From: "Mattias Engdegård" <mattiase@acm.org>
To: 35418@debbugs.gnu.org
Cc: Michael Albinus <michael.albinus@gmx.de>
Subject: bug#35418: [PATCH] Don't poll auto-revert files that use notification
Date: Wed, 24 Apr 2019 20:14:46 +0200 [thread overview]
Message-ID: <DC246485-905B-4DD9-8849-8D1DF23F2EC5@acm.org> (raw)
[-- Attachment #1: Type: text/plain, Size: 1007 bytes --]
It is a waste of power, on battery-powered devices in particular, to poll files in auto-revert mode periodically when change notification is used. The change is straightforward (attached patch); the main concern is whether the notification system is reliable enough.
In general, it probably is. There is a comment in w32notify.c about SMB-mounted file systems from Samba servers; while Samba does support notification nowadays, there are probably older systems still be deficient in that regard. However, isn't this what `auto-revert-notify-exclude-dir-regexp' is for? I'm not familiar with the way Emacs is used on Windows, but would adding something like
(rx bos
(or "\\\\" "//")
(one-or-more (not (any "/:\\")))
(any "/\\"))
to `auto-revert-notify-exclude-dir-regexp' be a good start?
Another note about what this patch does not do: global-auto-revert-mode will still use polling. This could be added later on, if there is a good place to hook into for buffer creation.
[-- Attachment #2: 0001-Don-t-poll-auto-revert-files-that-use-notification.patch --]
[-- Type: application/octet-stream, Size: 9323 bytes --]
From 5074c65347736a716f335842206a1e2a2ad36a87 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Mattias=20Engdeg=C3=A5rd?= <mattiase@acm.org>
Date: Wed, 24 Apr 2019 18:39:05 +0200
Subject: [PATCH] Don't poll auto-revert files that use notification
It is a waste to periodically poll files that use change notification
in auto-revert mode; stop doing that. If no files need polling,
turn off the periodic execution entirely to further avoid wasting power.
Use a timer to inhibit immediate reversion for some time after a
notification.
This change does not apply to files in global-auto-revert-mode, where
polling is still necessary.
* lisp/autorevert.el (auto-revert--polled-buffers): New.
(auto-revert-remove-current-buffer, auto-revert-mode)
(global-auto-revert-mode, auto-revert-set-timer)
(auto-revert-notify-add-watch, auto-revert-buffers):
Maintain and use auto-revert--polled-buffers.
(auto-revert-buffers-counter): Remove.
(auto-revert-buffers-counter-lockedout): Remove.
(auto-revert--lockout-interval): New.
(auto-revert--lockout-timer): New.
(auto-revert-notify-handler): Maintain and use auto-revert--polled-buffers.
Honour new lockout timer. Start lockout timer if necessary.
(auto-revert--end-lockout): New.
---
lisp/autorevert.el | 84 +++++++++++++++++++++++++++++-----------------
1 file changed, 53 insertions(+), 31 deletions(-)
diff --git a/lisp/autorevert.el b/lisp/autorevert.el
index 1d20896c83..f7b33360ef 100644
--- a/lisp/autorevert.el
+++ b/lisp/autorevert.el
@@ -319,6 +319,11 @@ the list of old buffers.")
(defvar auto-revert-tail-pos 0
"Position of last known end of file.")
+(defvar auto-revert--polled-buffers ()
+ "List of buffers in Auto-Revert Mode that must be polled.
+It contains the buffers in `auto-revert-buffer-list' whose
+`auto-revert-notify-watch-descriptor' is nil.")
+
(defun auto-revert-find-file-function ()
(setq-local auto-revert-tail-pos
(file-attribute-size (file-attributes buffer-file-name))))
@@ -346,8 +351,12 @@ This has been reported by a file notification event.")
(defun auto-revert-remove-current-buffer (&optional buffer)
"Remove BUFFER from `auto-revert-buffer-list'.
BUFFER defaults to `current-buffer'."
+ (unless buffer
+ (setq buffer (current-buffer)))
(setq auto-revert-buffer-list
- (delq (or buffer (current-buffer)) auto-revert-buffer-list)))
+ (delq buffer auto-revert-buffer-list))
+ (setq auto-revert--polled-buffers
+ (delq buffer auto-revert--polled-buffers)))
;;;###autoload
(define-minor-mode auto-revert-mode
@@ -367,6 +376,7 @@ without being changed in the part that is already in the buffer."
(if auto-revert-mode
(when (not (memq (current-buffer) auto-revert-buffer-list))
(push (current-buffer) auto-revert-buffer-list)
+ (push (current-buffer) auto-revert--polled-buffers)
(add-hook
'kill-buffer-hook
#'auto-revert-remove-current-buffer
@@ -479,7 +489,8 @@ specifies in the mode line."
(auto-revert-buffers)
(dolist (buf (buffer-list))
(with-current-buffer buf
- (when auto-revert-notify-watch-descriptor
+ (when (and auto-revert-notify-watch-descriptor
+ (not (memq buf auto-revert-buffer-list)))
(auto-revert-notify-rm-watch))))))
(defun auto-revert-set-timer ()
@@ -492,7 +503,7 @@ will use an up-to-date value of `auto-revert-interval'"
(if (timerp auto-revert-timer)
(cancel-timer auto-revert-timer))
(setq auto-revert-timer
- (if (or global-auto-revert-mode auto-revert-buffer-list)
+ (if (or global-auto-revert-mode auto-revert--polled-buffers)
(run-with-timer auto-revert-interval
auto-revert-interval
'auto-revert-buffers))))
@@ -551,6 +562,8 @@ will use an up-to-date value of `auto-revert-interval'"
(gethash auto-revert-notify-watch-descriptor
auto-revert--buffers-by-watch-descriptor))
auto-revert--buffers-by-watch-descriptor)
+ (setq auto-revert--polled-buffers
+ (delq (current-buffer) auto-revert--polled-buffers))
(add-hook 'kill-buffer-hook #'auto-revert-notify-rm-watch nil t)))))
;; If we have file notifications, we want to update the auto-revert buffers
@@ -558,24 +571,20 @@ will use an up-to-date value of `auto-revert-interval'"
;; often, we want to skip some revert operations so that we don't spend all our
;; time reverting the buffer.
;;
-;; We do this by reverting immediately in response to the first in a flurry of
-;; notifications. We suppress subsequent notifications until the next time
-;; `auto-revert-buffers' is called (this happens on a timer with a period set by
-;; `auto-revert-interval').
-(defvar auto-revert-buffers-counter 1
- "Incremented each time `auto-revert-buffers' is called")
-(defvar-local auto-revert-buffers-counter-lockedout 0
- "Buffer-local value to indicate whether we should immediately
-update the buffer on a notification event or not. If
-
- (= auto-revert-buffers-counter-lockedout
- auto-revert-buffers-counter)
-
-then the updates are locked out, and we wait until the next call
-of `auto-revert-buffers' to revert the buffer. If no lockout is
-present, then we revert immediately and set the lockout, so that
-no more reverts are possible until the next call of
-`auto-revert-buffers'")
+;; We do this by reverting immediately in response to the first in a
+;; flurry of notifications. Any notifications during the following
+;; `auto-revert-lockout-interval' seconds are noted but not acted upon
+;; until the end of that interval.
+
+(defconst auto-revert--lockout-interval 2.5
+ "Duration, in seconds, of the Auto-Revert Mode notification lockout.
+This is the quiescence after each notification of a file being
+changed during which no automatic reverting takes place, to
+prevent many updates in rapid succession from overwhelming the
+system.")
+
+(defvar-local auto-revert--lockout-timer nil
+ "Timer awaiting the end of the notification lockout interval, or nil.")
(defun auto-revert-notify-handler (event)
"Handle an EVENT returned from file notification."
@@ -604,7 +613,13 @@ no more reverts are possible until the next call of
(file-name-nondirectory buffer-file-name)))
;; A buffer w/o a file, like dired.
(null buffer-file-name))
- (auto-revert-notify-rm-watch))))
+ (auto-revert-notify-rm-watch)
+ (when (memq buffer auto-revert-buffer-list)
+ (unless (memq buffer auto-revert--polled-buffers)
+ (push buffer auto-revert--polled-buffers))
+ ;; Restart the timer if it wasn't running.
+ (unless auto-revert-timer
+ (auto-revert-set-timer))))))
;; Loop over all buffers, in order to find the intended one.
(cl-dolist (buffer buffers)
@@ -630,11 +645,21 @@ no more reverts are possible until the next call of
(setq auto-revert-notify-modified-p t)
;; Revert the buffer now if we're not locked out.
- (when (/= auto-revert-buffers-counter-lockedout
- auto-revert-buffers-counter)
+ (unless auto-revert--lockout-timer
(auto-revert-handler)
- (setq auto-revert-buffers-counter-lockedout
- auto-revert-buffers-counter))))))))))
+ (setq auto-revert--lockout-timer
+ (run-with-timer
+ auto-revert--lockout-interval nil
+ #'auto-revert--end-lockout buffer)))))))))))
+
+(defun auto-revert--end-lockout (buffer)
+ "End the lockout period after a notification.
+If the buffer needs to be reverted, do it now."
+ (when (buffer-live-p buffer)
+ (with-current-buffer buffer
+ (setq auto-revert--lockout-timer nil)
+ (when auto-revert-notify-modified-p
+ (auto-revert-handler)))))
(defun auto-revert-active-p ()
"Check if auto-revert is active (in current buffer or globally)."
@@ -755,13 +780,10 @@ 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."
- (setq auto-revert-buffers-counter
- (1+ auto-revert-buffers-counter))
-
(save-match-data
(let ((bufs (if global-auto-revert-mode
(buffer-list)
- auto-revert-buffer-list))
+ auto-revert--polled-buffers))
remaining new)
;; Buffers with remote contents shall be reverted only if the
;; connection is established already.
@@ -811,7 +833,7 @@ the timer when no buffers need to be checked."
(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))
+ (null auto-revert--polled-buffers))
(if (timerp auto-revert-timer)
(cancel-timer auto-revert-timer))
(setq auto-revert-timer nil)))))
--
2.20.1 (Apple Git-117)
next reply other threads:[~2019-04-24 18:14 UTC|newest]
Thread overview: 101+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-04-24 18:14 Mattias Engdegård [this message]
2019-04-24 18:58 ` bug#35418: [PATCH] Don't poll auto-revert files that use notification Eli Zaretskii
2019-04-24 19:36 ` Michael Albinus
2019-04-26 20:46 ` Mattias Engdegård
2019-04-27 9:40 ` Michael Albinus
2019-04-27 16:28 ` Mattias Engdegård
2019-04-25 9:56 ` Mattias Engdegård
2019-04-25 10:04 ` Eli Zaretskii
2019-04-25 18:07 ` Mattias Engdegård
2019-04-27 9:27 ` Michael Albinus
2019-04-27 9:54 ` Eli Zaretskii
2019-04-27 10:23 ` Michael Albinus
2019-04-27 16:19 ` Mattias Engdegård
2019-04-27 16:52 ` Eli Zaretskii
2019-04-28 10:21 ` Mattias Engdegård
2019-04-29 7:53 ` Michael Albinus
2019-04-29 11:06 ` Mattias Engdegård
2019-04-29 12:18 ` Michael Albinus
2019-04-29 16:24 ` Eli Zaretskii
2019-04-29 18:29 ` Mattias Engdegård
2019-04-29 20:17 ` Michael Albinus
2019-04-30 3:57 ` Eli Zaretskii
2019-04-30 11:41 ` Mattias Engdegård
2019-04-30 12:59 ` Michael Albinus
2019-04-30 13:56 ` Mattias Engdegård
2019-04-30 14:19 ` Michael Albinus
2019-04-29 16:23 ` Eli Zaretskii
2019-04-29 19:21 ` Mattias Engdegård
2019-04-29 19:56 ` Michael Albinus
2019-04-30 21:09 ` Mattias Engdegård
2019-05-01 17:45 ` Eli Zaretskii
2019-05-01 19:41 ` Mattias Engdegård
2019-05-02 12:18 ` Michael Albinus
2019-05-02 12:53 ` Mattias Engdegård
2019-05-02 13:02 ` Michael Albinus
2019-05-03 12:00 ` Mattias Engdegård
2019-05-03 13:44 ` Eli Zaretskii
2019-05-03 14:47 ` Mattias Engdegård
2019-05-04 9:04 ` Eli Zaretskii
2019-05-04 11:21 ` Mattias Engdegård
2019-05-04 13:41 ` Eli Zaretskii
2019-05-04 16:53 ` Michael Albinus
2019-05-04 17:08 ` Eli Zaretskii
2019-05-04 18:50 ` Mattias Engdegård
2019-05-04 19:43 ` Michael Albinus
2019-05-04 20:31 ` Michael Albinus
2019-05-04 20:46 ` Mattias Engdegård
2019-05-05 8:22 ` Michael Albinus
2019-05-05 9:58 ` Mattias Engdegård
2019-05-08 8:34 ` Mattias Engdegård
2019-05-08 8:47 ` Eli Zaretskii
2019-05-08 10:18 ` Mattias Engdegård
2019-05-08 10:58 ` Eli Zaretskii
2019-05-08 11:48 ` Mattias Engdegård
2019-05-08 12:35 ` Eli Zaretskii
2019-05-08 12:58 ` Mattias Engdegård
2019-05-08 13:09 ` Michael Albinus
2019-05-08 13:28 ` Eli Zaretskii
2019-05-08 14:13 ` Mattias Engdegård
2019-05-08 17:24 ` Eli Zaretskii
2019-05-08 18:17 ` Michael Albinus
2019-05-09 11:50 ` Michael Albinus
2019-05-10 15:22 ` Mattias Engdegård
2019-05-12 8:48 ` Michael Albinus
2019-05-12 19:49 ` Mattias Engdegård
2019-05-13 13:35 ` Michael Albinus
2019-05-14 12:41 ` Mattias Engdegård
2019-05-14 14:52 ` Michael Albinus
2019-05-08 10:23 ` Mattias Engdegård
2019-05-09 10:00 ` Mattias Engdegård
2019-05-09 10:48 ` Eli Zaretskii
2019-05-09 11:15 ` Mattias Engdegård
2019-05-10 9:49 ` Michael Albinus
2019-05-10 12:27 ` Mattias Engdegård
2019-05-10 12:43 ` Michael Albinus
2019-05-13 11:34 ` Mattias Engdegård
2019-05-13 15:08 ` Michael Albinus
2019-05-18 17:39 ` Mattias Engdegård
2019-05-19 9:12 ` Michael Albinus
2019-05-19 20:25 ` Mattias Engdegård
2019-05-20 7:30 ` Michael Albinus
2019-05-20 19:19 ` Mattias Engdegård
2019-04-29 7:19 ` Michael Albinus
2019-04-29 11:54 ` Mattias Engdegård
2019-04-29 12:26 ` Michael Albinus
2019-04-29 18:58 ` Mattias Engdegård
2019-04-29 20:04 ` Michael Albinus
2019-04-30 15:14 ` Eli Zaretskii
2019-04-24 19:59 ` Michael Albinus
2019-04-25 9:58 ` Mattias Engdegård
2019-04-25 11:04 ` Michael Albinus
2019-04-25 15:22 ` Mattias Engdegård
2019-04-30 1:03 ` Zhang Haijun
2019-04-30 7:06 ` Michael Albinus
2019-05-01 2:17 ` Zhang Haijun
2019-05-01 2:59 ` Zhang Haijun
2019-05-01 3:10 ` Zhang Haijun
2019-05-02 12:30 ` Michael Albinus
2019-05-02 13:24 ` Zhang Haijun
2019-05-02 12:28 ` Michael Albinus
2019-05-02 12:24 ` Michael Albinus
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