cl.texi flet clarification
[emacs.git] / lisp / autorevert.el
blob0f082d2ee9c33edb3f49c2c2793731fd106f8c9a
1 ;;; autorevert.el --- revert buffers when files on disk change
3 ;; Copyright (C) 1997-1999, 2001-2012 Free Software Foundation, Inc.
5 ;; Author: Anders Lindgren <andersl@andersl.com>
6 ;; Keywords: convenience
7 ;; Created: 1997-06-01
8 ;; Date: 1999-11-30
10 ;; This file is part of GNU Emacs.
12 ;; GNU Emacs is free software: you can redistribute it and/or modify
13 ;; it under the terms of the GNU General Public License as published by
14 ;; the Free Software Foundation, either version 3 of the License, or
15 ;; (at your option) any later version.
17 ;; GNU Emacs is distributed in the hope that it will be useful,
18 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
19 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
20 ;; GNU General Public License for more details.
22 ;; You should have received a copy of the GNU General Public License
23 ;; along with GNU Emacs. If not, see <http://www.gnu.org/licenses/>.
25 ;;; Commentary:
27 ;; Introduction:
29 ;; Whenever a file that Emacs is editing has been changed by another
30 ;; program the user normally has to execute the command `revert-buffer'
31 ;; to load the new content of the file into Emacs.
33 ;; This package contains two minor modes: Global Auto-Revert Mode and
34 ;; Auto-Revert Mode. Both modes automatically revert buffers
35 ;; whenever the corresponding files have been changed on disk and the
36 ;; buffer contains no unsaved changes.
38 ;; Auto-Revert Mode can be activated for individual buffers. Global
39 ;; Auto-Revert Mode applies to all file buffers. (If the user option
40 ;; `global-auto-revert-non-file-buffers' is non-nil, it also applies
41 ;; to some non-file buffers. This option is disabled by default.)
42 ;; Since checking a remote file is too slow, these modes do not check
43 ;; or revert remote files.
45 ;; Both modes operate by checking the time stamp of all files at
46 ;; intervals of `auto-revert-interval'. The default is every five
47 ;; seconds. The check is aborted whenever the user actually uses
48 ;; Emacs. You should never even notice that this package is active
49 ;; (except that your buffers will be reverted, of course).
51 ;; After reverting a file buffer, Auto Revert Mode normally puts point
52 ;; at the same position that a regular manual revert would. However,
53 ;; there is one exception to this rule. If point is at the end of the
54 ;; buffer before reverting, it stays at the end. Similarly if point
55 ;; is displayed at the end of a file buffer in any window, it will stay
56 ;; at the end of the buffer in that window, even if the window is not
57 ;; selected. This way, you can use Auto Revert Mode to `tail' a file.
58 ;; Just put point at the end of the buffer and it will stay there.
59 ;; These rules apply to file buffers. For non-file buffers, the
60 ;; behavior may be mode dependent.
62 ;; While you can use Auto Revert Mode to tail a file, this package
63 ;; contains a third minor mode, Auto Revert Tail Mode, which does so
64 ;; more efficiently, as long as you are sure that the file will only
65 ;; change by growing at the end. It only appends the new output,
66 ;; instead of reverting the entire buffer. It does so even if the
67 ;; buffer contains unsaved changes. (Because they will not be lost.)
68 ;; Auto Revert Tail Mode works also for remote files.
70 ;; Usage:
72 ;; Go to the appropriate buffer and press either of:
73 ;; M-x auto-revert-mode RET
74 ;; M-x auto-revert-tail-mode RET
76 ;; To activate Global Auto-Revert Mode, press:
77 ;; M-x global-auto-revert-mode RET
79 ;; To activate Global Auto-Revert Mode every time Emacs is started
80 ;; customize the option `global-auto-revert-mode' or the following
81 ;; line could be added to your ~/.emacs:
82 ;; (global-auto-revert-mode 1)
84 ;; The function `turn-on-auto-revert-mode' could be added to any major
85 ;; mode hook to activate Auto-Revert Mode for all buffers in that
86 ;; mode. For example, the following line will activate Auto-Revert
87 ;; Mode in all C mode buffers:
89 ;; (add-hook 'c-mode-hook 'turn-on-auto-revert-mode)
91 ;;; Code:
93 ;; Dependencies:
95 (require 'timer)
97 ;; Custom Group:
99 ;; The two modes will be placed next to Auto Save Mode under the
100 ;; Files group under Emacs.
102 (defgroup auto-revert nil
103 "Revert individual buffers when files on disk change.
104 Auto-Revert mode enables auto-revert in individual buffers.
105 Global Auto-Revert mode does so in all buffers."
106 :group 'files
107 :group 'convenience)
110 ;; Variables:
112 ;;; What's this?: ;; Autoload for the benefit of `make-mode-line-mouse-sensitive'.
113 ;;; What's this?: ;;;###autoload
114 (defvar auto-revert-mode nil
115 "Non-nil when Auto-Revert Mode is active.
116 Never set this variable directly, use the command `auto-revert-mode' instead.")
117 (put 'auto-revert-mode 'permanent-local t)
119 (defvar auto-revert-tail-mode nil
120 "Non-nil when Auto-Revert Tail Mode is active.
121 Never set this variable directly, use the command
122 `auto-revert-tail-mode' instead.")
123 (put 'auto-revert-tail-mode 'permanent-local t)
125 (defvar auto-revert-timer nil
126 "Timer used by Auto-Revert Mode.")
128 (defcustom auto-revert-interval 5
129 "Time, in seconds, between Auto-Revert Mode file checks.
130 The value may be an integer or floating point number.
132 If a timer is already active, there are two ways to make sure
133 that the new value will take effect immediately. You can set
134 this variable through Custom or you can call the command
135 `auto-revert-set-timer' after setting the variable. Otherwise,
136 the new value will take effect the first time Auto Revert Mode
137 calls `auto-revert-set-timer' for internal reasons or in your
138 next editing session."
139 :group 'auto-revert
140 :type 'number
141 :set (lambda (variable value)
142 (set-default variable value)
143 (and (boundp 'auto-revert-timer)
144 auto-revert-timer
145 (auto-revert-set-timer))))
147 (defcustom auto-revert-stop-on-user-input t
148 "When non-nil, user input temporarily interrupts Auto-Revert Mode.
149 With this setting, Auto-Revert Mode checks for user input after
150 handling each buffer and does not process any further buffers
151 \(until the next run of the timer) if user input is available.
152 When nil, Auto-Revert Mode checks files and reverts buffers,
153 with quitting disabled, without paying attention to user input.
154 Thus, with this setting, Emacs might be non-responsive at times."
155 :group 'auto-revert
156 :type 'boolean)
158 (defcustom auto-revert-verbose t
159 "When nil, Auto-Revert Mode does not generate any messages.
160 When non-nil, a message is generated whenever a file is reverted."
161 :group 'auto-revert
162 :type 'boolean)
164 (defcustom auto-revert-mode-text " ARev"
165 "String to display in the mode line when Auto-Revert Mode is active.
167 \(When the string is not empty, make sure that it has a leading space.)"
168 :tag "Auto Revert Mode Text" ; To separate it from `global-...'
169 :group 'auto-revert
170 :type 'string)
172 (defcustom auto-revert-tail-mode-text " Tail"
173 "String to display in the mode line when Auto-Revert Tail Mode is active.
175 \(When the string is not empty, make sure that it has a leading space.)"
176 :group 'auto-revert
177 :type 'string
178 :version "22.1")
180 (defcustom auto-revert-mode-hook nil
181 "Functions to run when Auto-Revert Mode is activated."
182 :tag "Auto Revert Mode Hook" ; To separate it from `global-...'
183 :group 'auto-revert
184 :type 'hook)
186 (defcustom global-auto-revert-mode-text ""
187 "String to display when Global Auto-Revert Mode is active.
189 The default is nothing since when this mode is active this text doesn't
190 vary over time, or between buffers. Hence mode line text
191 would only waste precious space."
192 :group 'auto-revert
193 :type 'string)
195 (defcustom global-auto-revert-mode-hook nil
196 "Hook called when Global Auto-Revert Mode is activated."
197 :group 'auto-revert
198 :type 'hook)
200 (defcustom global-auto-revert-non-file-buffers nil
201 "When nil, Global Auto-Revert mode operates only on file-visiting buffers.
203 When non-nil, both file buffers and buffers with a custom
204 `revert-buffer-function' and a `buffer-stale-function' are
205 reverted by Global Auto-Revert mode. These include the Buffer
206 List buffer displayed by `buffer-menu', and Dired buffers showing
207 complete local directories. The Buffer List buffer reverts every
208 `auto-revert-interval' seconds; Dired buffers when the file list of
209 the main directory changes. Dired buffers do not auto-revert as
210 a result of changes in subdirectories, or in the contents, size,
211 modes, etc., of files. You may still sometimes want to revert
212 them manually.
214 Use this option with care since it could lead to excessive auto-reverts.
215 For more information, see Info node `(emacs)Autorevert'."
216 :group 'auto-revert
217 :type 'boolean
218 :link '(info-link "(emacs)Autorevert"))
220 (defcustom global-auto-revert-ignore-modes ()
221 "List of major modes Global Auto-Revert Mode should not check."
222 :group 'auto-revert
223 :type '(repeat sexp))
225 (defcustom auto-revert-load-hook nil
226 "Functions to run when Auto-Revert Mode is first loaded."
227 :tag "Load Hook"
228 :group 'auto-revert
229 :type 'hook)
231 (defcustom auto-revert-check-vc-info nil
232 "If non-nil Auto Revert Mode reliably updates version control info.
233 Auto Revert Mode updates version control info whenever the buffer
234 needs reverting, regardless of the value of this variable.
235 However, the version control state can change without changes to
236 the work file. If the change is made from the current Emacs
237 session, all info is updated. But if, for instance, a new
238 version is checked in from outside the current Emacs session, the
239 version control number in the mode line, as well as other version
240 control related information, may not be properly updated. If you
241 are worried about this, set this variable to a non-nil value.
243 This currently works by automatically updating the version
244 control info every `auto-revert-interval' seconds. Nevertheless,
245 it should not cause excessive CPU usage on a reasonably fast
246 machine, if it does not apply to too many version controlled
247 buffers. CPU usage depends on the version control system."
248 :group 'auto-revert
249 :type 'boolean
250 :version "22.1")
252 (defvar global-auto-revert-ignore-buffer nil
253 "When non-nil, Global Auto-Revert Mode will not revert this buffer.
254 This variable becomes buffer local when set in any fashion.")
255 (make-variable-buffer-local 'global-auto-revert-ignore-buffer)
257 ;; Internal variables:
259 (defvar auto-revert-buffer-list ()
260 "List of buffers in Auto-Revert Mode.
262 Note that only Auto-Revert Mode, never Global Auto-Revert Mode, adds
263 buffers to this list.
265 The timer function `auto-revert-buffers' is responsible for purging
266 the list of old buffers.")
268 (defvar auto-revert-remaining-buffers ()
269 "Buffers not checked when user input stopped execution.")
271 (defvar auto-revert-tail-pos 0
272 "Position of last known end of file.")
274 (add-hook 'find-file-hook
275 (lambda ()
276 (set (make-local-variable 'auto-revert-tail-pos)
277 (nth 7 (file-attributes buffer-file-name)))))
279 ;; Functions:
281 ;;;###autoload
282 (define-minor-mode auto-revert-mode
283 "Toggle reverting buffer when the file changes (Auto Revert mode).
284 With a prefix argument ARG, enable Auto Revert mode if ARG is
285 positive, and disable it otherwise. If called from Lisp, enable
286 the mode if ARG is omitted or nil.
288 Auto Revert mode is a minor mode that affects only the current
289 buffer. When enabled, it reverts the buffer when the file on
290 disk changes.
292 Use `global-auto-revert-mode' to automatically revert all buffers.
293 Use `auto-revert-tail-mode' if you know that the file will only grow
294 without being changed in the part that is already in the buffer."
295 :group 'auto-revert :lighter auto-revert-mode-text
296 (if auto-revert-mode
297 (if (not (memq (current-buffer) auto-revert-buffer-list))
298 (push (current-buffer) auto-revert-buffer-list))
299 (setq auto-revert-buffer-list
300 (delq (current-buffer) auto-revert-buffer-list)))
301 (auto-revert-set-timer)
302 (when auto-revert-mode
303 (auto-revert-buffers)
304 (setq auto-revert-tail-mode nil)))
307 ;;;###autoload
308 (defun turn-on-auto-revert-mode ()
309 "Turn on Auto-Revert Mode.
311 This function is designed to be added to hooks, for example:
312 (add-hook 'c-mode-hook 'turn-on-auto-revert-mode)"
313 (auto-revert-mode 1))
316 ;;;###autoload
317 (define-minor-mode auto-revert-tail-mode
318 "Toggle reverting tail of buffer when the file grows.
319 With a prefix argument ARG, enable Auto-Revert Tail mode if ARG
320 is positive, and disable it otherwise. If called from Lisp,
321 enable the mode if ARG is omitted or nil.
323 When Auto Revert Tail mode is enabled, the tail of the file is
324 constantly followed, as with the shell command `tail -f'. This
325 means that whenever the file grows on disk (presumably because
326 some background process is appending to it from time to time),
327 this is reflected in the current buffer.
329 You can edit the buffer and turn this mode off and on again as
330 you please. But make sure the background process has stopped
331 writing before you save the file!
333 Use `auto-revert-mode' for changes other than appends!"
334 :group 'find-file :lighter auto-revert-tail-mode-text
335 (when auto-revert-tail-mode
336 (unless buffer-file-name
337 (auto-revert-tail-mode 0)
338 (error "This buffer is not visiting a file"))
339 (if (and (buffer-modified-p)
340 (zerop auto-revert-tail-pos) ; library was loaded only after finding file
341 (not (y-or-n-p "Buffer is modified, so tail offset may be wrong. Proceed? ")))
342 (auto-revert-tail-mode 0)
343 ;; a-r-tail-pos stores the size of the file at the time of the
344 ;; last revert. After this package loads, it adds a
345 ;; find-file-hook to set this variable every time a file is
346 ;; loaded. If the package is loaded only _after_ visiting the
347 ;; file to be reverted, then we have no idea what the value of
348 ;; a-r-tail-pos should have been when the file was visited. If
349 ;; the file has changed on disk in the meantime, all we can do
350 ;; is offer to revert the whole thing. If you choose not to
351 ;; revert, then you might miss some output then happened
352 ;; between visiting the file and activating a-r-t-mode.
353 (and (zerop auto-revert-tail-pos)
354 (not (verify-visited-file-modtime (current-buffer)))
355 (y-or-n-p "File changed on disk, content may be missing. \
356 Perform a full revert? ")
357 ;; Use this (not just revert-buffer) for point-preservation.
358 (auto-revert-handler))
359 ;; else we might reappend our own end when we save
360 (add-hook 'before-save-hook (lambda () (auto-revert-tail-mode 0)) nil t)
361 (or (local-variable-p 'auto-revert-tail-pos) ; don't lose prior position
362 (set (make-local-variable 'auto-revert-tail-pos)
363 (nth 7 (file-attributes buffer-file-name))))
364 ;; let auto-revert-mode set up the mechanism for us if it isn't already
365 (or auto-revert-mode
366 (let ((auto-revert-tail-mode t))
367 (auto-revert-mode 1)))
368 (setq auto-revert-mode nil))))
371 ;;;###autoload
372 (defun turn-on-auto-revert-tail-mode ()
373 "Turn on Auto-Revert Tail mode.
375 This function is designed to be added to hooks, for example:
376 (add-hook 'my-logfile-mode-hook 'turn-on-auto-revert-tail-mode)"
377 (auto-revert-tail-mode 1))
380 ;;;###autoload
381 (define-minor-mode global-auto-revert-mode
382 "Toggle Global Auto Revert mode.
383 With a prefix argument ARG, enable Global Auto Revert mode if ARG
384 is positive, and disable it otherwise. If called from Lisp,
385 enable the mode if ARG is omitted or nil.
387 Global Auto Revert mode is a global minor mode that reverts any
388 buffer associated with a file when the file changes on disk. Use
389 `auto-revert-mode' to revert a particular buffer.
391 If `global-auto-revert-non-file-buffers' is non-nil, this mode
392 may also revert some non-file buffers, as described in the
393 documentation of that variable. It ignores buffers with modes
394 matching `global-auto-revert-ignore-modes', and buffers with a
395 non-nil vale of `global-auto-revert-ignore-buffer'.
397 This function calls the hook `global-auto-revert-mode-hook'.
398 It displays the text that `global-auto-revert-mode-text'
399 specifies in the mode line."
400 :global t :group 'auto-revert :lighter global-auto-revert-mode-text
401 (auto-revert-set-timer)
402 (when global-auto-revert-mode
403 (auto-revert-buffers)))
406 (defun auto-revert-set-timer ()
407 "Restart or cancel the timer used by Auto-Revert Mode.
408 If such a timer is active, cancel it. Start a new timer if
409 Global Auto-Revert Mode is active or if Auto-Revert Mode is active
410 in some buffer. Restarting the timer ensures that Auto-Revert Mode
411 will use an up-to-date value of `auto-revert-interval'"
412 (interactive)
413 (if (timerp auto-revert-timer)
414 (cancel-timer auto-revert-timer))
415 (setq auto-revert-timer
416 (if (or global-auto-revert-mode auto-revert-buffer-list)
417 (run-with-timer auto-revert-interval
418 auto-revert-interval
419 'auto-revert-buffers))))
421 (defun auto-revert-active-p ()
422 "Check if auto-revert is active (in current buffer or globally)."
423 (or auto-revert-mode
424 auto-revert-tail-mode
425 (and
426 global-auto-revert-mode
427 (not global-auto-revert-ignore-buffer)
428 (not (memq major-mode
429 global-auto-revert-ignore-modes)))))
431 (defun auto-revert-handler ()
432 "Revert current buffer, if appropriate.
433 This is an internal function used by Auto-Revert Mode."
434 (when (or auto-revert-tail-mode (not (buffer-modified-p)))
435 (let* ((buffer (current-buffer)) size
436 (revert
437 (or (and buffer-file-name
438 (if auto-revert-tail-mode
439 ;; Tramp caches the file attributes. Setting
440 ;; `remote-file-name-inhibit-cache' forces Tramp
441 ;; to reread the values.
442 (let ((remote-file-name-inhibit-cache t))
443 (and (file-readable-p buffer-file-name)
444 (/= auto-revert-tail-pos
445 (setq size
446 (nth 7 (file-attributes
447 buffer-file-name))))))
448 (and (not (file-remote-p buffer-file-name))
449 (file-readable-p buffer-file-name)
450 (not (verify-visited-file-modtime buffer)))))
451 (and (or auto-revert-mode
452 global-auto-revert-non-file-buffers)
453 revert-buffer-function
454 (boundp 'buffer-stale-function)
455 (functionp buffer-stale-function)
456 (funcall buffer-stale-function t))))
457 eob eoblist)
458 (when revert
459 (when (and auto-revert-verbose
460 (not (eq revert 'fast)))
461 (message "Reverting buffer `%s'." (buffer-name)))
462 ;; If point (or a window point) is at the end of the buffer,
463 ;; we want to keep it at the end after reverting. This allows
464 ;; to tail a file.
465 (when buffer-file-name
466 (setq eob (eobp))
467 (walk-windows
468 (lambda (window)
469 (and (eq (window-buffer window) buffer)
470 (= (window-point window) (point-max))
471 (push window eoblist)))
472 'no-mini t))
473 (if auto-revert-tail-mode
474 (auto-revert-tail-handler size)
475 ;; Bind buffer-read-only in case user has done C-x C-q,
476 ;; so as not to forget that. This gives undesirable results
477 ;; when the file's mode changes, but that is less common.
478 (let ((buffer-read-only buffer-read-only))
479 (revert-buffer 'ignore-auto 'dont-ask 'preserve-modes)))
480 (when buffer-file-name
481 (when eob (goto-char (point-max)))
482 (dolist (window eoblist)
483 (set-window-point window (point-max)))))
484 ;; `preserve-modes' avoids changing the (minor) modes. But we
485 ;; do want to reset the mode for VC, so we do it manually.
486 (when (or revert auto-revert-check-vc-info)
487 (vc-find-file-hook)))))
489 (defun auto-revert-tail-handler (size)
490 (let ((modified (buffer-modified-p))
491 (inhibit-read-only t) ; Ignore.
492 (file buffer-file-name)
493 (buffer-file-name nil)) ; Ignore that file has changed.
494 (when (/= auto-revert-tail-pos size)
495 (run-hooks 'before-revert-hook)
496 (undo-boundary)
497 (save-restriction
498 (widen)
499 (save-excursion
500 (goto-char (point-max))
501 (insert-file-contents file nil
502 (and (< auto-revert-tail-pos size)
503 auto-revert-tail-pos)
504 size)))
505 (run-hooks 'after-revert-hook)
506 (undo-boundary)
507 (setq auto-revert-tail-pos size)
508 (restore-buffer-modified-p modified)))
509 (set-visited-file-modtime))
511 (defun auto-revert-buffers ()
512 "Revert buffers as specified by Auto-Revert and Global Auto-Revert Mode.
514 Should `global-auto-revert-mode' be active all file buffers are checked.
516 Should `auto-revert-mode' be active in some buffers, those buffers
517 are checked.
519 Non-file buffers that have a custom `revert-buffer-function' and
520 a `buffer-stale-function' are reverted either when Auto-Revert
521 Mode is active in that buffer, or when the variable
522 `global-auto-revert-non-file-buffers' is non-nil and Global
523 Auto-Revert Mode is active.
525 This function stops whenever there is user input. The buffers not
526 checked are stored in the variable `auto-revert-remaining-buffers'.
528 To avoid starvation, the buffers in `auto-revert-remaining-buffers'
529 are checked first the next time this function is called.
531 This function is also responsible for removing buffers no longer in
532 Auto-Revert mode from `auto-revert-buffer-list', and for canceling
533 the timer when no buffers need to be checked."
534 (save-match-data
535 (let ((bufs (if global-auto-revert-mode
536 (buffer-list)
537 auto-revert-buffer-list))
538 (remaining ())
539 (new ()))
540 ;; Partition `bufs' into two halves depending on whether or not
541 ;; the buffers are in `auto-revert-remaining-buffers'. The two
542 ;; halves are then re-joined with the "remaining" buffers at the
543 ;; head of the list.
544 (dolist (buf auto-revert-remaining-buffers)
545 (if (memq buf bufs)
546 (push buf remaining)))
547 (dolist (buf bufs)
548 (if (not (memq buf remaining))
549 (push buf new)))
550 (setq bufs (nreverse (nconc new remaining)))
551 (while (and bufs
552 (not (and auto-revert-stop-on-user-input
553 (input-pending-p))))
554 (let ((buf (car bufs)))
555 (if (buffer-live-p buf)
556 (with-current-buffer buf
557 ;; Test if someone has turned off Auto-Revert Mode in a
558 ;; non-standard way, for example by changing major mode.
559 (if (and (not auto-revert-mode)
560 (not auto-revert-tail-mode)
561 (memq buf auto-revert-buffer-list))
562 (setq auto-revert-buffer-list
563 (delq buf auto-revert-buffer-list)))
564 (when (auto-revert-active-p) (auto-revert-handler)))
565 ;; Remove dead buffer from `auto-revert-buffer-list'.
566 (setq auto-revert-buffer-list
567 (delq buf auto-revert-buffer-list))))
568 (setq bufs (cdr bufs)))
569 (setq auto-revert-remaining-buffers bufs)
570 ;; Check if we should cancel the timer.
571 (when (and (not global-auto-revert-mode)
572 (null auto-revert-buffer-list))
573 (cancel-timer auto-revert-timer)
574 (setq auto-revert-timer nil)))))
577 ;; The end:
578 (provide 'autorevert)
580 (run-hooks 'auto-revert-load-hook)
582 ;;; autorevert.el ends here