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Do all accesses to shared buffer headers through volatile-qualified

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pointers, to ensure that compilers won't rearrange accesses to occur
while we're not holding the buffer header spinlock.  It's probably
not necessary to mark volatile in every single place in bufmgr.c,
but better safe than sorry.  Per trouble report from Kevin Grittner.
This commit is contained in:
Tom Lane
2005-10-12 16:45:14 +00:00
parent 6b97e437ca
commit 07eeb9d109
4 changed files with 64 additions and 71 deletions
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27
contrib/pg_buffercache/pg_buffercache_pages.c
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@ -3,7 +3,7 @@
* pg_buffercache_pages.c
* display some contents of the buffer cache
*
* $PostgreSQL: pgsql/contrib/pg_buffercache/pg_buffercache_pages.c,v 1.4 2005/05/31 00:07:47 tgl Exp $
* $PostgreSQL: pgsql/contrib/pg_buffercache/pg_buffercache_pages.c,v 1.5 2005/10/12 16:45:13 tgl Exp $
*-------------------------------------------------------------------------
*/
#include "postgres.h"
@ -72,10 +72,8 @@ pg_buffercache_pages(PG_FUNCTION_ARGS)
if (SRF_IS_FIRSTCALL())
{
RelFileNode rnode;
uint32 i;
BufferDesc *bufHdr;
volatile BufferDesc *bufHdr;
funcctx = SRF_FIRSTCALL_INIT();
@ -136,35 +134,24 @@ pg_buffercache_pages(PG_FUNCTION_ARGS)
/* Lock each buffer header before inspecting. */
LockBufHdr(bufHdr);
rnode = bufHdr->tag.rnode;
fctx->record[i].bufferid = BufferDescriptorGetBuffer(bufHdr);
fctx->record[i].relfilenode = rnode.relNode;
fctx->record[i].reltablespace = rnode.spcNode;
fctx->record[i].reldatabase = rnode.dbNode;
fctx->record[i].relfilenode = bufHdr->tag.rnode.relNode;
fctx->record[i].reltablespace = bufHdr->tag.rnode.spcNode;
fctx->record[i].reldatabase = bufHdr->tag.rnode.dbNode;
fctx->record[i].blocknum = bufHdr->tag.blockNum;
if ( bufHdr->flags & BM_DIRTY)
{
if (bufHdr->flags & BM_DIRTY)
fctx->record[i].isdirty = true;
}
else
{
fctx->record[i].isdirty = false;
}
/* Note if the buffer is valid, and has storage created */
if ( (bufHdr->flags & BM_VALID) && (bufHdr->flags & BM_TAG_VALID))
{
if ((bufHdr->flags & BM_VALID) && (bufHdr->flags & BM_TAG_VALID))
fctx->record[i].isvalid = true;
}
else
{
fctx->record[i].isvalid = false;
}
UnlockBufHdr(bufHdr);
}
/* Release Buffer map. */