Date: Mon, 17 Oct 2022 17:26:42 +0900 (JST)
Message-Id: <20221017.172642.45253962719866795.horikyota.ntt@gmail.com>
To: kuroda.hayato@fujitsu.com
Cc: onderkalaci@gmail.com, andres@anarazel.de, masao.fujii@oss.nttdata.com,
 pgsql-hackers@lists.postgresql.org, Shinya11.Kato@oss.nttdata.com,
 zyu@yugabyte.com
Subject: Re: [Proposal] Add foreign-server health checks infrastructure
From: Kyotaro Horiguchi <horikyota.ntt@gmail.com>
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At Mon, 17 Oct 2022 07:27:21 +0000, "kuroda.hayato@fujitsu.com" <kuroda=
.hayato@fujitsu.com> wrote in =

> > In other words, a variation of pgfdw_connection_check_internal()
> > could potentially go into interfaces/libpq/libpq-fe.h
> > (backend/libpq/pqcomm.c or src/interfaces/libpq/fe-connect.c).
> =

> Hmm, IIUC libpq related function and data structures cannot be access=
ed from core source,
> so we cannot move to pqcomm.c.
> (This is a motivation for introducing libpqwalreceiver library. It is=
 used to avoid to link libpq directly)
> And functions in libpq/fe-connect.c will be included libpq.so,
> but latch related functions like WaitEventSetWait() should not be cal=
led from client application.
> So it is also not appropriate.
> In short, there are no good position to place the function because th=
is requires both of libpq and core functions.

Might be on slight different direction, but it looks to me a bit too
much to use WaitEventSet to check only if a socket is live or not.

A quick search in the tree told me that we could use pqSocketCheck()
instead, and I think it would be the something that "could potentially
go into libpq-fe.h" as =D6nder mentioned, if I understand what he said
correctly.

regards.

-- =

Kyotaro Horiguchi
NTT Open Source Software Center