[Emacs-diffs] Changes to emacs/lispref/os.texi,v

[Richard M. Stallman]

CVSROOT:        /cvsroot/emacs
Module name:    emacs
Changes by:     Richard M. Stallman <rms>       06/09/21 01:51:55

Index: os.texi
===================================================================
RCS file: /cvsroot/emacs/emacs/lispref/os.texi,v
retrieving revision 1.94
retrieving revision 1.95
diff -u -b -r1.94 -r1.95
--- os.texi     4 Sep 2006 15:07:32 -0000       1.94
+++ os.texi     21 Sep 2006 01:51:55 -0000      1.95
@@ -1407,9 +1407,9 @@
 @deffn Command run-at-time time repeat function &rest args
 This sets up a timer that calls the function @var{function} with
 arguments @var{args} at time @var{time}.  If @var{repeat} is a number
-(integer or floating point), the timer also runs every @var{repeat}
-seconds after that.  If @var{repeat} is @code{nil}, the timer runs
-only once.
+(integer or floating point), the timer is scheduled to run again every
address@hidden seconds after @var{time}.  If @var{repeat} is @code{nil},
+the timer runs only once.
 
 @var{time} may specify an absolute or a relative time.
 
@@ -1458,6 +1458,17 @@
 @code{cancel-timer} (see below).
 @end deffn
 
+  A repeating timer nominally ought to run every @var{repeat} seconds,
+but remember that any invocation of a timer can be late.  Lateness of
+one repetition has no effect on the scheduled time of the next
+repetition.  For instance, if Emacs is busy computing for long enough
+to cover three scheduled repetitions of the timer, and then starts to
+wait, it will immediately call the timer function three times in
+immediate succession (presuming no other timers trigger before or
+between them).  If you want a timer to run again no less than @var{n}
+seconds after the last invocation, don't use the @var{repeat} argument.
+Instead, the timer function should explicitly reschedule the timer.
+
 @defmac with-timeout (seconds address@hidden) address@hidden
 Execute @var{body}, but give up after @var{seconds} seconds.  If
 @var{body} finishes before the time is up, @code{with-timeout} returns