Remove redundant PGPROC.lockGroupLeaderIdentifier field.

We don't really need this field, because it's either zero or redundant with
PGPROC.pid.  The use of zero to mark "not a group leader" is not necessary
since we can just as well test whether lockGroupLeader is NULL.  This does
not save very much, either as to code or data, but the simplification seems
worthwhile anyway.

1 files changed, 6 insertions, 6 deletions

diff --git a/src/backend/storage/lmgr/proc.c b/src/backend/storage/lmgr/proc.c
index 114fba0d384..6453b88a5b8 100644
--- a/src/backend/storage/lmgr/proc.c
+++ b/src/backend/storage/lmgr/proc.c
@@ -401,7 +401,6 @@ InitProcess(void)
 	pg_atomic_init_u32(&MyProc->procArrayGroupNext, INVALID_PGPROCNO);
 
 	/* Check that group locking fields are in a proper initial state. */
-	Assert(MyProc->lockGroupLeaderIdentifier == 0);
 	Assert(MyProc->lockGroupLeader == NULL);
 	Assert(dlist_is_empty(&MyProc->lockGroupMembers));
 
@@ -565,7 +564,6 @@ InitAuxiliaryProcess(void)
 	SwitchToSharedLatch();
 
 	/* Check that group locking fields are in a proper initial state. */
-	Assert(MyProc->lockGroupLeaderIdentifier == 0);
 	Assert(MyProc->lockGroupLeader == NULL);
 	Assert(dlist_is_empty(&MyProc->lockGroupMembers));
 
@@ -822,7 +820,6 @@ ProcKill(int code, Datum arg)
 		dlist_delete(&MyProc->lockGroupLink);
 		if (dlist_is_empty(&leader->lockGroupMembers))
 		{
-			leader->lockGroupLeaderIdentifier = 0;
 			leader->lockGroupLeader = NULL;
 			if (leader != MyProc)
 			{
@@ -1771,7 +1768,6 @@ BecomeLockGroupLeader(void)
 	leader_lwlock = LockHashPartitionLockByProc(MyProc);
 	LWLockAcquire(leader_lwlock, LW_EXCLUSIVE);
 	MyProc->lockGroupLeader = MyProc;
-	MyProc->lockGroupLeaderIdentifier = MyProcPid;
 	dlist_push_head(&MyProc->lockGroupMembers, &MyProc->lockGroupLink);
 	LWLockRelease(leader_lwlock);
 }
@@ -1795,6 +1791,9 @@ BecomeLockGroupMember(PGPROC *leader, int pid)
 	/* Group leader can't become member of group */
 	Assert(MyProc != leader);
 
+	/* Can't already be a member of a group */
+	Assert(MyProc->lockGroupLeader == NULL);
+
 	/* PID must be valid. */
 	Assert(pid != 0);
 
@@ -1808,9 +1807,10 @@ BecomeLockGroupMember(PGPROC *leader, int pid)
 	leader_lwlock = LockHashPartitionLockByProc(leader);
 	LWLockAcquire(leader_lwlock, LW_EXCLUSIVE);
 
-	/* Try to join the group */
-	if (leader->lockGroupLeaderIdentifier == pid)
+	/* Is this the leader we're looking for? */
+	if (leader->pid == pid && leader->lockGroupLeader == leader)
 	{
+		/* OK, join the group */
 		ok = true;
 		MyProc->lockGroupLeader = leader;
 		dlist_push_tail(&leader->lockGroupMembers, &MyProc->lockGroupLink);