GNU bug report logs - #48264
28.0.50; Changing the default for DEFVAR_PER_BUFFER variables takes O(#buffers) time

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Message #161 received at 48264 <at> debbugs.gnu.org (full text, mbox):

From: Spencer Baugh <sbaugh <at> catern.com>
To: 48264 <at> debbugs.gnu.org
Cc: Spencer Baugh <sbaugh <at> catern.com>
Subject: [PATCH v4 03/14] Add and use BVAR_HAS_DEFAULT_VALUE_P
Date: Fri,  7 May 2021 22:08:54 -0400

This makes the code more clear and allows us to more easily change how
this property is determined.

* src/buffer.h (BVAR_HAS_DEFAULT_VALUE_P): New function.
* src/buffer.c (reset_buffer_local_variables):
* src/data.c (set_default_internal, Fkill_local_variable): Use
BVAR_HAS_DEFAULT_VALUE_P.
---
 src/buffer.c |  2 +-
 src/buffer.h | 10 ++++++++++
 src/data.c   |  5 ++---
 3 files changed, 13 insertions(+), 4 deletions(-)

diff --git a/src/buffer.c b/src/buffer.c
index c395c6ec98..efc85bf378 100644
--- a/src/buffer.c
+++ b/src/buffer.c
@@ -1108,7 +1108,7 @@ reset_buffer_local_variables (struct buffer *b, bool permanent_too)
   FOR_EACH_PER_BUFFER_OBJECT_AT (offset)
     {
       int idx = PER_BUFFER_IDX (offset);
-      if ((idx > 0
+      if ((BVAR_HAS_DEFAULT_VALUE_P (offset)
 	   && (permanent_too
 	       || buffer_permanent_local_flags[idx] == 0)))
 	set_per_buffer_value (b, offset, per_buffer_default (offset));
diff --git a/src/buffer.h b/src/buffer.h
index 7367c2cb2b..13fda0c702 100644
--- a/src/buffer.h
+++ b/src/buffer.h
@@ -1481,6 +1481,16 @@ set_per_buffer_value (struct buffer *b, int offset, Lisp_Object value)
   *(Lisp_Object *)(offset + (char *) b) = value;
 }
 
+/* Value is true if the variable with offset OFFSET has a default
+   value; false if the variable has no default, and is therefore
+   always local. */
+
+INLINE bool
+BVAR_HAS_DEFAULT_VALUE_P (int offset)
+{
+  return PER_BUFFER_IDX (offset) > 0;
+}
+
 /* Value is true if the variable with offset OFFSET has a local value
    in buffer B.  */
 
diff --git a/src/data.c b/src/data.c
index bd399e0439..891a81b7f3 100644
--- a/src/data.c
+++ b/src/data.c
@@ -1879,13 +1879,12 @@ set_default_internal (Lisp_Object symbol, Lisp_Object value,
 	if (BUFFER_OBJFWDP (valcontents))
 	  {
 	    int offset = XBUFFER_OBJFWD (valcontents)->offset;
-	    int idx = PER_BUFFER_IDX (offset);
 
 	    set_per_buffer_default (offset, value);
 
 	    /* If this variable is not always local in all buffers,
 	       set it in the buffers that don't nominally have a local value.  */
-	    if (idx > 0)
+	    if (BVAR_HAS_DEFAULT_VALUE_P (offset))
 	      {
 		Lisp_Object buf, tail;
 
@@ -2157,7 +2156,7 @@ From now on the default value will apply in this buffer.  Return VARIABLE.  */)
 	    int offset = XBUFFER_OBJFWD (valcontents)->offset;
 	    int idx = PER_BUFFER_IDX (offset);
 
-	    if (idx > 0)
+	    if (BVAR_HAS_DEFAULT_VALUE_P (offset))
 	      {
 		SET_PER_BUFFER_VALUE_P (current_buffer, idx, 0);
 		set_per_buffer_value (current_buffer, offset,
-- 
2.31.1

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