Fix LMGR for MVCC.

Get rid of Extend lock mode.

1 files changed, 113 insertions, 138 deletions

diff --git a/src/backend/storage/lmgr/lock.c b/src/backend/storage/lmgr/lock.c
index c39138ff129..c1996fe0713 100644
--- a/src/backend/storage/lmgr/lock.c
+++ b/src/backend/storage/lmgr/lock.c
@@ -7,7 +7,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/storage/lmgr/lock.c,v 1.49 1999/04/30 17:03:04 momjian Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/storage/lmgr/lock.c,v 1.50 1999/05/07 01:23:03 vadim Exp $
  *
  * NOTES
  *	  Outside modules can create a lock table and acquire/release
@@ -50,8 +50,7 @@
 #include "utils/trace.h"
 #include "utils/ps_status.h"
 
-static int WaitOnLock(LOCKMETHOD lockmethod, LOCK *lock, LOCKMODE lockmode,
-		   TransactionId xid);
+static int WaitOnLock(LOCKMETHOD lockmethod, LOCK *lock, LOCKMODE lockmode);
 
 /*
  * lockDebugRelation can be used to trace unconditionally a single relation,
@@ -143,12 +142,14 @@ static int WaitOnLock(LOCKMETHOD lockmethod, LOCK *lock, LOCKMODE lockmode,
 #endif	 /* !LOCK_MGR_DEBUG */
 
 static char *lock_types[] = {
-	"",
-	"WRITE",
-	"READ",
-	"WRITE INTENT",
-	"READ INTENT",
-	"EXTEND"
+	"INVALID",
+	"AccessShareLock",
+	"RowShareLock",
+	"RowExclusiveLock",
+	"ShareLock",
+	"ShareRowExclusiveLock",
+	"ExclusiveLock",
+	"AccessExclusiveLock"
 };
 
 SPINLOCK	LockMgrLock;		/* in Shmem or created in
@@ -631,12 +632,11 @@ LockAcquire(LOCKMETHOD lockmethod, LOCKTAG *locktag, LOCKMODE lockmode)
 
 	/* --------------------
 	 * If I'm the only one holding a lock, then there
-	 * cannot be a conflict.  Need to subtract one from the
-	 * lock's count since we just bumped the count up by 1
-	 * above.
+	 * cannot be a conflict. The same is true if we already
+	 * hold this lock.
 	 * --------------------
 	 */
-	if (result->nHolding == lock->nActive)
+	if (result->nHolding == lock->nActive || result->holders[lockmode] != 0)
 	{
 		result->holders[lockmode]++;
 		result->nHolding++;
@@ -647,7 +647,39 @@ LockAcquire(LOCKMETHOD lockmethod, LOCKTAG *locktag, LOCKMODE lockmode)
 		return TRUE;
 	}
 
-	status = LockResolveConflicts(lockmethod, lock, lockmode, xid, result);
+	/*
+	 * If lock requested conflicts with locks requested by waiters...
+	 */
+	if (lockMethodTable->ctl->conflictTab[lockmode] & lock->waitMask)
+	{
+		int		i = 1;
+
+		/*
+		 * If I don't hold locks or my locks don't conflict 
+		 * with waiters then force to sleep.
+		 */
+		if (result->nHolding > 0)
+		{
+			for ( ; i <= lockMethodTable->ctl->numLockModes; i++)
+			{
+				if (result->holders[i] > 0 && 
+					lockMethodTable->ctl->conflictTab[i] & lock->waitMask)
+					break;	/* conflict */
+			}
+		}
+	
+		if (result->nHolding == 0 || i > lockMethodTable->ctl->numLockModes)
+		{
+			XID_PRINT("LockAcquire: higher priority proc waiting",
+					  result);
+			status = STATUS_FOUND;
+		}
+		else
+			status = LockResolveConflicts(lockmethod, lock, lockmode, xid, result);
+	}
+	else
+		status = LockResolveConflicts(lockmethod, lock, lockmode, xid, result);
+
 	if (status == STATUS_OK)
 		GrantLock(lock, lockmode);
 	else if (status == STATUS_FOUND)
@@ -680,7 +712,25 @@ LockAcquire(LOCKMETHOD lockmethod, LOCKTAG *locktag, LOCKMODE lockmode)
 			return FALSE;
 		}
 #endif
-		status = WaitOnLock(lockmethod, lock, lockmode, xid);
+		/*
+		 * Construct bitmask of locks we hold before going to sleep.
+		 */
+		MyProc->holdLock = 0;
+		if (result->nHolding > 0)
+		{
+			int		i,
+					tmpMask = 2;
+
+			for (i = 1; i <= lockMethodTable->ctl->numLockModes; 
+					i++, tmpMask <<= 1)
+			{
+				if (result->holders[i] > 0)
+					MyProc->holdLock |= tmpMask;
+			}
+			Assert(MyProc->holdLock != 0);
+		}
+
+		status = WaitOnLock(lockmethod, lock, lockmode);
 
 		/*
 		 * Check the xid entry status, in case something in the ipc
@@ -712,10 +762,6 @@ LockAcquire(LOCKMETHOD lockmethod, LOCKTAG *locktag, LOCKMODE lockmode)
  * determining whether or not any new lock acquired conflicts with
  * the old ones.
  *
- *	For example, if I am already holding a WRITE_INTENT lock,
- *	there will not be a conflict with my own READ_LOCK.  If I
- *	don't consider the intent lock when checking for conflicts,
- *	I find no conflict.
  * ----------------------------
  */
 int
@@ -812,32 +858,6 @@ LockResolveConflicts(LOCKMETHOD lockmethod,
 	}
 	Assert((result->nHolding >= 0) && (result->holders[lockmode] >= 0));
 
-	/*
-	 * We can control runtime this option. Default is lockReadPriority=0
-	 */
-	if (!lockReadPriority)
-	{
-		/* ------------------------
-		 * If someone with a greater priority is waiting for the lock,
-		 * do not continue and share the lock, even if we can.
-		 * Don't do this if the process already has some locks, because
-		 * this could hold up other people waiting on our locks, causing
-		 * a priority inversion.  bjm
-		 * ------------------------
-		 */
-		int			myprio = LockMethodTable[lockmethod]->ctl->prio[lockmode];
-		PROC_QUEUE *waitQueue = &(lock->waitProcs);
-		PROC	   *topproc = (PROC *) MAKE_PTR(waitQueue->links.prev);
-
-		if (SHMQueueEmpty(&MyProc->lockQueue) && waitQueue->size &&
-			topproc->prio > myprio)
-		{
-			XID_PRINT("LockResolveConflicts: higher priority proc waiting",
-					  result);
-			return STATUS_FOUND;
-		}
-	}
-
 	/* ----------------------------
 	 * first check for global conflicts: If no locks conflict
 	 * with mine, then I get the lock.
@@ -909,12 +929,10 @@ GrantLock(LOCK *lock, LOCKMODE lockmode)
 }
 
 static int
-WaitOnLock(LOCKMETHOD lockmethod, LOCK *lock, LOCKMODE lockmode,
-		   TransactionId xid)
+WaitOnLock(LOCKMETHOD lockmethod, LOCK *lock, LOCKMODE lockmode)
 {
 	PROC_QUEUE *waitQueue = &(lock->waitProcs);
 	LOCKMETHODTABLE *lockMethodTable = LockMethodTable[lockmethod];
-	int			prio = lockMethodTable->ctl->prio[lockmode];
 	char		old_status[64],
 				new_status[64];
 
@@ -934,11 +952,9 @@ WaitOnLock(LOCKMETHOD lockmethod, LOCK *lock, LOCKMODE lockmode,
 	strcat(new_status, " waiting");
 	PS_SET_STATUS(new_status);
 	if (ProcSleep(waitQueue,
-				  lockMethodTable->ctl->masterLock,
+				  lockMethodTable->ctl,
 				  lockmode,
-				  prio,
-				  lock,
-				  xid) != NO_ERROR)
+				  lock) != NO_ERROR)
 	{
 		/* -------------------
 		 * This could have happend as a result of a deadlock,
@@ -952,12 +968,16 @@ WaitOnLock(LOCKMETHOD lockmethod, LOCK *lock, LOCKMODE lockmode,
 		LOCK_PRINT_AUX("WaitOnLock: aborting on lock", lock, lockmode);
 		Assert((lock->nHolding >= 0) && (lock->holders[lockmode] >= 0));
 		Assert(lock->nActive <= lock->nHolding);
+		if (lock->activeHolders[lockmode] == lock->holders[lockmode])
+			lock->waitMask &= BITS_OFF[lockmode];
 		SpinRelease(lockMethodTable->ctl->masterLock);
 		elog(ERROR, "WaitOnLock: error on wakeup - Aborting this transaction");
 
 		/* not reached */
 	}
 
+	if (lock->activeHolders[lockmode] == lock->holders[lockmode])
+		lock->waitMask &= BITS_OFF[lockmode];
 	PS_SET_STATUS(old_status);
 	LOCK_PRINT_AUX("WaitOnLock: wakeup on lock", lock, lockmode);
 	return STATUS_OK;
@@ -1129,6 +1149,7 @@ LockRelease(LOCKMETHOD lockmethod, LOCKTAG *locktag, LOCKMODE lockmode)
 	lock->nActive--;
 	lock->activeHolders[lockmode]--;
 
+#ifdef NOT_USED
 	/* --------------------------
 	 * If there are still active locks of the type I just released, no one
 	 * should be woken up.	Whoever is asleep will still conflict
@@ -1138,6 +1159,19 @@ LockRelease(LOCKMETHOD lockmethod, LOCKTAG *locktag, LOCKMODE lockmode)
 	if (lock->activeHolders[lockmode])
 		wakeupNeeded = false;
 	else
+#endif
+	/*
+	 * Above is not valid any more (due to MVCC lock modes). 
+	 * Actually we should compare activeHolders[lockmode] with 
+	 * number of waiters holding lock of this type and try to
+	 * wakeup only if these numbers are equal (and lock released 
+	 * conflicts with locks requested by waiters). For the moment
+	 * we only check the last condition.
+	 */
+	if (lockMethodTable->ctl->conflictTab[lockmode] & lock->waitMask)
+		wakeupNeeded = true;
+
+	if (!(lock->activeHolders[lockmode]))
 	{
 		/* change the conflict mask.  No more of this lock type. */
 		lock->mask &= BITS_OFF[lockmode];
@@ -1199,12 +1233,6 @@ LockRelease(LOCKMETHOD lockmethod, LOCKTAG *locktag, LOCKMODE lockmode)
 
 	if (wakeupNeeded)
 	{
-		/* --------------------------
-		 * Wake the first waiting process and grant him the lock if it
-		 * doesn't conflict.  The woken process must record the lock
-		 * himself.
-		 * --------------------------
-		 */
 		ProcLockWakeup(&(lock->waitProcs), lockmethod, lock);
 	}
 	else
@@ -1275,6 +1303,7 @@ LockReleaseAll(LOCKMETHOD lockmethod, SHM_QUEUE *lockQueue)
 
 	for (;;)
 	{
+		bool	wakeupNeeded = false;
 
 		/*
 		 * Sometimes the queue appears to be messed up.
@@ -1380,6 +1409,12 @@ LockReleaseAll(LOCKMETHOD lockmethod, SHM_QUEUE *lockQueue)
 					   &&(lock->activeHolders[i] >= 0));
 				if (!lock->activeHolders[i])
 					lock->mask &= BITS_OFF[i];
+				/*
+				 * Read comments in LockRelease
+				 */
+				if (!wakeupNeeded && xidLook->holders[i] > 0 && 
+					lockMethodTable->ctl->conflictTab[i] & lock->waitMask)
+					wakeupNeeded = true;
 			}
 			lock->nHolding -= xidLook->nHolding;
 			lock->nActive -= xidLook->nHolding;
@@ -1444,14 +1479,8 @@ LockReleaseAll(LOCKMETHOD lockmethod, SHM_QUEUE *lockQueue)
 				return FALSE;
 			}
 		}
-		else
+		else if (wakeupNeeded)
 		{
-			/* --------------------
-			 * Wake the first waiting process and grant him the lock if it
-			 * doesn't conflict.  The woken process must record the lock
-			 * him/herself.
-			 * --------------------
-			 */
 			waitQueue = &(lock->waitProcs);
 			ProcLockWakeup(waitQueue, lockmethod, lock);
 		}
@@ -1534,46 +1563,22 @@ LockingDisabled()
 bool
 DeadLockCheck(SHM_QUEUE *lockQueue, LOCK *findlock, bool skip_check)
 {
-	int			done;
-	XIDLookupEnt *xidLook = NULL;
-	XIDLookupEnt *tmp = NULL;
-	SHMEM_OFFSET end = MAKE_OFFSET(lockQueue);
-	LOCK	   *lock;
+	int						done;
+	XIDLookupEnt		   *xidLook = NULL;
+	XIDLookupEnt		   *tmp = NULL;
+	SHMEM_OFFSET			end = MAKE_OFFSET(lockQueue);
+	LOCK				   *lock;
 
-	LOCKMETHODTABLE *lockMethodTable;
-	XIDLookupEnt *result,
-				item;
-	HTAB	   *xidTable;
-	bool		found;
-
-	static PROC *checked_procs[MAXBACKENDS];
-	static int	nprocs;
-	static bool MyNHolding;
+	static PROC			   *checked_procs[MAXBACKENDS];
+	static int				nprocs;
 
 	/* initialize at start of recursion */
 	if (skip_check)
 	{
 		checked_procs[0] = MyProc;
 		nprocs = 1;
-
-		lockMethodTable = LockMethodTable[DEFAULT_LOCKMETHOD];
-		xidTable = lockMethodTable->xidHash;
-
-		MemSet(&item, 0, XID_TAGSIZE);
-		TransactionIdStore(MyProc->xid, &item.tag.xid);
-		item.tag.lock = MAKE_OFFSET(findlock);
-#ifdef NOT_USED
-		item.tag.pid = pid;
-#endif
-
-		if (!(result = (XIDLookupEnt *)
-			  hash_search(xidTable, (Pointer) &item, HASH_FIND, &found)) || !found)
-		{
-			elog(NOTICE, "LockAcquire: xid table corrupted");
-			return true;
-		}
-		MyNHolding = result->nHolding;
 	}
+
 	if (SHMQueueEmpty(lockQueue))
 		return false;
 
@@ -1583,12 +1588,6 @@ DeadLockCheck(SHM_QUEUE *lockQueue, LOCK *findlock, bool skip_check)
 
 	for (;;)
 	{
-		/* ---------------------------
-		 * XXX Here we assume the shared memory queue is circular and
-		 * that we know its internal structure.  Should have some sort of
-		 * macros to allow one to walk it.	mer 20 July 1991
-		 * ---------------------------
-		 */
 		done = (xidLook->queue.next == end);
 		lock = (LOCK *) MAKE_PTR(xidLook->tag.lock);
 
@@ -1613,45 +1612,21 @@ DeadLockCheck(SHM_QUEUE *lockQueue, LOCK *findlock, bool skip_check)
 			proc = (PROC *) MAKE_PTR(waitQueue->links.prev);
 			for (i = 0; i < waitQueue->size; i++)
 			{
+				/*
+				 * If I hold some locks on findlock and another proc 
+				 * waits on it holding locks too - check if we are
+				 * waiting one another.
+				 */
 				if (proc != MyProc &&
-					lock == findlock && /* skip_check also true */
-					MyNHolding) /* I already hold some lock on it */
+					lock == findlock &&	/* skip_check also true */
+					MyProc->holdLock)
 				{
-
-					/*
-					 * For findlock's wait queue, we are interested in
-					 * procs who are blocked waiting for a write-lock on
-					 * the table we are waiting on, and already hold a
-					 * lock on it. We first check to see if there is an
-					 * escalation deadlock, where we hold a readlock and
-					 * want a writelock, and someone else holds readlock
-					 * on the same table, and wants a writelock.
-					 *
-					 * Basically, the test is, "Do we both hold some lock on
-					 * findlock, and we are both waiting in the lock
-					 * queue?"   bjm
-					 */
+					LOCKMETHODCTL  *lockctl = 
+							LockMethodTable[DEFAULT_LOCKMETHOD]->ctl;
 
 					Assert(skip_check);
-					Assert(MyProc->prio >= 2);
-
-					lockMethodTable = LockMethodTable[1];
-					xidTable = lockMethodTable->xidHash;
-
-					MemSet(&item, 0, XID_TAGSIZE);
-					TransactionIdStore(proc->xid, &item.tag.xid);
-					item.tag.lock = MAKE_OFFSET(findlock);
-#ifdef NOT_USED
-					item.tag.pid = pid;
-#endif
-
-					if (!(result = (XIDLookupEnt *)
-						  hash_search(xidTable, (Pointer) &item, HASH_FIND, &found)) || !found)
-					{
-						elog(NOTICE, "LockAcquire: xid table corrupted");
-						return true;
-					}
-					if (result->nHolding)
+					if (lockctl->conflictTab[MyProc->token] & proc->holdLock && 
+						lockctl->conflictTab[proc->token] & MyProc->holdLock)
 						return true;
 				}