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.

3 files changed, 22 insertions, 14 deletions

diff --git a/src/backend/access/transam/generic_xlog.c b/src/backend/access/transam/generic_xlog.c
index e62179d2fb5..4118d7bb08e 100644
--- a/src/backend/access/transam/generic_xlog.c
+++ b/src/backend/access/transam/generic_xlog.c
@@ -95,7 +95,8 @@ writeFragment(PageData *pageData, OffsetNumber offset, OffsetNumber length,
 static void
 writeDelta(PageData *pageData)
 {
-	Page			page = BufferGetPage(pageData->buffer),
+	Page			page = BufferGetPage(pageData->buffer, NULL, NULL,
+										 BGP_NO_SNAPSHOT_TEST),
 					image = (Page) pageData->image;
 	int				i,
 					fragmentBegin = -1,
@@ -220,7 +221,8 @@ GenericXLogRegister(GenericXLogState *state, Buffer buffer, bool isNew)
 		if (BufferIsInvalid(page->buffer))
 		{
 			page->buffer = buffer;
-			memcpy(page->image, BufferGetPage(buffer), BLCKSZ);
+			memcpy(page->image, BufferGetPage(buffer, NULL, NULL,
+											  BGP_NO_SNAPSHOT_TEST), BLCKSZ);
 			page->dataLen = 0;
 			page->fullImage = isNew;
 			return (Page)page->image;
@@ -295,8 +297,10 @@ GenericXLogFinish(GenericXLogState *state)
 
 			/* Swap current and saved page image. */
 			memcpy(tmp, page->image, BLCKSZ);
-			memcpy(page->image, BufferGetPage(page->buffer), BLCKSZ);
-			memcpy(BufferGetPage(page->buffer), tmp, BLCKSZ);
+			memcpy(page->image, BufferGetPage(page->buffer, NULL, NULL,
+											  BGP_NO_SNAPSHOT_TEST), BLCKSZ);
+			memcpy(BufferGetPage(page->buffer, NULL, NULL,
+								 BGP_NO_SNAPSHOT_TEST), tmp, BLCKSZ);
 
 			if (page->fullImage)
 			{
@@ -325,7 +329,8 @@ GenericXLogFinish(GenericXLogState *state)
 
 			if (BufferIsInvalid(page->buffer))
 				continue;
-			PageSetLSN(BufferGetPage(page->buffer), lsn);
+			PageSetLSN(BufferGetPage(page->buffer, NULL, NULL,
+									 BGP_NO_SNAPSHOT_TEST), lsn);
 			MarkBufferDirty(page->buffer);
 		}
 		END_CRIT_SECTION();
@@ -340,7 +345,8 @@ GenericXLogFinish(GenericXLogState *state)
 
 			if (BufferIsInvalid(page->buffer))
 				continue;
-			memcpy(BufferGetPage(page->buffer), page->image, BLCKSZ);
+			memcpy(BufferGetPage(page->buffer, NULL, NULL,
+								 BGP_NO_SNAPSHOT_TEST), page->image, BLCKSZ);
 			MarkBufferDirty(page->buffer);
 		}
 		END_CRIT_SECTION();
@@ -413,7 +419,7 @@ generic_redo(XLogReaderState *record)
 			Size	blockDataSize;
 			Page	page;
 
-			page = BufferGetPage(buffers[block_id]);
+			page = BufferGetPage(buffers[block_id], NULL, NULL, BGP_NO_SNAPSHOT_TEST);
 			blockData = XLogRecGetBlockData(record, block_id, &blockDataSize);
 			applyPageRedo(page, blockData, blockDataSize);
 
diff --git a/src/backend/access/transam/xloginsert.c b/src/backend/access/transam/xloginsert.c
index c37003a24c2..1e336edfb59 100644
--- a/src/backend/access/transam/xloginsert.c
+++ b/src/backend/access/transam/xloginsert.c
@@ -228,7 +228,7 @@ XLogRegisterBuffer(uint8 block_id, Buffer buffer, uint8 flags)
 	regbuf = &registered_buffers[block_id];
 
 	BufferGetTag(buffer, &regbuf->rnode, &regbuf->forkno, &regbuf->block);
-	regbuf->page = BufferGetPage(buffer);
+	regbuf->page = BufferGetPage(buffer, NULL, NULL, BGP_NO_SNAPSHOT_TEST);
 	regbuf->flags = flags;
 	regbuf->rdata_tail = (XLogRecData *) &regbuf->rdata_head;
 	regbuf->rdata_len = 0;
@@ -825,7 +825,7 @@ XLogCheckBufferNeedsBackup(Buffer buffer)
 
 	GetFullPageWriteInfo(&RedoRecPtr, &doPageWrites);
 
-	page = BufferGetPage(buffer);
+	page = BufferGetPage(buffer, NULL, NULL, BGP_NO_SNAPSHOT_TEST);
 
 	if (doPageWrites && PageGetLSN(page) <= RedoRecPtr)
 		return true;			/* buffer requires backup */
@@ -896,7 +896,7 @@ XLogSaveBufferForHint(Buffer buffer, bool buffer_std)
 		if (buffer_std)
 		{
 			/* Assume we can omit data between pd_lower and pd_upper */
-			Page		page = BufferGetPage(buffer);
+			Page		page = BufferGetPage(buffer, NULL, NULL, BGP_NO_SNAPSHOT_TEST);
 			uint16		lower = ((PageHeader) page)->pd_lower;
 			uint16		upper = ((PageHeader) page)->pd_upper;
 
@@ -973,7 +973,7 @@ log_newpage(RelFileNode *rnode, ForkNumber forkNum, BlockNumber blkno,
 XLogRecPtr
 log_newpage_buffer(Buffer buffer, bool page_std)
 {
-	Page		page = BufferGetPage(buffer);
+	Page		page = BufferGetPage(buffer, NULL, NULL, BGP_NO_SNAPSHOT_TEST);
 	RelFileNode rnode;
 	ForkNumber	forkNum;
 	BlockNumber blkno;
diff --git a/src/backend/access/transam/xlogutils.c b/src/backend/access/transam/xlogutils.c
index f6ca2b95e51..c3213ac0b6f 100644
--- a/src/backend/access/transam/xlogutils.c
+++ b/src/backend/access/transam/xlogutils.c
@@ -358,7 +358,7 @@ XLogReadBufferForRedoExtended(XLogReaderState *record,
 	{
 		*buf = XLogReadBufferExtended(rnode, forknum, blkno,
 		   get_cleanup_lock ? RBM_ZERO_AND_CLEANUP_LOCK : RBM_ZERO_AND_LOCK);
-		page = BufferGetPage(*buf);
+		page = BufferGetPage(*buf, NULL, NULL, BGP_NO_SNAPSHOT_TEST);
 		if (!RestoreBlockImage(record, block_id, page))
 			elog(ERROR, "failed to restore block image");
 
@@ -396,7 +396,8 @@ XLogReadBufferForRedoExtended(XLogReaderState *record,
 				else
 					LockBuffer(*buf, BUFFER_LOCK_EXCLUSIVE);
 			}
-			if (lsn <= PageGetLSN(BufferGetPage(*buf)))
+			if (lsn <= PageGetLSN(BufferGetPage(*buf, NULL, NULL,
+												BGP_NO_SNAPSHOT_TEST)))
 				return BLK_DONE;
 			else
 				return BLK_NEEDS_REDO;
@@ -502,7 +503,8 @@ XLogReadBufferExtended(RelFileNode rnode, ForkNumber forknum,
 	if (mode == RBM_NORMAL)
 	{
 		/* check that page has been initialized */
-		Page		page = (Page) BufferGetPage(buffer);
+		Page		page = BufferGetPage(buffer, NULL, NULL,
+										 BGP_NO_SNAPSHOT_TEST);
 
 		/*
 		 * We assume that PageIsNew is safe without a lock. During recovery,