From 558084c7f736bebcb3cffc2bf4f617158d92357f Mon Sep 17 00:00:00 2001
From: Gregory Heytings <gregory@heytings.org>
Date: Sat, 26 Nov 2022 14:09:41 +0000
Subject: [PATCH] Improve locked narrowing around low-level hooks.
* src/buffer.c (syms_of_buffer): Two new variables,
'long-line-locked-narrowing-region-size' and
'long-line-locked-narrowing-bol-search-limit', to make the locked
narrowing around low-level hooks configurable.
Increase the default value of 'long-line-threshold'. After
carefully considering the (few) bug reports about long line
optimizations, I concluded that the previous default value was too
low.
* src/xdisp.c (get_locked_narrowing_begv)
(get_locked_narrowing_zv): Two new functions.
(handle_fontified_prop, reseat): Use them.
* src/keyboard.c (safe_run_hooks_maybe_narrowed): Use them.
* src/dispextern.h (struct it): Add two new fields to store the
values returned by these functions.
Make them externally visible.
* src/editfns.c: (Fsave_restriction): Update docstring.
---
src/buffer.c | 35 ++++++++++++++++++++++++++++++++++-
src/dispextern.h | 10 ++++++++++
src/editfns.c | 11 ++++++-----
src/keyboard.c | 4 ++--
src/xdisp.c | 44 ++++++++++++++++++++++++++++++++++++++++----
5 files changed, 92 insertions(+), 12 deletions(-)
diff --git a/src/buffer.c b/src/buffer.c
index d948aaa2662..ef7e6f18340 100644
--- a/src/buffer.c
+++ b/src/buffer.c
@@ -5882,7 +5882,40 @@ this threshold.
If nil, these display shortcuts will always remain disabled.
There is no reason to change that value except for debugging purposes. */);
- XSETFASTINT (Vlong_line_threshold, 10000);
+ XSETFASTINT (Vlong_line_threshold, 50000);
+
+ DEFVAR_INT ("long-line-locked-narrowing-region-size",
+ long_line_locked_narrowing_region_size,
+ doc: /* Region size for locked narrowing in buffers with long lines.
+
+This variable has effect only in buffers which contain one or more
+lines whose length is above `long-line-threshold', which see. For
+performance reasons, in such buffers, low-level hooks such as
+`fontification-functions' or `post-command-hook' are executed on a
+narrowed buffer, with a narrowing locked with `narrowing-lock'. This
+variable specifies the size of the narrowed region around point.
+
+To disable that narrowing, set this variable to 0.
+
+There is no reason to change that value except for debugging purposes. */);
+ long_line_locked_narrowing_region_size = 500000;
+
+ DEFVAR_INT ("long-line-locked-narrowing-bol-search-limit",
+ long_line_locked_narrowing_bol_search_limit,
+ doc: /* Limit for beginning of line search in buffers with long lines.
+
+This variable has effect only in buffers which contain one or more
+lines whose length is above `long-line-threshold', which see. For
+performance reasons, in such buffers, low-level hooks such as
+`fontification-functions' or `post-command-hook' are executed on a
+narrowed buffer, with a narrowing locked with `narrowing-lock'. The
+variable `long-line-locked-narrowing-region-size' specifies the size
+of the narrowed region around point. This variable, which should be a
+small integer, specifies the number of characters by which that region
+can be extended backwards to start it at the beginning of a line.
+
+There is no reason to change that value except for debugging purposes. */);
+ long_line_locked_narrowing_bol_search_limit = 128;
DEFVAR_INT ("large-hscroll-threshold", large_hscroll_threshold,
doc: /* Horizontal scroll of truncated lines above which to use redisplay shortcuts.
diff --git a/src/dispextern.h b/src/dispextern.h
index 2afbdeabaab..df6134e68f0 100644
--- a/src/dispextern.h
+++ b/src/dispextern.h
@@ -2342,6 +2342,14 @@ struct it
optimize display. */
ptrdiff_t narrowed_zv;
+ /* Begin position of the buffer for the locked narrowing around
+ low-level hooks. */
+ ptrdiff_t locked_narrowing_begv;
+
+ /* End position of the buffer for the locked narrowing around
+ low-level hooks. */
+ ptrdiff_t locked_narrowing_zv;
+
/* C string to iterate over. Non-null means get characters from
this string, otherwise characters are read from current_buffer
or it->string. */
@@ -3405,6 +3413,8 @@ void init_iterator (struct it *, struct window *, ptrdiff_t,
ptrdiff_t get_narrowed_begv (struct window *, ptrdiff_t);
ptrdiff_t get_narrowed_zv (struct window *, ptrdiff_t);
ptrdiff_t get_closer_narrowed_begv (struct window *, ptrdiff_t);
+ptrdiff_t get_locked_narrowing_begv (ptrdiff_t);
+ptrdiff_t get_locked_narrowing_zv (ptrdiff_t);
void init_iterator_to_row_start (struct it *, struct window *,
struct glyph_row *);
void start_display (struct it *, struct window *, struct text_pos);
diff --git a/src/editfns.c b/src/editfns.c
index f73331fb53c..e6b66209b8b 100644
--- a/src/editfns.c
+++ b/src/editfns.c
@@ -2659,7 +2659,7 @@ DEFUN ("delete-and-extract-region", Fdelete_and_extract_region,
the (uninterned) Qoutermost_narrowing tag and records the narrowing
bounds that were set by the user and that are visible on display.
This alist is used internally by narrow-to-region, widen,
- narrowing-lock and narrowing-unlock. */
+ narrowing-lock, narrowing-unlock and save-restriction. */
static Lisp_Object narrowing_locks;
/* Retrieve one of the BEGV/ZV bounds of a narrowing in BUF from the
@@ -3061,11 +3061,12 @@ DEFUN ("save-restriction", Fsave_restriction, Ssave_restriction, 0, UNEVALLED, 0
doc: /* Execute BODY, saving and restoring current buffer's restrictions.
The buffer's restrictions make parts of the beginning and end invisible.
\(They are set up with `narrow-to-region' and eliminated with `widen'.)
-This special form, `save-restriction', saves the current buffer's restrictions
-when it is entered, and restores them when it is exited.
+This special form, `save-restriction', saves the current buffer's
+restrictions, as well as their locks if they have been locked with
+`narrowing-lock', when it is entered, and restores them when it is exited.
So any `narrow-to-region' within BODY lasts only until the end of the form.
-The old restrictions settings are restored
-even in case of abnormal exit (throw or error).
+The old restrictions settings are restored even in case of abnormal exit
+\(throw or error).
The value returned is the value of the last form in BODY.
diff --git a/src/keyboard.c b/src/keyboard.c
index 4b35a044eb0..cb308f5bfc1 100644
--- a/src/keyboard.c
+++ b/src/keyboard.c
@@ -1911,8 +1911,8 @@ safe_run_hooks_maybe_narrowed (Lisp_Object hook, struct window *w)
specbind (Qinhibit_quit, Qt);
if (current_buffer->long_line_optimizations_p)
- narrow_to_region_locked (make_fixnum (get_narrowed_begv (w, PT)),
- make_fixnum (get_narrowed_zv (w, PT)),
+ narrow_to_region_locked (make_fixnum (get_locked_narrowing_begv (PT)),
+ make_fixnum (get_locked_narrowing_zv (PT)),
hook);
run_hook_with_args (2, ((Lisp_Object []) {hook, hook}),
diff --git a/src/xdisp.c b/src/xdisp.c
index 658ce57b7ea..430201874c3 100644
--- a/src/xdisp.c
+++ b/src/xdisp.c
@@ -3533,6 +3533,34 @@ get_closer_narrowed_begv (struct window *w, ptrdiff_t pos)
return max ((pos / len - 1) * len, BEGV);
}
+ptrdiff_t
+get_locked_narrowing_begv (ptrdiff_t pos)
+{
+ if (long_line_locked_narrowing_region_size == 0)
+ return BEGV;
+ int begv;
+ int len = long_line_locked_narrowing_region_size / 2;
+ begv = max (pos - len, BEGV);
+ int limit = long_line_locked_narrowing_bol_search_limit;
+ while (limit)
+ {
+ if (begv == BEGV || FETCH_BYTE (CHAR_TO_BYTE (begv) - 1) == '\n')
+ return begv;
+ begv--;
+ limit--;
+ }
+ return begv;
+}
+
+ptrdiff_t
+get_locked_narrowing_zv (ptrdiff_t pos)
+{
+ if (long_line_locked_narrowing_region_size == 0)
+ return ZV;
+ int len = long_line_locked_narrowing_region_size / 2;
+ return min (pos + len, ZV);
+}
+
static void
unwind_narrowed_begv (Lisp_Object point_min)
{
@@ -4368,13 +4396,13 @@ handle_fontified_prop (struct it *it)
if (current_buffer->long_line_optimizations_p)
{
- ptrdiff_t begv = it->narrowed_begv;
- ptrdiff_t zv = it->narrowed_zv;
+ ptrdiff_t begv = it->locked_narrowing_begv;
+ ptrdiff_t zv = it->locked_narrowing_zv;
ptrdiff_t charpos = IT_CHARPOS (*it);
if (charpos < begv || charpos > zv)
{
- begv = get_narrowed_begv (it->w, charpos);
- zv = get_narrowed_zv (it->w, charpos);
+ begv = get_locked_narrowing_begv (charpos);
+ zv = get_locked_narrowing_zv (charpos);
}
narrow_to_region_locked (make_fixnum (begv), make_fixnum (zv),
Qfontification_functions);
@@ -7435,12 +7463,20 @@ reseat (struct it *it, struct text_pos pos, bool force_p)
{
it->narrowed_begv = get_narrowed_begv (it->w, window_point (it->w));
it->narrowed_zv = get_narrowed_zv (it->w, window_point (it->w));
+ it->locked_narrowing_begv
+ = get_locked_narrowing_begv (window_point (it->w));
+ it->locked_narrowing_zv
+ = get_locked_narrowing_zv (window_point (it->w));
}
else if ((pos.charpos < it->narrowed_begv || pos.charpos > it->narrowed_zv)
&& (!redisplaying_p || it->line_wrap == TRUNCATE))
{
it->narrowed_begv = get_narrowed_begv (it->w, pos.charpos);
it->narrowed_zv = get_narrowed_zv (it->w, pos.charpos);
+ it->locked_narrowing_begv
+ = get_locked_narrowing_begv (window_point (it->w));
+ it->locked_narrowing_zv
+ = get_locked_narrowing_zv (window_point (it->w));
}
}
--
2.39.5