Re: Fix comments related to pending statistics

Hi,

On Wed, Dec 11, 2024 at 02:56:08PM +0900, Michael Paquier wrote:
> On Tue, Dec 10, 2024 at 02:16:14PM +0000, Bertrand Drouvot wrote:
> >
> > 2. One linked to PgStat_FunctionCounts pending stats, mentioning the use of
> > memcmp() against zeroes to detect whether there are any pending stats: I think
> > it has never been the case.
>
> * PgStat_FunctionCounts The actual per-function counts kept by a backend
> *
> - * This struct should contain only actual event counters, because we memcmp
> - * it against zeroes to detect whether there are any pending stats.
> + * This struct should contain only actual event counters, because pending stats
> + * always has non-zero content.
>
> pgstat_function_flush_cb() in pgstat_function.c says since
> 5891c7a8ed8f, so that seems like a remnant from the original patch
> that has introduced this inconsistency across its reviews:
> "/* localent always has non-zero content */"

Thanks for looking at it!

Yeah and same in pgstat_subscription_flush_cb().

> Your suggestion does not look completely right to me. There is
> nothing preventing us from using something else than event counters
> since we don't use memcpy() and there is no comparison work, no? It
> seems to me that we could remove the entire sentence instead.

Do you mean also remove the comments in pgstat_function_flush_cb() and
pgstat_subscription_flush_cb()? Those comments look fine to me given
the places where those pending entries are created meaning in
pgstat_init_function_usage() for the functions and pgstat_report_subscription_error()
and pgstat_report_subscription_conflict() for the subscriptions.

Regards,

--
Bertrand Drouvot
PostgreSQL Contributors Team
RDS Open Source Databases
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