On 16.08.22 15:50, Tom Lane wrote:
Peter Eisentraut <peter.eisentr...@enterprisedb.com> writes:
Looking to tidy up c.h a bit, I think the NON_EXEC_STATIC #define
doesn't need to be known globally, and it's not related to establishing
a portable C environment, so I propose to move it to a more localized
header, such as postmaster.h, as in the attached patch.
Hmm, postgres.h seems like a better choice, since in principle any
backend file might need this. This arrangement could require
postmaster.h to be included just for this macro.
I picked postmaster.h because the other side of the code, where the
no-longer-static symbols are used, is in postmaster.c. But postgres.h
is also ok.
Also, the macro was severely underdocumented already, and I don't
find "no comment at all" to be better. Can't we afford a couple
of lines of explanation?
Here is a new patch with more comments.
From 06f30dcf46ed4f89e0c9c5e67615a5c9ad492988 Mon Sep 17 00:00:00 2001
From: Peter Eisentraut <pe...@eisentraut.org>
Date: Tue, 23 Aug 2022 20:24:21 +0200
Subject: [PATCH v2] Move NON_EXEC_STATIC from c.h to postgres.h
It is not needed at the scope of c.h, only in backend code.
Discussion:
https://www.postgresql.org/message-id/flat/a6a6b48e-ca0a-b58d-18de-98e40d94b842%40enterprisedb.com
---
src/include/c.h | 7 -------
src/include/postgres.h | 20 ++++++++++++++++++++
2 files changed, 20 insertions(+), 7 deletions(-)
diff --git a/src/include/c.h b/src/include/c.h
index dfc366b026..aad9554de6 100644
--- a/src/include/c.h
+++ b/src/include/c.h
@@ -1338,13 +1338,6 @@ typedef intptr_t sigjmp_buf[5];
#endif /* __MINGW64__ */
#endif /* WIN32 */
-/* EXEC_BACKEND defines */
-#ifdef EXEC_BACKEND
-#define NON_EXEC_STATIC
-#else
-#define NON_EXEC_STATIC static
-#endif
-
/* /port compatibility functions */
#include "port.h"
diff --git a/src/include/postgres.h b/src/include/postgres.h
index 31358110dc..13903fa022 100644
--- a/src/include/postgres.h
+++ b/src/include/postgres.h
@@ -25,6 +25,7 @@
* ------- ------------------------------------------------
* 1) variable-length datatypes (TOAST support)
* 2) Datum type + support macros
+ * 3) miscellaneous
*
* NOTES
*
@@ -805,4 +806,23 @@ extern Datum Float8GetDatum(float8 X);
#define Float8GetDatumFast(X) PointerGetDatum(&(X))
#endif
+
+/* ----------------------------------------------------------------
+ * Section 3: miscellaneous
+ * ----------------------------------------------------------------
+ */
+
+/*
+ * NON_EXEC_STATIC: It's sometimes useful to define a variable or function
+ * that is normally static but extern when using EXEC_BACKEND (see
+ * pg_config_manual.h). There would then typically be some code in
+ * postmaster.c that uses those extern symbols to transfer state between
+ * processes or do whatever other things it needs to do in EXEC_BACKEND mode.
+ */
+#ifdef EXEC_BACKEND
+#define NON_EXEC_STATIC
+#else
+#define NON_EXEC_STATIC static
+#endif
+
#endif /* POSTGRES_H */
--
2.37.1
