Re: [RFC] building postgres with meson - v12

On Mon, Sep 5, 2022 at 4:11 AM Andres Freund <andres(at)anarazel(dot)de> wrote:
>
> Hi,
>
> On 2022-09-04 13:12:52 +0700, John Naylor wrote:
> > On Fri, Sep 2, 2022 at 11:35 PM Andres Freund <andres(at)anarazel(dot)de> wrote:
> > >
> > > Hi,
> > >
> > > On 2022-09-02 14:17:26 +0700, John Naylor wrote:
> > > > On Thu, Sep 1, 2022 at 1:12 AM Andres Freund <andres(at)anarazel(dot)de> wrote:
> > > > > [v12]
> > > >
> > > > +# Build a small utility static lib for the parser. This makes it easier to not
> > > > +# depend on gram.h already having been generated for most of the other code
> > > > +# (which depends on generated headers having been generated). The generation
> > > > +# of the parser is slow...
> > > >
> > > > It's not obvious whether this is intended to be a Meson-only
> > > > optimization or a workaround for something awkward to specify.
> > >
> > > It is an optimization. The parser generation is by far the slowest part of a
> > > build. If other files can only be compiled once gram.h is generated, there's a
> > > long initial period where little can happen. So instead of having all .c files
> > > have a dependency on gram.h having been generated, the above makes only
> > > scan.c, gram.c compilation depend on gram.h. It only matters for the first
> > > compilation, because such dependencies are added as order-only dependencies,
> > > supplanted by more precise compiler generated dependencies after.
> >
> > Okay, I think the comment could include some of this info for clarity.
>
> Working on that.
>
>
> > > It's still pretty annoying that so much of the build is initially idle,
> > > waiting for genbki.pl to finish.
> > >
> > > Part of that is due to some ugly dependencies of src/common on backend headers
> > > that IMO probably shouldn't exist (e.g. src/common/relpath.c includes
> > > catalog/pg_tablespace_d.h).
> >
> > Technically, *_d.h headers are not backend, that's why it's safe to
> > include them anywhere. relpath.c in its current form has to know the
> > tablespace OIDs, which I guess is what you think is ugly. (I agree
> > it's not great)
>
> Yea, I'm not saying it's unsafe in a produces-wrong-results way, just that it
> seems architecturally dubious / circular.
>
>
> > > Looks like it'd not be hard to get at least the
> > > _shlib version of src/common and libpq build without waiting for that. But for
> > > all the backend code I don't really see a way, so it'd be nice to make genbki
> > > faster at some point.
> >
> > The attached gets me a ~15% reduction in clock time by having
> > Catalog.pm parse the .dat files in one sweep, when we don't care about
> > formatting, i.e. most of the time:
>
> Cool. Seems worthwhile.

Okay, here's a cleaned up version with more idiomatic style and a new
copy of the perlcritic exception.

Note that the indentation hasn't changed. My thought there: perltidy
will be run again next year, at which time it will be part of a listed
whitespace-only commit. Any objections, since that could confuse
someone before then?

--
John Naylor
EDB: http://www.enterprisedb.com