Re: Using LibPq in TAP tests via FFI

On Fri, Jun 14, 2024 at 12:25 PM Andres Freund <andres(at)anarazel(dot)de> wrote:

> Hi,
>
> On 2024-06-14 11:11:38 -0400, Andrew Dunstan wrote:
> > On 2024-06-14 Fr 11:09, Andrew Dunstan 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.
>
> What are your current thoughts about a fallback for this? It seems
> possible
> to implement the session module ontop of BackgroundPsql.pm, if necessary.
> But
> I suspect we'll eventually get to a point where that gets less and less
> convenient.
>

I guess it's a question of how widely available FFI::Platypus is. I know
it's available pretty much out of the box on Strawberry Perl and Msys2'
ucrt perl. It works fine on my Ubuntu ARM64 instance. On my Mac I had to
install it via cpan, but that worked fine. For the moment CYgwin has me
beat, but I believe it's possible to make it work - at least the docs
suggest it is. Not sure about other platforms.

I agree with you that falling back on BackgroundPsql is not a terribly
satisfactory solution.

>
>
> How much of a dependency is FFI::Platypus, compared to requiring perl
> headers
> to be installed? In case FFI::Platypus is a complicted dependency, a
> small XS
> wrapper could be an alternative.
>
>
>

Sure we could look at it. I might need to enlist some assistance there :-).
Using FFI is really nice because it does so much of the work for you.

cheers

andrew