From 5f47d17d33948e3802843c3552be544e7c8e5cf1 Mon Sep 17 00:00:00 2001
From: Eli Zaretskii <eliz@gnu.org>
Date: Tue, 17 Aug 2021 15:31:53 +0300
Subject: [PATCH] Fix TTY display performance degradation due to many markers
* src/coding.c (encode_coding_object): Don't assume that
src_object == dst_object means src_object is the current buffer.
Add the missing commentary that explains the arguments.
(Bug#49127)
---
src/coding.c | 44 ++++++++++++++++++++++++++++++++++++++++----
1 file changed, 40 insertions(+), 4 deletions(-)
diff --git a/src/coding.c b/src/coding.c
index 87b55aecc05..d027c7d5399 100644
--- a/src/coding.c
+++ b/src/coding.c
@@ -8250,6 +8250,39 @@ decode_coding_object (struct coding_system *coding,
}
+/* Encode the text in the range FROM/FROM_BYTE and TO/TO_BYTE in
+ SRC_OBJECT into DST_OBJECT by coding context CODING.
+
+ SRC_OBJECT is a buffer, a string, or Qnil.
+
+ If it is a buffer, the text is at point of the buffer. FROM and TO
+ are positions in the buffer.
+
+ If it is a string, the text is at the beginning of the string.
+ FROM and TO are indices into the string.
+
+ If it is nil, the text is at coding->source. FROM and TO are
+ indices into coding->source.
+
+ DST_OBJECT is a buffer, Qt, or Qnil.
+
+ If it is a buffer, the encoded text is inserted at point of the
+ buffer. If the buffer is the same as SRC_OBJECT, the source text
+ is replaced with the encoded text.
+
+ If it is Qt, a string is made from the encoded text, and set in
+ CODING->dst_object. However, if CODING->raw_destination is non-zero,
+ the encoded text is instead returned in CODING->destination as a C string,
+ and the caller is responsible for freeing CODING->destination. This
+ feature is meant to be used when the caller doesn't need the result as
+ a Lisp string, and wants to avoid unnecessary consing of large strings.
+
+ If it is Qnil, the encoded text is stored at CODING->destination.
+ The caller must allocate CODING->dst_bytes bytes at
+ CODING->destination by xmalloc. If the encoded text is longer than
+ CODING->dst_bytes, CODING->destination is reallocated by xrealloc
+ (and CODING->dst_bytes is enlarged accordingly). */
+
void
encode_coding_object (struct coding_system *coding,
Lisp_Object src_object,
@@ -8275,11 +8308,14 @@ encode_coding_object (struct coding_system *coding,
attrs = CODING_ID_ATTRS (coding->id);
- if (EQ (src_object, dst_object))
+ bool same_buffer = false;
+ if (EQ (src_object, dst_object) && BUFFERP (src_object))
{
struct Lisp_Marker *tail;
- for (tail = BUF_MARKERS (current_buffer); tail; tail = tail->next)
+ same_buffer = true;
+
+ for (tail = BUF_MARKERS (XBUFFER (src_object)); tail; tail = tail->next)
{
tail->need_adjustment
= tail->charpos == (tail->insertion_type ? from : to);
@@ -8298,7 +8334,7 @@ encode_coding_object (struct coding_system *coding,
else
insert_1_both ((char *) coding->source + from, chars, bytes, 0, 0, 0);
- if (EQ (src_object, dst_object))
+ if (same_buffer)
{
set_buffer_internal (XBUFFER (src_object));
saved_pt = PT, saved_pt_byte = PT_BYTE;
@@ -8329,7 +8365,7 @@ encode_coding_object (struct coding_system *coding,
{
code_conversion_save (0, 0);
set_buffer_internal (XBUFFER (src_object));
- if (EQ (src_object, dst_object))
+ if (same_buffer)
{
saved_pt = PT, saved_pt_byte = PT_BYTE;
coding->src_object = del_range_1 (from, to, 1, 1);
--
2.39.5