Use XLogRecPtrIsValid() in various places

Now that commit 06edbed has introduced XLogRecPtrIsValid(), we can
use that instead of:

- XLogRecPtrIsInvalid()
- direct comparisons with InvalidXLogRecPtr
- direct comparisons with literal 0

This makes the code more consistent.

Author: Bertrand Drouvot <bertranddrouvot.pg@gmail.com>
Discussion: https://postgr.es/m/aQB7EvGqrbZXrMlg@ip-10-97-1-34.eu-west-3.compute.internal

Author: alvherre

contrib/pg_walinspect/pg_walinspect.c

@@ -83,7 +83,7 @@ GetCurrentLSN(void)
 	else
 		curr_lsn = GetXLogReplayRecPtr(NULL);
 
-	Assert(!XLogRecPtrIsInvalid(curr_lsn));
+	Assert(XLogRecPtrIsValid(curr_lsn));
 
 	return curr_lsn;
 }
@@ -127,7 +127,7 @@ InitXLogReaderState(XLogRecPtr lsn)
 	/* first find a valid recptr to start from */
 	first_valid_record = XLogFindNextRecord(xlogreader, lsn);
 
-	if (XLogRecPtrIsInvalid(first_valid_record))
+	if (!XLogRecPtrIsValid(first_valid_record))
 		ereport(ERROR,
 				errmsg("could not find a valid record after %X/%08X",
 					   LSN_FORMAT_ARGS(lsn)));

src/backend/access/gist/gist.c

@@ -682,7 +682,7 @@ gistdoinsert(Relation r, IndexTuple itup, Size freespace,
 			state.stack = stack = stack->parent;
 		}
 
-		if (XLogRecPtrIsInvalid(stack->lsn))
+		if (!XLogRecPtrIsValid(stack->lsn))
 			stack->buffer = ReadBuffer(state.r, stack->blkno);
 
 		/*
@@ -698,7 +698,7 @@ gistdoinsert(Relation r, IndexTuple itup, Size freespace,
 		stack->page = BufferGetPage(stack->buffer);
 		stack->lsn = xlocked ?
 			PageGetLSN(stack->page) : BufferGetLSNAtomic(stack->buffer);
-		Assert(!RelationNeedsWAL(state.r) || !XLogRecPtrIsInvalid(stack->lsn));
+		Assert(!RelationNeedsWAL(state.r) || XLogRecPtrIsValid(stack->lsn));
 
 		/*
 		 * If this page was split but the downlink was never inserted to the

src/backend/access/gist/gistget.c

@@ -46,7 +46,7 @@ gistkillitems(IndexScanDesc scan)
 	bool		killedsomething = false;
 
 	Assert(so->curBlkno != InvalidBlockNumber);
-	Assert(!XLogRecPtrIsInvalid(so->curPageLSN));
+	Assert(XLogRecPtrIsValid(so->curPageLSN));
 	Assert(so->killedItems != NULL);
 
 	buffer = ReadBuffer(scan->indexRelation, so->curBlkno);
@@ -353,7 +353,7 @@ gistScanPage(IndexScanDesc scan, GISTSearchItem *pageItem,
 	 * parentlsn < nsn), or if the system crashed after a page split but
 	 * before the downlink was inserted into the parent.
 	 */
-	if (!XLogRecPtrIsInvalid(pageItem->data.parentlsn) &&
+	if (XLogRecPtrIsValid(pageItem->data.parentlsn) &&
 		(GistFollowRight(page) ||
 		 pageItem->data.parentlsn < GistPageGetNSN(page)) &&
 		opaque->rightlink != InvalidBlockNumber /* sanity check */ )

src/backend/access/gist/gistutil.c

@@ -1040,7 +1040,7 @@ gistGetFakeLSN(Relation rel)
 		Assert(!RelationNeedsWAL(rel));
 
 		/* No need for an actual record if we already have a distinct LSN */
-		if (!XLogRecPtrIsInvalid(lastlsn) && lastlsn == currlsn)
+		if (XLogRecPtrIsValid(lastlsn) && lastlsn == currlsn)
 			currlsn = gistXLogAssignLSN();
 
 		lastlsn = currlsn;

src/backend/access/heap/rewriteheap.c

@@ -1169,7 +1169,7 @@ CheckPointLogicalRewriteHeap(void)
 	cutoff = ReplicationSlotsComputeLogicalRestartLSN();
 
 	/* don't start earlier than the restart lsn */
-	if (cutoff != InvalidXLogRecPtr && redo < cutoff)
+	if (XLogRecPtrIsValid(cutoff) && redo < cutoff)
 		cutoff = redo;
 
 	mappings_dir = AllocateDir(PG_LOGICAL_MAPPINGS_DIR);
@@ -1204,7 +1204,7 @@ CheckPointLogicalRewriteHeap(void)
 
 		lsn = ((uint64) hi) << 32 | lo;
 
-		if (lsn < cutoff || cutoff == InvalidXLogRecPtr)
+		if (lsn < cutoff || !XLogRecPtrIsValid(cutoff))
 		{
 			elog(DEBUG1, "removing logical rewrite file \"%s\"", path);
 			if (unlink(path) < 0)

src/backend/access/heap/vacuumlazy.c

@@ -1901,7 +1901,7 @@ lazy_scan_new_or_empty(LVRelState *vacrel, Buffer buf, BlockNumber blkno,
 			 * WAL-logged, and if not, do that now.
 			 */
 			if (RelationNeedsWAL(vacrel->rel) &&
-				PageGetLSN(page) == InvalidXLogRecPtr)
+				!XLogRecPtrIsValid(PageGetLSN(page)))
 				log_newpage_buffer(buf, true);
 
 			PageSetAllVisible(page);

src/backend/access/heap/visibilitymap.c

@@ -260,7 +260,7 @@ visibilitymap_set(Relation rel, BlockNumber heapBlk, Buffer heapBuf,
 		 flags, RelationGetRelationName(rel), heapBlk);
 #endif
 
-	Assert(InRecovery || XLogRecPtrIsInvalid(recptr));
+	Assert(InRecovery || !XLogRecPtrIsValid(recptr));
 	Assert(InRecovery || PageIsAllVisible(BufferGetPage(heapBuf)));
 	Assert((flags & VISIBILITYMAP_VALID_BITS) == flags);
 
@@ -292,7 +292,7 @@ visibilitymap_set(Relation rel, BlockNumber heapBlk, Buffer heapBuf,
 
 		if (RelationNeedsWAL(rel))
 		{
-			if (XLogRecPtrIsInvalid(recptr))
+			if (!XLogRecPtrIsValid(recptr))
 			{
 				Assert(!InRecovery);
 				recptr = log_heap_visible(rel, heapBuf, vmBuf, cutoff_xid, flags);

src/backend/access/transam/clog.c

@@ -381,7 +381,8 @@ TransactionIdSetPageStatusInternal(TransactionId xid, int nsubxids,
 	 * write-busy, since we don't care if the update reaches disk sooner than
 	 * we think.
 	 */
-	slotno = SimpleLruReadPage(XactCtl, pageno, XLogRecPtrIsInvalid(lsn), xid);
+	slotno = SimpleLruReadPage(XactCtl, pageno, !XLogRecPtrIsValid(lsn),
+							   xid);
 
 	/*
 	 * Set the main transaction id, if any.
@@ -705,7 +706,7 @@ TransactionIdSetStatusBit(TransactionId xid, XidStatus status, XLogRecPtr lsn, i
 	 * recovery. After recovery completes the next clog change will set the
 	 * LSN correctly.
 	 */
-	if (!XLogRecPtrIsInvalid(lsn))
+	if (XLogRecPtrIsValid(lsn))
 	{
 		int			lsnindex = GetLSNIndex(slotno, xid);
 

src/backend/access/transam/slru.c

@@ -937,7 +937,7 @@ SlruPhysicalWritePage(SlruCtl ctl, int64 pageno, int slotno, SlruWriteAll fdata)
 				max_lsn = this_lsn;
 		}
 
-		if (!XLogRecPtrIsInvalid(max_lsn))
+		if (XLogRecPtrIsValid(max_lsn))
 		{
 			/*
 			 * As noted above, elog(ERROR) is not acceptable here, so if

src/backend/access/transam/timeline.c

@@ -549,8 +549,8 @@ tliOfPointInHistory(XLogRecPtr ptr, List *history)
 	{
 		TimeLineHistoryEntry *tle = (TimeLineHistoryEntry *) lfirst(cell);
 
-		if ((XLogRecPtrIsInvalid(tle->begin) || tle->begin <= ptr) &&
-			(XLogRecPtrIsInvalid(tle->end) || ptr < tle->end))
+		if ((!XLogRecPtrIsValid(tle->begin) || tle->begin <= ptr) &&
+			(!XLogRecPtrIsValid(tle->end) || ptr < tle->end))
 		{
 			/* found it */
 			return tle->tli;