1 files changed, 139 insertions, 103 deletions

diff --git a/src/backend/storage/lmgr/proc.c b/src/backend/storage/lmgr/proc.c
index 6b5159dbf04..406aa35f7c6 100644
--- a/src/backend/storage/lmgr/proc.c
+++ b/src/backend/storage/lmgr/proc.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/storage/lmgr/proc.c,v 1.88 2000/12/18 17:33:41 tgl Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/storage/lmgr/proc.c,v 1.89 2000/12/22 00:51:54 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -48,7 +48,7 @@
  *		This is so that we can support more backends. (system-wide semaphore
  *		sets run out pretty fast.)				  -ay 4/95
  *
- * $Header: /cvsroot/pgsql/src/backend/storage/lmgr/proc.c,v 1.88 2000/12/18 17:33:41 tgl Exp $
+ * $Header: /cvsroot/pgsql/src/backend/storage/lmgr/proc.c,v 1.89 2000/12/22 00:51:54 tgl Exp $
  */
 #include "postgres.h"
 
@@ -74,13 +74,14 @@
 #include <sys/sem.h>
 #endif
 
+#include "access/xact.h"
 #include "storage/proc.h"
 
 
 
 void		HandleDeadLock(SIGNAL_ARGS);
 static void ProcFreeAllSemaphores(void);
-static bool GetOffWaitqueue(PROC *);
+static bool GetOffWaitQueue(PROC *);
 
 int DeadlockTimeout = 1000;
 
@@ -300,50 +301,76 @@ InitProcess(void)
 
 /* -----------------------
  * get process off any wait queue it might be on
+ *
+ * NB: this does not remove the process' holder object, nor the lock object,
+ * even though their holder counts might now have gone to zero.  That will
+ * happen during a subsequent LockReleaseAll call, which we expect will happen
+ * during transaction cleanup.  (Removal of a proc from its wait queue by
+ * this routine can only happen if we are aborting the transaction.)
  * -----------------------
  */
 static bool
-GetOffWaitqueue(PROC *proc)
+GetOffWaitQueue(PROC *proc)
 {
-	bool		getoffed = false;
+	bool		gotoff = false;
 
 	LockLockTable();
 	if (proc->links.next != INVALID_OFFSET)
 	{
-		int			lockmode = proc->token;
-		LOCK	*waitLock = proc->waitLock;
+		LOCK   *waitLock = proc->waitLock;
+		LOCKMODE lockmode = proc->waitLockMode;
 
+		/* Remove proc from lock's wait queue */
 		Assert(waitLock);
 		Assert(waitLock->waitProcs.size > 0);
 		SHMQueueDelete(&(proc->links));
 		--waitLock->waitProcs.size;
+
+		/* Undo increments of holder counts by waiting process */
 		Assert(waitLock->nHolding > 0);
 		Assert(waitLock->nHolding > proc->waitLock->nActive);
 		--waitLock->nHolding;
 		Assert(waitLock->holders[lockmode] > 0);
 		--waitLock->holders[lockmode];
+		/* don't forget to clear waitMask bit if appropriate */
 		if (waitLock->activeHolders[lockmode] == waitLock->holders[lockmode])
 			waitLock->waitMask &= ~(1 << lockmode);
-		ProcLockWakeup(&(waitLock->waitProcs), LOCK_LOCKMETHOD(*waitLock), waitLock);
-		getoffed = true;
+
+		/* Clean up the proc's own state */
+		SHMQueueElemInit(&(proc->links));
+		proc->waitLock = NULL;
+		proc->waitHolder = NULL;
+
+		/* See if any other waiters can be woken up now */
+		ProcLockWakeup(LOCK_LOCKMETHOD(*waitLock), waitLock);
+
+		gotoff = true;
 	}
-	SHMQueueElemInit(&(proc->links));
 	UnlockLockTable();
 
-	return getoffed;
+	return gotoff;
 }
 
 /*
- * ProcReleaseLocks() -- release all locks associated with current transaction
+ * ProcReleaseLocks() -- release locks associated with current transaction
+ *			at transaction commit or abort
+ *
+ * At commit, we release only locks tagged with the current transaction's XID,
+ * leaving those marked with XID 0 (ie, session locks) undisturbed.  At abort,
+ * we release all locks including XID 0, because we need to clean up after
+ * a failure.  This logic will need extension if we ever support nested
+ * transactions.
  *
+ * Note that user locks are not released in either case.
  */
 void
-ProcReleaseLocks()
+ProcReleaseLocks(bool isCommit)
 {
 	if (!MyProc)
 		return;
-	LockReleaseAll(DEFAULT_LOCKMETHOD, &MyProc->lockQueue);
-	GetOffWaitqueue(MyProc);
+	GetOffWaitQueue(MyProc);
+	LockReleaseAll(DEFAULT_LOCKMETHOD, MyProc,
+				   !isCommit, GetCurrentTransactionId());
 }
 
 /*
@@ -384,47 +411,47 @@ static void
 ProcKill(int exitStatus, Datum pid)
 {
 	PROC	   *proc;
-	SHMEM_OFFSET location;
 
 	/* --------------------
 	 * If this is a FATAL exit the postmaster will have to kill all the
-	 * existing backends and reinitialize shared memory.  So all we don't
+	 * existing backends and reinitialize shared memory.  So we don't
 	 * need to do anything here.
 	 * --------------------
 	 */
 	if (exitStatus != 0)
 		return;
 
-	ShmemPIDLookup(MyProcPid, &location);
-	if (location == INVALID_OFFSET)
-		return;
-
-	proc = (PROC *) MAKE_PTR(location);
+	if ((int) pid == MyProcPid)
+	{
+		proc = MyProc;
+		MyProc = NULL;
+	}
+	else
+	{
+		/* This path is dead code at the moment ... */
+		SHMEM_OFFSET location = INVALID_OFFSET;
 
-	Assert(proc == MyProc || (int)pid != MyProcPid);
+		ShmemPIDLookup((int) pid, &location);
+		if (location == INVALID_OFFSET)
+			return;
+		proc = (PROC *) MAKE_PTR(location);
+	}
 
-	MyProc = NULL;
+	Assert(proc);
 
-	/* ---------------
-	 * Assume one lock table.
-	 * ---------------
-	 */
+	/* Release any spinlocks the proc is holding */
 	ProcReleaseSpins(proc);
-	LockReleaseAll(DEFAULT_LOCKMETHOD, &proc->lockQueue);
 
-#ifdef USER_LOCKS
+	/* Get the proc off any wait queue it might be on */
+	GetOffWaitQueue(proc);
 
-	/*
-	 * Assume we have a second lock table.
-	 */
-	LockReleaseAll(USER_LOCKMETHOD, &proc->lockQueue);
-#endif
+	/* Remove from the standard lock table */
+	LockReleaseAll(DEFAULT_LOCKMETHOD, proc, true, InvalidTransactionId);
 
-	/* ----------------
-	 * get off the wait queue
-	 * ----------------
-	 */
-	GetOffWaitqueue(proc);
+#ifdef USER_LOCKS
+	/* Remove from the user lock table */
+	LockReleaseAll(USER_LOCKMETHOD, proc, true, InvalidTransactionId);
+#endif
 }
 
 /*
@@ -488,10 +515,10 @@ SetWaitingForLock(bool waiting)
 		}
 		if (QueryCancel)		/* cancel request pending */
 		{
-			if (GetOffWaitqueue(MyProc))
+			if (GetOffWaitQueue(MyProc))
 			{
 				lockWaiting = false;
-				elog(ERROR, "Query cancel requested while waiting lock");
+				elog(ERROR, "Query cancel requested while waiting for lock");
 			}
 		}
 	}
@@ -519,8 +546,8 @@ LockWaitCancel(void)
     set_alarm(B_INFINITE_TIMEOUT, B_PERIODIC_ALARM);
 #endif /* __BEOS__ */
         
-	if (GetOffWaitqueue(MyProc))
-		elog(ERROR, "Query cancel requested while waiting lock");
+	if (GetOffWaitQueue(MyProc))
+		elog(ERROR, "Query cancel requested while waiting for lock");
 }
 
 /*
@@ -538,18 +565,19 @@ LockWaitCancel(void)
  * NOTES: The process queue is now a priority queue for locking.
  */
 int
-ProcSleep(PROC_QUEUE *waitQueue,/* lock->waitProcs */
-		  LOCKMETHODCTL *lockctl,
-		  int token,			/* lockmode */
-		  LOCK *lock)
+ProcSleep(LOCKMETHODCTL *lockctl,
+		  LOCKMODE lockmode,
+		  LOCK *lock,
+		  HOLDER *holder)
 {
-	int			i;
+	PROC_QUEUE *waitQueue = &(lock->waitProcs);
 	SPINLOCK	spinlock = lockctl->masterLock;
-	PROC	   *proc;
-	int			myMask = (1 << token);
+	int			myMask = (1 << lockmode);
 	int			waitMask = lock->waitMask;
+	PROC	   *proc;
+	int			i;
 	int			aheadHolders[MAX_LOCKMODES];
-	bool		selfConflict = (lockctl->conflictTab[token] & myMask),
+	bool		selfConflict = (lockctl->conflictTab[lockmode] & myMask),
 				prevSame = false;
 #ifndef __BEOS__
 	struct itimerval timeval,
@@ -558,26 +586,28 @@ ProcSleep(PROC_QUEUE *waitQueue,/* lock->waitProcs */
     bigtime_t time_interval;
 #endif
 
-	MyProc->token = token;
 	MyProc->waitLock = lock;
+	MyProc->waitHolder = holder;
+	MyProc->waitLockMode = lockmode;
+	/* We assume the caller set up MyProc->holdLock */
 
 	proc = (PROC *) MAKE_PTR(waitQueue->links.prev);
 
 	/* if we don't conflict with any waiter - be first in queue */
-	if (!(lockctl->conflictTab[token] & waitMask))
+	if (!(lockctl->conflictTab[lockmode] & waitMask))
 		goto ins;
 
 	for (i = 1; i < MAX_LOCKMODES; i++)
 		aheadHolders[i] = lock->activeHolders[i];
-	(aheadHolders[token])++;
+	(aheadHolders[lockmode])++;
 
 	for (i = 0; i < waitQueue->size; i++)
 	{
 		/* am I waiting for him ? */
-		if (lockctl->conflictTab[token] & proc->holdLock)
+		if (lockctl->conflictTab[lockmode] & proc->holdLock)
 		{
 			/* is he waiting for me ? */
-			if (lockctl->conflictTab[proc->token] & MyProc->holdLock)
+			if (lockctl->conflictTab[proc->waitLockMode] & MyProc->holdLock)
 			{
 				/* Yes, report deadlock failure */
 				MyProc->errType = STATUS_ERROR;
@@ -586,10 +616,10 @@ ProcSleep(PROC_QUEUE *waitQueue,/* lock->waitProcs */
 			/* being waiting for him - go past */
 		}
 		/* if he waits for me */
-		else if (lockctl->conflictTab[proc->token] & MyProc->holdLock)
+		else if (lockctl->conflictTab[proc->waitLockMode] & MyProc->holdLock)
 			break;
 		/* if conflicting locks requested */
-		else if (lockctl->conflictTab[proc->token] & myMask)
+		else if (lockctl->conflictTab[proc->waitLockMode] & myMask)
 		{
 
 			/*
@@ -604,13 +634,13 @@ ProcSleep(PROC_QUEUE *waitQueue,/* lock->waitProcs */
 		 * Last attempt to don't move any more: if we don't conflict with
 		 * rest waiters in queue.
 		 */
-		else if (!(lockctl->conflictTab[token] & waitMask))
+		else if (!(lockctl->conflictTab[lockmode] & waitMask))
 			break;
 
-		prevSame = (proc->token == token);
-		(aheadHolders[proc->token])++;
-		if (aheadHolders[proc->token] == lock->holders[proc->token])
-			waitMask &= ~(1 << proc->token);
+		prevSame = (proc->waitLockMode == lockmode);
+		(aheadHolders[proc->waitLockMode])++;
+		if (aheadHolders[proc->waitLockMode] == lock->holders[proc->waitLockMode])
+			waitMask &= ~(1 << proc->waitLockMode);
 		proc = (PROC *) MAKE_PTR(proc->links.prev);
 	}
 
@@ -692,10 +722,8 @@ ins:;
 
 rt:;
 
-#ifdef LOCK_DEBUG
-	/* Just to get meaningful debug messages from DumpLocks() */
-	MyProc->waitLock = (LOCK *) NULL;
-#endif
+	MyProc->waitLock = NULL;
+	MyProc->waitHolder = NULL;
 
 	return MyProc->errType;
 }
@@ -704,7 +732,7 @@ rt:;
 /*
  * ProcWakeup -- wake up a process by releasing its private semaphore.
  *
- *	 remove the process from the wait queue and set its links invalid.
+ *	 Also remove the process from the wait queue and set its links invalid.
  *	 RETURN: the next process in the wait queue.
  */
 PROC *
@@ -720,9 +748,9 @@ ProcWakeup(PROC *proc, int errType)
 
 	retProc = (PROC *) MAKE_PTR(proc->links.prev);
 
-	/* you have to update waitLock->waitProcs.size yourself */
 	SHMQueueDelete(&(proc->links));
 	SHMQueueElemInit(&(proc->links));
+	(proc->waitLock->waitProcs.size)--;
 
 	proc->errType = errType;
 
@@ -736,65 +764,70 @@ ProcWakeup(PROC *proc, int errType)
  *		released.
  */
 int
-ProcLockWakeup(PROC_QUEUE *queue, LOCKMETHOD lockmethod, LOCK *lock)
+ProcLockWakeup(LOCKMETHOD lockmethod, LOCK *lock)
 {
+	PROC_QUEUE *queue = &(lock->waitProcs);
 	PROC	   *proc;
-	int			count = 0;
-	int			last_locktype = 0;
+	int			awoken = 0;
+	LOCKMODE	last_lockmode = 0;
 	int			queue_size = queue->size;
 
-	Assert(queue->size >= 0);
+	Assert(queue_size >= 0);
 
-	if (!queue->size)
+	if (!queue_size)
 		return STATUS_NOT_FOUND;
 
 	proc = (PROC *) MAKE_PTR(queue->links.prev);
-	while ((queue_size--) && (proc))
-	{
 
-		/*
-		 * This proc will conflict as the previous one did, don't even
-		 * try.
-		 */
-		if (proc->token == last_locktype)
-			continue;
+	while (queue_size-- > 0)
+	{
+		if (proc->waitLockMode == last_lockmode)
+		{
+			/*
+			 * This proc will conflict as the previous one did, don't even
+			 * try.
+			 */
+			goto nextProc;
+		}
 
 		/*
 		 * Does this proc conflict with locks held by others ?
 		 */
 		if (LockResolveConflicts(lockmethod,
+								 proc->waitLockMode,
 								 lock,
-								 proc->token,
-								 proc->xid,
-								 (XIDLookupEnt *) NULL) != STATUS_OK)
+								 proc->waitHolder,
+								 proc,
+								 NULL) != STATUS_OK)
 		{
-			if (count != 0)
+			/* Yes.  Quit if we already awoke at least one process. */
+			if (awoken != 0)
 				break;
-			last_locktype = proc->token;
-			continue;
+			/* Otherwise, see if any later waiters can be awoken. */
+			last_lockmode = proc->waitLockMode;
+			goto nextProc;
 		}
 
 		/*
-		 * there was a waiting process, grant it the lock before waking it
-		 * up.	This will prevent another process from seizing the lock
-		 * between the time we release the lock master (spinlock) and the
-		 * time that the awoken process begins executing again.
+		 * OK to wake up this sleeping process.
 		 */
-		GrantLock(lock, proc->token);
+		GrantLock(lock, proc->waitHolder, proc->waitLockMode);
+		proc = ProcWakeup(proc, NO_ERROR);
+		awoken++;
 
 		/*
-		 * ProcWakeup removes proc from the lock waiting process queue and
-		 * returns the next proc in chain.
+		 * ProcWakeup removes proc from the lock's waiting process queue
+		 * and returns the next proc in chain; don't use prev link.
 		 */
+		continue;
 
-		count++;
-		queue->size--;
-		proc = ProcWakeup(proc, NO_ERROR);
+nextProc:
+		proc = (PROC *) MAKE_PTR(proc->links.prev);
 	}
 
 	Assert(queue->size >= 0);
 
-	if (count)
+	if (awoken)
 		return STATUS_OK;
 	else
 	{
@@ -802,9 +835,10 @@ ProcLockWakeup(PROC_QUEUE *queue, LOCKMETHOD lockmethod, LOCK *lock)
 #ifdef LOCK_DEBUG
 		if (lock->tag.lockmethod == USER_LOCKMETHOD ? Trace_userlocks : Trace_locks)
 		{
-			elog(DEBUG, "ProcLockWakeup: lock(%lx) can't wake up any process", MAKE_OFFSET(lock));
+			elog(DEBUG, "ProcLockWakeup: lock(%lx) can't wake up any process",
+				 MAKE_OFFSET(lock));
 			if (Debug_deadlocks)
-			DumpAllLocks();
+				DumpAllLocks();
 		}
 #endif
 		return STATUS_NOT_FOUND;
@@ -872,10 +906,12 @@ HandleDeadLock(SIGNAL_ARGS)
 	 */
 	mywaitlock = MyProc->waitLock;
 	Assert(mywaitlock->waitProcs.size > 0);
-	lockWaiting = false;
 	--mywaitlock->waitProcs.size;
 	SHMQueueDelete(&(MyProc->links));
 	SHMQueueElemInit(&(MyProc->links));
+	MyProc->waitLock = NULL;
+	MyProc->waitHolder = NULL;
+	lockWaiting = false;
 
 	/* ------------------
 	 * Unlock my semaphore so that the interrupted ProcSleep() call can finish.