc
+ "Schedule TIMER to be triggered at TIME. If ABSOLUTE-P then TIME is
+universal time, but non-integral values are also allowed, else TIME is
+measured as the number of seconds from the current time. If
+REPEAT-INTERVAL is given, TIMER is automatically rescheduled upon
+expiry."
+ ;; CANCEL-FUNCTION may block until all interruptors finish, let's
+ ;; try to cancel without the scheduler lock first.
+ (when (%timer-cancel-function timer)
+ (funcall (%timer-cancel-function timer)))