Movatterモバイル変換

[0]ホーム
URL:

Skip to content

Navigation Menu

Sign in
Appearance settings

Search code, repositories, users, issues, pull requests...

Provide feedback

We read every piece of feedback, and take your input very seriously.

Saved searches

Use saved searches to filter your results more quickly

 Sign up
Appearance settings

Commit9543eff

Browse files
committed
Remove MemoryContextContains().
MemoryContextContains is no longer reliable in the wake ofc6e0fe1,because there's no longer very much redundancy in chunk headers.(It wasn't *completely* reliable even before that, as there was achance of a false positive if you passed it something that didn'tpoint to an mcxt chunk at all. But it was generally good enough.)Hence, remove it. There is no remaining core code that requires it.Extensions that have been using it might be able to substitute atest like "GetMemoryChunkContext(ptr) == context", recognizing thatthis explicitly requires that the pointer point to some chunk.Tom Lane and David RowleyDiscussion:https://postgr.es/m/1913788.1664898906@sss.pgh.pa.us
1 parent42b746d commit9543eff

File tree

2 files changed

+2
-57
lines changed

2 files changed

+2
-57
lines changed

‎src/backend/utils/mmgr/mcxt.c

Lines changed: 2 additions & 56 deletions
Original file line numberDiff line numberDiff line change
@@ -224,10 +224,8 @@ MemoryContextResetOnly(MemoryContext context)
224224
* If context->ident points into the context's memory, it will become
225225
* a dangling pointer. We could prevent that by setting it to NULL
226226
* here, but that would break valid coding patterns that keep the
227-
* ident elsewhere, e.g. in a parent context. Another idea is to use
228-
* MemoryContextContains(), but we don't require ident strings to be
229-
* in separately-palloc'd chunks, so that risks false positives. So
230-
* for now we assume the programmer got it right.
227+
* ident elsewhere, e.g. in a parent context. So for now we assume
228+
* the programmer got it right.
231229
*/
232230

233231
context->methods->reset(context);
@@ -482,15 +480,6 @@ MemoryContextAllowInCriticalSection(MemoryContext context, bool allow)
482480
MemoryContext
483481
GetMemoryChunkContext(void*pointer)
484482
{
485-
/*
486-
* Try to detect bogus pointers handed to us, poorly though we can.
487-
* Presumably, a pointer that isn't MAXALIGNED isn't pointing at an
488-
* allocated chunk.
489-
*/
490-
Assert(pointer!=NULL);
491-
Assert(pointer== (void*)MAXALIGN(pointer));
492-
/* adding further Asserts here? See pre-checks in MemoryContextContains */
493-
494483
returnMCXT_METHOD(pointer,get_chunk_context) (pointer);
495484
}
496485

@@ -813,49 +802,6 @@ MemoryContextCheck(MemoryContext context)
813802
}
814803
#endif
815804

816-
/*
817-
* MemoryContextContains
818-
*Detect whether an allocated chunk of memory belongs to a given
819-
*context or not.
820-
*
821-
* Caution: 'pointer' must point to a pointer which was allocated by a
822-
* MemoryContext. It's not safe or valid to use this function on arbitrary
823-
* pointers as obtaining the MemoryContext which 'pointer' belongs to requires
824-
* possibly several pointer dereferences.
825-
*/
826-
bool
827-
MemoryContextContains(MemoryContextcontext,void*pointer)
828-
{
829-
/*
830-
* Temporarily make this always return false as we don't yet have a fully
831-
* baked idea on how to make it work correctly with the new MemoryChunk
832-
* code.
833-
*/
834-
return false;
835-
836-
#ifdefNOT_USED
837-
MemoryContextptr_context;
838-
839-
/*
840-
* NB: We must perform run-time checks here which GetMemoryChunkContext()
841-
* does as assertions before calling GetMemoryChunkContext().
842-
*
843-
* Try to detect bogus pointers handed to us, poorly though we can.
844-
* Presumably, a pointer that isn't MAXALIGNED isn't pointing at an
845-
* allocated chunk.
846-
*/
847-
if (pointer==NULL||pointer!= (void*)MAXALIGN(pointer))
848-
return false;
849-
850-
/*
851-
* OK, it's probably safe to look at the context.
852-
*/
853-
ptr_context=GetMemoryChunkContext(pointer);
854-
855-
returnptr_context==context;
856-
#endif
857-
}
858-
859805
/*
860806
* MemoryContextCreate
861807
*Context-type-independent part of context creation.

‎src/include/utils/memutils.h

Lines changed: 0 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -96,7 +96,6 @@ extern void MemoryContextAllowInCriticalSection(MemoryContext context,
9696
#ifdefMEMORY_CONTEXT_CHECKING
9797
externvoidMemoryContextCheck(MemoryContextcontext);
9898
#endif
99-
externboolMemoryContextContains(MemoryContextcontext,void*pointer);
10099

101100
/* Handy macro for copying and assigning context ID ... but note double eval */
102101
#defineMemoryContextCopyAndSetIdentifier(cxt,id) \

0 commit comments

Comments
 (0)
[8]ページ先頭
©2009-2025 Movatter.jp