Modify BufferGetPage() to prepare for "snapshot too old" feature

This patch is a no-op patch which is intended to reduce the chances
of failures of omission once the functional part of the "snapshot
too old" patch goes in.  It adds parameters for snapshot, relation,
and an enum to specify whether the snapshot age check needs to be
done for the page at this point.  This initial patch passes NULL
for the first two new parameters and BGP_NO_SNAPSHOT_TEST for the
third.  The follow-on patch will change the places where the test
needs to be made.

1 files changed, 25 insertions, 22 deletions

diff --git a/src/backend/access/nbtree/nbtinsert.c b/src/backend/access/nbtree/nbtinsert.c
index 3e100aabec7..bf7a8175517 100644
--- a/src/backend/access/nbtree/nbtinsert.c
+++ b/src/backend/access/nbtree/nbtinsert.c
@@ -255,7 +255,7 @@ _bt_check_unique(Relation rel, IndexTuple itup, Relation heapRel,
 
 	InitDirtySnapshot(SnapshotDirty);
 
-	page = BufferGetPage(buf);
+	page = BufferGetPage(buf, NULL, NULL, BGP_NO_SNAPSHOT_TEST);
 	opaque = (BTPageOpaque) PageGetSpecialPointer(page);
 	maxoff = PageGetMaxOffsetNumber(page);
 
@@ -472,7 +472,7 @@ _bt_check_unique(Relation rel, IndexTuple itup, Relation heapRel,
 			{
 				nblkno = opaque->btpo_next;
 				nbuf = _bt_relandgetbuf(rel, nbuf, nblkno, BT_READ);
-				page = BufferGetPage(nbuf);
+				page = BufferGetPage(nbuf, NULL, NULL, BGP_NO_SNAPSHOT_TEST);
 				opaque = (BTPageOpaque) PageGetSpecialPointer(page);
 				if (!P_IGNORE(opaque))
 					break;
@@ -546,7 +546,7 @@ _bt_findinsertloc(Relation rel,
 				  Relation heapRel)
 {
 	Buffer		buf = *bufptr;
-	Page		page = BufferGetPage(buf);
+	Page		page = BufferGetPage(buf, NULL, NULL, BGP_NO_SNAPSHOT_TEST);
 	Size		itemsz;
 	BTPageOpaque lpageop;
 	bool		movedright,
@@ -646,7 +646,7 @@ _bt_findinsertloc(Relation rel,
 		for (;;)
 		{
 			rbuf = _bt_relandgetbuf(rel, rbuf, rblkno, BT_WRITE);
-			page = BufferGetPage(rbuf);
+			page = BufferGetPage(rbuf, NULL, NULL, BGP_NO_SNAPSHOT_TEST);
 			lpageop = (BTPageOpaque) PageGetSpecialPointer(page);
 
 			/*
@@ -742,7 +742,7 @@ _bt_insertonpg(Relation rel,
 	OffsetNumber firstright = InvalidOffsetNumber;
 	Size		itemsz;
 
-	page = BufferGetPage(buf);
+	page = BufferGetPage(buf, NULL, NULL, BGP_NO_SNAPSHOT_TEST);
 	lpageop = (BTPageOpaque) PageGetSpecialPointer(page);
 
 	/* child buffer must be given iff inserting on an internal page */
@@ -824,7 +824,7 @@ _bt_insertonpg(Relation rel,
 			Assert(!P_ISLEAF(lpageop));
 
 			metabuf = _bt_getbuf(rel, BTREE_METAPAGE, BT_WRITE);
-			metapg = BufferGetPage(metabuf);
+			metapg = BufferGetPage(metabuf, NULL, NULL, BGP_NO_SNAPSHOT_TEST);
 			metad = BTPageGetMeta(metapg);
 
 			if (metad->btm_fastlevel >= lpageop->btpo.level)
@@ -854,7 +854,7 @@ _bt_insertonpg(Relation rel,
 		/* clear INCOMPLETE_SPLIT flag on child if inserting a downlink */
 		if (BufferIsValid(cbuf))
 		{
-			Page		cpage = BufferGetPage(cbuf);
+			Page		cpage = BufferGetPage(cbuf, NULL, NULL, BGP_NO_SNAPSHOT_TEST);
 			BTPageOpaque cpageop = (BTPageOpaque) PageGetSpecialPointer(cpage);
 
 			Assert(P_INCOMPLETE_SPLIT(cpageop));
@@ -922,7 +922,8 @@ _bt_insertonpg(Relation rel,
 			}
 			if (BufferIsValid(cbuf))
 			{
-				PageSetLSN(BufferGetPage(cbuf), recptr);
+				PageSetLSN(BufferGetPage(cbuf, NULL, NULL,
+										 BGP_NO_SNAPSHOT_TEST), recptr);
 			}
 
 			PageSetLSN(page, recptr);
@@ -995,9 +996,9 @@ _bt_split(Relation rel, Buffer buf, Buffer cbuf, OffsetNumber firstright,
 	 * possibly-confusing junk behind, we are careful to rewrite rightpage as
 	 * zeroes before throwing any error.
 	 */
-	origpage = BufferGetPage(buf);
+	origpage = BufferGetPage(buf, NULL, NULL, BGP_NO_SNAPSHOT_TEST);
 	leftpage = PageGetTempPage(origpage);
-	rightpage = BufferGetPage(rbuf);
+	rightpage = BufferGetPage(rbuf, NULL, NULL, BGP_NO_SNAPSHOT_TEST);
 
 	origpagenumber = BufferGetBlockNumber(buf);
 	rightpagenumber = BufferGetBlockNumber(rbuf);
@@ -1186,7 +1187,7 @@ _bt_split(Relation rel, Buffer buf, Buffer cbuf, OffsetNumber firstright,
 	if (!P_RIGHTMOST(oopaque))
 	{
 		sbuf = _bt_getbuf(rel, oopaque->btpo_next, BT_WRITE);
-		spage = BufferGetPage(sbuf);
+		spage = BufferGetPage(sbuf, NULL, NULL, BGP_NO_SNAPSHOT_TEST);
 		sopaque = (BTPageOpaque) PageGetSpecialPointer(spage);
 		if (sopaque->btpo_prev != origpagenumber)
 		{
@@ -1256,7 +1257,8 @@ _bt_split(Relation rel, Buffer buf, Buffer cbuf, OffsetNumber firstright,
 	 */
 	if (!isleaf)
 	{
-		Page		cpage = BufferGetPage(cbuf);
+		Page		cpage = BufferGetPage(cbuf, NULL, NULL,
+										  BGP_NO_SNAPSHOT_TEST);
 		BTPageOpaque cpageop = (BTPageOpaque) PageGetSpecialPointer(cpage);
 
 		cpageop->btpo_flags &= ~BTP_INCOMPLETE_SPLIT;
@@ -1343,7 +1345,8 @@ _bt_split(Relation rel, Buffer buf, Buffer cbuf, OffsetNumber firstright,
 		}
 		if (!isleaf)
 		{
-			PageSetLSN(BufferGetPage(cbuf), recptr);
+			PageSetLSN(BufferGetPage(cbuf, NULL, NULL, BGP_NO_SNAPSHOT_TEST),
+					   recptr);
 		}
 	}
 
@@ -1666,7 +1669,7 @@ _bt_insert_parent(Relation rel,
 	{
 		BlockNumber bknum = BufferGetBlockNumber(buf);
 		BlockNumber rbknum = BufferGetBlockNumber(rbuf);
-		Page		page = BufferGetPage(buf);
+		Page		page = BufferGetPage(buf, NULL, NULL, BGP_NO_SNAPSHOT_TEST);
 		IndexTuple	new_item;
 		BTStackData fakestack;
 		IndexTuple	ritem;
@@ -1741,7 +1744,7 @@ _bt_insert_parent(Relation rel,
 void
 _bt_finish_split(Relation rel, Buffer lbuf, BTStack stack)
 {
-	Page		lpage = BufferGetPage(lbuf);
+	Page		lpage = BufferGetPage(lbuf, NULL, NULL, BGP_NO_SNAPSHOT_TEST);
 	BTPageOpaque lpageop = (BTPageOpaque) PageGetSpecialPointer(lpage);
 	Buffer		rbuf;
 	Page		rpage;
@@ -1753,7 +1756,7 @@ _bt_finish_split(Relation rel, Buffer lbuf, BTStack stack)
 
 	/* Lock right sibling, the one missing the downlink */
 	rbuf = _bt_getbuf(rel, lpageop->btpo_next, BT_WRITE);
-	rpage = BufferGetPage(rbuf);
+	rpage = BufferGetPage(rbuf, NULL, NULL, BGP_NO_SNAPSHOT_TEST);
 	rpageop = (BTPageOpaque) PageGetSpecialPointer(rpage);
 
 	/* Could this be a root split? */
@@ -1765,7 +1768,7 @@ _bt_finish_split(Relation rel, Buffer lbuf, BTStack stack)
 
 		/* acquire lock on the metapage */
 		metabuf = _bt_getbuf(rel, BTREE_METAPAGE, BT_WRITE);
-		metapg = BufferGetPage(metabuf);
+		metapg = BufferGetPage(metabuf, NULL, NULL, BGP_NO_SNAPSHOT_TEST);
 		metad = BTPageGetMeta(metapg);
 
 		was_root = (metad->btm_root == BufferGetBlockNumber(lbuf));
@@ -1813,7 +1816,7 @@ _bt_getstackbuf(Relation rel, BTStack stack, int access)
 		BTPageOpaque opaque;
 
 		buf = _bt_getbuf(rel, blkno, access);
-		page = BufferGetPage(buf);
+		page = BufferGetPage(buf, NULL, NULL, BGP_NO_SNAPSHOT_TEST);
 		opaque = (BTPageOpaque) PageGetSpecialPointer(page);
 
 		if (access == BT_WRITE && P_INCOMPLETE_SPLIT(opaque))
@@ -1939,17 +1942,17 @@ _bt_newroot(Relation rel, Buffer lbuf, Buffer rbuf)
 
 	lbkno = BufferGetBlockNumber(lbuf);
 	rbkno = BufferGetBlockNumber(rbuf);
-	lpage = BufferGetPage(lbuf);
+	lpage = BufferGetPage(lbuf, NULL, NULL, BGP_NO_SNAPSHOT_TEST);
 	lopaque = (BTPageOpaque) PageGetSpecialPointer(lpage);
 
 	/* get a new root page */
 	rootbuf = _bt_getbuf(rel, P_NEW, BT_WRITE);
-	rootpage = BufferGetPage(rootbuf);
+	rootpage = BufferGetPage(rootbuf, NULL, NULL, BGP_NO_SNAPSHOT_TEST);
 	rootblknum = BufferGetBlockNumber(rootbuf);
 
 	/* acquire lock on the metapage */
 	metabuf = _bt_getbuf(rel, BTREE_METAPAGE, BT_WRITE);
-	metapg = BufferGetPage(metabuf);
+	metapg = BufferGetPage(metabuf, NULL, NULL, BGP_NO_SNAPSHOT_TEST);
 	metad = BTPageGetMeta(metapg);
 
 	/*
@@ -2173,7 +2176,7 @@ _bt_vacuum_one_page(Relation rel, Buffer buffer, Relation heapRel)
 	OffsetNumber offnum,
 				minoff,
 				maxoff;
-	Page		page = BufferGetPage(buffer);
+	Page		page = BufferGetPage(buffer, NULL, NULL, BGP_NO_SNAPSHOT_TEST);
 	BTPageOpaque opaque = (BTPageOpaque) PageGetSpecialPointer(page);
 
 	/*