diff options
Diffstat (limited to 'src/backend/storage/lmgr/proc.c')
| -rw-r--r-- | src/backend/storage/lmgr/proc.c | 71 |
1 files changed, 35 insertions, 36 deletions
diff --git a/src/backend/storage/lmgr/proc.c b/src/backend/storage/lmgr/proc.c index bc461f0f86f..af345e6e825 100644 --- a/src/backend/storage/lmgr/proc.c +++ b/src/backend/storage/lmgr/proc.c @@ -8,7 +8,7 @@ * * * IDENTIFICATION - * $Header: /cvsroot/pgsql/src/backend/storage/lmgr/proc.c,v 1.94 2001/01/16 20:59:34 tgl Exp $ + * $Header: /cvsroot/pgsql/src/backend/storage/lmgr/proc.c,v 1.95 2001/01/22 22:30:06 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -48,7 +48,7 @@ * This is so that we can support more backends. (system-wide semaphore * sets run out pretty fast.) -ay 4/95 * - * $Header: /cvsroot/pgsql/src/backend/storage/lmgr/proc.c,v 1.94 2001/01/16 20:59:34 tgl Exp $ + * $Header: /cvsroot/pgsql/src/backend/storage/lmgr/proc.c,v 1.95 2001/01/22 22:30:06 tgl Exp $ */ #include "postgres.h" @@ -228,9 +228,6 @@ InitProcess(void) SpinRelease(ProcStructLock); elog(FATAL, "cannot create new proc: out of memory"); } - - /* this cannot be initialized until after the buffer pool */ - SHMQueueInit(&(MyProc->holderQueue)); } /* @@ -259,10 +256,15 @@ InitProcess(void) MyProc->sem.semNum = -1; } + SHMQueueElemInit(&(MyProc->links)); + MyProc->errType = NO_ERROR; MyProc->pid = MyProcPid; MyProc->databaseId = MyDatabaseId; MyProc->xid = InvalidTransactionId; MyProc->xmin = InvalidTransactionId; + MyProc->waitLock = NULL; + MyProc->waitHolder = NULL; + SHMQueueInit(&(MyProc->procHolders)); /* ---------------------- * Release the lock. @@ -282,9 +284,6 @@ InitProcess(void) (location != MAKE_OFFSET(MyProc))) elog(STOP, "InitProcess: ShmemPID table broken"); - MyProc->errType = NO_ERROR; - SHMQueueElemInit(&(MyProc->links)); - on_shmem_exit(ProcKill, 0); } @@ -342,7 +341,6 @@ RemoveFromWaitQueue(PROC *proc) waitLock->waitMask &= ~(1 << lockmode); /* Clean up the proc's own state */ - SHMQueueElemInit(&(proc->links)); proc->waitLock = NULL; proc->waitHolder = NULL; @@ -451,6 +449,7 @@ ProcRemove(int pid) ProcFreeSem(proc->sem.semId, proc->sem.semNum); + /* Add PROC struct to freelist so space can be recycled in future */ proc->links.next = ProcGlobal->freeProcs; ProcGlobal->freeProcs = MAKE_OFFSET(proc); @@ -565,12 +564,7 @@ ProcSleep(LOCKMETHODCTL *lockctl, bigtime_t time_interval; #endif - MyProc->waitLock = lock; - MyProc->waitHolder = holder; - MyProc->waitLockMode = lockmode; - /* We assume the caller set up MyProc->heldLocks */ - - proc = (PROC *) MAKE_PTR(waitQueue->links.prev); + proc = (PROC *) MAKE_PTR(waitQueue->links.next); /* if we don't conflict with any waiter - be first in queue */ if (!(lockctl->conflictTab[lockmode] & waitMask)) @@ -593,7 +587,7 @@ ProcSleep(LOCKMETHODCTL *lockctl, { /* Yes, report deadlock failure */ MyProc->errType = STATUS_ERROR; - goto rt; + return STATUS_ERROR; } /* I must go after him in queue - so continue loop */ } @@ -624,20 +618,25 @@ ProcSleep(LOCKMETHODCTL *lockctl, (aheadGranted[procWaitMode])++; if (aheadGranted[procWaitMode] == lock->requested[procWaitMode]) waitMask &= ~(1 << procWaitMode); - proc = (PROC *) MAKE_PTR(proc->links.prev); + proc = (PROC *) MAKE_PTR(proc->links.next); } ins:; /* ------------------- - * Insert self into queue, ahead of the given proc. - * These operations are atomic (because of the spinlock). + * Insert self into queue, ahead of the given proc (or at tail of queue). * ------------------- */ - SHMQueueInsertTL(&(proc->links), &(MyProc->links)); + SHMQueueInsertBefore(&(proc->links), &(MyProc->links)); waitQueue->size++; lock->waitMask |= myMask; + /* Set up wait information in PROC object, too */ + MyProc->waitLock = lock; + MyProc->waitHolder = holder; + MyProc->waitLockMode = lockmode; + /* We assume the caller set up MyProc->heldLocks */ + MyProc->errType = NO_ERROR; /* initialize result for success */ /* mark that we are waiting for a lock */ @@ -723,11 +722,10 @@ ins:; */ SpinAcquire(spinlock); -rt:; - - MyProc->waitLock = NULL; - MyProc->waitHolder = NULL; - + /* + * We don't have to do anything else, because the awaker did all the + * necessary update of the lock table and MyProc. + */ return MyProc->errType; } @@ -745,18 +743,24 @@ ProcWakeup(PROC *proc, int errType) /* assume that spinlock has been acquired */ + /* Proc should be sleeping ... */ if (proc->links.prev == INVALID_OFFSET || proc->links.next == INVALID_OFFSET) return (PROC *) NULL; - retProc = (PROC *) MAKE_PTR(proc->links.prev); + /* Save next process before we zap the list link */ + retProc = (PROC *) MAKE_PTR(proc->links.next); + /* Remove process from wait queue */ SHMQueueDelete(&(proc->links)); - SHMQueueElemInit(&(proc->links)); (proc->waitLock->waitProcs.size)--; + /* Clean up process' state and pass it the ok/fail signal */ + proc->waitLock = NULL; + proc->waitHolder = NULL; proc->errType = errType; + /* And awaken it */ IpcSemaphoreUnlock(proc->sem.semId, proc->sem.semNum); return retProc; @@ -780,7 +784,7 @@ ProcLockWakeup(LOCKMETHOD lockmethod, LOCK *lock) if (!queue_size) return STATUS_NOT_FOUND; - proc = (PROC *) MAKE_PTR(queue->links.prev); + proc = (PROC *) MAKE_PTR(queue->links.next); while (queue_size-- > 0) { @@ -820,12 +824,13 @@ ProcLockWakeup(LOCKMETHOD lockmethod, LOCK *lock) /* * ProcWakeup removes proc from the lock's waiting process queue - * and returns the next proc in chain; don't use prev link. + * and returns the next proc in chain; don't use proc's next-link, + * because it's been cleared. */ continue; nextProc: - proc = (PROC *) MAKE_PTR(proc->links.prev); + proc = (PROC *) MAKE_PTR(proc->links.next); } Assert(queue->size >= 0); @@ -848,12 +853,6 @@ nextProc: } } -void -ProcAddLock(SHM_QUEUE *elem) -{ - SHMQueueInsertTL(&MyProc->holderQueue, elem); -} - /* -------------------- * We only get to this routine if we got SIGALRM after DeadlockTimeout * while waiting for a lock to be released by some other process. 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