HAVE_SPINLOCKS still requests exctra shared memory - Mailing list pgsql-hackers

From Kyotaro HORIGUCHI
Subject HAVE_SPINLOCKS still requests exctra shared memory
Date
Msg-id 20180215.200703.242189033.horiguchi.kyotaro@lab.ntt.co.jp
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Responses Re: HAVE_SPINLOCKS still requests exctra shared memory
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Hello.

As in another mail just before, spin.c seems a bit strange
(without acutual harm).

spin.h doesn't include pg_sema.h when HAVE_SPINLOCKS is defined,
but spin.c always includes it even in the case. The file is
included only to use sizeof(PGSemaphore) to calcualte
SpinlockSemaSize as 0.

The codes that requires PGSempaphore is inactivated when the
symbol is defined in all other places so it seems to me that we
ought to refrain from using it there, too. The attched patch does
that.

regards,

-- 
Kyotaro Horiguchi
NTT Open Source Software Center
diff --git a/src/backend/storage/lmgr/spin.c b/src/backend/storage/lmgr/spin.c
index 6d59a7f..353a3a9 100644
--- a/src/backend/storage/lmgr/spin.c
+++ b/src/backend/storage/lmgr/spin.c
@@ -22,13 +22,15 @@
  */
 #include "postgres.h"
 
-#include "storage/pg_sema.h"
 #include "storage/shmem.h"
 #include "storage/spin.h"
 
 
 #ifndef HAVE_SPINLOCKS
+#define RequredShmemSize (SpinlockSemas() * sizeof(PGSemaphore))
 PGSemaphore *SpinlockSemaArray;
+#else
+#define RequiredShmemSize 0
 #endif
 
 /*
@@ -38,7 +40,7 @@ PGSemaphore *SpinlockSemaArray;
 Size
 SpinlockSemaSize(void)
 {
-    return SpinlockSemas() * sizeof(PGSemaphore);
+    return RequiredShmemSize;
 }
 
 #ifdef HAVE_SPINLOCKS

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