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Fix a variety of locking problems like newer lock waiters getting 

lock before older waiters, and having readlock people not share
locks if a writer is waiting for a lock, and waiting writers not
getting priority over waiting readers.
This commit is contained in:
Bruce Momjian 1998-01-23 22:16:48 +00:00
parent 1de8926bbe
commit 0e8ac82c63
2 changed files with 18 additions and 4 deletions
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16
src/backend/storage/lmgr/lock.c
View File

@ -7,7 +7,7 @@
* *
* *
* IDENTIFICATION * IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/storage/lmgr/lock.c,v 1.19 1998/01/23 06:01:03 momjian Exp $ * $Header: /cvsroot/pgsql/src/backend/storage/lmgr/lock.c,v 1.20 1998/01/23 22:16:46 momjian Exp $
* *
* NOTES * NOTES
* Outside modules can create a lock table and acquire/release * Outside modules can create a lock table and acquire/release
@ -708,6 +708,20 @@ LockResolveConflicts(LOCKTAB *ltable,
result->nHolding = 0; result->nHolding = 0;
} }
{
/* ------------------------
* If someone with a greater priority is waiting for the lock,
* do not continue and share the lock, even if we can. bjm
* ------------------------
*/
int myprio = ltable->ctl->prio[lockt];
PROC_QUEUE *waitQueue = &(lock->waitProcs);
PROC *topproc = (PROC *) MAKE_PTR(waitQueue->links.prev);
if (waitQueue->size && topproc->prio > myprio)
return STATUS_FOUND;
}
/* ---------------------------- /* ----------------------------
* first check for global conflicts: If no locks conflict * first check for global conflicts: If no locks conflict
* with mine, then I get the lock. * with mine, then I get the lock.

6
src/backend/storage/lmgr/proc.c
View File

@ -7,7 +7,7 @@
* *
* *
* IDENTIFICATION * IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/storage/lmgr/proc.c,v 1.26 1998/01/23 06:01:05 momjian Exp $ * $Header: /cvsroot/pgsql/src/backend/storage/lmgr/proc.c,v 1.27 1998/01/23 22:16:48 momjian Exp $
* *
*------------------------------------------------------------------------- *-------------------------------------------------------------------------
*/ */
@ -46,7 +46,7 @@
* This is so that we can support more backends. (system-wide semaphore * This is so that we can support more backends. (system-wide semaphore
* sets run out pretty fast.) -ay 4/95 * sets run out pretty fast.) -ay 4/95
* *
* $Header: /cvsroot/pgsql/src/backend/storage/lmgr/proc.c,v 1.26 1998/01/23 06:01:05 momjian Exp $ * $Header: /cvsroot/pgsql/src/backend/storage/lmgr/proc.c,v 1.27 1998/01/23 22:16:48 momjian Exp $
*/ */
#include <sys/time.h> #include <sys/time.h>
#include <unistd.h> #include <unistd.h>
@ -469,7 +469,7 @@ ProcSleep(PROC_QUEUE *queue,
proc = (PROC *) MAKE_PTR(queue->links.prev); proc = (PROC *) MAKE_PTR(queue->links.prev);
for (i = 0; i < queue->size; i++) for (i = 0; i < queue->size; i++)
{ {
if (proc->prio < prio) if (proc->prio >= prio)
proc = (PROC *) MAKE_PTR(proc->links.prev); proc = (PROC *) MAKE_PTR(proc->links.prev);
else else
break; break;