diff options
Diffstat (limited to 'src/backend/storage/buffer/bufmgr.c')
| -rw-r--r-- | src/backend/storage/buffer/bufmgr.c | 149 |
1 files changed, 146 insertions, 3 deletions
diff --git a/src/backend/storage/buffer/bufmgr.c b/src/backend/storage/buffer/bufmgr.c index cab1e8084e0..d5fa26b6035 100644 --- a/src/backend/storage/buffer/bufmgr.c +++ b/src/backend/storage/buffer/bufmgr.c @@ -7,7 +7,7 @@ * * * IDENTIFICATION - * $Header: /cvsroot/pgsql/src/backend/storage/buffer/bufmgr.c,v 1.44 1998/10/08 18:29:54 momjian Exp $ + * $Header: /cvsroot/pgsql/src/backend/storage/buffer/bufmgr.c,v 1.45 1998/12/15 12:46:19 vadim Exp $ * *------------------------------------------------------------------------- */ @@ -86,7 +86,6 @@ static void WaitIO(BufferDesc *buf, SPINLOCK spinlock); #ifndef HAS_TEST_AND_SET static void SignalIO(BufferDesc *buf); extern long *NWaitIOBackendP; /* defined in buf_init.c */ - #endif /* HAS_TEST_AND_SET */ static Buffer ReadBufferWithBufferLock(Relation relation, BlockNumber blockNum, @@ -583,7 +582,6 @@ BufferAlloc(Relation reln, if (buf->refcount > 1) SignalIO(buf); #endif /* !HAS_TEST_AND_SET */ - /* give up the buffer since we don't need it any more */ buf->refcount--; PrivateRefCount[BufferDescriptorGetBuffer(buf) - 1] = 0; @@ -1096,6 +1094,7 @@ WaitIO(BufferDesc *buf, SPINLOCK spinlock) #else /* HAS_TEST_AND_SET */ IpcSemaphoreId WaitIOSemId; +IpcSemaphoreId WaitCLSemId; static void WaitIO(BufferDesc *buf, SPINLOCK spinlock) @@ -1933,3 +1932,147 @@ SetBufferCommitInfoNeedsSave(Buffer buffer) if (!BufferIsLocal(buffer)) CommitInfoNeedsSave[buffer - 1]++; } + +void +UnlockBuffers() +{ + BufferDesc *buf; + int i; + + for (i = 0; i < NBuffers; i++) + { + if (BufferLocks[i] == 0) + continue; + + Assert(BufferIsValid(i+1)); + buf = &(BufferDescriptors[i]); + +#ifdef HAS_TEST_AND_SET + S_LOCK(&(buf->cntx_lock)); +#else + IpcSemaphoreLock(WaitCLSemId, 0, IpcExclusiveLock); +#endif + + if (BufferLocks[i] & BL_R_LOCK) + { + Assert(buf->r_locks > 0); + (buf->r_locks)--; + } + if (BufferLocks[i] & BL_RI_LOCK) + { + Assert(buf->ri_lock); + buf->ri_lock = false; + } + if (BufferLocks[i] & BL_W_LOCK) + { + Assert(buf->w_lock); + buf->w_lock = false; + } +#ifdef HAS_TEST_AND_SET + S_UNLOCK(&(buf->cntx_lock)); +#else + IpcSemaphoreUnlock(WaitCLSemId, 0, IpcExclusiveLock); +#endif + BufferLocks[i] = 0; + } +} + +void +LockBuffer (Buffer buffer, int mode) +{ + BufferDesc *buf; + + Assert(BufferIsValid(buffer)); + if (BufferIsLocal(buffer)) + return; + + buf = &(BufferDescriptors[buffer-1]); + +#ifdef HAS_TEST_AND_SET + S_LOCK(&(buf->cntx_lock)); +#else + IpcSemaphoreLock(WaitCLSemId, 0, IpcExclusiveLock); +#endif + + if (mode == BUFFER_LOCK_UNLOCK) + { + if (BufferLocks[buffer-1] & BL_R_LOCK) + { + Assert(buf->r_locks > 0); + Assert(!(buf->w_lock)); + Assert(!(BufferLocks[buffer-1] & (BL_W_LOCK | BL_RI_LOCK))) + (buf->r_locks)--; + BufferLocks[buffer-1] &= ~BL_R_LOCK; + } + else if (BufferLocks[buffer-1] & BL_W_LOCK) + { + Assert(buf->w_lock); + Assert(buf->r_locks == 0 && !buf->ri_lock); + Assert(!(BufferLocks[buffer-1] & (BL_R_LOCK | BL_RI_LOCK))) + buf->w_lock = false; + BufferLocks[buffer-1] &= ~BL_W_LOCK; + } + else + elog(ERROR, "UNLockBuffer: buffer %u is not locked", buffer); + } + else if (mode == BUFFER_LOCK_SHARE) + { + unsigned i = 0; + + Assert(!(BufferLocks[buffer-1] & (BL_R_LOCK | BL_W_LOCK | BL_RI_LOCK))); + while (buf->ri_lock || buf->w_lock) + { +#ifdef HAS_TEST_AND_SET + S_UNLOCK(&(buf->cntx_lock)); + s_lock_sleep(i++); + S_LOCK(&(buf->cntx_lock)); +#else + IpcSemaphoreUnlock(WaitCLSemId, 0, IpcExclusiveLock); + s_lock_sleep(i++) + IpcSemaphoreLock(WaitCLSemId, 0, IpcExclusiveLock); +#endif + } + (buf->r_locks)++; + BufferLocks[buffer-1] |= BL_R_LOCK; + } + else if (mode == BUFFER_LOCK_EXCLUSIVE) + { + unsigned i = 0; + + Assert(!(BufferLocks[buffer-1] & (BL_R_LOCK | BL_W_LOCK | BL_RI_LOCK))); + while (buf->r_locks > 0 || buf->w_lock) + { + if (buf->r_locks > 3) + { + if (!(BufferLocks[buffer-1] & BL_RI_LOCK)) + BufferLocks[buffer-1] |= BL_RI_LOCK; + buf->ri_lock = true; + } +#ifdef HAS_TEST_AND_SET + S_UNLOCK(&(buf->cntx_lock)); + s_lock_sleep(i++); + S_LOCK(&(buf->cntx_lock)); +#else + IpcSemaphoreUnlock(WaitCLSemId, 0, IpcExclusiveLock); + s_lock_sleep(i++) + IpcSemaphoreLock(WaitCLSemId, 0, IpcExclusiveLock); +#endif + } + buf->w_lock = true; + BufferLocks[buffer-1] |= BL_W_LOCK; + if (BufferLocks[buffer-1] & BL_RI_LOCK) + { + buf->ri_lock = false; + BufferLocks[buffer-1] &= ~BL_RI_LOCK; + } + } + else + elog(ERROR, "LockBuffer: unknown lock mode %d", mode); + +#ifdef HAS_TEST_AND_SET + S_UNLOCK(&(buf->cntx_lock)); +#else + IpcSemaphoreUnlock(WaitCLSemId, 0, IpcExclusiveLock); +#endif + +} |