(Fsearch_forward): Doc fix.

[emacs.git] / lisp / emacs-lisp / timer.el

;;; timer.el --- run a function with args at some time in future

;; Copyright (C) 1996, 2001, 2002, 2003, 2004, 2005,
;;   2006 Free Software Foundation, Inc.

;; Maintainer: FSF

;; This file is part of GNU Emacs.

;; GNU Emacs is free software; you can redistribute it and/or modify
;; it under the terms of the GNU General Public License as published by
;; the Free Software Foundation; either version 2, or (at your option)
;; any later version.

;; GNU Emacs is distributed in the hope that it will be useful,
;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
;; GNU General Public License for more details.

;; You should have received a copy of the GNU General Public License
;; along with GNU Emacs; see the file COPYING.  If not, write to the
;; Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
;; Boston, MA 02110-1301, USA.

;;; Commentary:

;; This package gives you the capability to run Emacs Lisp commands at
;; specified times in the future, either as one-shots or periodically.

;;; Code:

;; Layout of a timer vector:
;; [triggered-p high-seconds low-seconds usecs repeat-delay
;;  function args idle-delay]
;; triggered-p is nil if the timer is active (waiting to be triggered),
;;  t if it is inactive ("already triggered", in theory)

(defun timer-create ()
  "Create a timer object which can be passed to `timer-activate'."
  (let ((timer (make-vector 8 nil)))
    (aset timer 0 t)
    timer))

(defun timerp (object)
  "Return t if OBJECT is a timer."
  (and (vectorp object) (= (length object) 8)))

(defun timer-set-time (timer time &optional delta)
  "Set the trigger time of TIMER to TIME.
TIME must be in the internal format returned by, e.g., `current-time'.
If optional third argument DELTA is a positive number, make the timer
fire repeatedly that many seconds apart."
  (or (timerp timer)
      (error "Invalid timer"))
  (aset timer 1 (car time))
  (aset timer 2 (if (consp (cdr time)) (car (cdr time)) (cdr time)))
  (aset timer 3 (or (and (consp (cdr time)) (consp (cdr (cdr time)))
                         (nth 2 time))
                    0))
  (aset timer 4 (and (numberp delta) (> delta 0) delta))
  timer)

(defun timer-set-idle-time (timer secs &optional repeat)
  "Set the trigger idle time of TIMER to SECS.
SECS may be an integer, floating point number, or the internal
time format (HIGH LOW USECS) returned by, e.g., `current-idle-time'.
If optional third argument REPEAT is non-nil, make the timer
fire each time Emacs is idle for that many seconds."
  (or (timerp timer)
      (error "Invalid timer"))
  (if (consp secs)
      (progn (aset timer 1 (car secs))
             (aset timer 2 (if (consp (cdr secs)) (car (cdr secs)) (cdr secs)))
             (aset timer 3 (or (and (consp (cdr secs)) (consp (cdr (cdr secs)))
                                    (nth 2 secs))
                               0)))
    (aset timer 1 0)
    (aset timer 2 0)
    (aset timer 3 0)
    (timer-inc-time timer secs))
  (aset timer 4 repeat)
  timer)

(defun timer-next-integral-multiple-of-time (time secs)
  "Yield the next value after TIME that is an integral multiple of SECS.
More precisely, the next value, after TIME, that is an integral multiple
of SECS seconds since the epoch.  SECS may be a fraction."
  (let ((time-base (ash 1 16)))
    (if (fboundp 'atan)
        ;; Use floating point, taking care to not lose precision.
        (let* ((float-time-base (float time-base))
               (million 1000000.0)
               (time-usec (+ (* million
                                (+ (* float-time-base (nth 0 time))
                                   (nth 1 time)))
                             (nth 2 time)))
               (secs-usec (* million secs))
               (mod-usec (mod time-usec secs-usec))
               (next-usec (+ (- time-usec mod-usec) secs-usec))
               (time-base-million (* float-time-base million)))
          (list (floor next-usec time-base-million)
                (floor (mod next-usec time-base-million) million)
                (floor (mod next-usec million))))
      ;; Floating point is not supported.
      ;; Use integer arithmetic, avoiding overflow if possible.
      (let* ((mod-sec (mod (+ (* (mod time-base secs)
                                 (mod (nth 0 time) secs))
                              (nth 1 time))
                           secs))
             (next-1-sec (+ (- (nth 1 time) mod-sec) secs)))
        (list (+ (nth 0 time) (floor next-1-sec time-base))
              (mod next-1-sec time-base)
              0)))))

(defun timer-relative-time (time secs &optional usecs)
  "Advance TIME by SECS seconds and optionally USECS microseconds.
SECS may be either an integer or a floating point number."
  (let ((high (car time))
        (low (if (consp (cdr time)) (nth 1 time) (cdr time)))
        (micro (if (numberp (car-safe (cdr-safe (cdr time))))
                   (nth 2 time)
                 0)))
    ;; Add
    (if usecs (setq micro (+ micro usecs)))
    (if (floatp secs)
        (setq micro (+ micro (floor (* 1000000 (- secs (floor secs)))))))
    (setq low (+ low (floor secs)))

    ;; Normalize
    ;; `/' rounds towards zero while `mod' returns a positive number,
    ;; so we can't rely on (= a (+ (* 100 (/ a 100)) (mod a 100))).
    (setq low (+ low (/ micro 1000000) (if (< micro 0) -1 0)))
    (setq micro (mod micro 1000000))
    (setq high (+ high (/ low 65536) (if (< low 0) -1 0)))
    (setq low (logand low 65535))

    (list high low (and (/= micro 0) micro))))

(defun timer-inc-time (timer secs &optional usecs)
  "Increment the time set in TIMER by SECS seconds and USECS microseconds.
SECS may be a fraction.  If USECS is omitted, that means it is zero."
  (let ((time (timer-relative-time
               (list (aref timer 1) (aref timer 2) (aref timer 3))
               secs
               usecs)))
    (aset timer 1 (nth 0 time))
    (aset timer 2 (nth 1 time))
    (aset timer 3 (or (nth 2 time) 0))))

(defun timer-set-time-with-usecs (timer time usecs &optional delta)
  "Set the trigger time of TIMER to TIME plus USECS.
TIME must be in the internal format returned by, e.g., `current-time'.
The microsecond count from TIME is ignored, and USECS is used instead.
If optional fourth argument DELTA is a positive number, make the timer
fire repeatedly that many seconds apart."
  (or (timerp timer)
      (error "Invalid timer"))
  (aset timer 1 (nth 0 time))
  (aset timer 2 (nth 1 time))
  (aset timer 3 usecs)
  (aset timer 4 (and (numberp delta) (> delta 0) delta))
  timer)
(make-obsolete 'timer-set-time-with-usecs
               "use `timer-set-time' and `timer-inc-time' instead."
               "22.1")

(defun timer-set-function (timer function &optional args)
  "Make TIMER call FUNCTION with optional ARGS when triggering."
  (or (timerp timer)
      (error "Invalid timer"))
  (aset timer 5 function)
  (aset timer 6 args)
  timer)
\f
(defun timer-activate (timer &optional triggered-p reuse-cell)
  "Put TIMER on the list of active timers.

If TRIGGERED-P is t, that means to make the timer inactive
\(put it on the list, but mark it as already triggered).
To remove from the list, use `cancel-timer'.

REUSE-CELL, if non-nil, is a cons cell to reuse instead
of allocating a new one."
  (if (and (timerp timer)
           (integerp (aref timer 1))
           (integerp (aref timer 2))
           (integerp (aref timer 3))
           (aref timer 5))
      (let ((timers timer-list)
            last)
        ;; Skip all timers to trigger before the new one.
        (while (and timers
                    (or (> (aref timer 1) (aref (car timers) 1))
                        (and (= (aref timer 1) (aref (car timers) 1))
                             (> (aref timer 2) (aref (car timers) 2)))
                        (and (= (aref timer 1) (aref (car timers) 1))
                             (= (aref timer 2) (aref (car timers) 2))
                             (> (aref timer 3) (aref (car timers) 3)))))
          (setq last timers
                timers (cdr timers)))
        (if reuse-cell
            (progn
              (setcar reuse-cell timer)
              (setcdr reuse-cell timers))
          (setq reuse-cell (cons timer timers)))
        ;; Insert new timer after last which possibly means in front of queue.
        (if last
            (setcdr last reuse-cell)
          (setq timer-list reuse-cell))
        (aset timer 0 triggered-p)
        (aset timer 7 nil)
        nil)
    (error "Invalid or uninitialized timer")))

(defun timer-activate-when-idle (timer &optional dont-wait reuse-cell)
  "Arrange to activate TIMER whenever Emacs is next idle.
If optional argument DONT-WAIT is non-nil, then enable the
timer to activate immediately, or at the right time, if Emacs
is already idle.

REUSE-CELL, if non-nil, is a cons cell to reuse instead
of allocating a new one."
  (if (and (timerp timer)
           (integerp (aref timer 1))
           (integerp (aref timer 2))
           (integerp (aref timer 3))
           (aref timer 5))
      (let ((timers timer-idle-list)
            last)
        ;; Skip all timers to trigger before the new one.
        (while (and timers
                    (or (> (aref timer 1) (aref (car timers) 1))
                        (and (= (aref timer 1) (aref (car timers) 1))
                             (> (aref timer 2) (aref (car timers) 2)))
                        (and (= (aref timer 1) (aref (car timers) 1))
                             (= (aref timer 2) (aref (car timers) 2))
                             (> (aref timer 3) (aref (car timers) 3)))))
          (setq last timers
                timers (cdr timers)))
        (if reuse-cell
            (progn
              (setcar reuse-cell timer)
              (setcdr reuse-cell timers))
          (setq reuse-cell (cons timer timers)))
        ;; Insert new timer after last which possibly means in front of queue.
        (if last
            (setcdr last reuse-cell)
          (setq timer-idle-list reuse-cell))
        (aset timer 0 (not dont-wait))
        (aset timer 7 t)
        nil)
    (error "Invalid or uninitialized timer")))

;;;###autoload
(defalias 'disable-timeout 'cancel-timer)
;;;###autoload
(defun cancel-timer (timer)
  "Remove TIMER from the list of active timers."
  (or (timerp timer)
      (error "Invalid timer"))
  (setq timer-list (delq timer timer-list))
  (setq timer-idle-list (delq timer timer-idle-list))
  nil)

(defun cancel-timer-internal (timer)
  "Remove TIMER from the list of active timers or idle timers.
Only to be used in this file.  It returns the cons cell
that was removed from the timer list."
  (let ((cell1 (memq timer timer-list))
        (cell2 (memq timer timer-idle-list)))
    (if cell1
        (setq timer-list (delq timer timer-list)))
    (if cell2
        (setq timer-idle-list (delq timer timer-idle-list)))
    (or cell1 cell2)))

;;;###autoload
(defun cancel-function-timers (function)
  "Cancel all timers which would run FUNCTION.
This affects ordinary timers such as are scheduled by `run-at-time',
and idle timers such as are scheduled by `run-with-idle-timer'."
  (interactive "aCancel timers of function: ")
  (let ((tail timer-list))
    (while tail
      (if (eq (aref (car tail) 5) function)
          (setq timer-list (delq (car tail) timer-list)))
      (setq tail (cdr tail))))
  (let ((tail timer-idle-list))
    (while tail
      (if (eq (aref (car tail) 5) function)
          (setq timer-idle-list (delq (car tail) timer-idle-list)))
      (setq tail (cdr tail)))))
\f
;; Record the last few events, for debugging.
(defvar timer-event-last nil
  "Last timer that was run.")
(defvar timer-event-last-1 nil
  "Next-to-last timer that was run.")
(defvar timer-event-last-2 nil
  "Third-to-last timer that was run.")

(defvar timer-max-repeats 10
  "*Maximum number of times to repeat a timer, if many repeats are delayed.
Timer invocations can be delayed because Emacs is suspended or busy,
or because the system's time changes.  If such an occurrence makes it
appear that many invocations are overdue, this variable controls
how many will really happen.")

(defun timer-until (timer time)
  "Calculate number of seconds from when TIMER will run, until TIME.
TIMER is a timer, and stands for the time when its next repeat is scheduled.
TIME is a time-list."
  (let ((high (- (car time) (aref timer 1)))
        (low (- (nth 1 time) (aref timer 2))))
    (+ low (* high 65536))))

(defun timer-event-handler (timer)
  "Call the handler for the timer TIMER.
This function is called, by name, directly by the C code."
  (setq timer-event-last-2 timer-event-last-1)
  (setq timer-event-last-1 timer-event-last)
  (setq timer-event-last timer)
  (let ((inhibit-quit t))
    (if (timerp timer)
        (let (retrigger cell)
          ;; Delete from queue.  Record the cons cell that was used.
          (setq cell (cancel-timer-internal timer))
          ;; Re-schedule if requested.
          (if (aref timer 4)
              (if (aref timer 7)
                  (timer-activate-when-idle timer nil cell)
                (timer-inc-time timer (aref timer 4) 0)
                ;; If real time has jumped forward,
                ;; perhaps because Emacs was suspended for a long time,
                ;; limit how many times things get repeated.
                (if (and (numberp timer-max-repeats)
                         (< 0 (timer-until timer (current-time))))
                    (let ((repeats (/ (timer-until timer (current-time))
                                      (aref timer 4))))
                      (if (> repeats timer-max-repeats)
                          (timer-inc-time timer (* (aref timer 4) repeats)))))
                (timer-activate timer t cell)
                (setq retrigger t)))
          ;; Run handler.
          ;; We do this after rescheduling so that the handler function
          ;; can cancel its own timer successfully with cancel-timer.
          (condition-case nil
              (apply (aref timer 5) (aref timer 6))
            (error nil))
          (if retrigger
              (aset timer 0 nil)))
      (error "Bogus timer event"))))

;; This function is incompatible with the one in levents.el.
(defun timeout-event-p (event)
  "Non-nil if EVENT is a timeout event."
  (and (listp event) (eq (car event) 'timer-event)))
\f
;;;###autoload
(defun run-at-time (time repeat function &rest args)
  "Perform an action at time TIME.
Repeat the action every REPEAT seconds, if REPEAT is non-nil.
TIME should be a string like \"11:23pm\", nil meaning now, a number of seconds
from now, a value from `current-time', or t (with non-nil REPEAT)
meaning the next integral multiple of REPEAT.
REPEAT may be an integer or floating point number.
The action is to call FUNCTION with arguments ARGS.

This function returns a timer object which you can use in `cancel-timer'."
  (interactive "sRun at time: \nNRepeat interval: \naFunction: ")

  (or (null repeat)
      (and (numberp repeat) (< 0 repeat))
      (error "Invalid repetition interval"))

  ;; Special case: nil means "now" and is useful when repeating.
  (if (null time)
      (setq time (current-time)))

  ;; Special case: t means the next integral multiple of REPEAT.
  (if (and (eq time t) repeat)
      (setq time (timer-next-integral-multiple-of-time (current-time) repeat)))

  ;; Handle numbers as relative times in seconds.
  (if (numberp time)
      (setq time (timer-relative-time (current-time) time)))

  ;; Handle relative times like "2 hours and 35 minutes"
  (if (stringp time)
      (let ((secs (timer-duration time)))
        (if secs
            (setq time (timer-relative-time (current-time) secs)))))

  ;; Handle "11:23pm" and the like.  Interpret it as meaning today
  ;; which admittedly is rather stupid if we have passed that time
  ;; already.  (Though only Emacs hackers hack Emacs at that time.)
  (if (stringp time)
      (progn
        (require 'diary-lib)
        (let ((hhmm (diary-entry-time time))
              (now (decode-time)))
          (if (>= hhmm 0)
              (setq time
                    (encode-time 0 (% hhmm 100) (/ hhmm 100) (nth 3 now)
                                 (nth 4 now) (nth 5 now) (nth 8 now)))))))

  (or (consp time)
      (error "Invalid time format"))

  (let ((timer (timer-create)))
    (timer-set-time timer time repeat)
    (timer-set-function timer function args)
    (timer-activate timer)
    timer))

;;;###autoload
(defun run-with-timer (secs repeat function &rest args)
  "Perform an action after a delay of SECS seconds.
Repeat the action every REPEAT seconds, if REPEAT is non-nil.
SECS and REPEAT may be integers or floating point numbers.
The action is to call FUNCTION with arguments ARGS.

This function returns a timer object which you can use in `cancel-timer'."
  (interactive "sRun after delay (seconds): \nNRepeat interval: \naFunction: ")
  (apply 'run-at-time secs repeat function args))

;;;###autoload
(defun add-timeout (secs function object &optional repeat)
  "Add a timer to run SECS seconds from now, to call FUNCTION on OBJECT.
If REPEAT is non-nil, repeat the timer every REPEAT seconds.
This function is for compatibility; see also `run-with-timer'."
  (run-with-timer secs repeat function object))

;;;###autoload
(defun run-with-idle-timer (secs repeat function &rest args)
  "Perform an action the next time Emacs is idle for SECS seconds.
The action is to call FUNCTION with arguments ARGS.
SECS may be an integer, a floating point number, or the internal
time format (HIGH LOW USECS) returned by, e.g., `current-idle-time'.
If Emacs is currently idle, and has been idle for N seconds (N < SECS),
then it will call FUNCTION in SECS - N seconds from now.

If REPEAT is non-nil, do the action each time Emacs has been idle for
exactly SECS seconds (that is, only once for each time Emacs becomes idle).

This function returns a timer object which you can use in `cancel-timer'."
  (interactive
   (list (read-from-minibuffer "Run after idle (seconds): " nil nil t)
         (y-or-n-p "Repeat each time Emacs is idle? ")
         (intern (completing-read "Function: " obarray 'fboundp t))))
  (let ((timer (timer-create)))
    (timer-set-function timer function args)
    (timer-set-idle-time timer secs repeat)
    (timer-activate-when-idle timer t)
    timer))
\f
(defun with-timeout-handler (tag)
  "This is the timer function used for the timer made by `with-timeout'."
  (throw tag 'timeout))

;;;###autoload (put 'with-timeout 'lisp-indent-function 1)

(defvar with-timeout-timers nil
  "List of all timers used by currently pending `with-timeout' calls.")

;;;###autoload
(defmacro with-timeout (list &rest body)
  "Run BODY, but if it doesn't finish in SECONDS seconds, give up.
If we give up, we run the TIMEOUT-FORMS and return the value of the last one.
The timeout is checked whenever Emacs waits for some kind of external
event (such as keyboard input, input from subprocesses, or a certain time);
if the program loops without waiting in any way, the timeout will not
be detected.
\n(fn (SECONDS TIMEOUT-FORMS...) BODY)"
  (let ((seconds (car list))
        (timeout-forms (cdr list)))
    `(let ((with-timeout-tag (cons nil nil))
           with-timeout-value with-timeout-timer
           (with-timeout-timers with-timeout-timers))
       (if (catch with-timeout-tag
             (progn
               (setq with-timeout-timer
                     (run-with-timer ,seconds nil
                                      'with-timeout-handler
                                      with-timeout-tag))
               (push with-timeout-timer with-timeout-timers)
               (setq with-timeout-value (progn . ,body))
               nil))
           (progn . ,timeout-forms)
         (cancel-timer with-timeout-timer)
         with-timeout-value))))

(defun with-timeout-suspend ()
  "Stop the clock for `with-timeout'.  Used by debuggers.
The idea is that the time you spend in the debugger should not
count against these timeouts.

The value is a list that the debugger can pass to `with-timeout-unsuspend'
when it exits, to make these timers start counting again."
  (mapcar (lambda (timer)
            (cancel-timer timer)
            (list timer
                  (time-subtract
                   ;; The time that this timer will go off.
                   (list (aref timer 1) (aref timer 2) (aref timer 3))
                   (current-time))))
          with-timeout-timers))

(defun with-timeout-unsuspend (timer-spec-list)
  "Restart the clock for `with-timeout'.
The argument should be a value previously returned by `with-timeout-suspend'."
  (dolist (elt timer-spec-list)
    (let ((timer (car elt))
          (delay (cadr elt)))
      (timer-set-time timer (time-add (current-time) delay)) 
      (timer-activate timer))))

(defun y-or-n-p-with-timeout (prompt seconds default-value)
  "Like (y-or-n-p PROMPT), with a timeout.
If the user does not answer after SECONDS seconds, return DEFAULT-VALUE."
  (with-timeout (seconds default-value)
    (y-or-n-p prompt)))
\f
(defvar timer-duration-words
  (list (cons "microsec" 0.000001)
        (cons "microsecond" 0.000001)
        (cons "millisec" 0.001)
        (cons "millisecond" 0.001)
        (cons "sec" 1)
        (cons "second" 1)
        (cons "min" 60)
        (cons "minute" 60)
        (cons "hour" (* 60 60))
        (cons "day" (* 24 60 60))
        (cons "week" (* 7 24 60 60))
        (cons "fortnight" (* 14 24 60 60))
        (cons "month" (* 30 24 60 60))    ; Approximation
        (cons "year" (* 365.25 24 60 60)) ; Approximation
        )
  "Alist mapping temporal words to durations in seconds")

(defun timer-duration (string)
  "Return number of seconds specified by STRING, or nil if parsing fails."
  (let ((secs 0)
        (start 0)
        (case-fold-search t))
    (while (string-match
            "[ \t]*\\([0-9.]+\\)?[ \t]*\\([a-z]+[a-rt-z]\\)s?[ \t]*"
            string start)
      (let ((count (if (match-beginning 1)
                       (string-to-number (match-string 1 string))
                     1))
            (itemsize (cdr (assoc (match-string 2 string)
                                  timer-duration-words))))
        (if itemsize
            (setq start (match-end 0)
                  secs (+ secs (* count itemsize)))
          (setq secs nil
                start (length string)))))
    (if (= start (length string))
        secs
      (if (string-match "\\`[0-9.]+\\'" string)
          (string-to-number string)))))
\f
(provide 'timer)

;;; arch-tag: b1a9237b-7787-4382-9e46-8f2c3b3273e0
;;; timer.el ends here