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Code review for superuser_reserved_connections patch. Don't try to do

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database access outside a transaction; revert bogus performance improvement
in SIBackendInit(); improve comments; add documentation (this part courtesy
Neil Conway).
This commit is contained in:
Tom Lane
2002-11-21 06:36:08 +00:00
parent 02d83d7565
commit 8362be35e8
5 changed files with 90 additions and 63 deletions
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13
src/backend/storage/ipc/sinval.c
View File

@@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/storage/ipc/sinval.c,v 1.52 2002/09/04 20:31:25 momjian Exp $
* $Header: /cvsroot/pgsql/src/backend/storage/ipc/sinval.c,v 1.53 2002/11/21 06:36:08 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -542,12 +542,11 @@ BackendIdGetProc(BackendId procId)
/*
* CountEmptyBackendSlots - count empty slots in backend process table
*
* Doesn't count since the procState array could be large and we've already
* allowed for that by running a freeBackends counter in the SI segment.
* Unlike CountActiveBackends() we do not need to interrogate the
* backends to determine the free slot count.
* Goes for a lock despite being a trival look up in case other backends
* are busy starting or exiting since there is scope for confusion.
* We don't actually need to count, since sinvaladt.c maintains a
* freeBackends counter in the SI segment.
*
* Acquiring the lock here is almost certainly overkill, but just in
* case fetching an int is not atomic on your machine ...
*/
int
CountEmptyBackendSlots(void)

24
src/backend/storage/ipc/sinvaladt.c
View File

@@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/storage/ipc/sinvaladt.c,v 1.48 2002/08/29 21:02:12 momjian Exp $
* $Header: /cvsroot/pgsql/src/backend/storage/ipc/sinvaladt.c,v 1.49 2002/11/21 06:36:08 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -92,13 +92,6 @@ SIBackendInit(SISeg *segP)
int index;
ProcState *stateP = NULL;
if (segP->freeBackends == 0)
{
/* out of procState slots */
MyBackendId = InvalidBackendId;
return 0;
}
/* Look for a free entry in the procState array */
for (index = 0; index < segP->lastBackend; index++)
{
@@ -111,9 +104,18 @@ SIBackendInit(SISeg *segP)
if (stateP == NULL)
{
stateP = &segP->procState[segP->lastBackend];
Assert(stateP->nextMsgNum < 0);
segP->lastBackend++;
if (segP->lastBackend < segP->maxBackends)
{
stateP = &segP->procState[segP->lastBackend];
Assert(stateP->nextMsgNum < 0);
segP->lastBackend++;
}
else
{
/* out of procState slots */
MyBackendId = InvalidBackendId;
return 0;
}
}
MyBackendId = (stateP - &segP->procState[0]) + 1;