remove volatile qualifiers from pg_stat_statements

Hi,

On Tue, Jul 30, 2024 at 01:24:54PM -0500, Nathan Bossart wrote:

While looking into converting pgssEntry->mutex to an LWLock (per a
suggestion elsewhere [0]), I noticed that pg_stat_statements uses
"volatile" quite liberally. IIUC we can remove these as of commit 0709b7e
(like commits 8f6bb85, df4077c, and 6ba4ecb did in other areas). All of
the uses in pg_stat_statements except those added by commit 9fbc3f3 predate
that commit (0709b7e), and I assume commit 9fbc3f3 was just following the
examples in surrounding code.

Am I missing something? Or can we remove these qualifiers now?

I share the same understanding and I think those can be removed.

The patch LGTM.

Regards,

--
Bertrand Drouvot
PostgreSQL Contributors Team
RDS Open Source Databases
Amazon Web Services: https://aws.amazon.com

On Wed, Jul 31, 2024 at 07:01:38AM +0000, Bertrand Drouvot wrote:

I share the same understanding and I think those can be removed.

The patch LGTM.

That sounds about right. All the volatile references we have here
have been kept under the assumption that a memory barrier is required.
As we hold spin locks in these areas, that should not be necessary
anyway. So LGTM as well.

A quick lookup at the rest of contrib/ is showing me that the
remaining volatile references point at uses with TRY/CATCH blocks,
where we require them.
--
Michael

On Tue, Aug 06, 2024 at 04:04:01PM +0900, Michael Paquier wrote:

On Wed, Jul 31, 2024 at 07:01:38AM +0000, Bertrand Drouvot wrote:

I share the same understanding and I think those can be removed.

The patch LGTM.

That sounds about right. All the volatile references we have here
have been kept under the assumption that a memory barrier is required.
As we hold spin locks in these areas, that should not be necessary
anyway. So LGTM as well.

Committed, thanks.

--
nathan