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-rw-r--r--src/backend/storage/lmgr/lmgr.c38
1 files changed, 38 insertions, 0 deletions
diff --git a/src/backend/storage/lmgr/lmgr.c b/src/backend/storage/lmgr/lmgr.c
index 1543da6..2acba39 100644
--- a/src/backend/storage/lmgr/lmgr.c
+++ b/src/backend/storage/lmgr/lmgr.c
@@ -1020,6 +1020,44 @@ LockDatabaseObject(Oid classid, Oid objid, uint16 objsubid,
}
/*
+ * ConditionalLockDatabaseObject
+ *
+ * As above, but only lock if we can get the lock without blocking.
+ * Returns true iff the lock was acquired.
+ */
+bool
+ConditionalLockDatabaseObject(Oid classid, Oid objid, uint16 objsubid,
+ LOCKMODE lockmode)
+{
+ LOCKTAG tag;
+ LOCALLOCK *locallock;
+ LockAcquireResult res;
+
+ SET_LOCKTAG_OBJECT(tag,
+ MyDatabaseId,
+ classid,
+ objid,
+ objsubid);
+
+ res = LockAcquireExtended(&tag, lockmode, false, true, true, &locallock);
+
+ if (res == LOCKACQUIRE_NOT_AVAIL)
+ return false;
+
+ /*
+ * Now that we have the lock, check for invalidation messages; see notes
+ * in LockRelationOid.
+ */
+ if (res != LOCKACQUIRE_ALREADY_CLEAR)
+ {
+ AcceptInvalidationMessages();
+ MarkLockClear(locallock);
+ }
+
+ return true;
+}
+
+/*
* UnlockDatabaseObject
*/
void