v11-0003-New-interface-to-lock-relation-id.patch

From 2b54a88af311c67f7c36418f4e530c81d36e5a78 Mon Sep 17 00:00:00 2001
From: Dilip Kumar <dilipkumar@localhost.localdomain>
Date: Fri, 24 Sep 2021 18:29:17 +0530
Subject: [PATCH v11 3/4] New interface to lock relation id

Currently, we have LockRelationOid which provide a mechanism to
lock the relation oid but we must be connected to the database
from which this relation belong.  As part of this patch we are
providing a new interface which can lock the relation even if we
are not connected to the containing database.
---
 src/backend/storage/lmgr/lmgr.c | 28 ++++++++++++++++++++++++++++
 src/include/storage/lmgr.h      |  1 +
 2 files changed, 29 insertions(+)

diff --git a/src/backend/storage/lmgr/lmgr.c b/src/backend/storage/lmgr/lmgr.c
index 5ae52dd..1543da6 100644
--- a/src/backend/storage/lmgr/lmgr.c
+++ b/src/backend/storage/lmgr/lmgr.c
@@ -176,6 +176,34 @@ ConditionalLockRelationOid(Oid relid, LOCKMODE lockmode)
 }
 
 /*
+ *		LockRelationId
+ *
+ * Lock, given a LockRelId.  Same as LockRelationOid but take LockRelId as an
+ * input.
+ */
+void
+LockRelationId(LockRelId *relid, LOCKMODE lockmode)
+{
+	LOCKTAG		tag;
+	LOCALLOCK  *locallock;
+	LockAcquireResult res;
+
+	SET_LOCKTAG_RELATION(tag, relid->dbId, relid->relId);
+
+	res = LockAcquireExtended(&tag, lockmode, false, false, true, &locallock);
+
+	/*
+	 * Now that we have the lock, check for invalidation messages; see notes
+	 * in LockRelationOid.
+	 */
+	if (res != LOCKACQUIRE_ALREADY_CLEAR)
+	{
+		AcceptInvalidationMessages();
+		MarkLockClear(locallock);
+	}
+}
+
+/*
  *		UnlockRelationId
  *
  * Unlock, given a LockRelId.  This is preferred over UnlockRelationOid
diff --git a/src/include/storage/lmgr.h b/src/include/storage/lmgr.h
index 49edbcc..be1d2c9 100644
--- a/src/include/storage/lmgr.h
+++ b/src/include/storage/lmgr.h
@@ -38,6 +38,7 @@ extern void RelationInitLockInfo(Relation relation);
 
 /* Lock a relation */
 extern void LockRelationOid(Oid relid, LOCKMODE lockmode);
+extern void LockRelationId(LockRelId *relid, LOCKMODE lockmode);
 extern bool ConditionalLockRelationOid(Oid relid, LOCKMODE lockmode);
 extern void UnlockRelationId(LockRelId *relid, LOCKMODE lockmode);
 extern void UnlockRelationOid(Oid relid, LOCKMODE lockmode);
-- 
1.8.3.1