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.

4 files changed, 63 insertions, 38 deletions

diff --git a/src/backend/access/brin/brin.c b/src/backend/access/brin/brin.c
index c7409529234..6f6f1b1b415 100644
--- a/src/backend/access/brin/brin.c
+++ b/src/backend/access/brin/brin.c
@@ -208,7 +208,8 @@ brininsert(Relation idxRel, Datum *values, bool *nulls,
 		}
 		else
 		{
-			Page		page = BufferGetPage(buf);
+			Page		page = BufferGetPage(buf, NULL, NULL,
+											 BGP_NO_SNAPSHOT_TEST);
 			ItemId		lp = PageGetItemId(page, off);
 			Size		origsz;
 			BrinTuple  *origtup;
@@ -617,7 +618,8 @@ brinbuild(Relation heap, Relation index, IndexInfo *indexInfo)
 	Assert(BufferGetBlockNumber(meta) == BRIN_METAPAGE_BLKNO);
 	LockBuffer(meta, BUFFER_LOCK_EXCLUSIVE);
 
-	brin_metapage_init(BufferGetPage(meta), BrinGetPagesPerRange(index),
+	brin_metapage_init(BufferGetPage(meta, NULL, NULL, BGP_NO_SNAPSHOT_TEST),
+					   BrinGetPagesPerRange(index),
 					   BRIN_CURRENT_VERSION);
 	MarkBufferDirty(meta);
 
@@ -636,7 +638,7 @@ brinbuild(Relation heap, Relation index, IndexInfo *indexInfo)
 
 		recptr = XLogInsert(RM_BRIN_ID, XLOG_BRIN_CREATE_INDEX);
 
-		page = BufferGetPage(meta);
+		page = BufferGetPage(meta, NULL, NULL, BGP_NO_SNAPSHOT_TEST);
 		PageSetLSN(page, recptr);
 	}
 
@@ -686,7 +688,9 @@ brinbuildempty(Relation index)
 
 	/* Initialize and xlog metabuffer. */
 	START_CRIT_SECTION();
-	brin_metapage_init(BufferGetPage(metabuf), BrinGetPagesPerRange(index),
+	brin_metapage_init(BufferGetPage(metabuf, NULL, NULL,
+									 BGP_NO_SNAPSHOT_TEST),
+					   BrinGetPagesPerRange(index),
 					   BRIN_CURRENT_VERSION);
 	MarkBufferDirty(metabuf);
 	log_newpage_buffer(metabuf, false);
@@ -941,7 +945,8 @@ terminate_brin_buildstate(BrinBuildState *state)
 	{
 		Page		page;
 
-		page = BufferGetPage(state->bs_currentInsertBuf);
+		page = BufferGetPage(state->bs_currentInsertBuf, NULL, NULL,
+							 BGP_NO_SNAPSHOT_TEST);
 		RecordPageWithFreeSpace(state->bs_irel,
 							BufferGetBlockNumber(state->bs_currentInsertBuf),
 								PageGetFreeSpace(page));
diff --git a/src/backend/access/brin/brin_pageops.c b/src/backend/access/brin/brin_pageops.c
index d0ca485caa6..a522b0b5dce 100644
--- a/src/backend/access/brin/brin_pageops.c
+++ b/src/backend/access/brin/brin_pageops.c
@@ -110,7 +110,7 @@ brin_doupdate(Relation idxrel, BlockNumber pagesPerRange,
 		newbuf = InvalidBuffer;
 		extended = false;
 	}
-	oldpage = BufferGetPage(oldbuf);
+	oldpage = BufferGetPage(oldbuf, NULL, NULL, BGP_NO_SNAPSHOT_TEST);
 	oldlp = PageGetItemId(oldpage, oldoff);
 
 	/*
@@ -228,7 +228,8 @@ brin_doupdate(Relation idxrel, BlockNumber pagesPerRange,
 		 * Not enough free space on the oldpage. Put the new tuple on the new
 		 * page, and update the revmap.
 		 */
-		Page		newpage = BufferGetPage(newbuf);
+		Page		newpage = BufferGetPage(newbuf, NULL, NULL,
+											BGP_NO_SNAPSHOT_TEST);
 		Buffer		revmapbuf;
 		ItemPointerData newtid;
 		OffsetNumber newoff;
@@ -245,7 +246,9 @@ brin_doupdate(Relation idxrel, BlockNumber pagesPerRange,
 		 * need to do that here.
 		 */
 		if (extended)
-			brin_page_init(BufferGetPage(newbuf), BRIN_PAGETYPE_REGULAR);
+			brin_page_init(BufferGetPage(newbuf, NULL, NULL,
+										 BGP_NO_SNAPSHOT_TEST),
+						   BRIN_PAGETYPE_REGULAR);
 
 		PageIndexDeleteNoCompact(oldpage, &oldoff, 1);
 		newoff = PageAddItem(newpage, (Item) newtup, newsz,
@@ -298,7 +301,9 @@ brin_doupdate(Relation idxrel, BlockNumber pagesPerRange,
 
 			PageSetLSN(oldpage, recptr);
 			PageSetLSN(newpage, recptr);
-			PageSetLSN(BufferGetPage(revmapbuf), recptr);
+			PageSetLSN(BufferGetPage(revmapbuf, NULL, NULL,
+									 BGP_NO_SNAPSHOT_TEST),
+					   recptr);
 		}
 
 		END_CRIT_SECTION();
@@ -326,7 +331,9 @@ brin_can_do_samepage_update(Buffer buffer, Size origsz, Size newsz)
 {
 	return
 		((newsz <= origsz) ||
-		 PageGetExactFreeSpace(BufferGetPage(buffer)) >= (newsz - origsz));
+		 PageGetExactFreeSpace(BufferGetPage(buffer, NULL, NULL,
+											 BGP_NO_SNAPSHOT_TEST))
+			>= (newsz - origsz));
 }
 
 /*
@@ -381,7 +388,9 @@ brin_doinsert(Relation idxrel, BlockNumber pagesPerRange,
 		 * it's still a regular page.
 		 */
 		LockBuffer(*buffer, BUFFER_LOCK_EXCLUSIVE);
-		if (br_page_get_freespace(BufferGetPage(*buffer)) < itemsz)
+		if (br_page_get_freespace(BufferGetPage(*buffer, NULL, NULL,
+												BGP_NO_SNAPSHOT_TEST))
+			< itemsz)
 		{
 			UnlockReleaseBuffer(*buffer);
 			*buffer = InvalidBuffer;
@@ -404,13 +413,15 @@ brin_doinsert(Relation idxrel, BlockNumber pagesPerRange,
 	/* Now obtain lock on revmap buffer */
 	revmapbuf = brinLockRevmapPageForUpdate(revmap, heapBlk);
 
-	page = BufferGetPage(*buffer);
+	page = BufferGetPage(*buffer, NULL, NULL, BGP_NO_SNAPSHOT_TEST);
 	blk = BufferGetBlockNumber(*buffer);
 
 	/* Execute the actual insertion */
 	START_CRIT_SECTION();
 	if (extended)
-		brin_page_init(BufferGetPage(*buffer), BRIN_PAGETYPE_REGULAR);
+		brin_page_init(BufferGetPage(*buffer, NULL, NULL,
+									 BGP_NO_SNAPSHOT_TEST),
+					   BRIN_PAGETYPE_REGULAR);
 	off = PageAddItem(page, (Item) tup, itemsz, InvalidOffsetNumber,
 					  false, false);
 	if (off == InvalidOffsetNumber)
@@ -447,7 +458,8 @@ brin_doinsert(Relation idxrel, BlockNumber pagesPerRange,
 		recptr = XLogInsert(RM_BRIN_ID, info);
 
 		PageSetLSN(page, recptr);
-		PageSetLSN(BufferGetPage(revmapbuf), recptr);
+		PageSetLSN(BufferGetPage(revmapbuf, NULL, NULL,
+								 BGP_NO_SNAPSHOT_TEST), recptr);
 	}
 
 	END_CRIT_SECTION();
@@ -515,7 +527,7 @@ brin_start_evacuating_page(Relation idxRel, Buffer buf)
 	OffsetNumber maxoff;
 	Page		page;
 
-	page = BufferGetPage(buf);
+	page = BufferGetPage(buf, NULL, NULL, BGP_NO_SNAPSHOT_TEST);
 
 	if (PageIsNew(page))
 		return false;
@@ -551,7 +563,7 @@ brin_evacuate_page(Relation idxRel, BlockNumber pagesPerRange,
 	OffsetNumber maxoff;
 	Page		page;
 
-	page = BufferGetPage(buf);
+	page = BufferGetPage(buf, NULL, NULL, BGP_NO_SNAPSHOT_TEST);
 
 	Assert(BrinPageFlags(page) & BRIN_EVACUATE_PAGE);
 
@@ -598,7 +610,7 @@ brin_evacuate_page(Relation idxRel, BlockNumber pagesPerRange,
 bool
 brin_page_cleanup(Relation idxrel, Buffer buf)
 {
-	Page		page = BufferGetPage(buf);
+	Page		page = BufferGetPage(buf, NULL, NULL, BGP_NO_SNAPSHOT_TEST);
 	Size		freespace;
 
 	/*
@@ -627,8 +639,10 @@ brin_page_cleanup(Relation idxrel, Buffer buf)
 	}
 
 	/* Nothing to be done for non-regular index pages */
-	if (BRIN_IS_META_PAGE(BufferGetPage(buf)) ||
-		BRIN_IS_REVMAP_PAGE(BufferGetPage(buf)))
+	if (BRIN_IS_META_PAGE(BufferGetPage(buf, NULL, NULL,
+										BGP_NO_SNAPSHOT_TEST)) ||
+		BRIN_IS_REVMAP_PAGE(BufferGetPage(buf, NULL, NULL,
+										  BGP_NO_SNAPSHOT_TEST)))
 		return false;
 
 	/* Measure free space and record it */
@@ -738,7 +752,8 @@ brin_getinsertbuffer(Relation irel, Buffer oldbuf, Size itemsz,
 		if (BufferIsValid(oldbuf) && oldblk < newblk)
 		{
 			LockBuffer(oldbuf, BUFFER_LOCK_EXCLUSIVE);
-			if (!BRIN_IS_REGULAR_PAGE(BufferGetPage(oldbuf)))
+			if (!BRIN_IS_REGULAR_PAGE(BufferGetPage(oldbuf, NULL, NULL,
+													BGP_NO_SNAPSHOT_TEST)))
 			{
 				LockBuffer(oldbuf, BUFFER_LOCK_UNLOCK);
 
@@ -770,7 +785,7 @@ brin_getinsertbuffer(Relation irel, Buffer oldbuf, Size itemsz,
 		if (extensionLockHeld)
 			UnlockRelationForExtension(irel, ExclusiveLock);
 
-		page = BufferGetPage(buf);
+		page = BufferGetPage(buf, NULL, NULL, BGP_NO_SNAPSHOT_TEST);
 
 		/*
 		 * We have a new buffer to insert into.  Check that the new page has
@@ -805,7 +820,8 @@ brin_getinsertbuffer(Relation irel, Buffer oldbuf, Size itemsz,
 			if (BufferIsValid(oldbuf) && oldblk > newblk)
 			{
 				LockBuffer(oldbuf, BUFFER_LOCK_EXCLUSIVE);
-				Assert(BRIN_IS_REGULAR_PAGE(BufferGetPage(oldbuf)));
+				Assert(BRIN_IS_REGULAR_PAGE(BufferGetPage(oldbuf, NULL, NULL,
+														  BGP_NO_SNAPSHOT_TEST)));
 			}
 
 			return buf;
@@ -862,7 +878,7 @@ brin_initialize_empty_new_buffer(Relation idxrel, Buffer buffer)
 			   BufferGetBlockNumber(buffer)));
 
 	START_CRIT_SECTION();
-	page = BufferGetPage(buffer);
+	page = BufferGetPage(buffer, NULL, NULL, BGP_NO_SNAPSHOT_TEST);
 	brin_page_init(page, BRIN_PAGETYPE_REGULAR);
 	MarkBufferDirty(buffer);
 	log_newpage_buffer(buffer, true);
diff --git a/src/backend/access/brin/brin_revmap.c b/src/backend/access/brin/brin_revmap.c
index b2c273daf6e..ce21cbabb7a 100644
--- a/src/backend/access/brin/brin_revmap.c
+++ b/src/backend/access/brin/brin_revmap.c
@@ -73,10 +73,12 @@ brinRevmapInitialize(Relation idxrel, BlockNumber *pagesPerRange)
 	BrinRevmap *revmap;
 	Buffer		meta;
 	BrinMetaPageData *metadata;
+	Page		page;
 
 	meta = ReadBuffer(idxrel, BRIN_METAPAGE_BLKNO);
 	LockBuffer(meta, BUFFER_LOCK_SHARE);
-	metadata = (BrinMetaPageData *) PageGetContents(BufferGetPage(meta));
+	page = BufferGetPage(meta, NULL, NULL, BGP_NO_SNAPSHOT_TEST);
+	metadata = (BrinMetaPageData *) PageGetContents(page);
 
 	revmap = palloc(sizeof(BrinRevmap));
 	revmap->rm_irel = idxrel;
@@ -159,7 +161,7 @@ brinSetHeapBlockItemptr(Buffer buf, BlockNumber pagesPerRange,
 	Page		page;
 
 	/* The correct page should already be pinned and locked */
-	page = BufferGetPage(buf);
+	page = BufferGetPage(buf, NULL, NULL, BGP_NO_SNAPSHOT_TEST);
 	contents = (RevmapContents *) PageGetContents(page);
 	iptr = (ItemPointerData *) contents->rm_tids;
 	iptr += HEAPBLK_TO_REVMAP_INDEX(pagesPerRange, heapBlk);
@@ -226,7 +228,8 @@ brinGetTupleForHeapBlock(BrinRevmap *revmap, BlockNumber heapBlk,
 		LockBuffer(revmap->rm_currBuf, BUFFER_LOCK_SHARE);
 
 		contents = (RevmapContents *)
-			PageGetContents(BufferGetPage(revmap->rm_currBuf));
+			PageGetContents(BufferGetPage(revmap->rm_currBuf, NULL, NULL,
+										  BGP_NO_SNAPSHOT_TEST));
 		iptr = contents->rm_tids;
 		iptr += HEAPBLK_TO_REVMAP_INDEX(revmap->rm_pagesPerRange, heapBlk);
 
@@ -261,7 +264,7 @@ brinGetTupleForHeapBlock(BrinRevmap *revmap, BlockNumber heapBlk,
 			*buf = ReadBuffer(idxRel, blk);
 		}
 		LockBuffer(*buf, mode);
-		page = BufferGetPage(*buf);
+		page = BufferGetPage(*buf, NULL, NULL, BGP_NO_SNAPSHOT_TEST);
 
 		/* If we land on a revmap page, start over */
 		if (BRIN_IS_REGULAR_PAGE(page))
@@ -393,7 +396,8 @@ revmap_physical_extend(BrinRevmap *revmap)
 	 * another backend can extend the index with regular BRIN pages.
 	 */
 	LockBuffer(revmap->rm_metaBuf, BUFFER_LOCK_EXCLUSIVE);
-	metapage = BufferGetPage(revmap->rm_metaBuf);
+	metapage = BufferGetPage(revmap->rm_metaBuf, NULL, NULL,
+							 BGP_NO_SNAPSHOT_TEST);
 	metadata = (BrinMetaPageData *) PageGetContents(metapage);
 
 	/*
@@ -413,7 +417,7 @@ revmap_physical_extend(BrinRevmap *revmap)
 	{
 		buf = ReadBuffer(irel, mapBlk);
 		LockBuffer(buf, BUFFER_LOCK_EXCLUSIVE);
-		page = BufferGetPage(buf);
+		page = BufferGetPage(buf, NULL, NULL, BGP_NO_SNAPSHOT_TEST);
 	}
 	else
 	{
@@ -436,7 +440,7 @@ revmap_physical_extend(BrinRevmap *revmap)
 			return;
 		}
 		LockBuffer(buf, BUFFER_LOCK_EXCLUSIVE);
-		page = BufferGetPage(buf);
+		page = BufferGetPage(buf, NULL, NULL, BGP_NO_SNAPSHOT_TEST);
 
 		if (needLock)
 			UnlockRelationForExtension(irel, ExclusiveLock);
diff --git a/src/backend/access/brin/brin_xlog.c b/src/backend/access/brin/brin_xlog.c
index deb7af4ca6e..36e4a99fc10 100644
--- a/src/backend/access/brin/brin_xlog.c
+++ b/src/backend/access/brin/brin_xlog.c
@@ -30,7 +30,7 @@ brin_xlog_createidx(XLogReaderState *record)
 	/* create the index' metapage */
 	buf = XLogInitBufferForRedo(record, 0);
 	Assert(BufferIsValid(buf));
-	page = (Page) BufferGetPage(buf);
+	page = BufferGetPage(buf, NULL, NULL, BGP_NO_SNAPSHOT_TEST);
 	brin_metapage_init(page, xlrec->pagesPerRange, xlrec->version);
 	PageSetLSN(page, lsn);
 	MarkBufferDirty(buf);
@@ -58,7 +58,7 @@ brin_xlog_insert_update(XLogReaderState *record,
 	if (XLogRecGetInfo(record) & XLOG_BRIN_INIT_PAGE)
 	{
 		buffer = XLogInitBufferForRedo(record, 0);
-		page = BufferGetPage(buffer);
+		page = BufferGetPage(buffer, NULL, NULL, BGP_NO_SNAPSHOT_TEST);
 		brin_page_init(page, BRIN_PAGETYPE_REGULAR);
 		action = BLK_NEEDS_REDO;
 	}
@@ -81,7 +81,7 @@ brin_xlog_insert_update(XLogReaderState *record,
 
 		Assert(tuple->bt_blkno == xlrec->heapBlk);
 
-		page = (Page) BufferGetPage(buffer);
+		page = BufferGetPage(buffer, NULL, NULL, BGP_NO_SNAPSHOT_TEST);
 		offnum = xlrec->offnum;
 		if (PageGetMaxOffsetNumber(page) + 1 < offnum)
 			elog(PANIC, "brin_xlog_insert_update: invalid max offset number");
@@ -103,7 +103,7 @@ brin_xlog_insert_update(XLogReaderState *record,
 		ItemPointerData tid;
 
 		ItemPointerSet(&tid, regpgno, xlrec->offnum);
-		page = (Page) BufferGetPage(buffer);
+		page = BufferGetPage(buffer, NULL, NULL, BGP_NO_SNAPSHOT_TEST);
 
 		brinSetHeapBlockItemptr(buffer, xlrec->pagesPerRange, xlrec->heapBlk,
 								tid);
@@ -145,7 +145,7 @@ brin_xlog_update(XLogReaderState *record)
 		Page		page;
 		OffsetNumber offnum;
 
-		page = (Page) BufferGetPage(buffer);
+		page = BufferGetPage(buffer, NULL, NULL, BGP_NO_SNAPSHOT_TEST);
 
 		offnum = xlrec->oldOffnum;
 		if (PageGetMaxOffsetNumber(page) + 1 < offnum)
@@ -186,7 +186,7 @@ brin_xlog_samepage_update(XLogReaderState *record)
 
 		brintuple = (BrinTuple *) XLogRecGetBlockData(record, 0, &tuplen);
 
-		page = (Page) BufferGetPage(buffer);
+		page = BufferGetPage(buffer, NULL, NULL, BGP_NO_SNAPSHOT_TEST);
 
 		offnum = xlrec->offnum;
 		if (PageGetMaxOffsetNumber(page) + 1 < offnum)
@@ -232,7 +232,7 @@ brin_xlog_revmap_extend(XLogReaderState *record)
 		Page		metapg;
 		BrinMetaPageData *metadata;
 
-		metapg = BufferGetPage(metabuf);
+		metapg = BufferGetPage(metabuf, NULL, NULL, BGP_NO_SNAPSHOT_TEST);
 		metadata = (BrinMetaPageData *) PageGetContents(metapg);
 
 		Assert(metadata->lastRevmapPage == xlrec->targetBlk - 1);
@@ -248,7 +248,7 @@ brin_xlog_revmap_extend(XLogReaderState *record)
 	 */
 
 	buf = XLogInitBufferForRedo(record, 1);
-	page = (Page) BufferGetPage(buf);
+	page = BufferGetPage(buf, NULL, NULL, BGP_NO_SNAPSHOT_TEST);
 	brin_page_init(page, BRIN_PAGETYPE_REVMAP);
 
 	PageSetLSN(page, lsn);