Re: [Proposal] Add foreign-server health checks infrastructure

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 accessed 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 called from client application.
> So it is also not appropriate.
> In short, there are no good position to place the function because this 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 Önder mentioned, if I understand what he said
correctly.

regards.

--
Kyotaro Horiguchi
NTT Open Source Software Center