lisp/autorevert.el

   1 ;;; autorevert.el --- revert buffers when files on disk change
   2
   3 ;; Copyright (C) 1997, 1998, 1999, 2001, 2004, 2005 Free Software Foundation, Inc.
   4
   5 ;; Author: Anders Lindgren <andersl@andersl.com>
   6 ;; Keywords: convenience
   7 ;; Created: 1997-06-01
   8 ;; Date: 1999-11-30
   9
  10 ;; This file is part of GNU Emacs.
  11
  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 2, or (at your option)
  15 ;; any later version.
  16
  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.
  21
  22 ;; You should have received a copy of the GNU General Public License
  23 ;; along with GNU Emacs; see the file COPYING.  If not, write to the
  24 ;; Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
  25 ;; Boston, MA 02110-1301, USA.
  26
  27 ;;; Commentary:
  28
  29 ;; Introduction:
  30 ;;
  31 ;; Whenever a file that Emacs is editing has been changed by another
  32 ;; program the user normally has to execute the command `revert-buffer'
  33 ;; to load the new content of the file into Emacs.
  34 ;;
  35 ;; This package contains two minor modes: Global Auto-Revert Mode and
  36 ;; Auto-Revert Mode.  Both modes automatically revert buffers
  37 ;; whenever the corresponding files have been changed on disk and the
  38 ;; buffer contains no unsaved changes.
  39 ;;
  40 ;; Auto-Revert Mode can be activated for individual buffers.  Global
  41 ;; Auto-Revert Mode applies to all file buffers. (If the user option
  42 ;; `global-auto-revert-non-file-buffers' is non-nil, it also applies
  43 ;; to some non-file buffers.  This option is disabled by default.)
  44 ;; Since checking a remote file is too slow, these modes do not check
  45 ;; or revert remote files.
  46 ;;
  47 ;; Both modes operate by checking the time stamp of all files at
  48 ;; intervals of `auto-revert-interval'.  The default is every five
  49 ;; seconds.  The check is aborted whenever the user actually uses
  50 ;; Emacs.  You should never even notice that this package is active
  51 ;; (except that your buffers will be reverted, of course).
  52 ;;
  53 ;; After reverting a file buffer, Auto Revert Mode normally puts point
  54 ;; at the same position that a regular manual revert would.  However,
  55 ;; there is one exception to this rule.  If point is at the end of the
  56 ;; buffer before reverting, it stays at the end.  Similarly if point
  57 ;; is displayed at the end of a file buffer in any window, it will stay
  58 ;; at the end of the buffer in that window, even if the window is not
  59 ;; selected.  This way, you can use Auto Revert Mode to `tail' a file.
  60 ;; Just put point at the end of the buffer and it will stay there.
  61 ;; These rules apply to file buffers. For non-file buffers, the
  62 ;; behavior may be mode dependent.
  63 ;;
  64 ;; While you can use Auto Revert Mode to tail a file, this package
  65 ;; contains a third minor mode, Auto Revert Tail Mode, which does so
  66 ;; more efficiently, as long as you are sure that the file will only
  67 ;; change by growing at the end.  It only appends the new output,
  68 ;; instead of reverting the entire buffer.  It does so even if the
  69 ;; buffer contains unsaved changes.  (Because they will not be lost.)
  70
  71 ;; Usage:
  72 ;;
  73 ;; Go to the appropriate buffer and press either of:
  74 ;;   M-x auto-revert-mode RET
  75 ;;   M-x auto-revert-tail-mode RET
  76 ;;
  77 ;; To activate Global Auto-Revert Mode, press:
  78 ;;   M-x global-auto-revert-mode RET
  79 ;;
  80 ;; To activate Global Auto-Revert Mode every time Emacs is started
  81 ;; customise the option `global-auto-revert-mode' or the following
  82 ;; line could be added to your ~/.emacs:
  83 ;;   (global-auto-revert-mode 1)
  84 ;;
  85 ;; The function `turn-on-auto-revert-mode' could be added to any major
  86 ;; mode hook to activate Auto-Revert Mode for all buffers in that
  87 ;; mode.  For example, the following line will activate Auto-Revert
  88 ;; Mode in all C mode buffers:
  89 ;;
  90 ;; (add-hook 'c-mode-hook 'turn-on-auto-revert-mode)
  91
  92 ;;; Code:
  93
  94 ;; Dependencies:
  95
  96 (require 'timer)
  97
  98 (eval-when-compile (require 'cl))
  99
 100
 101 ;; Custom Group:
 102 ;;
 103 ;; The two modes will be placed next to Auto Save Mode under the
 104 ;; Files group under Emacs.
 105
 106 (defgroup auto-revert nil
 107   "Revert individual buffers when files on disk change.
 108
 109 Auto-Revert Mode can be activated for individual buffer.
 110 Global Auto-Revert Mode applies to all buffers."
 111   :group 'files
 112   :group 'convenience)
 113
 114
 115 ;; Variables:
 116
 117 ;;; What's this?: ;; Autoload for the benefit of `make-mode-line-mouse-sensitive'.
 118 ;;; What's this?: ;;;###autoload
 119 (defvar auto-revert-mode nil
 120   "*Non-nil when Auto-Revert Mode is active.
 121 Never set this variable directly, use the command `auto-revert-mode' instead.")
 122 (put 'auto-revert-mode 'permanent-local t)
 123
 124 (defvar auto-revert-tail-mode nil
 125   "*Non-nil when Auto-Revert Tail Mode is active.
 126 Never set this variable directly, use the command
 127 `auto-revert-tail-mode' instead.")
 128 (put 'auto-revert-tail-mode 'permanent-local t)
 129
 130 (defvar auto-revert-timer nil
 131   "Timer used by Auto-Revert Mode.")
 132
 133 (defcustom auto-revert-interval 5
 134   "Time, in seconds, between Auto-Revert Mode file checks.
 135 The value may be an integer or floating point number.
 136
 137 If a timer is already active, there are two ways to make sure
 138 that the new value will take effect immediately.  You can set
 139 this variable through Custom or you can call the command
 140 `auto-revert-set-timer' after setting the variable.  Otherwise,
 141 the new value will take effect the first time Auto Revert Mode
 142 calls `auto-revert-set-timer' for internal reasons or in your
 143 next editing session."
 144   :group 'auto-revert
 145   :type 'number
 146   :set (lambda (variable value)
 147          (set-default variable value)
 148          (and (boundp 'auto-revert-timer)
 149               auto-revert-timer
 150               (auto-revert-set-timer))))
 151
 152 (defcustom auto-revert-stop-on-user-input t
 153   "When non-nil, user input temporarily interrupts Auto-Revert Mode.
 154 With this setting, Auto-Revert Mode checks for user input after
 155 handling each buffer and does not process any further buffers
 156 \(until the next run of the timer) if user input is available.
 157 When nil, Auto-Revert Mode checks files and reverts buffers,
 158 with quitting disabled, without paying attention to user input.
 159 Thus, with this setting, Emacs might be non-responsive at times."
 160   :group 'auto-revert
 161   :type 'boolean)
 162
 163 (defcustom auto-revert-verbose t
 164   "When nil, Auto-Revert Mode does not generate any messages.
 165 When non-nil, a message is generated whenever a file is reverted."
 166   :group 'auto-revert
 167   :type 'boolean)
 168
 169 (defcustom auto-revert-mode-text " ARev"
 170   "String to display in the mode line when Auto-Revert Mode is active.
 171
 172 \(When the string is not empty, make sure that it has a leading space.)"
 173   :tag "Auto Revert Mode Text"          ; To separate it from `global-...'
 174   :group 'auto-revert
 175   :type 'string)
 176
 177 (defcustom auto-revert-tail-mode-text " Tail"
 178   "String to display in the mode line when Auto-Revert Tail Mode is active.
 179
 180 \(When the string is not empty, make sure that it has a leading space.)"
 181   :group 'auto-revert
 182   :type 'string
 183   :version "22.1")
 184
 185 (defcustom auto-revert-mode-hook nil
 186   "Functions to run when Auto-Revert Mode is activated."
 187   :tag "Auto Revert Mode Hook"          ; To separate it from `global-...'
 188   :group 'auto-revert
 189   :type 'hook)
 190
 191 (defcustom global-auto-revert-mode-text ""
 192   "String to display when Global Auto-Revert Mode is active.
 193
 194 The default is nothing since when this mode is active this text doesn't
 195 vary over time, or between buffers.  Hence mode line text
 196 would only waste precious space."
 197   :group 'auto-revert
 198   :type 'string)
 199
 200 (defcustom global-auto-revert-mode-hook nil
 201   "Hook called when Global Auto-Revert Mode is activated."
 202   :group 'auto-revert
 203   :type 'hook)
 204
 205 (defcustom global-auto-revert-non-file-buffers nil
 206   "When nil, Global Auto-Revert mode operates only on file-visiting buffers.
 207
 208 When non-nil, both file buffers and buffers with a custom
 209 `revert-buffer-function' and a `buffer-stale-function' are
 210 reverted by Global Auto-Revert mode.  These include the Buffer
 211 List buffer, and Dired buffers showing complete local
 212 directories.  Dired buffers do not auto-revert as a result of
 213 changes in subdirectories or in the contents, size, modes, etc.,
 214 of files.  You may still sometimes want to revert them manually.
 215
 216 Use this option with care since it could lead to excessive auto-reverts.
 217 For more information, see Info node `(emacs-xtra)Autorevert'."
 218   :group 'auto-revert
 219   :type 'boolean
 220   :link '(info-link "(emacs-xtra)Autorevert"))
 221
 222 (defcustom global-auto-revert-ignore-modes ()
 223   "List of major modes Global Auto-Revert Mode should not check."
 224   :group 'auto-revert
 225   :type '(repeat sexp))
 226
 227 (defcustom auto-revert-load-hook nil
 228   "Functions to run when Auto-Revert Mode is first loaded."
 229   :tag "Load Hook"
 230   :group 'auto-revert
 231   :type 'hook)
 232
 233 (defcustom auto-revert-check-vc-info nil
 234   "If non-nil Auto Revert Mode reliably updates version control info.
 235 Auto Revert Mode updates version control info whenever the buffer
 236 needs reverting, regardless of the value of this variable.
 237 However, the version control state can change without changes to
 238 the work file.  If the change is made from the current Emacs
 239 session, all info is updated.  But if, for instance, a new
 240 version is checked in from outside the current Emacs session, the
 241 version control number in the mode line, as well as other version
 242 control related information, may not be properly updated.  If you
 243 are worried about this, set this variable to a non-nil value.
 244
 245 This currently works by automatically updating the version
 246 control info every `auto-revert-interval' seconds.  Nevertheless,
 247 it should not cause excessive CPU usage on a reasonably fast
 248 machine, if it does not apply to too many version controlled
 249 buffers.  CPU usage depends on the version control system."
 250   :group 'auto-revert
 251   :type 'boolean
 252   :version "22.1")
 253
 254 (defvar global-auto-revert-ignore-buffer nil
 255   "*When non-nil, Global Auto-Revert Mode will not revert this buffer.
 256
 257 This variable becomes buffer local when set in any fashion.")
 258 (make-variable-buffer-local 'global-auto-revert-ignore-buffer)
 259
 260 ;; Internal variables:
 261
 262 (defvar auto-revert-buffer-list ()
 263   "List of buffers in Auto-Revert Mode.
 264
 265 Note that only Auto-Revert Mode, never Global Auto-Revert Mode, adds
 266 buffers to this list.
 267
 268 The timer function `auto-revert-buffers' is responsible for purging
 269 the list of old buffers.")
 270
 271 (defvar auto-revert-remaining-buffers ()
 272   "Buffers not checked when user input stopped execution.")
 273
 274 (defvar auto-revert-tail-pos 0
 275   "Position of last known end of file.")
 276
 277 (add-hook 'find-file-hook
 278           (lambda ()
 279             (set (make-local-variable 'auto-revert-tail-pos)
 280                  (save-restriction (widen) (1- (point-max))))))
 281
 282 ;; Functions:
 283
 284 ;;;###autoload
 285 (define-minor-mode auto-revert-mode
 286   "Toggle reverting buffer when file on disk changes.
 287
 288 With arg, turn Auto Revert mode on if and only if arg is positive.
 289 This is a minor mode that affects only the current buffer.
 290 Use `global-auto-revert-mode' to automatically revert all buffers.
 291 Use `auto-revert-tail-mode' if you know that the file will only grow
 292 without being changed in the part that is already in the buffer."
 293   :group 'auto-revert :lighter auto-revert-mode-text
 294   (if auto-revert-mode
 295       (if (not (memq (current-buffer) auto-revert-buffer-list))
 296           (push (current-buffer) auto-revert-buffer-list))
 297     (setq auto-revert-buffer-list
 298           (delq (current-buffer) auto-revert-buffer-list)))
 299   (auto-revert-set-timer)
 300   (when auto-revert-mode
 301     (auto-revert-buffers)
 302     (setq auto-revert-tail-mode nil)))
 303
 304
 305 ;;;###autoload
 306 (defun turn-on-auto-revert-mode ()
 307   "Turn on Auto-Revert Mode.
 308
 309 This function is designed to be added to hooks, for example:
 310   (add-hook 'c-mode-hook 'turn-on-auto-revert-mode)"
 311   (auto-revert-mode 1))
 312
 313
 314 ;;;###autoload
 315 (define-minor-mode auto-revert-tail-mode
 316   "Toggle reverting tail of buffer when file on disk grows.
 317 With arg, turn Tail mode on iff arg is positive.
 318
 319 When Tail mode is enabled, the tail of the file is constantly
 320 followed, as with the shell command `tail -f'.  This means that
 321 whenever the file grows on disk (presumably because some
 322 background process is appending to it from time to time), this is
 323 reflected in the current buffer.
 324
 325 You can edit the buffer and turn this mode off and on again as
 326 you please.  But make sure the background process has stopped
 327 writing before you save the file!
 328
 329 Use `auto-revert-mode' for changes other than appends!"
 330   :group 'find-file :lighter auto-revert-tail-mode-text
 331   (when auto-revert-tail-mode
 332     (unless buffer-file-name
 333       (auto-revert-tail-mode 0)
 334       (error "This buffer is not visiting a file"))
 335     (if (and (buffer-modified-p)
 336              (not auto-revert-tail-pos) ; library was loaded only after finding file
 337              (not (y-or-n-p "Buffer is modified, so tail offset may be wrong.  Proceed? ")))
 338         (auto-revert-tail-mode 0)
 339       ;; else we might reappend our own end when we save
 340       (add-hook 'before-save-hook (lambda () (auto-revert-tail-mode 0)) nil t)
 341       (or (local-variable-p 'auto-revert-tail-pos) ; don't lose prior position
 342           (set (make-variable-buffer-local 'auto-revert-tail-pos)
 343                (save-restriction (widen) (1- (point-max)))))
 344       ;; let auto-revert-mode set up the mechanism for us if it isn't already
 345       (or auto-revert-mode
 346           (let ((auto-revert-tail-mode t))
 347             (auto-revert-mode 1)))
 348       (setq auto-revert-mode nil))))
 349
 350
 351 ;;;###autoload
 352 (defun turn-on-auto-revert-tail-mode ()
 353   "Turn on Auto-Revert Tail Mode.
 354
 355 This function is designed to be added to hooks, for example:
 356   (add-hook 'my-logfile-mode-hook 'turn-on-auto-revert-tail-mode)"
 357   (auto-revert-tail-mode 1))
 358
 359
 360 ;;;###autoload
 361 (define-minor-mode global-auto-revert-mode
 362   "Revert any buffer when file on disk changes.
 363
 364 With arg, turn Auto Revert mode on globally if and only if arg is positive.
 365 This is a minor mode that affects all buffers.
 366 Use `auto-revert-mode' to revert a particular buffer."
 367   :global t :group 'auto-revert :lighter global-auto-revert-mode-text
 368   (auto-revert-set-timer)
 369   (when global-auto-revert-mode
 370     (auto-revert-buffers)))
 371
 372
 373 (defun auto-revert-set-timer ()
 374   "Restart or cancel the timer used by Auto-Revert Mode.
 375 If such a timer is active, cancel it.  Start a new timer if
 376 Global Auto-Revert Mode is active or if Auto-Revert Mode is active
 377 in some buffer.  Restarting the timer ensures that Auto-Revert Mode
 378 will use an up-to-date value of `auto-revert-interval'"
 379   (interactive)
 380   (if (timerp auto-revert-timer)
 381       (cancel-timer auto-revert-timer))
 382   (setq auto-revert-timer
 383         (if (or global-auto-revert-mode auto-revert-buffer-list)
 384             (run-with-timer auto-revert-interval
 385                             auto-revert-interval
 386                             'auto-revert-buffers))))
 387
 388 (defun auto-revert-active-p ()
 389   "Check if auto-revert is active (in current buffer or globally)."
 390   (or auto-revert-mode
 391       auto-revert-tail-mode
 392       (and
 393        global-auto-revert-mode
 394        (not global-auto-revert-ignore-buffer)
 395        (not (memq major-mode
 396                   global-auto-revert-ignore-modes)))))
 397
 398 (defun auto-revert-handler ()
 399   "Revert current buffer, if appropriate.
 400 This is an internal function used by Auto-Revert Mode."
 401   (when (or auto-revert-tail-mode (not (buffer-modified-p)))
 402     (let* ((buffer (current-buffer))
 403            (revert
 404             (or (and buffer-file-name
 405                      (not (file-remote-p buffer-file-name))
 406                      (file-readable-p buffer-file-name)
 407                      (not (verify-visited-file-modtime buffer)))
 408                 (and (or auto-revert-mode
 409                          global-auto-revert-non-file-buffers)
 410                      revert-buffer-function
 411                      (boundp 'buffer-stale-function)
 412                      (functionp buffer-stale-function)
 413                      (funcall buffer-stale-function t))))
 414            eob eoblist)
 415       (when revert
 416         (when (and auto-revert-verbose
 417                    (not (eq revert 'fast)))
 418           (message "Reverting buffer `%s'." (buffer-name)))
 419         ;; If point (or a window point) is at the end of the buffer,
 420         ;; we want to keep it at the end after reverting.  This allows
 421         ;; to tail a file.
 422         (when buffer-file-name
 423           (setq eob (eobp))
 424           (walk-windows
 425            #'(lambda (window)
 426                (and (eq (window-buffer window) buffer)
 427                     (= (window-point window) (point-max))
 428                     (push window eoblist)))
 429            'no-mini t))
 430         (if auto-revert-tail-mode
 431             (auto-revert-tail-handler)
 432           ;; Bind buffer-read-only in case user has done C-x C-q,
 433           ;; so as not to forget that.  This gives undesirable results
 434           ;; when the file's mode changes, but that is less common.
 435           (let ((buffer-read-only buffer-read-only))
 436             (revert-buffer 'ignore-auto 'dont-ask 'preserve-modes)))
 437         (when buffer-file-name
 438           (when eob (goto-char (point-max)))
 439           (dolist (window eoblist)
 440             (set-window-point window (point-max)))))
 441       ;; `preserve-modes' avoids changing the (minor) modes.  But we
 442       ;; do want to reset the mode for VC, so we do it manually.
 443       (when (or revert auto-revert-check-vc-info)
 444         (vc-find-file-hook)))))
 445
 446 (defun auto-revert-tail-handler ()
 447   (let ((size (nth 7 (file-attributes buffer-file-name)))
 448         (modified (buffer-modified-p))
 449         buffer-read-only                ; ignore
 450         (file buffer-file-name)
 451         buffer-file-name)               ; ignore that file has changed
 452     (when (> size auto-revert-tail-pos)
 453       (undo-boundary)
 454       (save-restriction
 455         (widen)
 456         (save-excursion
 457           (goto-char (point-max))
 458           (insert-file-contents file nil auto-revert-tail-pos size)))
 459       (undo-boundary)
 460       (setq auto-revert-tail-pos size)
 461       (set-buffer-modified-p modified)))
 462   (set-visited-file-modtime))
 463
 464 (defun auto-revert-buffers ()
 465   "Revert buffers as specified by Auto-Revert and Global Auto-Revert Mode.
 466
 467 Should `global-auto-revert-mode' be active all file buffers are checked.
 468
 469 Should `auto-revert-mode' be active in some buffers, those buffers
 470 are checked.
 471
 472 Non-file buffers that have a custom `revert-buffer-function' and
 473 a `buffer-stale-function' are reverted either when Auto-Revert
 474 Mode is active in that buffer, or when the variable
 475 `global-auto-revert-non-file-buffers' is non-nil and Global
 476 Auto-Revert Mode is active.
 477
 478 This function stops whenever there is user input.  The buffers not
 479 checked are stored in the variable `auto-revert-remaining-buffers'.
 480
 481 To avoid starvation, the buffers in `auto-revert-remaining-buffers'
 482 are checked first the next time this function is called.
 483
 484 This function is also responsible for removing buffers no longer in
 485 Auto-Revert mode from `auto-revert-buffer-list', and for canceling
 486 the timer when no buffers need to be checked."
 487   (save-match-data
 488     (let ((bufs (if global-auto-revert-mode
 489                     (buffer-list)
 490                   auto-revert-buffer-list))
 491           (remaining ())
 492           (new ()))
 493       ;; Partition `bufs' into two halves depending on whether or not
 494       ;; the buffers are in `auto-revert-remaining-buffers'.  The two
 495       ;; halves are then re-joined with the "remaining" buffers at the
 496       ;; head of the list.
 497       (dolist (buf auto-revert-remaining-buffers)
 498         (if (memq buf bufs)
 499             (push buf remaining)))
 500       (dolist (buf bufs)
 501         (if (not (memq buf remaining))
 502             (push buf new)))
 503       (setq bufs (nreverse (nconc new remaining)))
 504       (while (and bufs
 505                   (not (and auto-revert-stop-on-user-input
 506                             (input-pending-p))))
 507         (let ((buf (car bufs)))
 508           (if (buffer-name buf)         ; Buffer still alive?
 509               (with-current-buffer buf
 510                 ;; Test if someone has turned off Auto-Revert Mode in a
 511                 ;; non-standard way, for example by changing major mode.
 512                 (if (and (not auto-revert-mode)
 513                          (not auto-revert-tail-mode)
 514                          (memq buf auto-revert-buffer-list))
 515                     (setq auto-revert-buffer-list
 516                           (delq buf auto-revert-buffer-list)))
 517                 (when (auto-revert-active-p) (auto-revert-handler)))
 518             ;; Remove dead buffer from `auto-revert-buffer-list'.
 519             (setq auto-revert-buffer-list
 520                   (delq buf auto-revert-buffer-list))))
 521         (setq bufs (cdr bufs)))
 522       (setq auto-revert-remaining-buffers bufs)
 523       ;; Check if we should cancel the timer.
 524       (when (and (not global-auto-revert-mode)
 525                  (null auto-revert-buffer-list))
 526         (cancel-timer auto-revert-timer)
 527         (setq auto-revert-timer nil)))))
 528
 529
 530 ;; The end:
 531 (provide 'autorevert)
 532
 533 (run-hooks 'auto-revert-load-hook)
 534
 535 ;;; arch-tag: f6bcb07b-4841-477e-9e44-b18678e58876
 536 ;;; autorevert.el ends here