Subject: bug#18958: 25.0.50; auto-revert-mode reacts slowly even if using an event-driven backend

From: Dima Kogan <[email-masked]>
Date: Fri, 20 Feb 2015 19:38:39 -0800

Dima Kogan <[email-masked]> writes:

> The notification throttling seems to have a problem. Recipe:

Hi. I figured this out. The notification handler was being installed
during a timer update, NOT when auto-revert-mode was initiated. So in
order for the code to work you'd have to

- M-x auto-revert-mode
- wait for the timer. ~5 seconds or so
- update file

If you didn't wait, then this first update would be ignored.

The code to install the handler when needed was already there, but for
some reason it was disabled. Attaching a patch that makes it work for
all of auto-revert-mode, auto-revert-tail-mode and
global-auto-revert-mode. This patch removes

 (let (auto-revert-use-notify) ... )

wrappers to let the existing code to its thing, and for
auto-revert-tail-mode this patch calls (auto-revert-buffers) instead of
(auto-revert-handler), like the other two code paths already do.
Truthfully, it probably does make sense to call (auto-revert-handler)
for the two non-global functions, but the handler-install code would
then need to be moved.

I still need to double-check the gfile stuff, and I'll do that when I
get your ok on this. The gfile also has a delay in glib itself, so this
wouldn't be as nice as inotify until glib is patched.

>From bb2dec478fce20a25a737f16f26c0b338d599552 Mon Sep 17 00:00:00 2001
From: Dima Kogan <[email-masked]>
Date: Fri, 20 Feb 2015 19:38:17 -0800
Subject: [PATCH] notification handler is now installed when auto-revert-mode
 is entered

---
 lisp/autorevert.el | 11 ++++-------
 1 file changed, 4 insertions(+), 7 deletions(-)

diff --git a/lisp/autorevert.el b/lisp/autorevert.el
index 02cef24..4dd021e 100644
--- a/lisp/autorevert.el
+++ b/lisp/autorevert.el
@@ -361,9 +361,8 @@ without being changed in the part that is already in the buffer."
 	  (delq (current-buffer) auto-revert-buffer-list)))
   (auto-revert-set-timer)
   (when auto-revert-mode
-    (let (auto-revert-use-notify)
-      (auto-revert-buffers)
-      (setq auto-revert-tail-mode nil))))
+    (auto-revert-buffers)
+    (setq auto-revert-tail-mode nil)))

 ;;;###autoload
@@ -417,8 +416,7 @@ Use `auto-revert-mode' for changes other than appends!"
            (y-or-n-p "File changed on disk, content may be missing.  \
 Perform a full revert? ")
            ;; Use this (not just revert-buffer) for point-preservation.
-	   (let (auto-revert-use-notify)
-	     (auto-revert-handler)))
+           (auto-revert-buffers))
       ;; 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
@@ -463,8 +461,7 @@ specifies in the mode line."
   :global t :group 'auto-revert :lighter global-auto-revert-mode-text
   (auto-revert-set-timer)
   (if global-auto-revert-mode
-      (let (auto-revert-use-notify)
-	(auto-revert-buffers))
+      (auto-revert-buffers)
     (dolist (buf (buffer-list))
       (with-current-buffer buf
 	(when auto-revert-use-notify
-- 
2.0.0