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 0940b64ca6bef63956d1863885d9781088e99723..aeb4a31732423ccfaef4b11ef647f60fc5e4e5ac 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)
 
 /*