From: | Neil Conway <neilc(at)samurai(dot)com> |
---|---|
To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
Cc: | pgsql-committers(at)postgresql(dot)org |
Subject: | Re: pgsql: Do all accesses to shared buffer headers |
Date: | 2005-10-12 23:36:30 |
Message-ID: | 1129160190.8718.32.camel@localhost.localdomain |
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Lists: | pgsql-committers pgsql-hackers |
On Wed, 2005-12-10 at 18:54 -0400, Tom Lane wrote:
> How would a typedef make it safer? I see no particular difference
> between omitting the "volatile" and choosing the wrong typedef.
IMHO it is notationally clearer to define a "BufferDescPtr" that
contains the "volatile" qualifier than to make sure that "volatile" is
used everywhere that it is needed -- obviously, neither approach is
fool-proof. But perhaps that's just me...
> We do however have here a New Coding Rule that's good for all parts
> of the backend: if you are accessing a spinlock-protected data structure
> then you should be using a volatile-qualified pointer for it.
I think this is worth documenting more clearly (I realize you added a
note in buf_internals.h, but perhaps a note in the spinlock headers
would be appropriate as well? The comment circa line 49 of s_lock.h
seems to need updating, for example.)
-Neil
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