diff options
Diffstat (limited to 'src/backend/storage/ipc/spin.c')
| -rw-r--r-- | src/backend/storage/ipc/spin.c | 88 |
1 files changed, 81 insertions, 7 deletions
diff --git a/src/backend/storage/ipc/spin.c b/src/backend/storage/ipc/spin.c index 3443c2db95b..5300e2ecd4d 100644 --- a/src/backend/storage/ipc/spin.c +++ b/src/backend/storage/ipc/spin.c @@ -7,7 +7,7 @@ * * * IDENTIFICATION - * $Header: /cvsroot/pgsql/src/backend/storage/ipc/Attic/spin.c,v 1.8 1997/09/08 02:29:02 momjian Exp $ + * $Header: /cvsroot/pgsql/src/backend/storage/ipc/Attic/spin.c,v 1.9 1997/09/18 14:20:18 momjian Exp $ * *------------------------------------------------------------------------- */ @@ -27,6 +27,7 @@ #include <errno.h> #include "postgres.h" #include "storage/ipc.h" +#include "storage/s_lock.h" #include "storage/shmem.h" #include "storage/spin.h" #include "storage/proc.h" @@ -80,18 +81,91 @@ InitSpinLocks(int init, IPCKey key) return (TRUE); } +#ifdef LOCKDEBUG +#define PRINT_LOCK(LOCK) printf("(locklock = %d, flag = %d, nshlocks = %d, \ +shlock = %d, exlock =%d)\n", LOCK->locklock, \ + LOCK->flag, LOCK->nshlocks, LOCK->shlock, \ + LOCK->exlock) +#endif + +/* from ipc.c */ +extern SLock *SLockArray; + void -SpinAcquire(SPINLOCK lock) +SpinAcquire(SPINLOCK lockid) { - ExclusiveLock(lock); - PROC_INCR_SLOCK(lock); + SLock *slckP; + + /* This used to be in ipc.c, but move here to reduce function calls */ + slckP = &(SLockArray[lockid]); +#ifdef LOCKDEBUG + printf("SpinAcquire(%d)\n", lockid); + printf("IN: "); + PRINT_LOCK(slckP); +#endif +ex_try_again: + S_LOCK(&(slckP->locklock)); + switch (slckP->flag) + { + case NOLOCK: + slckP->flag = EXCLUSIVELOCK; + S_LOCK(&(slckP->exlock)); + S_LOCK(&(slckP->shlock)); + S_UNLOCK(&(slckP->locklock)); +#ifdef LOCKDEBUG + printf("OUT: "); + PRINT_LOCK(slckP); +#endif + return; + case SHAREDLOCK: + case EXCLUSIVELOCK: + S_UNLOCK(&(slckP->locklock)); + S_LOCK(&(slckP->exlock)); + S_UNLOCK(&(slckP->exlock)); + goto ex_try_again; + } + PROC_INCR_SLOCK(lockid); } void -SpinRelease(SPINLOCK lock) +SpinRelease(SPINLOCK lockid) { - PROC_DECR_SLOCK(lock); - ExclusiveUnlock(lock); + SLock *slckP; + + PROC_DECR_SLOCK(lockid); + + /* This used to be in ipc.c, but move here to reduce function calls */ + slckP = &(SLockArray[lockid]); +#ifdef LOCKDEBUG + printf("SpinRelease(%d)\n", lockid); + printf("IN: "); + PRINT_LOCK(slckP); +#endif + S_LOCK(&(slckP->locklock)); + /* ------------- + * give favor to read processes + * ------------- + */ + slckP->flag = NOLOCK; + if (slckP->nshlocks > 0) + { + while (slckP->nshlocks > 0) + { + S_UNLOCK(&(slckP->shlock)); + S_LOCK(&(slckP->comlock)); + } + S_UNLOCK(&(slckP->shlock)); + } + else + { + S_UNLOCK(&(slckP->shlock)); + } + S_UNLOCK(&(slckP->exlock)); + S_UNLOCK(&(slckP->locklock)); +#ifdef LOCKDEBUG + printf("OUT: "); + PRINT_LOCK(slckP); +#endif } #else /* HAS_TEST_AND_SET */ |