Revert no-op changes to BufferGetPage()

The reverted changes were intended to force a choice of whether any
newly-added BufferGetPage() calls needed to be accompanied by a
test of the snapshot age, to support the "snapshot too old"
feature.  Such an accompanying test is needed in about 7% of the
cases, where the page is being used as part of a scan rather than
positioning for other purposes (such as DML or vacuuming).  The
additional effort required for back-patching, and the doubt whether
the intended benefit would really be there, have indicated it is
best just to rely on developers to do the right thing based on
comments and existing usage, as we do with many other conventions.

This change should have little or no effect on generated executable
code.

Motivated by the back-patching pain of Tom Lane and Robert Haas

1 files changed, 57 insertions, 71 deletions

diff --git a/src/backend/access/heap/heapam.c b/src/backend/access/heap/heapam.c
index 29fd31a819d..950bfc8e364 100644
--- a/src/backend/access/heap/heapam.c
+++ b/src/backend/access/heap/heapam.c
@@ -394,8 +394,8 @@ heapgetpage(HeapScanDesc scan, BlockNumber page)
 	 */
 	LockBuffer(buffer, BUFFER_LOCK_SHARE);
 
-	dp = BufferGetPage(buffer, snapshot, scan->rs_rd,
-					   BGP_TEST_FOR_OLD_SNAPSHOT);
+	dp = BufferGetPage(buffer);
+	TestForOldSnapshot(snapshot, scan->rs_rd, dp);
 	lines = PageGetMaxOffsetNumber(dp);
 	ntup = 0;
 
@@ -538,7 +538,8 @@ heapgettup(HeapScanDesc scan,
 
 		LockBuffer(scan->rs_cbuf, BUFFER_LOCK_SHARE);
 
-		dp = BufferGetPage(scan->rs_cbuf, snapshot, scan->rs_rd, BGP_TEST_FOR_OLD_SNAPSHOT);
+		dp = BufferGetPage(scan->rs_cbuf);
+		TestForOldSnapshot(snapshot, scan->rs_rd, dp);
 		lines = PageGetMaxOffsetNumber(dp);
 		/* page and lineoff now reference the physically next tid */
 
@@ -583,8 +584,8 @@ heapgettup(HeapScanDesc scan,
 
 		LockBuffer(scan->rs_cbuf, BUFFER_LOCK_SHARE);
 
-		dp = BufferGetPage(scan->rs_cbuf, snapshot, scan->rs_rd,
-						   BGP_TEST_FOR_OLD_SNAPSHOT);
+		dp = BufferGetPage(scan->rs_cbuf);
+		TestForOldSnapshot(snapshot, scan->rs_rd, dp);
 		lines = PageGetMaxOffsetNumber(dp);
 
 		if (!scan->rs_inited)
@@ -618,8 +619,8 @@ heapgettup(HeapScanDesc scan,
 			heapgetpage(scan, page);
 
 		/* Since the tuple was previously fetched, needn't lock page here */
-		dp = BufferGetPage(scan->rs_cbuf, snapshot, scan->rs_rd,
-						   BGP_TEST_FOR_OLD_SNAPSHOT);
+		dp = BufferGetPage(scan->rs_cbuf);
+		TestForOldSnapshot(snapshot, scan->rs_rd, dp);
 		lineoff = ItemPointerGetOffsetNumber(&(tuple->t_self));
 		lpp = PageGetItemId(dp, lineoff);
 		Assert(ItemIdIsNormal(lpp));
@@ -748,8 +749,8 @@ heapgettup(HeapScanDesc scan,
 
 		LockBuffer(scan->rs_cbuf, BUFFER_LOCK_SHARE);
 
-		dp = BufferGetPage(scan->rs_cbuf, snapshot, scan->rs_rd,
-						   BGP_TEST_FOR_OLD_SNAPSHOT);
+		dp = BufferGetPage(scan->rs_cbuf);
+		TestForOldSnapshot(snapshot, scan->rs_rd, dp);
 		lines = PageGetMaxOffsetNumber((Page) dp);
 		linesleft = lines;
 		if (backward)
@@ -836,8 +837,8 @@ heapgettup_pagemode(HeapScanDesc scan,
 			lineindex = scan->rs_cindex + 1;
 		}
 
-		dp = BufferGetPage(scan->rs_cbuf, scan->rs_snapshot, scan->rs_rd,
-						   BGP_TEST_FOR_OLD_SNAPSHOT);
+		dp = BufferGetPage(scan->rs_cbuf);
+		TestForOldSnapshot(scan->rs_snapshot, scan->rs_rd, dp);
 		lines = scan->rs_ntuples;
 		/* page and lineindex now reference the next visible tid */
 
@@ -880,8 +881,8 @@ heapgettup_pagemode(HeapScanDesc scan,
 			page = scan->rs_cblock;		/* current page */
 		}
 
-		dp = BufferGetPage(scan->rs_cbuf, scan->rs_snapshot, scan->rs_rd,
-						   BGP_TEST_FOR_OLD_SNAPSHOT);
+		dp = BufferGetPage(scan->rs_cbuf);
+		TestForOldSnapshot(scan->rs_snapshot, scan->rs_rd, dp);
 		lines = scan->rs_ntuples;
 
 		if (!scan->rs_inited)
@@ -914,8 +915,8 @@ heapgettup_pagemode(HeapScanDesc scan,
 			heapgetpage(scan, page);
 
 		/* Since the tuple was previously fetched, needn't lock page here */
-		dp = BufferGetPage(scan->rs_cbuf, scan->rs_snapshot, scan->rs_rd,
-						   BGP_TEST_FOR_OLD_SNAPSHOT);
+		dp = BufferGetPage(scan->rs_cbuf);
+		TestForOldSnapshot(scan->rs_snapshot, scan->rs_rd, dp);
 		lineoff = ItemPointerGetOffsetNumber(&(tuple->t_self));
 		lpp = PageGetItemId(dp, lineoff);
 		Assert(ItemIdIsNormal(lpp));
@@ -1034,8 +1035,8 @@ heapgettup_pagemode(HeapScanDesc scan,
 
 		heapgetpage(scan, page);
 
-		dp = BufferGetPage(scan->rs_cbuf, scan->rs_snapshot, scan->rs_rd,
-						   BGP_TEST_FOR_OLD_SNAPSHOT);
+		dp = BufferGetPage(scan->rs_cbuf);
+		TestForOldSnapshot(scan->rs_snapshot, scan->rs_rd, dp);
 		lines = scan->rs_ntuples;
 		linesleft = lines;
 		if (backward)
@@ -1879,7 +1880,8 @@ heap_fetch(Relation relation,
 	 * Need share lock on buffer to examine tuple commit status.
 	 */
 	LockBuffer(buffer, BUFFER_LOCK_SHARE);
-	page = BufferGetPage(buffer, snapshot, relation, BGP_TEST_FOR_OLD_SNAPSHOT);
+	page = BufferGetPage(buffer);
+	TestForOldSnapshot(snapshot, relation, page);
 
 	/*
 	 * We'd better check for out-of-range offnum in case of VACUUM since the
@@ -1994,7 +1996,7 @@ heap_hot_search_buffer(ItemPointer tid, Relation relation, Buffer buffer,
 					   Snapshot snapshot, HeapTuple heapTuple,
 					   bool *all_dead, bool first_call)
 {
-	Page		dp = BufferGetPage(buffer, NULL, NULL, BGP_NO_SNAPSHOT_TEST);
+	Page		dp = (Page) BufferGetPage(buffer);
 	TransactionId prev_xmax = InvalidTransactionId;
 	OffsetNumber offnum;
 	bool		at_chain_start;
@@ -2208,8 +2210,8 @@ heap_get_latest_tid(Relation relation,
 		 */
 		buffer = ReadBuffer(relation, ItemPointerGetBlockNumber(&ctid));
 		LockBuffer(buffer, BUFFER_LOCK_SHARE);
-		page = BufferGetPage(buffer, snapshot, relation,
-							 BGP_TEST_FOR_OLD_SNAPSHOT);
+		page = BufferGetPage(buffer);
+		TestForOldSnapshot(snapshot, relation, page);
 
 		/*
 		 * Check for bogus item number.  This is not treated as an error
@@ -2427,12 +2429,10 @@ heap_insert(Relation relation, HeapTuple tup, CommandId cid,
 	RelationPutHeapTuple(relation, buffer, heaptup,
 						 (options & HEAP_INSERT_SPECULATIVE) != 0);
 
-	if (PageIsAllVisible(BufferGetPage(buffer, NULL, NULL,
-									   BGP_NO_SNAPSHOT_TEST)))
+	if (PageIsAllVisible(BufferGetPage(buffer)))
 	{
 		all_visible_cleared = true;
-		PageClearAllVisible(BufferGetPage(buffer, NULL, NULL,
-										  BGP_NO_SNAPSHOT_TEST));
+		PageClearAllVisible(BufferGetPage(buffer));
 		visibilitymap_clear(relation,
 							ItemPointerGetBlockNumber(&(heaptup->t_self)),
 							vmbuffer);
@@ -2457,8 +2457,7 @@ heap_insert(Relation relation, HeapTuple tup, CommandId cid,
 		xl_heap_insert xlrec;
 		xl_heap_header xlhdr;
 		XLogRecPtr	recptr;
-		Page		page = BufferGetPage(buffer, NULL, NULL,
-										 BGP_NO_SNAPSHOT_TEST);
+		Page		page = BufferGetPage(buffer);
 		uint8		info = XLOG_HEAP_INSERT;
 		int			bufflags = 0;
 
@@ -2717,7 +2716,7 @@ heap_multi_insert(Relation relation, HeapTuple *tuples, int ntuples,
 		buffer = RelationGetBufferForTuple(relation, heaptuples[ndone]->t_len,
 										   InvalidBuffer, options, bistate,
 										   &vmbuffer, NULL);
-		page = BufferGetPage(buffer, NULL, NULL, BGP_NO_SNAPSHOT_TEST);
+		page = BufferGetPage(buffer);
 
 		/* NO EREPORT(ERROR) from here till changes are logged */
 		START_CRIT_SECTION();
@@ -3031,7 +3030,7 @@ heap_delete(Relation relation, ItemPointer tid,
 
 	block = ItemPointerGetBlockNumber(tid);
 	buffer = ReadBuffer(relation, block);
-	page = BufferGetPage(buffer, NULL, NULL, BGP_NO_SNAPSHOT_TEST);
+	page = BufferGetPage(buffer);
 
 	/*
 	 * Before locking the buffer, pin the visibility map page if it appears to
@@ -3521,7 +3520,7 @@ heap_update(Relation relation, ItemPointer otid, HeapTuple newtup,
 
 	block = ItemPointerGetBlockNumber(otid);
 	buffer = ReadBuffer(relation, block);
-	page = BufferGetPage(buffer, NULL, NULL, BGP_NO_SNAPSHOT_TEST);
+	page = BufferGetPage(buffer);
 
 	/*
 	 * Before locking the buffer, pin the visibility map page if it appears to
@@ -4122,22 +4121,17 @@ l2:
 	oldtup.t_data->t_ctid = heaptup->t_self;
 
 	/* clear PD_ALL_VISIBLE flags */
-	if (PageIsAllVisible(BufferGetPage(buffer, NULL, NULL,
-									   BGP_NO_SNAPSHOT_TEST)))
+	if (PageIsAllVisible(BufferGetPage(buffer)))
 	{
 		all_visible_cleared = true;
-		PageClearAllVisible(BufferGetPage(buffer, NULL, NULL,
-										  BGP_NO_SNAPSHOT_TEST));
+		PageClearAllVisible(BufferGetPage(buffer));
 		visibilitymap_clear(relation, BufferGetBlockNumber(buffer),
 							vmbuffer);
 	}
-	if (newbuf != buffer &&
-		PageIsAllVisible(BufferGetPage(newbuf, NULL, NULL,
-									   BGP_NO_SNAPSHOT_TEST)))
+	if (newbuf != buffer && PageIsAllVisible(BufferGetPage(newbuf)))
 	{
 		all_visible_cleared_new = true;
-		PageClearAllVisible(BufferGetPage(newbuf, NULL, NULL,
-										  BGP_NO_SNAPSHOT_TEST));
+		PageClearAllVisible(BufferGetPage(newbuf));
 		visibilitymap_clear(relation, BufferGetBlockNumber(newbuf),
 							vmbuffer_new);
 	}
@@ -4168,12 +4162,9 @@ l2:
 								 all_visible_cleared_new);
 		if (newbuf != buffer)
 		{
-			PageSetLSN(BufferGetPage(newbuf, NULL, NULL,
-									 BGP_NO_SNAPSHOT_TEST),
-					   recptr);
+			PageSetLSN(BufferGetPage(newbuf), recptr);
 		}
-		PageSetLSN(BufferGetPage(buffer, NULL, NULL, BGP_NO_SNAPSHOT_TEST),
-				   recptr);
+		PageSetLSN(BufferGetPage(buffer), recptr);
 	}
 
 	END_CRIT_SECTION();
@@ -4537,7 +4528,7 @@ heap_lock_tuple(Relation relation, HeapTuple tuple,
 	*buffer = ReadBuffer(relation, ItemPointerGetBlockNumber(tid));
 	LockBuffer(*buffer, BUFFER_LOCK_EXCLUSIVE);
 
-	page = BufferGetPage(*buffer, NULL, NULL, BGP_NO_SNAPSHOT_TEST);
+	page = BufferGetPage(*buffer);
 	lp = PageGetItemId(page, ItemPointerGetOffsetNumber(tid));
 	Assert(ItemIdIsNormal(lp));
 
@@ -5715,8 +5706,7 @@ l4:
 		{
 			xl_heap_lock_updated xlrec;
 			XLogRecPtr	recptr;
-			Page		page = BufferGetPage(buf, NULL, NULL,
-											 BGP_NO_SNAPSHOT_TEST);
+			Page		page = BufferGetPage(buf);
 
 			XLogBeginInsert();
 			XLogRegisterBuffer(0, buf, REGBUF_STANDARD);
@@ -5823,7 +5813,7 @@ heap_finish_speculative(Relation relation, HeapTuple tuple)
 
 	buffer = ReadBuffer(relation, ItemPointerGetBlockNumber(&(tuple->t_self)));
 	LockBuffer(buffer, BUFFER_LOCK_EXCLUSIVE);
-	page = BufferGetPage(buffer, NULL, NULL, BGP_NO_SNAPSHOT_TEST);
+	page = (Page) BufferGetPage(buffer);
 
 	offnum = ItemPointerGetOffsetNumber(&(tuple->t_self));
 	if (PageGetMaxOffsetNumber(page) >= offnum)
@@ -5917,7 +5907,7 @@ heap_abort_speculative(Relation relation, HeapTuple tuple)
 
 	block = ItemPointerGetBlockNumber(tid);
 	buffer = ReadBuffer(relation, block);
-	page = BufferGetPage(buffer, NULL, NULL, BGP_NO_SNAPSHOT_TEST);
+	page = BufferGetPage(buffer);
 
 	LockBuffer(buffer, BUFFER_LOCK_EXCLUSIVE);
 
@@ -6064,7 +6054,7 @@ heap_inplace_update(Relation relation, HeapTuple tuple)
 
 	buffer = ReadBuffer(relation, ItemPointerGetBlockNumber(&(tuple->t_self)));
 	LockBuffer(buffer, BUFFER_LOCK_EXCLUSIVE);
-	page = BufferGetPage(buffer, NULL, NULL, BGP_NO_SNAPSHOT_TEST);
+	page = (Page) BufferGetPage(buffer);
 
 	offnum = ItemPointerGetOffsetNumber(&(tuple->t_self));
 	if (PageGetMaxOffsetNumber(page) >= offnum)
@@ -7319,8 +7309,7 @@ log_heap_update(Relation reln, Buffer oldbuf,
 	uint16		prefixlen = 0,
 				suffixlen = 0;
 	XLogRecPtr	recptr;
-	Page		page = BufferGetPage(newbuf, NULL, NULL,
-									 BGP_NO_SNAPSHOT_TEST);
+	Page		page = BufferGetPage(newbuf);
 	bool		need_tuple_data = RelationIsLogicallyLogged(reln);
 	bool		init;
 	int			bufflags;
@@ -7769,8 +7758,7 @@ heap_xlog_clean(XLogReaderState *record)
 										   &buffer);
 	if (action == BLK_NEEDS_REDO)
 	{
-		Page		page = BufferGetPage(buffer, NULL, NULL,
-										 BGP_NO_SNAPSHOT_TEST);
+		Page		page = (Page) BufferGetPage(buffer);
 		OffsetNumber *end;
 		OffsetNumber *redirected;
 		OffsetNumber *nowdead;
@@ -7876,7 +7864,7 @@ heap_xlog_visible(XLogReaderState *record)
 		 * XLOG record's LSN, we mustn't mark the page all-visible, because
 		 * the subsequent update won't be replayed to clear the flag.
 		 */
-		page = BufferGetPage(buffer, NULL, NULL, BGP_NO_SNAPSHOT_TEST);
+		page = BufferGetPage(buffer);
 
 		PageSetAllVisible(page);
 
@@ -7902,8 +7890,7 @@ heap_xlog_visible(XLogReaderState *record)
 	if (XLogReadBufferForRedoExtended(record, 0, RBM_ZERO_ON_ERROR, false,
 									  &vmbuffer) == BLK_NEEDS_REDO)
 	{
-		Page		vmpage = BufferGetPage(vmbuffer, NULL, NULL,
-										   BGP_NO_SNAPSHOT_TEST);
+		Page		vmpage = BufferGetPage(vmbuffer);
 		Relation	reln;
 
 		/* initialize the page if it was read as zeros */
@@ -7970,8 +7957,7 @@ heap_xlog_freeze_page(XLogReaderState *record)
 
 	if (XLogReadBufferForRedo(record, 0, &buffer) == BLK_NEEDS_REDO)
 	{
-		Page		page = BufferGetPage(buffer, NULL, NULL,
-										 BGP_NO_SNAPSHOT_TEST);
+		Page		page = BufferGetPage(buffer);
 		xl_heap_freeze_tuple *tuples;
 
 		tuples = (xl_heap_freeze_tuple *) XLogRecGetBlockData(record, 0, NULL);
@@ -8058,7 +8044,7 @@ heap_xlog_delete(XLogReaderState *record)
 
 	if (XLogReadBufferForRedo(record, 0, &buffer) == BLK_NEEDS_REDO)
 	{
-		page = BufferGetPage(buffer, NULL, NULL, BGP_NO_SNAPSHOT_TEST);
+		page = BufferGetPage(buffer);
 
 		if (PageGetMaxOffsetNumber(page) >= xlrec->offnum)
 			lp = PageGetItemId(page, xlrec->offnum);
@@ -8141,7 +8127,7 @@ heap_xlog_insert(XLogReaderState *record)
 	if (XLogRecGetInfo(record) & XLOG_HEAP_INIT_PAGE)
 	{
 		buffer = XLogInitBufferForRedo(record, 0);
-		page = BufferGetPage(buffer, NULL, NULL, BGP_NO_SNAPSHOT_TEST);
+		page = BufferGetPage(buffer);
 		PageInit(page, BufferGetPageSize(buffer), 0);
 		action = BLK_NEEDS_REDO;
 	}
@@ -8152,7 +8138,7 @@ heap_xlog_insert(XLogReaderState *record)
 		Size		datalen;
 		char	   *data;
 
-		page = BufferGetPage(buffer, NULL, NULL, BGP_NO_SNAPSHOT_TEST);
+		page = BufferGetPage(buffer);
 
 		if (PageGetMaxOffsetNumber(page) + 1 < xlrec->offnum)
 			elog(PANIC, "invalid max offset number");
@@ -8257,7 +8243,7 @@ heap_xlog_multi_insert(XLogReaderState *record)
 	if (isinit)
 	{
 		buffer = XLogInitBufferForRedo(record, 0);
-		page = BufferGetPage(buffer, NULL, NULL, BGP_NO_SNAPSHOT_TEST);
+		page = BufferGetPage(buffer);
 		PageInit(page, BufferGetPageSize(buffer), 0);
 		action = BLK_NEEDS_REDO;
 	}
@@ -8273,7 +8259,7 @@ heap_xlog_multi_insert(XLogReaderState *record)
 		tupdata = XLogRecGetBlockData(record, 0, &len);
 		endptr = tupdata + len;
 
-		page = BufferGetPage(buffer, NULL, NULL, BGP_NO_SNAPSHOT_TEST);
+		page = (Page) BufferGetPage(buffer);
 
 		for (i = 0; i < xlrec->ntuples; i++)
 		{
@@ -8424,7 +8410,7 @@ heap_xlog_update(XLogReaderState *record, bool hot_update)
 									  &obuffer);
 	if (oldaction == BLK_NEEDS_REDO)
 	{
-		page = BufferGetPage(obuffer, NULL, NULL, BGP_NO_SNAPSHOT_TEST);
+		page = BufferGetPage(obuffer);
 		offnum = xlrec->old_offnum;
 		if (PageGetMaxOffsetNumber(page) >= offnum)
 			lp = PageGetItemId(page, offnum);
@@ -8471,7 +8457,7 @@ heap_xlog_update(XLogReaderState *record, bool hot_update)
 	else if (XLogRecGetInfo(record) & XLOG_HEAP_INIT_PAGE)
 	{
 		nbuffer = XLogInitBufferForRedo(record, 0);
-		page = BufferGetPage(nbuffer, NULL, NULL, BGP_NO_SNAPSHOT_TEST);
+		page = (Page) BufferGetPage(nbuffer);
 		PageInit(page, BufferGetPageSize(nbuffer), 0);
 		newaction = BLK_NEEDS_REDO;
 	}
@@ -8504,7 +8490,7 @@ heap_xlog_update(XLogReaderState *record, bool hot_update)
 		recdata = XLogRecGetBlockData(record, 0, &datalen);
 		recdata_end = recdata + datalen;
 
-		page = BufferGetPage(nbuffer, NULL, NULL, BGP_NO_SNAPSHOT_TEST);
+		page = BufferGetPage(nbuffer);
 
 		offnum = xlrec->new_offnum;
 		if (PageGetMaxOffsetNumber(page) + 1 < offnum)
@@ -8634,7 +8620,7 @@ heap_xlog_confirm(XLogReaderState *record)
 
 	if (XLogReadBufferForRedo(record, 0, &buffer) == BLK_NEEDS_REDO)
 	{
-		page = BufferGetPage(buffer, NULL, NULL, BGP_NO_SNAPSHOT_TEST);
+		page = BufferGetPage(buffer);
 
 		offnum = xlrec->offnum;
 		if (PageGetMaxOffsetNumber(page) >= offnum)
@@ -8670,7 +8656,7 @@ heap_xlog_lock(XLogReaderState *record)
 
 	if (XLogReadBufferForRedo(record, 0, &buffer) == BLK_NEEDS_REDO)
 	{
-		page = BufferGetPage(buffer, NULL, NULL, BGP_NO_SNAPSHOT_TEST);
+		page = (Page) BufferGetPage(buffer);
 
 		offnum = xlrec->offnum;
 		if (PageGetMaxOffsetNumber(page) >= offnum)
@@ -8720,7 +8706,7 @@ heap_xlog_lock_updated(XLogReaderState *record)
 
 	if (XLogReadBufferForRedo(record, 0, &buffer) == BLK_NEEDS_REDO)
 	{
-		page = BufferGetPage(buffer, NULL, NULL, BGP_NO_SNAPSHOT_TEST);
+		page = BufferGetPage(buffer);
 
 		offnum = xlrec->offnum;
 		if (PageGetMaxOffsetNumber(page) >= offnum)
@@ -8759,7 +8745,7 @@ heap_xlog_inplace(XLogReaderState *record)
 	{
 		char	   *newtup = XLogRecGetBlockData(record, 0, &newlen);
 
-		page = BufferGetPage(buffer, NULL, NULL, BGP_NO_SNAPSHOT_TEST);
+		page = BufferGetPage(buffer);
 
 		offnum = xlrec->offnum;
 		if (PageGetMaxOffsetNumber(page) >= offnum)