|Subject:||bug#16129: 24.3.50; Emacs slow with follow-mode when buffer ends before last window|
|Date:||Tue, 7 Jan 2014 09:13:19 +0100|
=== modified file 'lisp/follow.el'
--- lisp/follow.el 2014-01-01 07:43:34 +0000
+++ lisp/follow.el 2014-01-07 07:48:40 +0000
@@ -311,7 +311,7 @@
(set-default symbol value)))
- '(next-line previous-line forward-char backward-char)
+ '(next-line previous-line forward-char backward-char right-char left-char)
"List of commands that don't require recalculation.
In order to be able to use the cache, a command should not change the
> Date: Mon, 6 Jan 2014 09:20:03 +0100
> From: Anders Lindgren <address@hidden>
> Cc: Stefan Monnier <address@hidden>, address@hidden
>Indeed, this was my conclusion as well. (Except that PT is not quite
> I think the incorrect state occurs when the new early exit occurs from
> redsplay_window. When I added the condition "&& PT == w->last_point", both
> the recentering problem and speed issues were solved.
right, as the window could be displaying a buffer that is not the
current one at that early point in redisplay_window.)
What this caused was that the window redisplay was mistakenly skipped,
but then we marked that window's display "accurate", which confused
the heck out of the display engine.
So I installed the patch below to fix this regression, and I'm marking
this bug done. Feel free to reopen if there are any leftovers.
Btw, I strongly recommend against messing with window-start (or
anything else that potentially requires redisplay) in a
post-command-hook: doing so disables some important redisplay
optimizations, and can easily trigger subtle misfeatures. I suggest
to look for a better method to do what follow-mode needs to do, even
if that means we'd have to implement a special hook we don't yet have.
=== modified file 'src/xdisp.c'
--- src/xdisp.c 2014-01-01 17:44:48 +0000
+++ src/xdisp.c 2014-01-06 16:21:39 +0000
@@ -15621,7 +15621,8 @@ redisplay_window (Lisp_Object window, bo
&& REDISPLAY_SOME_P ()
- && !buffer->text->redisplay)
+ && !buffer->text->redisplay
+ && BUF_PT (buffer) == w->last_point)
/* Make sure that both W's markers are valid. */
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