diff options
Diffstat (limited to 'src/backend/storage/lmgr/proc.c')
| -rw-r--r-- | src/backend/storage/lmgr/proc.c | 46 |
1 files changed, 22 insertions, 24 deletions
diff --git a/src/backend/storage/lmgr/proc.c b/src/backend/storage/lmgr/proc.c index e232020597d..be91266cf6f 100644 --- a/src/backend/storage/lmgr/proc.c +++ b/src/backend/storage/lmgr/proc.c @@ -7,7 +7,7 @@ * * * IDENTIFICATION - * $Header: /cvsroot/pgsql/src/backend/storage/lmgr/proc.c,v 1.33 1998/02/25 00:31:14 momjian Exp $ + * $Header: /cvsroot/pgsql/src/backend/storage/lmgr/proc.c,v 1.34 1998/02/26 04:36:12 momjian Exp $ * *------------------------------------------------------------------------- */ @@ -46,7 +46,7 @@ * 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 1.33 1998/02/25 00:31:14 momjian Exp $ + * $Header: /cvsroot/pgsql/src/backend/storage/lmgr/proc.c,v 1.34 1998/02/26 04:36:12 momjian Exp $ */ #include <sys/time.h> #include <unistd.h> @@ -457,25 +457,22 @@ ProcSleep(PROC_QUEUE *waitQueue, dummy; /* - * If the first entries in the waitQueue have a greater priority than - * we have, we must be a reader, and they must be a writers, and we - * must be here because the current holder is a writer or a - * reader but we don't share shared locks if a writer is waiting. - * We put ourselves after the writers. This way, we have a FIFO, but - * keep the readers together to give them decent priority, and no one - * starves. Because we group all readers together, a non-empty queue - * only has a few possible configurations: + * If the first entries in the waitQueue have a greater priority than + * we have, we must be a reader, and they must be a writers, and we + * must be here because the current holder is a writer or a reader but + * we don't share shared locks if a writer is waiting. We put + * ourselves after the writers. This way, we have a FIFO, but keep + * the readers together to give them decent priority, and no one + * starves. Because we group all readers together, a non-empty queue + * only has a few possible configurations: * - * [readers] - * [writers] - * [readers][writers] - * [writers][readers] - * [writers][readers][writers] + * [readers] [writers] [readers][writers] [writers][readers] + * [writers][readers][writers] * - * In a full queue, we would have a reader holding a lock, then a - * writer gets the lock, then a bunch of readers, made up of readers - * who could not share the first readlock because a writer was waiting, - * and new readers arriving while the writer had the lock. + * In a full queue, we would have a reader holding a lock, then a writer + * gets the lock, then a bunch of readers, made up of readers who + * could not share the first readlock because a writer was waiting, + * and new readers arriving while the writer had the lock. * */ proc = (PROC *) MAKE_PTR(waitQueue->links.prev); @@ -486,13 +483,13 @@ ProcSleep(PROC_QUEUE *waitQueue, proc = (PROC *) MAKE_PTR(proc->links.prev); /* The rest of the queue is FIFO, with readers first, writers last */ - for ( ; i < waitQueue->size && proc->prio <= prio; i++) + for (; i < waitQueue->size && proc->prio <= prio; i++) proc = (PROC *) MAKE_PTR(proc->links.prev); MyProc->prio = prio; MyProc->token = token; MyProc->waitLock = lock; - + /* ------------------- * currently, we only need this for the ProcWakeup routines * ------------------- @@ -523,7 +520,7 @@ ProcSleep(PROC_QUEUE *waitQueue, do { - MyProc->errType = NO_ERROR; /* reset flag after deadlock check */ + MyProc->errType = NO_ERROR; /* reset flag after deadlock check */ if (setitimer(ITIMER_REAL, &timeval, &dummy)) elog(FATAL, "ProcSleep: Unable to set timer for process wakeup"); @@ -535,8 +532,9 @@ ProcSleep(PROC_QUEUE *waitQueue, * -------------- */ IpcSemaphoreLock(MyProc->sem.semId, MyProc->sem.semNum, IpcExclusiveLock); - } while (MyProc->errType == STATUS_NOT_FOUND); /* sleep after deadlock check */ - + } while (MyProc->errType == STATUS_NOT_FOUND); /* sleep after deadlock + * check */ + /* --------------- * We were awoken before a timeout - now disable the timer * --------------- |