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Initial MVCC code.

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New code for locking buffer' context.
This commit is contained in:
Vadim B. Mikheev
1998-12-15 12:47:01 +00:00
parent c5a27161a1
commit 3f7fbf85dc
65 changed files with 1391 additions and 1282 deletions
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149
src/backend/storage/buffer/bufmgr.c
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@ -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
}