lisp/autorevert.el

   1 ;;; autorevert.el --- revert buffers when files on disk change
   2
   3 ;; Copyright (C) 1997, 1998, 1999, 2001 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., 59 Temple Place - Suite 330,
  25 ;; Boston, MA 02111-1307, 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.
  38 ;;
  39 ;; Auto-Revert Mode can be activated for individual buffers.  Global
  40 ;; Auto-Revert Mode applies to all file buffers. (If the user option
  41 ;; `global-auto-revert-non-file-buffers' is non-nil, it also applies
  42 ;; to some non-file buffers.  This option is disabled by default.)
  43 ;; Since checking a remote file is too slow, these modes do not check
  44 ;; or revert remote files.
  45 ;;
  46 ;; Both modes operate by checking the time stamp of all files at
  47 ;; intervals of `auto-revert-interval'.  The default is every five
  48 ;; seconds.  The check is aborted whenever the user actually uses
  49 ;; Emacs.  You should never even notice that this package is active
  50 ;; (except that your buffers will be reverted, of course).
  51 ;;
  52 ;; After reverting a file buffer, Auto Revert Mode normally puts point
  53 ;; at the same position that a regular manual revert would.  However,
  54 ;; there is one exception to this rule.  If point is at the end of the
  55 ;; buffer before reverting, it stays at the end.  Similarly if point
  56 ;; is displayed at the end of a file buffer in any window, it will stay
  57 ;; at the end of the buffer in that window, even if the window is not
  58 ;; selected.  This way, you can use Auto Revert Mode to `tail' a file.
  59 ;; Just put point at the end of the buffer and it will stay there.
  60 ;; These rules apply to file buffers. For non-file buffers, the
  61 ;; behavior may be mode dependent.
  62
  63 ;; Usage:
  64 ;;
  65 ;; Go to the appropriate buffer and press:
  66 ;;   M-x auto-revert-mode RET
  67 ;;
  68 ;; To activate Global Auto-Revert Mode, press:
  69 ;;   M-x global-auto-revert-mode RET
  70 ;;
  71 ;; To activate Global Auto-Revert Mode every time Emacs is started
  72 ;; customise the option `global-auto-revert-mode' or the following
  73 ;; line could be added to your ~/.emacs:
  74 ;;   (global-auto-revert-mode 1)
  75 ;;
  76 ;; The function `turn-on-auto-revert-mode' could be added to any major
  77 ;; mode hook to activate Auto-Revert Mode for all buffers in that
  78 ;; mode.  For example, the following line will activate Auto-Revert
  79 ;; Mode in all C mode buffers:
  80 ;;
  81 ;; (add-hook 'c-mode-hook 'turn-on-auto-revert-mode)
  82
  83 ;;; Code:
  84
  85 ;; Dependencies:
  86
  87 (require 'timer)
  88
  89 (eval-when-compile (require 'cl))
  90
  91
  92 ;; Custom Group:
  93 ;;
  94 ;; The two modes will be placed next to Auto Save Mode under the
  95 ;; Files group under Emacs.
  96
  97 (defgroup auto-revert nil
  98   "Revert individual buffers when files on disk change.
  99
 100 Auto-Revert Mode can be activated for individual buffer.
 101 Global Auto-Revert Mode applies to all buffers."
 102   :group 'files
 103   :group 'convenience)
 104
 105
 106 ;; Variables:
 107
 108 ;; Autoload for the benefit of `make-mode-line-mouse-sensitive'.
 109 ;;;###autoload
 110 (defvar auto-revert-mode nil
 111   "*Non-nil when Auto-Revert Mode is active.
 112 Never set this variable directly, use the command `auto-revert-mode' instead.")
 113 (put 'auto-revert-mode 'permanent-local t)
 114
 115 (defvar auto-revert-timer nil
 116   "Timer used by Auto-Revert Mode.")
 117
 118 (defcustom auto-revert-interval 5
 119   "Time, in seconds, between Auto-Revert Mode file checks.
 120 The value may be an integer or floating point number.
 121
 122 If a timer is already active, there are two ways to make sure
 123 that the new value will take effect immediately.  You can set
 124 this variable through Custom or you can call the command
 125 `auto-revert-set-timer' after setting the variable.  Otherwise,
 126 the new value will take effect the first time Auto Revert Mode
 127 calls `auto-revert-set-timer' for internal reasons or in your
 128 next editing session."
 129   :group 'auto-revert
 130   :type 'number
 131   :set (lambda (variable value)
 132          (set-default variable value)
 133          (and (boundp 'auto-revert-timer)
 134               auto-revert-timer
 135               (auto-revert-set-timer))))
 136
 137 (defcustom auto-revert-stop-on-user-input t
 138   "When non-nil Auto-Revert Mode stops checking files on user input."
 139   :group 'auto-revert
 140   :type 'boolean)
 141
 142 (defcustom auto-revert-verbose t
 143   "When nil, Auto-Revert Mode will not generate any messages.
 144 When non-nil, a message is generated whenever a file is reverted."
 145   :group 'auto-revert
 146   :type 'boolean)
 147
 148 (defcustom auto-revert-mode-text " ARev"
 149   "String to display in the mode line when Auto-Revert Mode is active.
 150
 151 \(When the string is not empty, make sure that it has a leading space.)"
 152   :tag "Auto Revert Mode Text"          ; To separate it from `global-...'
 153   :group 'auto-revert
 154   :type 'string)
 155
 156 (defcustom auto-revert-mode-hook nil
 157   "Functions to run when Auto-Revert Mode is activated."
 158   :tag "Auto Revert Mode Hook"          ; To separate it from `global-...'
 159   :group 'auto-revert
 160   :type 'hook)
 161
 162 (defcustom global-auto-revert-mode-text ""
 163   "String to display when Global Auto-Revert Mode is active.
 164
 165 The default is nothing since when this mode is active this text doesn't
 166 vary over time, or between buffers.  Hence mode line text
 167 would only waste precious space."
 168   :group 'auto-revert
 169   :type 'string)
 170
 171 (defcustom global-auto-revert-mode-hook nil
 172   "Hook called when Global Auto-Revert Mode is activated."
 173   :group 'auto-revert
 174   :type 'hook)
 175
 176 (defcustom global-auto-revert-non-file-buffers nil
 177   "When nil only file buffers are reverted by Global Auto-Revert Mode.
 178
 179 When non-nil, both file buffers and buffers with a custom
 180 `revert-buffer-function' and a `buffer-stale-function' are
 181 reverted by Global Auto-Revert Mode.
 182
 183 Use this option with care since it could lead to excessive reverts.
 184 Note also that for some non-file buffers the check whether the
 185 buffer needs updating may be imperfect, due to efficiency
 186 considerations, and may not take all information listed in the
 187 buffer into account.  Hence, a non-nil value for this option does
 188 not necessarily make manual updates useless for non-file buffers."
 189   :group 'auto-revert
 190   :type 'boolean)
 191
 192 (defcustom global-auto-revert-ignore-modes '()
 193   "List of major modes Global Auto-Revert Mode should not check."
 194   :group 'auto-revert
 195   :type '(repeat sexp))
 196
 197 (defcustom auto-revert-load-hook nil
 198   "Functions to run when Auto-Revert Mode is first loaded."
 199   :tag "Load Hook"
 200   :group 'auto-revert
 201   :type 'hook)
 202
 203 (defcustom auto-revert-check-vc-info nil
 204   "If non-nil Auto Revert Mode reliably updates version control info.
 205 Auto Revert Mode updates version control info whenever the buffer
 206 needs reverting, regardless of the value of this variable.
 207 However, the version control state can change without changes to
 208 the work file.  If the change is made from the current Emacs
 209 session, all info is updated.  But if, for instance, a new
 210 version is checked in from outside the current Emacs session, the
 211 version control number in the mode line, as well as other version
 212 control related information, may not be properly updated.  If you
 213 are worried about this, set this variable to a non-nil value.
 214
 215 This currently works by automatically updating the version
 216 control info every `auto-revert-interval' seconds.  Nevertheless,
 217 it should not cause excessive CPU usage on a reasonably fast
 218 machine, if it does not apply to too many version controlled
 219 buffers.  CPU usage depends on the version control system"
 220   :group 'auto-revert
 221   :type 'boolean
 222   :version "21.4")
 223
 224 (defvar global-auto-revert-ignore-buffer nil
 225   "*When non-nil, Global Auto-Revert Mode will not revert this buffer.
 226
 227 This variable becomes buffer local when set in any fashion.")
 228 (make-variable-buffer-local 'global-auto-revert-ignore-buffer)
 229
 230 ;; Internal variables:
 231
 232 (defvar auto-revert-buffer-list '()
 233   "List of buffers in Auto-Revert Mode.
 234
 235 Note that only Auto-Revert Mode, never Global Auto-Revert Mode, adds
 236 buffers to this list.
 237
 238 The timer function `auto-revert-buffers' is responsible for purging
 239 the list of old buffers.")
 240
 241 (defvar auto-revert-remaining-buffers '()
 242   "Buffers not checked when user input stopped execution.")
 243
 244
 245 ;; Functions:
 246
 247 ;;;###autoload
 248 (define-minor-mode auto-revert-mode
 249   "Toggle reverting buffer when file on disk changes.
 250
 251 With arg, turn Auto Revert mode on if and only if arg is positive.
 252 This is a minor mode that affects only the current buffer.
 253 Use `global-auto-revert-mode' to automatically revert all buffers."
 254   nil auto-revert-mode-text nil
 255   (if auto-revert-mode
 256       (if (not (memq (current-buffer) auto-revert-buffer-list))
 257           (push (current-buffer) auto-revert-buffer-list))
 258     (setq auto-revert-buffer-list
 259           (delq (current-buffer) auto-revert-buffer-list)))
 260   (auto-revert-set-timer)
 261   (when auto-revert-mode
 262     (auto-revert-buffers)))
 263
 264
 265 ;;;###autoload
 266 (defun turn-on-auto-revert-mode ()
 267   "Turn on Auto-Revert Mode.
 268
 269 This function is designed to be added to hooks, for example:
 270   (add-hook 'c-mode-hook 'turn-on-auto-revert-mode)"
 271   (auto-revert-mode 1))
 272
 273
 274 ;;;###autoload
 275 (define-minor-mode global-auto-revert-mode
 276   "Revert any buffer when file on disk changes.
 277
 278 With arg, turn Auto Revert mode on globally if and only if arg is positive.
 279 This is a minor mode that affects all buffers.
 280 Use `auto-revert-mode' to revert a particular buffer."
 281   :global t :group 'auto-revert :lighter global-auto-revert-mode-text
 282   (auto-revert-set-timer)
 283   (when global-auto-revert-mode
 284     (auto-revert-buffers)))
 285
 286
 287 (defun auto-revert-set-timer ()
 288   "Restart or cancel the timer used by Auto-Revert Mode.
 289 If such a timer is active, cancel it.  Start a new timer if
 290 Global Auto-Revert Mode is active or if Auto-Revert Mode is active
 291 in some buffer.  Restarting the timer ensures that Auto-Revert Mode
 292 will use an up-to-date value of `auto-revert-interval'"
 293   (interactive)
 294   (if (timerp auto-revert-timer)
 295       (cancel-timer auto-revert-timer))
 296   (setq auto-revert-timer
 297         (if (or global-auto-revert-mode auto-revert-buffer-list)
 298             (run-with-timer auto-revert-interval
 299                             auto-revert-interval
 300                             'auto-revert-buffers)
 301           nil)))
 302
 303 (defun auto-revert-active-p ()
 304   "Check if auto-revert is active (in current buffer or globally)."
 305   (or auto-revert-mode
 306       (and
 307        global-auto-revert-mode
 308        (not global-auto-revert-ignore-buffer)
 309        (not (memq major-mode
 310                   global-auto-revert-ignore-modes)))))
 311
 312 (defun auto-revert-handler ()
 313   "Revert current buffer, if appropriate.
 314 This is an internal function used by Auto-Revert Mode."
 315   (unless (buffer-modified-p)
 316     (let ((buffer (current-buffer)) revert eob eoblist)
 317       (or (and buffer-file-name
 318                (not (file-remote-p buffer-file-name))
 319                (file-readable-p buffer-file-name)
 320                (not (verify-visited-file-modtime buffer))
 321                (setq revert t))
 322           (and (or auto-revert-mode global-auto-revert-non-file-buffers)
 323                revert-buffer-function
 324                (boundp 'buffer-stale-function)
 325                (functionp buffer-stale-function)
 326                (setq revert (funcall buffer-stale-function t))))
 327       (when revert
 328         (when (and auto-revert-verbose
 329                    (not (eq revert 'fast)))
 330           (message "Reverting buffer `%s'." (buffer-name)))
 331         ;; If point (or a window point) is at the end of the buffer,
 332         ;; we want to keep it at the end after reverting.  This allows
 333         ;; to tail a file.
 334         (when buffer-file-name
 335           (setq eob (eobp))
 336           (walk-windows
 337            #'(lambda (window)
 338                (and (eq (window-buffer window) buffer)
 339                     (= (window-point window) (point-max))
 340                     (push window eoblist)))
 341            'no-mini t))
 342         (revert-buffer 'ignore-auto 'dont-ask 'preserve-modes)
 343         (when buffer-file-name
 344           (when eob (goto-char (point-max)))
 345           (dolist (window eoblist)
 346             (set-window-point window (point-max)))))
 347       ;; `preserve-modes' avoids changing the (minor) modes.  But we
 348       ;; do want to reset the mode for VC, so we do it manually.
 349       (when (or revert auto-revert-check-vc-info)
 350         (vc-find-file-hook)))))
 351
 352 (defun auto-revert-buffers ()
 353   "Revert buffers as specified by Auto-Revert and Global Auto-Revert Mode.
 354
 355 Should `global-auto-revert-mode' be active all file buffers are checked.
 356
 357 Should `auto-revert-mode' be active in some buffers, those buffers
 358 are checked.
 359
 360 Non-file buffers that have a custom `revert-buffer-function' and
 361 a `buffer-stale-function' are reverted either when Auto-Revert
 362 Mode is active in that buffer, or when the variable
 363 `global-auto-revert-non-file-buffers' is non-nil and Global
 364 Auto-Revert Mode is active.
 365
 366 This function stops whenever there is user input.  The buffers not
 367 checked are stored in the variable `auto-revert-remaining-buffers'.
 368
 369 To avoid starvation, the buffers in `auto-revert-remaining-buffers'
 370 are checked first the next time this function is called.
 371
 372 This function is also responsible for removing buffers no longer in
 373 Auto-Revert mode from `auto-revert-buffer-list', and for canceling
 374 the timer when no buffers need to be checked."
 375   (let ((bufs (if global-auto-revert-mode
 376                   (buffer-list)
 377                 auto-revert-buffer-list))
 378         (remaining '())
 379         (new '()))
 380     ;; Partition `bufs' into two halves depending on whether or not
 381     ;; the buffers are in `auto-revert-remaining-buffers'.  The two
 382     ;; halves are then re-joined with the "remaining" buffers at the
 383     ;; head of the list.
 384     (dolist (buf auto-revert-remaining-buffers)
 385       (if (memq buf bufs)
 386           (push buf remaining)))
 387     (dolist (buf bufs)
 388       (if (not (memq buf remaining))
 389           (push buf new)))
 390     (setq bufs (nreverse (nconc new remaining)))
 391     (while (and bufs
 392                 (not (and auto-revert-stop-on-user-input
 393                           (input-pending-p))))
 394       (let ((buf (car bufs)))
 395         (if (buffer-name buf)           ; Buffer still alive?
 396             (with-current-buffer buf
 397               ;; Test if someone has turned off Auto-Revert Mode in a
 398               ;; non-standard way, for example by changing major mode.
 399               (if (and (not auto-revert-mode)
 400                        (memq buf auto-revert-buffer-list))
 401                   (setq auto-revert-buffer-list
 402                         (delq buf auto-revert-buffer-list)))
 403               (when (auto-revert-active-p) (auto-revert-handler)))
 404           ;; Remove dead buffer from `auto-revert-buffer-list'.
 405           (setq auto-revert-buffer-list
 406                 (delq buf auto-revert-buffer-list))))
 407       (setq bufs (cdr bufs)))
 408     (setq auto-revert-remaining-buffers bufs)
 409     ;; Check if we should cancel the timer.
 410     (when (and (not global-auto-revert-mode)
 411                (null auto-revert-buffer-list))
 412       (cancel-timer auto-revert-timer)
 413       (setq auto-revert-timer nil))))
 414
 415
 416 ;; The end:
 417 (provide 'autorevert)
 418
 419 (run-hooks 'auto-revert-load-hook)
 420
 421 ;;; arch-tag: f6bcb07b-4841-477e-9e44-b18678e58876
 422 ;;; autorevert.el ends here