2 files changed, 69 insertions, 0 deletions
diff --git a/src/backend/storage/lmgr/lmgr.c b/src/backend/storage/lmgr/lmgr.c
index dc0a4396388..3f57507bce8 100644
--- a/src/backend/storage/lmgr/lmgr.c
+++ b/src/backend/storage/lmgr/lmgr.c
@@ -288,6 +288,51 @@ UnlockRelation(Relation relation, LOCKMODE lockmode)
 }
 
 /*
+ *		CheckRelationLockedByMe
+ *
+ * Returns true if current transaction holds a lock on 'relation' of mode
+ * 'lockmode'.  If 'orstronger' is true, a stronger lockmode is also OK.
+ * ("Stronger" is defined as "numerically higher", which is a bit
+ * semantically dubious but is OK for the purposes we use this for.)
+ */
+bool
+CheckRelationLockedByMe(Relation relation, LOCKMODE lockmode, bool orstronger)
+{
+	LOCKTAG		tag;
+
+	SET_LOCKTAG_RELATION(tag,
+						 relation->rd_lockInfo.lockRelId.dbId,
+						 relation->rd_lockInfo.lockRelId.relId);
+
+	if (LockHeldByMe(&tag, lockmode))
+		return true;
+
+	if (orstronger)
+	{
+		LOCKMODE	slockmode;
+
+		for (slockmode = lockmode + 1;
+			 slockmode <= MaxLockMode;
+			 slockmode++)
+		{
+			if (LockHeldByMe(&tag, slockmode))
+			{
+#ifdef NOT_USED
+				/* Sometimes this might be useful for debugging purposes */
+				elog(WARNING, "lock mode %s substituted for %s on relation %s",
+					 GetLockmodeName(tag.locktag_lockmethodid, slockmode),
+					 GetLockmodeName(tag.locktag_lockmethodid, lockmode),
+					 RelationGetRelationName(relation));
+#endif
+				return true;
+			}
+		}
+	}
+
+	return false;
+}
+
+/*
  *		LockHasWaitersRelation
  *
  * This is a function to check whether someone else is waiting for a
diff --git a/src/backend/storage/lmgr/lock.c b/src/backend/storage/lmgr/lock.c
index 831ae625258..10f6f60f1e2 100644
--- a/src/backend/storage/lmgr/lock.c
+++ b/src/backend/storage/lmgr/lock.c
@@ -564,6 +564,30 @@ DoLockModesConflict(LOCKMODE mode1, LOCKMODE mode2)
 }
 
 /*
+ * LockHeldByMe -- test whether lock 'locktag' is held with mode 'lockmode'
+ *		by the current transaction
+ */
+bool
+LockHeldByMe(const LOCKTAG *locktag, LOCKMODE lockmode)
+{
+	LOCALLOCKTAG localtag;
+	LOCALLOCK  *locallock;
+
+	/*
+	 * See if there is a LOCALLOCK entry for this lock and lockmode
+	 */
+	MemSet(&localtag, 0, sizeof(localtag)); /* must clear padding */
+	localtag.lock = *locktag;
+	localtag.mode = lockmode;
+
+	locallock = (LOCALLOCK *) hash_search(LockMethodLocalHash,
+										  (void *) &localtag,
+										  HASH_FIND, NULL);
+
+	return (locallock && locallock->nLocks > 0);
+}
+
+/*
  * LockHasWaiters -- look up 'locktag' and check if releasing this
  *		lock would wake up other processes waiting for it.
  */