Introduce XLogRecPtrIsValid()

XLogRecPtrIsInvalid() is inconsistent with the affirmative form of
macros used for other datatypes, and leads to awkward double negatives
in a few places.  This commit introduces XLogRecPtrIsValid(), which
allows code to be written more naturally.

This patch only adds the new macro.  XLogRecPtrIsInvalid() is left in
place, and all existing callers remain untouched.  This means all
supported branches can accept hypothetical bug fixes that use the new
macro, and at the same time any code that compiled with the original
formulation will continue to silently compile just fine.

Author: Bertrand Drouvot <bertranddrouvot.pg@gmail.com>
Backpatch-through: 13
Discussion: https://postgr.es/m/aQB7EvGqrbZXrMlg@ip-10-97-1-34.eu-west-3.compute.internal

diff --git a/src/include/access/xlogdefs.h b/src/include/access/xlogdefs.h
index 2397fb2411530159fda443b6c4e1d48e718177b6..5f07e57c8329b11a9d42a026f771ddcc9336b62e 100644 (file)
--- a/src/include/access/xlogdefs.h
+++ b/src/include/access/xlogdefs.h
@@ -25,7 +25,8 @@ typedef uint64 XLogRecPtr;
  * WAL segment, initializing the first WAL page at WAL segment size, so no XLOG
  * record can begin at zero.
  */
-#define InvalidXLogRecPtr      0
+#define InvalidXLogRecPtr              0
+#define XLogRecPtrIsValid(r)   ((r) != InvalidXLogRecPtr)
 #define XLogRecPtrIsInvalid(r) ((r) == InvalidXLogRecPtr)
 
 /*