diff options
Diffstat (limited to 'src/backend/storage/ipc/spin.c')
| -rw-r--r-- | src/backend/storage/ipc/spin.c | 76 |
1 files changed, 42 insertions, 34 deletions
diff --git a/src/backend/storage/ipc/spin.c b/src/backend/storage/ipc/spin.c index 479e0b27662..33308f0cc1f 100644 --- a/src/backend/storage/ipc/spin.c +++ b/src/backend/storage/ipc/spin.c @@ -14,7 +14,7 @@ * * * IDENTIFICATION - * $Header: /cvsroot/pgsql/src/backend/storage/ipc/Attic/spin.c,v 1.31 2001/01/24 19:43:07 momjian Exp $ + * $Header: /cvsroot/pgsql/src/backend/storage/ipc/Attic/spin.c,v 1.32 2001/03/22 03:59:45 momjian Exp $ * *------------------------------------------------------------------------- */ @@ -83,17 +83,18 @@ typedef struct slock } SLock; #ifdef LOCK_DEBUG -bool Trace_spinlocks = false; +bool Trace_spinlocks = false; inline static void -PRINT_SLDEBUG(const char * where, SPINLOCK lockid, const SLock * lock) +PRINT_SLDEBUG(const char *where, SPINLOCK lockid, const SLock *lock) { - if (Trace_spinlocks) - elog(DEBUG, "%s: id=%d", where, lockid); + if (Trace_spinlocks) + elog(DEBUG, "%s: id=%d", where, lockid); } -#else /* not LOCK_DEBUG */ + +#else /* not LOCK_DEBUG */ #define PRINT_SLDEBUG(a,b,c) -#endif /* not LOCK_DEBUG */ +#endif /* not LOCK_DEBUG */ static SLock *SLockArray = NULL; @@ -146,15 +147,17 @@ SpinAcquire(SPINLOCK lockid) SLock *slckP = &(SLockArray[lockid]); PRINT_SLDEBUG("SpinAcquire", lockid, slckP); + /* - * Acquire the lock, then record that we have done so (for recovery - * in case of elog(ERROR) while holding the lock). Note we assume - * here that S_LOCK will not accept cancel/die interrupts once it has + * Acquire the lock, then record that we have done so (for recovery in + * case of elog(ERROR) while holding the lock). Note we assume here + * that S_LOCK will not accept cancel/die interrupts once it has * acquired the lock. However, interrupts should be accepted while * waiting, if InterruptHoldoffCount is zero. */ S_LOCK(&(slckP->shlock)); PROC_INCR_SLOCK(lockid); + /* * Lock out cancel/die interrupts until we exit the code section * protected by the spinlock. This ensures that interrupts will not @@ -162,7 +165,7 @@ SpinAcquire(SPINLOCK lockid) */ HOLD_INTERRUPTS(); - PRINT_SLDEBUG("SpinAcquire/done", lockid, slckP); + PRINT_SLDEBUG("SpinAcquire/done", lockid, slckP); } void @@ -170,26 +173,29 @@ SpinRelease(SPINLOCK lockid) { SLock *slckP = &(SLockArray[lockid]); - PRINT_SLDEBUG("SpinRelease", lockid, slckP); + PRINT_SLDEBUG("SpinRelease", lockid, slckP); + /* * Check that we are actually holding the lock we are releasing. This * can be done only after MyProc has been initialized. */ - Assert(!MyProc || MyProc->sLocks[lockid] > 0); + Assert(!MyProc || MyProc->sLocks[lockid] > 0); + /* * Record that we no longer hold the spinlock, and release it. */ PROC_DECR_SLOCK(lockid); S_UNLOCK(&(slckP->shlock)); + /* * Exit the interrupt holdoff entered in SpinAcquire(). */ RESUME_INTERRUPTS(); - PRINT_SLDEBUG("SpinRelease/done", lockid, slckP); + PRINT_SLDEBUG("SpinRelease/done", lockid, slckP); } -#else /* !HAS_TEST_AND_SET */ +#else /* !HAS_TEST_AND_SET */ /* * No TAS, so spinlocks are implemented using SysV semaphores. @@ -217,9 +223,9 @@ SpinRelease(SPINLOCK lockid) static IpcSemaphoreId *SpinLockIds = NULL; -static int numSpinSets = 0; /* number of sema sets used */ -static int numSpinLocks = 0; /* total number of semas allocated */ -static int nextSpinLock = 0; /* next free spinlock index */ +static int numSpinSets = 0; /* number of sema sets used */ +static int numSpinLocks = 0; /* total number of semas allocated */ +static int nextSpinLock = 0; /* next free spinlock index */ static void SpinFreeAllSemaphores(void); @@ -238,17 +244,18 @@ SLockShmemSize(void) void CreateSpinlocks(PGShmemHeader *seghdr) { - int i; + int i; if (SpinLockIds == NULL) { + /* - * Compute number of spinlocks needed. If this logic gets any more - * complicated, it should be distributed into the affected modules, - * similar to the way shmem space estimation is handled. + * Compute number of spinlocks needed. If this logic gets any + * more complicated, it should be distributed into the affected + * modules, similar to the way shmem space estimation is handled. * - * For now, though, we just need the fixed spinlocks (MAX_SPINS), - * two spinlocks per shared disk buffer, and four spinlocks for XLOG. + * For now, though, we just need the fixed spinlocks (MAX_SPINS), two + * spinlocks per shared disk buffer, and four spinlocks for XLOG. */ numSpinLocks = (int) MAX_SPINS + 2 * NBuffers + 4; @@ -265,11 +272,11 @@ CreateSpinlocks(PGShmemHeader *seghdr) SpinLockIds[i] = -1; /* - * Arrange to delete semas on exit --- set this up now so that we - * will clean up if allocation fails. We use our own freeproc, - * rather than IpcSemaphoreCreate's removeOnExit option, because - * we don't want to fill up the on_shmem_exit list with a separate - * entry for each semaphore set. + * Arrange to delete semas on exit --- set this up now so that we will + * clean up if allocation fails. We use our own freeproc, rather than + * IpcSemaphoreCreate's removeOnExit option, because we don't want to + * fill up the on_shmem_exit list with a separate entry for each + * semaphore set. */ on_shmem_exit(SpinFreeAllSemaphores, 0); @@ -320,12 +327,13 @@ SpinFreeAllSemaphores(void) void SpinAcquire(SPINLOCK lock) { + /* * See the TAS() version of this routine for primary commentary. * * NOTE we must pass interruptOK = false to IpcSemaphoreLock, to ensure - * that a cancel/die interrupt cannot prevent us from recording ownership - * of a lock we have just acquired. + * that a cancel/die interrupt cannot prevent us from recording + * ownership of a lock we have just acquired. */ IpcSemaphoreLock(SpinLockIds[0], lock, false); PROC_INCR_SLOCK(lock); @@ -348,7 +356,7 @@ SpinRelease(SPINLOCK lock) semval = IpcSemaphoreGetValue(SpinLockIds[0], lock); Assert(semval < 1); #endif - Assert(!MyProc || MyProc->sLocks[lockid] > 0); + Assert(!MyProc || MyProc->sLocks[lockid] > 0); PROC_DECR_SLOCK(lock); IpcSemaphoreUnlock(SpinLockIds[0], lock); RESUME_INTERRUPTS(); @@ -384,7 +392,7 @@ int tas_sema(volatile slock_t *lock) { /* Note that TAS macros return 0 if *success* */ - return ! IpcSemaphoreTryLock(lock->semId, lock->sem); + return !IpcSemaphoreTryLock(lock->semId, lock->sem); } -#endif /* !HAS_TEST_AND_SET */ +#endif /* !HAS_TEST_AND_SET */ |