lisp/progmodes/python.el: Updated Copyright years.
[emacs.git] / lisp / autorevert.el
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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 (eval-when-compile (require 'cl))
100 ;; Custom Group:
102 ;; The two modes will be placed next to Auto Save Mode under the
103 ;; Files group under Emacs.
105 (defgroup auto-revert nil
106 "Revert individual buffers when files on disk change.
107 Auto-Revert mode enables auto-revert in individual buffers.
108 Global Auto-Revert mode does so in all buffers."
109 :group 'files
110 :group 'convenience)
113 ;; Variables:
115 ;;; What's this?: ;; Autoload for the benefit of `make-mode-line-mouse-sensitive'.
116 ;;; What's this?: ;;;###autoload
117 (defvar auto-revert-mode nil
118 "Non-nil when Auto-Revert Mode is active.
119 Never set this variable directly, use the command `auto-revert-mode' instead.")
120 (put 'auto-revert-mode 'permanent-local t)
122 (defvar auto-revert-tail-mode nil
123 "Non-nil when Auto-Revert Tail Mode is active.
124 Never set this variable directly, use the command
125 `auto-revert-tail-mode' instead.")
126 (put 'auto-revert-tail-mode 'permanent-local t)
128 (defvar auto-revert-timer nil
129 "Timer used by Auto-Revert Mode.")
131 (defcustom auto-revert-interval 5
132 "Time, in seconds, between Auto-Revert Mode file checks.
133 The value may be an integer or floating point number.
135 If a timer is already active, there are two ways to make sure
136 that the new value will take effect immediately. You can set
137 this variable through Custom or you can call the command
138 `auto-revert-set-timer' after setting the variable. Otherwise,
139 the new value will take effect the first time Auto Revert Mode
140 calls `auto-revert-set-timer' for internal reasons or in your
141 next editing session."
142 :group 'auto-revert
143 :type 'number
144 :set (lambda (variable value)
145 (set-default variable value)
146 (and (boundp 'auto-revert-timer)
147 auto-revert-timer
148 (auto-revert-set-timer))))
150 (defcustom auto-revert-stop-on-user-input t
151 "When non-nil, user input temporarily interrupts Auto-Revert Mode.
152 With this setting, Auto-Revert Mode checks for user input after
153 handling each buffer and does not process any further buffers
154 \(until the next run of the timer) if user input is available.
155 When nil, Auto-Revert Mode checks files and reverts buffers,
156 with quitting disabled, without paying attention to user input.
157 Thus, with this setting, Emacs might be non-responsive at times."
158 :group 'auto-revert
159 :type 'boolean)
161 (defcustom auto-revert-verbose t
162 "When nil, Auto-Revert Mode does not generate any messages.
163 When non-nil, a message is generated whenever a file is reverted."
164 :group 'auto-revert
165 :type 'boolean)
167 (defcustom auto-revert-mode-text " ARev"
168 "String to display in the mode line when Auto-Revert Mode is active.
170 \(When the string is not empty, make sure that it has a leading space.)"
171 :tag "Auto Revert Mode Text" ; To separate it from `global-...'
172 :group 'auto-revert
173 :type 'string)
175 (defcustom auto-revert-tail-mode-text " Tail"
176 "String to display in the mode line when Auto-Revert Tail Mode is active.
178 \(When the string is not empty, make sure that it has a leading space.)"
179 :group 'auto-revert
180 :type 'string
181 :version "22.1")
183 (defcustom auto-revert-mode-hook nil
184 "Functions to run when Auto-Revert Mode is activated."
185 :tag "Auto Revert Mode Hook" ; To separate it from `global-...'
186 :group 'auto-revert
187 :type 'hook)
189 (defcustom global-auto-revert-mode-text ""
190 "String to display when Global Auto-Revert Mode is active.
192 The default is nothing since when this mode is active this text doesn't
193 vary over time, or between buffers. Hence mode line text
194 would only waste precious space."
195 :group 'auto-revert
196 :type 'string)
198 (defcustom global-auto-revert-mode-hook nil
199 "Hook called when Global Auto-Revert Mode is activated."
200 :group 'auto-revert
201 :type 'hook)
203 (defcustom global-auto-revert-non-file-buffers nil
204 "When nil, Global Auto-Revert mode operates only on file-visiting buffers.
206 When non-nil, both file buffers and buffers with a custom
207 `revert-buffer-function' and a `buffer-stale-function' are
208 reverted by Global Auto-Revert mode. These include the Buffer
209 List buffer displayed by `buffer-menu', and Dired buffers showing
210 complete local directories. The Buffer List buffer reverts every
211 `auto-revert-interval' seconds; Dired buffers when the file list of
212 the main directory changes. Dired buffers do not auto-revert as
213 a result of changes in subdirectories, or in the contents, size,
214 modes, etc., of files. You may still sometimes want to revert
215 them manually.
217 Use this option with care since it could lead to excessive auto-reverts.
218 For more information, see Info node `(emacs)Autorevert'."
219 :group 'auto-revert
220 :type 'boolean
221 :link '(info-link "(emacs)Autorevert"))
223 (defcustom global-auto-revert-ignore-modes ()
224 "List of major modes Global Auto-Revert Mode should not check."
225 :group 'auto-revert
226 :type '(repeat sexp))
228 (defcustom auto-revert-load-hook nil
229 "Functions to run when Auto-Revert Mode is first loaded."
230 :tag "Load Hook"
231 :group 'auto-revert
232 :type 'hook)
234 (defcustom auto-revert-check-vc-info nil
235 "If non-nil Auto Revert Mode reliably updates version control info.
236 Auto Revert Mode updates version control info whenever the buffer
237 needs reverting, regardless of the value of this variable.
238 However, the version control state can change without changes to
239 the work file. If the change is made from the current Emacs
240 session, all info is updated. But if, for instance, a new
241 version is checked in from outside the current Emacs session, the
242 version control number in the mode line, as well as other version
243 control related information, may not be properly updated. If you
244 are worried about this, set this variable to a non-nil value.
246 This currently works by automatically updating the version
247 control info every `auto-revert-interval' seconds. Nevertheless,
248 it should not cause excessive CPU usage on a reasonably fast
249 machine, if it does not apply to too many version controlled
250 buffers. CPU usage depends on the version control system."
251 :group 'auto-revert
252 :type 'boolean
253 :version "22.1")
255 (defvar global-auto-revert-ignore-buffer nil
256 "When non-nil, Global Auto-Revert Mode will not revert this buffer.
257 This variable becomes buffer local when set in any fashion.")
258 (make-variable-buffer-local 'global-auto-revert-ignore-buffer)
260 ;; Internal variables:
262 (defvar auto-revert-buffer-list ()
263 "List of buffers in Auto-Revert Mode.
265 Note that only Auto-Revert Mode, never Global Auto-Revert Mode, adds
266 buffers to this list.
268 The timer function `auto-revert-buffers' is responsible for purging
269 the list of old buffers.")
271 (defvar auto-revert-remaining-buffers ()
272 "Buffers not checked when user input stopped execution.")
274 (defvar auto-revert-tail-pos 0
275 "Position of last known end of file.")
277 (add-hook 'find-file-hook
278 (lambda ()
279 (set (make-local-variable 'auto-revert-tail-pos)
280 (nth 7 (file-attributes buffer-file-name)))))
282 ;; Functions:
284 ;;;###autoload
285 (define-minor-mode auto-revert-mode
286 "Toggle reverting buffer when the file changes (Auto Revert mode).
287 With a prefix argument ARG, enable Auto Revert mode if ARG is
288 positive, and disable it otherwise. If called from Lisp, enable
289 the mode if ARG is omitted or nil.
291 Auto Revert mode is a minor mode that affects only the current
292 buffer. When enabled, it reverts the buffer when the file on
293 disk changes.
295 Use `global-auto-revert-mode' to automatically revert all buffers.
296 Use `auto-revert-tail-mode' if you know that the file will only grow
297 without being changed in the part that is already in the buffer."
298 :group 'auto-revert :lighter auto-revert-mode-text
299 (if auto-revert-mode
300 (if (not (memq (current-buffer) auto-revert-buffer-list))
301 (push (current-buffer) auto-revert-buffer-list))
302 (setq auto-revert-buffer-list
303 (delq (current-buffer) auto-revert-buffer-list)))
304 (auto-revert-set-timer)
305 (when auto-revert-mode
306 (auto-revert-buffers)
307 (setq auto-revert-tail-mode nil)))
310 ;;;###autoload
311 (defun turn-on-auto-revert-mode ()
312 "Turn on Auto-Revert Mode.
314 This function is designed to be added to hooks, for example:
315 (add-hook 'c-mode-hook 'turn-on-auto-revert-mode)"
316 (auto-revert-mode 1))
319 ;;;###autoload
320 (define-minor-mode auto-revert-tail-mode
321 "Toggle reverting tail of buffer when the file grows.
322 With a prefix argument ARG, enable Auto-Revert Tail mode if ARG
323 is positive, and disable it otherwise. If called from Lisp,
324 enable the mode if ARG is omitted or nil.
326 When Auto Revert Tail mode is enabled, the tail of the file is
327 constantly followed, as with the shell command `tail -f'. This
328 means that whenever the file grows on disk (presumably because
329 some background process is appending to it from time to time),
330 this is reflected in the current buffer.
332 You can edit the buffer and turn this mode off and on again as
333 you please. But make sure the background process has stopped
334 writing before you save the file!
336 Use `auto-revert-mode' for changes other than appends!"
337 :group 'find-file :lighter auto-revert-tail-mode-text
338 (when auto-revert-tail-mode
339 (unless buffer-file-name
340 (auto-revert-tail-mode 0)
341 (error "This buffer is not visiting a file"))
342 (if (and (buffer-modified-p)
343 (zerop auto-revert-tail-pos) ; library was loaded only after finding file
344 (not (y-or-n-p "Buffer is modified, so tail offset may be wrong. Proceed? ")))
345 (auto-revert-tail-mode 0)
346 ;; a-r-tail-pos stores the size of the file at the time of the
347 ;; last revert. After this package loads, it adds a
348 ;; find-file-hook to set this variable every time a file is
349 ;; loaded. If the package is loaded only _after_ visiting the
350 ;; file to be reverted, then we have no idea what the value of
351 ;; a-r-tail-pos should have been when the file was visited. If
352 ;; the file has changed on disk in the meantime, all we can do
353 ;; is offer to revert the whole thing. If you choose not to
354 ;; revert, then you might miss some output then happened
355 ;; between visiting the file and activating a-r-t-mode.
356 (and (zerop auto-revert-tail-pos)
357 (not (verify-visited-file-modtime (current-buffer)))
358 (y-or-n-p "File changed on disk, content may be missing. \
359 Perform a full revert? ")
360 ;; Use this (not just revert-buffer) for point-preservation.
361 (auto-revert-handler))
362 ;; else we might reappend our own end when we save
363 (add-hook 'before-save-hook (lambda () (auto-revert-tail-mode 0)) nil t)
364 (or (local-variable-p 'auto-revert-tail-pos) ; don't lose prior position
365 (set (make-local-variable 'auto-revert-tail-pos)
366 (nth 7 (file-attributes buffer-file-name))))
367 ;; let auto-revert-mode set up the mechanism for us if it isn't already
368 (or auto-revert-mode
369 (let ((auto-revert-tail-mode t))
370 (auto-revert-mode 1)))
371 (setq auto-revert-mode nil))))
374 ;;;###autoload
375 (defun turn-on-auto-revert-tail-mode ()
376 "Turn on Auto-Revert Tail mode.
378 This function is designed to be added to hooks, for example:
379 (add-hook 'my-logfile-mode-hook 'turn-on-auto-revert-tail-mode)"
380 (auto-revert-tail-mode 1))
383 ;;;###autoload
384 (define-minor-mode global-auto-revert-mode
385 "Toggle Global Auto Revert mode.
386 With a prefix argument ARG, enable Global Auto Revert mode if ARG
387 is positive, and disable it otherwise. If called from Lisp,
388 enable the mode if ARG is omitted or nil.
390 Global Auto Revert mode is a global minor mode that reverts any
391 buffer associated with a file when the file changes on disk. Use
392 `auto-revert-mode' to revert a particular buffer.
394 If `global-auto-revert-non-file-buffers' is non-nil, this mode
395 may also revert some non-file buffers, as described in the
396 documentation of that variable. It ignores buffers with modes
397 matching `global-auto-revert-ignore-modes', and buffers with a
398 non-nil vale of `global-auto-revert-ignore-buffer'.
400 This function calls the hook `global-auto-revert-mode-hook'.
401 It displays the text that `global-auto-revert-mode-text'
402 specifies in the mode line."
403 :global t :group 'auto-revert :lighter global-auto-revert-mode-text
404 (auto-revert-set-timer)
405 (when global-auto-revert-mode
406 (auto-revert-buffers)))
409 (defun auto-revert-set-timer ()
410 "Restart or cancel the timer used by Auto-Revert Mode.
411 If such a timer is active, cancel it. Start a new timer if
412 Global Auto-Revert Mode is active or if Auto-Revert Mode is active
413 in some buffer. Restarting the timer ensures that Auto-Revert Mode
414 will use an up-to-date value of `auto-revert-interval'"
415 (interactive)
416 (if (timerp auto-revert-timer)
417 (cancel-timer auto-revert-timer))
418 (setq auto-revert-timer
419 (if (or global-auto-revert-mode auto-revert-buffer-list)
420 (run-with-timer auto-revert-interval
421 auto-revert-interval
422 'auto-revert-buffers))))
424 (defun auto-revert-active-p ()
425 "Check if auto-revert is active (in current buffer or globally)."
426 (or auto-revert-mode
427 auto-revert-tail-mode
428 (and
429 global-auto-revert-mode
430 (not global-auto-revert-ignore-buffer)
431 (not (memq major-mode
432 global-auto-revert-ignore-modes)))))
434 (defun auto-revert-handler ()
435 "Revert current buffer, if appropriate.
436 This is an internal function used by Auto-Revert Mode."
437 (when (or auto-revert-tail-mode (not (buffer-modified-p)))
438 (let* ((buffer (current-buffer)) size
439 (revert
440 (or (and buffer-file-name
441 (if auto-revert-tail-mode
442 ;; Tramp caches the file attributes. Setting
443 ;; `remote-file-name-inhibit-cache' forces Tramp
444 ;; to reread the values.
445 (let ((remote-file-name-inhibit-cache t))
446 (and (file-readable-p buffer-file-name)
447 (/= auto-revert-tail-pos
448 (setq size
449 (nth 7 (file-attributes
450 buffer-file-name))))))
451 (and (not (file-remote-p buffer-file-name))
452 (file-readable-p buffer-file-name)
453 (not (verify-visited-file-modtime buffer)))))
454 (and (or auto-revert-mode
455 global-auto-revert-non-file-buffers)
456 revert-buffer-function
457 (boundp 'buffer-stale-function)
458 (functionp buffer-stale-function)
459 (funcall buffer-stale-function t))))
460 eob eoblist)
461 (when revert
462 (when (and auto-revert-verbose
463 (not (eq revert 'fast)))
464 (message "Reverting buffer `%s'." (buffer-name)))
465 ;; If point (or a window point) is at the end of the buffer,
466 ;; we want to keep it at the end after reverting. This allows
467 ;; to tail a file.
468 (when buffer-file-name
469 (setq eob (eobp))
470 (walk-windows
471 (lambda (window)
472 (and (eq (window-buffer window) buffer)
473 (= (window-point window) (point-max))
474 (push window eoblist)))
475 'no-mini t))
476 (if auto-revert-tail-mode
477 (auto-revert-tail-handler size)
478 ;; Bind buffer-read-only in case user has done C-x C-q,
479 ;; so as not to forget that. This gives undesirable results
480 ;; when the file's mode changes, but that is less common.
481 (let ((buffer-read-only buffer-read-only))
482 (revert-buffer 'ignore-auto 'dont-ask 'preserve-modes)))
483 (when buffer-file-name
484 (when eob (goto-char (point-max)))
485 (dolist (window eoblist)
486 (set-window-point window (point-max)))))
487 ;; `preserve-modes' avoids changing the (minor) modes. But we
488 ;; do want to reset the mode for VC, so we do it manually.
489 (when (or revert auto-revert-check-vc-info)
490 (vc-find-file-hook)))))
492 (defun auto-revert-tail-handler (size)
493 (let ((modified (buffer-modified-p))
494 (inhibit-read-only t) ; Ignore.
495 (file buffer-file-name)
496 (buffer-file-name nil)) ; Ignore that file has changed.
497 (when (/= auto-revert-tail-pos size)
498 (run-hooks 'before-revert-hook)
499 (undo-boundary)
500 (save-restriction
501 (widen)
502 (save-excursion
503 (goto-char (point-max))
504 (insert-file-contents file nil
505 (and (< auto-revert-tail-pos size)
506 auto-revert-tail-pos)
507 size)))
508 (run-hooks 'after-revert-hook)
509 (undo-boundary)
510 (setq auto-revert-tail-pos size)
511 (restore-buffer-modified-p modified)))
512 (set-visited-file-modtime))
514 (defun auto-revert-buffers ()
515 "Revert buffers as specified by Auto-Revert and Global Auto-Revert Mode.
517 Should `global-auto-revert-mode' be active all file buffers are checked.
519 Should `auto-revert-mode' be active in some buffers, those buffers
520 are checked.
522 Non-file buffers that have a custom `revert-buffer-function' and
523 a `buffer-stale-function' are reverted either when Auto-Revert
524 Mode is active in that buffer, or when the variable
525 `global-auto-revert-non-file-buffers' is non-nil and Global
526 Auto-Revert Mode is active.
528 This function stops whenever there is user input. The buffers not
529 checked are stored in the variable `auto-revert-remaining-buffers'.
531 To avoid starvation, the buffers in `auto-revert-remaining-buffers'
532 are checked first the next time this function is called.
534 This function is also responsible for removing buffers no longer in
535 Auto-Revert mode from `auto-revert-buffer-list', and for canceling
536 the timer when no buffers need to be checked."
537 (save-match-data
538 (let ((bufs (if global-auto-revert-mode
539 (buffer-list)
540 auto-revert-buffer-list))
541 (remaining ())
542 (new ()))
543 ;; Partition `bufs' into two halves depending on whether or not
544 ;; the buffers are in `auto-revert-remaining-buffers'. The two
545 ;; halves are then re-joined with the "remaining" buffers at the
546 ;; head of the list.
547 (dolist (buf auto-revert-remaining-buffers)
548 (if (memq buf bufs)
549 (push buf remaining)))
550 (dolist (buf bufs)
551 (if (not (memq buf remaining))
552 (push buf new)))
553 (setq bufs (nreverse (nconc new remaining)))
554 (while (and bufs
555 (not (and auto-revert-stop-on-user-input
556 (input-pending-p))))
557 (let ((buf (car bufs)))
558 (if (buffer-live-p buf)
559 (with-current-buffer buf
560 ;; Test if someone has turned off Auto-Revert Mode in a
561 ;; non-standard way, for example by changing major mode.
562 (if (and (not auto-revert-mode)
563 (not auto-revert-tail-mode)
564 (memq buf auto-revert-buffer-list))
565 (setq auto-revert-buffer-list
566 (delq buf auto-revert-buffer-list)))
567 (when (auto-revert-active-p) (auto-revert-handler)))
568 ;; Remove dead buffer from `auto-revert-buffer-list'.
569 (setq auto-revert-buffer-list
570 (delq buf auto-revert-buffer-list))))
571 (setq bufs (cdr bufs)))
572 (setq auto-revert-remaining-buffers bufs)
573 ;; Check if we should cancel the timer.
574 (when (and (not global-auto-revert-mode)
575 (null auto-revert-buffer-list))
576 (cancel-timer auto-revert-timer)
577 (setq auto-revert-timer nil)))))
580 ;; The end:
581 (provide 'autorevert)
583 (run-hooks 'auto-revert-load-hook)
585 ;;; autorevert.el ends here