diff options
Diffstat (limited to 'src')
| -rw-r--r-- | src/backend/utils/mmgr/aset.c | 59 |
1 files changed, 10 insertions, 49 deletions
diff --git a/src/backend/utils/mmgr/aset.c b/src/backend/utils/mmgr/aset.c index f517e05bc9c..7d080af86de 100644 --- a/src/backend/utils/mmgr/aset.c +++ b/src/backend/utils/mmgr/aset.c @@ -11,7 +11,7 @@ * Portions Copyright (c) 1994, Regents of the University of California * * IDENTIFICATION - * $PostgreSQL: pgsql/src/backend/utils/mmgr/aset.c,v 1.73 2007/08/07 06:25:14 neilc Exp $ + * $PostgreSQL: pgsql/src/backend/utils/mmgr/aset.c,v 1.74 2007/08/12 20:39:14 tgl Exp $ * * NOTE: * This is a new (Feb. 05, 1999) implementation of the allocation set @@ -932,57 +932,18 @@ AllocSetRealloc(MemoryContext context, void *pointer, Size size) else { /* - * Small-chunk case. If the chunk is the last one in its block, there - * might be enough free space after it that we can just enlarge the - * chunk in-place. It's relatively painful to find the containing - * block in the general case, but we can detect last-ness quite - * cheaply for the typical case where the chunk is in the active - * (topmost) allocation block. (At least with the regression tests - * and code as of 1/2001, realloc'ing the last chunk of a non-topmost - * block hardly ever happens, so it's not worth scanning the block - * list to catch that case.) - * - * NOTE: must be careful not to create a chunk of a size that - * AllocSetAlloc would not create, else we'll get confused later. + * Small-chunk case. We just do this by brute force, ie, allocate a + * new chunk and copy the data. Since we know the existing data isn't + * huge, this won't involve any great memcpy expense, so it's not + * worth being smarter. (At one time we tried to avoid memcpy when + * it was possible to enlarge the chunk in-place, but that turns out + * to misbehave unpleasantly for repeated cycles of + * palloc/repalloc/pfree: the eventually freed chunks go into the + * wrong freelist for the next initial palloc request, and so we leak + * memory indefinitely. See pgsql-hackers archives for 2007-08-11.) */ AllocPointer newPointer; - if (size <= set->allocChunkLimit) - { - AllocBlock block = set->blocks; - char *chunk_end; - - chunk_end = (char *) chunk + (oldsize + ALLOC_CHUNKHDRSZ); - if (chunk_end == block->freeptr) - { - /* OK, it's last in block ... is there room? */ - Size freespace = block->endptr - block->freeptr; - int fidx; - Size newsize; - Size delta; - - fidx = AllocSetFreeIndex(size); - newsize = 1 << (fidx + ALLOC_MINBITS); - Assert(newsize >= oldsize); - delta = newsize - oldsize; - if (freespace >= delta) - { - /* Yes, so just enlarge the chunk. */ - block->freeptr += delta; - chunk->size += delta; -#ifdef MEMORY_CONTEXT_CHECKING - chunk->requested_size = size; - /* set mark to catch clobber of "unused" space */ - if (size < chunk->size) - ((char *) pointer)[size] = 0x7E; -#endif - return pointer; - } - } - } - - /* Normal small-chunk case: just do it by brute force. */ - /* allocate new chunk */ newPointer = AllocSetAlloc((MemoryContext) set, size); |