Re: Using LibPq in TAP tests via FFI

On Fri, Jun 14, 2024 at 11:40 AM Andres Freund <andres(at)anarazel(dot)de> wrote:

> Hi,
>
> On June 14, 2024 8:09:43 AM PDT, Andrew Dunstan <andrew(at)dunslane(dot)net>
> wrote:
> >Over at [1] Andres expressed enthusiasm for enabling TAP tests to call
> LibPQ directly via FFI, and there was some support from others as well.
> Attached is a very rough POC for just that.There are two perl modules, one
> which wraps libpq (or almost all of it) in perl, and another which uses
> that module to create a session object that can be used to run SQL. Also in
> the patch is a modification of one TAP test (arbitrarily chosen as
> src/bin/pg_amcheck/t/004_verify_heapam.p) to use the new interface, so it
> doesn't use psql at all.
> >
> >There's a bunch of work to do here, but for a morning's work it's not too
> bad :-) Luckily I had most of the first file already to hand.
>
> Yay!
>
>
> >Next I plan to look at some of the recovery tests and other uses of
> background_psql, which might be more challenging,a dn require extension of
> the session API. Also there's a lot of error checking and documentation
> that need to be added.
>
> I'd suggest trying to convert the various looping constructs first,
> they're responsible for a large number of spawned shells. And I vaguely
> recall that there were none/very few that depend on actually being run via
> psql.
>
>
>
>
Yeah, here's a new version with a few more scripts modified, and also
poll_query_until() adjusted. That seems to be the biggest looping construct.

The biggest remaining unadjusted script users of psql are all in the
subscription and recovery tests.

cheers

andrew