X-Git-Url: https://code.delx.au/gnu-emacs/blobdiff_plain/71c8db4cd53ac3da32bd4fd2f76b9f1124675026..1b74c4346e92c9ac1ae0575c2ad69f8d81126d7e:/lisp/autorevert.el

diff --git a/lisp/autorevert.el b/lisp/autorevert.el
index 6e74a96eff..9892dca2d4 100644
--- a/lisp/autorevert.el
+++ b/lisp/autorevert.el
@@ -1,6 +1,7 @@
 ;;; autorevert.el --- revert buffers when files on disk change
 
-;; Copyright (C) 1997, 1998, 1999, 2001 Free Software Foundation, Inc.
+;; Copyright (C) 1997, 1998, 1999, 2001, 2002, 2003, 2004,
+;;   2005 Free Software Foundation, Inc.
 
 ;; Author: Anders Lindgren <andersl@andersl.com>
 ;; Keywords: convenience
@@ -21,8 +22,8 @@
 
 ;; 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., 59 Temple Place - Suite 330,
-;; Boston, MA 02111-1307, USA.
+;; Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
+;; Boston, MA 02110-1301, USA.
 
 ;;; Commentary:
 
@@ -34,21 +35,45 @@
 ;;
 ;; This package contains two minor modes: Global Auto-Revert Mode and
 ;; Auto-Revert Mode.  Both modes automatically revert buffers
-;; whenever the corresponding files have been changed on disk.
+;; whenever the corresponding files have been changed on disk and the
+;; buffer contains no unsaved changes.
 ;;
-;; Auto-Revert Mode can be activated for individual buffers.
-;; Global Auto-Revert Mode applies to all file buffers.
+;; Auto-Revert Mode can be activated for individual buffers.  Global
+;; Auto-Revert Mode applies to all file buffers. (If the user option
+;; `global-auto-revert-non-file-buffers' is non-nil, it also applies
+;; to some non-file buffers.  This option is disabled by default.)
+;; Since checking a remote file is too slow, these modes do not check
+;; or revert remote files.
 ;;
 ;; Both modes operate by checking the time stamp of all files at
 ;; intervals of `auto-revert-interval'.  The default is every five
 ;; seconds.  The check is aborted whenever the user actually uses
 ;; Emacs.  You should never even notice that this package is active
 ;; (except that your buffers will be reverted, of course).
+;;
+;; After reverting a file buffer, Auto Revert Mode normally puts point
+;; at the same position that a regular manual revert would.  However,
+;; there is one exception to this rule.  If point is at the end of the
+;; buffer before reverting, it stays at the end.  Similarly if point
+;; is displayed at the end of a file buffer in any window, it will stay
+;; at the end of the buffer in that window, even if the window is not
+;; selected.  This way, you can use Auto Revert Mode to `tail' a file.
+;; Just put point at the end of the buffer and it will stay there.
+;; These rules apply to file buffers. For non-file buffers, the
+;; behavior may be mode dependent.
+;;
+;; While you can use Auto Revert Mode to tail a file, this package
+;; contains a third minor mode, Auto Revert Tail Mode, which does so
+;; more efficiently, as long as you are sure that the file will only
+;; change by growing at the end.  It only appends the new output,
+;; instead of reverting the entire buffer.  It does so even if the
+;; buffer contains unsaved changes.  (Because they will not be lost.)
 
 ;; Usage:
 ;;
-;; Go to the appropriate buffer and press:
+;; Go to the appropriate buffer and press either of:
 ;;   M-x auto-revert-mode RET
+;;   M-x auto-revert-tail-mode RET
 ;;
 ;; To activate Global Auto-Revert Mode, press:
 ;;   M-x global-auto-revert-mode RET
@@ -90,13 +115,19 @@ Global Auto-Revert Mode applies to all buffers."
 
 ;; Variables:
 
-;; Autoload for the benefit of `make-mode-line-mouse-sensitive'.
-;;;###autoload
+;;; What's this?: ;; Autoload for the benefit of `make-mode-line-mouse-sensitive'.
+;;; What's this?: ;;;###autoload
 (defvar auto-revert-mode nil
   "*Non-nil when Auto-Revert Mode is active.
 Never set this variable directly, use the command `auto-revert-mode' instead.")
 (put 'auto-revert-mode 'permanent-local t)
 
+(defvar auto-revert-tail-mode nil
+  "*Non-nil when Auto-Revert Tail Mode is active.
+Never set this variable directly, use the command
+`auto-revert-tail-mode' instead.")
+(put 'auto-revert-tail-mode 'permanent-local t)
+
 (defvar auto-revert-timer nil
   "Timer used by Auto-Revert Mode.")
 
@@ -120,12 +151,18 @@ next editing session."
 	      (auto-revert-set-timer))))
 
 (defcustom auto-revert-stop-on-user-input t
-  "When non-nil Auto-Revert Mode stops checking files on user input."
+  "When non-nil, user input temporarily interrupts Auto-Revert Mode.
+With this setting, Auto-Revert Mode checks for user input after
+handling each buffer and does not process any further buffers
+\(until the next run of the timer) if user input is available.
+When nil, Auto-Revert Mode checks files and reverts buffers,
+with quitting disabled, without paying attention to user input.
+Thus, with this setting, Emacs might be non-responsive at times."
   :group 'auto-revert
   :type 'boolean)
 
 (defcustom auto-revert-verbose t
-  "When nil, Auto-Revert Mode will not generate any messages.
+  "When nil, Auto-Revert Mode does not generate any messages.
 When non-nil, a message is generated whenever a file is reverted."
   :group 'auto-revert
   :type 'boolean)
@@ -138,6 +175,14 @@ When non-nil, a message is generated whenever a file is reverted."
   :group 'auto-revert
   :type 'string)
 
+(defcustom auto-revert-tail-mode-text " Tail"
+  "String to display in the mode line when Auto-Revert Tail Mode is active.
+
+\(When the string is not empty, make sure that it has a leading space.)"
+  :group 'auto-revert
+  :type 'string
+  :version "22.1")
+
 (defcustom auto-revert-mode-hook nil
   "Functions to run when Auto-Revert Mode is activated."
   :tag "Auto Revert Mode Hook"		; To separate it from `global-...'
@@ -159,22 +204,23 @@ would only waste precious space."
   :type 'hook)
 
 (defcustom global-auto-revert-non-file-buffers nil
-  "When nil only file buffers are reverted by Global Auto-Revert Mode.
+  "When nil, Global Auto-Revert mode operates only on file-visiting buffers.
 
 When non-nil, both file buffers and buffers with a custom
 `revert-buffer-function' and a `buffer-stale-function' are
-reverted by Global Auto-Revert Mode.
-
-Use this option with care since it could lead to excessive reverts.
-Note also that for some non-file buffers the check whether the
-buffer needs updating may be imperfect, due to efficiency
-considerations, and may not take all information listed in the
-buffer into account.  Hence, a non-nil value for this option does
-not necessarily make manual updates useless for non-file buffers."
+reverted by Global Auto-Revert mode.  These include the Buffer
+List buffer, and Dired buffers showing complete local
+directories.  Dired buffers do not auto-revert as a result of
+changes in subdirectories or in the contents, size, modes, etc.,
+of files.  You may still sometimes want to revert them manually.
+
+Use this option with care since it could lead to excessive auto-reverts.
+For more information, see Info node `(emacs-xtra)Autorevert'."
   :group 'auto-revert
-  :type 'boolean)
+  :type 'boolean
+  :link '(info-link "(emacs-xtra)Autorevert"))
 
-(defcustom global-auto-revert-ignore-modes '()
+(defcustom global-auto-revert-ignore-modes ()
   "List of major modes Global Auto-Revert Mode should not check."
   :group 'auto-revert
   :type '(repeat sexp))
@@ -201,10 +247,10 @@ This currently works by automatically updating the version
 control info every `auto-revert-interval' seconds.  Nevertheless,
 it should not cause excessive CPU usage on a reasonably fast
 machine, if it does not apply to too many version controlled
-buffers.  CPU usage depends on the version control system"
+buffers.  CPU usage depends on the version control system."
   :group 'auto-revert
   :type 'boolean
-  :version "21.4")
+  :version "22.1")
 
 (defvar global-auto-revert-ignore-buffer nil
   "*When non-nil, Global Auto-Revert Mode will not revert this buffer.
@@ -214,7 +260,7 @@ This variable becomes buffer local when set in any fashion.")
 
 ;; Internal variables:
 
-(defvar auto-revert-buffer-list '()
+(defvar auto-revert-buffer-list ()
   "List of buffers in Auto-Revert Mode.
 
 Note that only Auto-Revert Mode, never Global Auto-Revert Mode, adds
@@ -223,9 +269,16 @@ buffers to this list.
 The timer function `auto-revert-buffers' is responsible for purging
 the list of old buffers.")
 
-(defvar auto-revert-remaining-buffers '()
+(defvar auto-revert-remaining-buffers ()
   "Buffers not checked when user input stopped execution.")
 
+(defvar auto-revert-tail-pos 0
+  "Position of last known end of file.")
+
+(add-hook 'find-file-hook
+	  (lambda ()
+	    (set (make-local-variable 'auto-revert-tail-pos)
+		 (save-restriction (widen) (1- (point-max))))))
 
 ;; Functions:
 
@@ -235,8 +288,10 @@ the list of old buffers.")
 
 With arg, turn Auto Revert mode on if and only if arg is positive.
 This is a minor mode that affects only the current buffer.
-Use `global-auto-revert-mode' to automatically revert all buffers."
-  nil auto-revert-mode-text nil
+Use `global-auto-revert-mode' to automatically revert all buffers.
+Use `auto-revert-tail-mode' if you know that the file will only grow
+without being changed in the part that is already in the buffer."
+  :group 'auto-revert :lighter auto-revert-mode-text
   (if auto-revert-mode
       (if (not (memq (current-buffer) auto-revert-buffer-list))
 	  (push (current-buffer) auto-revert-buffer-list))
@@ -244,7 +299,8 @@ Use `global-auto-revert-mode' to automatically revert all buffers."
 	  (delq (current-buffer) auto-revert-buffer-list)))
   (auto-revert-set-timer)
   (when auto-revert-mode
-    (auto-revert-buffers)))
+    (auto-revert-buffers)
+    (setq auto-revert-tail-mode nil)))
 
 
 ;;;###autoload
@@ -256,6 +312,52 @@ This function is designed to be added to hooks, for example:
   (auto-revert-mode 1))
 
 
+;;;###autoload
+(define-minor-mode auto-revert-tail-mode
+  "Toggle reverting tail of buffer when file on disk grows.
+With arg, turn Tail mode on iff arg is positive.
+
+When Tail mode is enabled, the tail of the file is constantly
+followed, as with the shell command `tail -f'.  This means that
+whenever the file grows on disk (presumably because some
+background process is appending to it from time to time), this is
+reflected in the current buffer.
+
+You can edit the buffer and turn this mode off and on again as
+you please.  But make sure the background process has stopped
+writing before you save the file!
+
+Use `auto-revert-mode' for changes other than appends!"
+  :group 'find-file :lighter auto-revert-tail-mode-text
+  (when auto-revert-tail-mode
+    (unless buffer-file-name
+      (auto-revert-tail-mode 0)
+      (error "This buffer is not visiting a file"))
+    (if (and (buffer-modified-p)
+	     (not auto-revert-tail-pos) ; library was loaded only after finding file
+	     (not (y-or-n-p "Buffer is modified, so tail offset may be wrong.  Proceed? ")))
+	(auto-revert-tail-mode 0)
+      ;; else we might reappend our own end when we save
+      (add-hook 'before-save-hook (lambda () (auto-revert-tail-mode 0)) nil t)
+      (or (local-variable-p 'auto-revert-tail-pos) ; don't lose prior position
+	  (set (make-local-variable 'auto-revert-tail-pos)
+	       (save-restriction (widen) (1- (point-max)))))
+      ;; let auto-revert-mode set up the mechanism for us if it isn't already
+      (or auto-revert-mode
+	  (let ((auto-revert-tail-mode t))
+	    (auto-revert-mode 1)))
+      (setq auto-revert-mode nil))))
+
+
+;;;###autoload
+(defun turn-on-auto-revert-tail-mode ()
+  "Turn on Auto-Revert Tail Mode.
+
+This function is designed to be added to hooks, for example:
+  (add-hook 'my-logfile-mode-hook 'turn-on-auto-revert-tail-mode)"
+  (auto-revert-tail-mode 1))
+
+
 ;;;###autoload
 (define-minor-mode global-auto-revert-mode
   "Revert any buffer when file on disk changes.
@@ -282,12 +384,12 @@ will use an up-to-date value of `auto-revert-interval'"
 	(if (or global-auto-revert-mode auto-revert-buffer-list)
 	    (run-with-timer auto-revert-interval
 			    auto-revert-interval
-			    'auto-revert-buffers)
-	  nil)))
+			    'auto-revert-buffers))))
 
 (defun auto-revert-active-p ()
   "Check if auto-revert is active (in current buffer or globally)."
   (or auto-revert-mode
+      auto-revert-tail-mode
       (and
        global-auto-revert-mode
        (not global-auto-revert-ignore-buffer)
@@ -297,27 +399,69 @@ will use an up-to-date value of `auto-revert-interval'"
 (defun auto-revert-handler ()
   "Revert current buffer, if appropriate.
 This is an internal function used by Auto-Revert Mode."
-  (unless (buffer-modified-p)
-    (let (revert)
-      (or (and (buffer-file-name)
-	       (file-readable-p (buffer-file-name))
-	       (not (verify-visited-file-modtime (current-buffer)))
-	       (setq revert t))
-	  (and (or auto-revert-mode global-auto-revert-non-file-buffers)
-	       revert-buffer-function
-	       (boundp 'buffer-stale-function)
-	       (functionp buffer-stale-function)
-	       (setq revert (funcall buffer-stale-function t))))
+  (when (or auto-revert-tail-mode (not (buffer-modified-p)))
+    (let* ((buffer (current-buffer))
+	   (revert
+	    (or (and buffer-file-name
+		     (not (file-remote-p buffer-file-name))
+		     (file-readable-p buffer-file-name)
+		     (not (verify-visited-file-modtime buffer)))
+		(and (or auto-revert-mode
+			 global-auto-revert-non-file-buffers)
+		     revert-buffer-function
+		     (boundp 'buffer-stale-function)
+		     (functionp buffer-stale-function)
+		     (funcall buffer-stale-function t))))
+	   eob eoblist)
       (when revert
 	(when (and auto-revert-verbose
 		   (not (eq revert 'fast)))
 	  (message "Reverting buffer `%s'." (buffer-name)))
-	(revert-buffer 'ignore-auto 'dont-ask 'preserve-modes))
+	;; If point (or a window point) is at the end of the buffer,
+	;; we want to keep it at the end after reverting.  This allows
+	;; to tail a file.
+	(when buffer-file-name
+	  (setq eob (eobp))
+	  (walk-windows
+	   #'(lambda (window)
+	       (and (eq (window-buffer window) buffer)
+		    (= (window-point window) (point-max))
+		    (push window eoblist)))
+	   'no-mini t))
+	(if auto-revert-tail-mode
+	    (auto-revert-tail-handler)
+	  ;; Bind buffer-read-only in case user has done C-x C-q,
+	  ;; so as not to forget that.  This gives undesirable results
+	  ;; when the file's mode changes, but that is less common.
+	  (let ((buffer-read-only buffer-read-only))
+	    (revert-buffer 'ignore-auto 'dont-ask 'preserve-modes)))
+	(when buffer-file-name
+	  (when eob (goto-char (point-max)))
+	  (dolist (window eoblist)
+	    (set-window-point window (point-max)))))
       ;; `preserve-modes' avoids changing the (minor) modes.  But we
       ;; do want to reset the mode for VC, so we do it manually.
       (when (or revert auto-revert-check-vc-info)
 	(vc-find-file-hook)))))
 
+(defun auto-revert-tail-handler ()
+  (let ((size (nth 7 (file-attributes buffer-file-name)))
+	(modified (buffer-modified-p))
+	buffer-read-only		; ignore
+	(file buffer-file-name)
+	buffer-file-name)		; ignore that file has changed
+    (when (> size auto-revert-tail-pos)
+      (undo-boundary)
+      (save-restriction
+	(widen)
+	(save-excursion
+	  (goto-char (point-max))
+	  (insert-file-contents file nil auto-revert-tail-pos size)))
+      (undo-boundary)
+      (setq auto-revert-tail-pos size)
+      (set-buffer-modified-p modified)))
+  (set-visited-file-modtime))
+
 (defun auto-revert-buffers ()
   "Revert buffers as specified by Auto-Revert and Global Auto-Revert Mode.
 
@@ -341,45 +485,47 @@ are checked first the next time this function is called.
 This function is also responsible for removing buffers no longer in
 Auto-Revert mode from `auto-revert-buffer-list', and for canceling
 the timer when no buffers need to be checked."
-  (let ((bufs (if global-auto-revert-mode
-		  (buffer-list)
-		auto-revert-buffer-list))
-	(remaining '())
-	(new '()))
-    ;; Partition `bufs' into two halves depending on whether or not
-    ;; the buffers are in `auto-revert-remaining-buffers'.  The two
-    ;; halves are then re-joined with the "remaining" buffers at the
-    ;; head of the list.
-    (dolist (buf auto-revert-remaining-buffers)
-      (if (memq buf bufs)
-	  (push buf remaining)))
-    (dolist (buf bufs)
-      (if (not (memq buf remaining))
-	  (push buf new)))
-    (setq bufs (nreverse (nconc new remaining)))
-    (while (and bufs
-		(not (and auto-revert-stop-on-user-input
-			  (input-pending-p))))
-      (let ((buf (car bufs)))
-	(if (buffer-name buf)		; Buffer still alive?
-	    (with-current-buffer buf
-	      ;; Test if someone has turned off Auto-Revert Mode in a
-	      ;; non-standard way, for example by changing major mode.
-	      (if (and (not auto-revert-mode)
-		       (memq buf auto-revert-buffer-list))
-		  (setq auto-revert-buffer-list
-			(delq buf auto-revert-buffer-list)))
-	      (when (auto-revert-active-p) (auto-revert-handler)))
-	  ;; Remove dead buffer from `auto-revert-buffer-list'.
-	  (setq auto-revert-buffer-list
-		(delq buf auto-revert-buffer-list))))
-      (setq bufs (cdr bufs)))
-    (setq auto-revert-remaining-buffers bufs)
-    ;; Check if we should cancel the timer.
-    (when (and (not global-auto-revert-mode)
-	       (null auto-revert-buffer-list))
-      (cancel-timer auto-revert-timer)
-      (setq auto-revert-timer nil))))
+  (save-match-data
+    (let ((bufs (if global-auto-revert-mode
+		    (buffer-list)
+		  auto-revert-buffer-list))
+	  (remaining ())
+	  (new ()))
+      ;; Partition `bufs' into two halves depending on whether or not
+      ;; the buffers are in `auto-revert-remaining-buffers'.  The two
+      ;; halves are then re-joined with the "remaining" buffers at the
+      ;; head of the list.
+      (dolist (buf auto-revert-remaining-buffers)
+	(if (memq buf bufs)
+	    (push buf remaining)))
+      (dolist (buf bufs)
+	(if (not (memq buf remaining))
+	    (push buf new)))
+      (setq bufs (nreverse (nconc new remaining)))
+      (while (and bufs
+		  (not (and auto-revert-stop-on-user-input
+			    (input-pending-p))))
+	(let ((buf (car bufs)))
+	  (if (buffer-name buf)		; Buffer still alive?
+	      (with-current-buffer buf
+		;; Test if someone has turned off Auto-Revert Mode in a
+		;; non-standard way, for example by changing major mode.
+		(if (and (not auto-revert-mode)
+			 (not auto-revert-tail-mode)
+			 (memq buf auto-revert-buffer-list))
+		    (setq auto-revert-buffer-list
+			  (delq buf auto-revert-buffer-list)))
+		(when (auto-revert-active-p) (auto-revert-handler)))
+	    ;; Remove dead buffer from `auto-revert-buffer-list'.
+	    (setq auto-revert-buffer-list
+		  (delq buf auto-revert-buffer-list))))
+	(setq bufs (cdr bufs)))
+      (setq auto-revert-remaining-buffers bufs)
+      ;; Check if we should cancel the timer.
+      (when (and (not global-auto-revert-mode)
+		 (null auto-revert-buffer-list))
+	(cancel-timer auto-revert-timer)
+	(setq auto-revert-timer nil)))))
 
 
 ;; The end: