v1-0001-Unity-NULL-snapshot-hadling.patch

From 358dda1591ca96bf8c6b9dbdc463148461d2709b Mon Sep 17 00:00:00 2001
From: reshke <reshke@double.cloud>
Date: Fri, 19 Dec 2025 21:23:38 +0000
Subject: [PATCH v1] Unity NULL snapshot hadling.

UnregisterSnapshot and UnregisterSnapshotFromOwner are ready to
accept NULL snapshot. However, there are places in code where we
call this function only for non-NULL argumnet. Remove this
unneccessary check to simplify coding.
---
 contrib/amcheck/verify_nbtree.c    | 7 ++++---
 src/backend/access/index/genam.c   | 9 +++++----
 src/backend/access/index/indexam.c | 4 ++--
 src/backend/libpq/be-fsstubs.c     | 4 ++--
 src/backend/utils/cache/relcache.c | 4 ++--
 src/backend/utils/mmgr/portalmem.c | 8 ++++----
 src/backend/utils/time/snapmgr.c   | 4 ++--
 7 files changed, 21 insertions(+), 19 deletions(-)

diff --git a/contrib/amcheck/verify_nbtree.c b/contrib/amcheck/verify_nbtree.c
index f91392a3a49..40a2dc8d69b 100644
--- a/contrib/amcheck/verify_nbtree.c
+++ b/contrib/amcheck/verify_nbtree.c
@@ -594,9 +594,10 @@ bt_check_every_level(Relation rel, Relation heaprel, bool heapkeyspace,
 		bloom_free(state->filter);
 	}
 
-	/* Be tidy: */
-	if (state->snapshot != InvalidSnapshot)
-		UnregisterSnapshot(state->snapshot);
+	/* Be tidy. Dont worry about snapshot being NULL here,
+	* as UnregisterSnapshot is ready to handle it. */
+	UnregisterSnapshot(state->snapshot);
+	
 	MemoryContextDelete(state->targetcontext);
 }
 
diff --git a/src/backend/access/index/genam.c b/src/backend/access/index/genam.c
index b7f10a1aed0..59607e2a160 100644
--- a/src/backend/access/index/genam.c
+++ b/src/backend/access/index/genam.c
@@ -616,8 +616,8 @@ systable_endscan(SysScanDesc sysscan)
 	else
 		table_endscan(sysscan->scan);
 
-	if (sysscan->snapshot)
-		UnregisterSnapshot(sysscan->snapshot);
+	/* Be tidy, unregister snaphot, if any. */
+	UnregisterSnapshot(sysscan->snapshot);
 
 	/*
 	 * Reset the bsysscan flag at the end of the systable scan.  See detailed
@@ -764,8 +764,9 @@ systable_endscan_ordered(SysScanDesc sysscan)
 
 	Assert(sysscan->irel);
 	index_endscan(sysscan->iscan);
-	if (sysscan->snapshot)
-		UnregisterSnapshot(sysscan->snapshot);
+	
+	/* Be tidy, unregister snaphot, if any. */
+	UnregisterSnapshot(sysscan->snapshot);
 
 	/*
 	 * Reset the bsysscan flag at the end of the systable scan.  See detailed
diff --git a/src/backend/access/index/indexam.c b/src/backend/access/index/indexam.c
index 0492d92d23b..6727bcf8565 100644
--- a/src/backend/access/index/indexam.c
+++ b/src/backend/access/index/indexam.c
@@ -407,8 +407,8 @@ index_endscan(IndexScanDesc scan)
 	/* Release index refcount acquired by index_beginscan */
 	RelationDecrementReferenceCount(scan->indexRelation);
 
-	if (scan->xs_temp_snap)
-		UnregisterSnapshot(scan->xs_snapshot);
+	/* Be tidy, unregister snaphot, if any. */
+	UnregisterSnapshot(scan->xs_snapshot);
 
 	/* Release the scan data structure itself */
 	IndexScanEnd(scan);
diff --git a/src/backend/libpq/be-fsstubs.c b/src/backend/libpq/be-fsstubs.c
index e5a34c61931..3015683f51e 100644
--- a/src/backend/libpq/be-fsstubs.c
+++ b/src/backend/libpq/be-fsstubs.c
@@ -729,8 +729,8 @@ closeLOfd(int fd)
 	lobj = cookies[fd];
 	cookies[fd] = NULL;
 
-	if (lobj->snapshot)
-		UnregisterSnapshotFromOwner(lobj->snapshot,
+	/* Be tidy, unregister snaphot, if any. */
+	UnregisterSnapshotFromOwner(lobj->snapshot,
 									TopTransactionResourceOwner);
 	inv_close(lobj);
 }
diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c
index 2d0cb7bcfd4..ef3707488b4 100644
--- a/src/backend/utils/cache/relcache.c
+++ b/src/backend/utils/cache/relcache.c
@@ -395,8 +395,8 @@ ScanPgRelation(Oid targetRelId, bool indexOK, bool force_non_historic)
 	/* all done */
 	systable_endscan(pg_class_scan);
 
-	if (snapshot)
-		UnregisterSnapshot(snapshot);
+	/* Be tidy, unregister snaphot, if any. */
+	UnregisterSnapshot(snapshot);
 
 	table_close(pg_class_desc, AccessShareLock);
 
diff --git a/src/backend/utils/mmgr/portalmem.c b/src/backend/utils/mmgr/portalmem.c
index 1f2a423f38a..5d4c565b4af 100644
--- a/src/backend/utils/mmgr/portalmem.c
+++ b/src/backend/utils/mmgr/portalmem.c
@@ -525,8 +525,8 @@ PortalDrop(Portal portal, bool isTopCommit)
 	 */
 	if (portal->holdSnapshot)
 	{
-		if (portal->resowner)
-			UnregisterSnapshotFromOwner(portal->holdSnapshot,
+		/* Be tidy, unregister snaphot, if any. */
+		UnregisterSnapshotFromOwner(portal->holdSnapshot,
 										portal->resowner);
 		portal->holdSnapshot = NULL;
 	}
@@ -708,8 +708,8 @@ PreCommit_Portals(bool isPrepare)
 		{
 			if (portal->holdSnapshot)
 			{
-				if (portal->resowner)
-					UnregisterSnapshotFromOwner(portal->holdSnapshot,
+				/* Be tidy, unregister snaphot, if any. */
+				UnregisterSnapshotFromOwner(portal->holdSnapshot,
 												portal->resowner);
 				portal->holdSnapshot = NULL;
 			}
diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c
index 5af8326d5e8..1350b21efa7 100644
--- a/src/backend/utils/time/snapmgr.c
+++ b/src/backend/utils/time/snapmgr.c
@@ -865,7 +865,7 @@ RegisterSnapshotOnOwner(Snapshot snapshot, ResourceOwner owner)
 void
 UnregisterSnapshot(Snapshot snapshot)
 {
-	if (snapshot == NULL)
+	if (snapshot == InvalidSnapshot)
 		return;
 
 	UnregisterSnapshotFromOwner(snapshot, CurrentResourceOwner);
@@ -878,7 +878,7 @@ UnregisterSnapshot(Snapshot snapshot)
 void
 UnregisterSnapshotFromOwner(Snapshot snapshot, ResourceOwner owner)
 {
-	if (snapshot == NULL)
+	if (snapshot == InvalidSnapshot)
 		return;
 
 	ResourceOwnerForgetSnapshot(owner, snapshot);
-- 
2.43.0