From: Karthik Nayak <karthik.188@gmail.com>
Date: Wed, 30 Sep 2026 12:00:48 GMT
Subject: Re: [PATCH 1/7] meson: avoid recompiling HTTP sources several times
Message-ID: <CAOLa=ZQ0qVCS2Bi3QrDokBRfgtTFH9bqudYiFozHtmEzKgRVeA@mail.gmail.com>
In-Reply-To: <20260924-pks-meson-improvements-v1-1-90b7f79f1c4e@pks.im>

Patrick Steinhardt <ps@pks.im> writes:

> We only link curl into a subset of our subcommands. Consequently, as
> both "http.c" and "http-walker.c" depend on curl, we don't compile these
> into "libgit.a" but instead only link those into the commands that
> depend on curl.
>
> In Meson, we wire these dependencies into the target executables by
> using the `sources:` keyword. But this has the consequence that we're
> recompiling those multiple several times, once for every different
> command they are linked into. In fact, each of these sources is compiled
> seven times, which of course has an impact on compilation speed.
>
> Fix this issue by instead linking these into a static library so that
> they only need to be compiled once. This gives us an almost 10% speedup
> in a clean build:
>
>   Benchmark 1: meson compile (version = HEAD~)
>     Time (mean ± σ):      6.781 s ±  0.052 s    [User: 100.775 s, System: 22.954 s]
>     Range (min … max):    6.709 s …  6.867 s    10 runs
>
>   Benchmark 2: meson compile (version = HEAD)
>     Time (mean ± σ):      6.274 s ±  0.021 s    [User: 91.882 s, System: 22.092 s]
>     Range (min … max):    6.242 s …  6.306 s    10 runs
>
>   Summary
>     meson compile (version = HEAD) ran
>       1.08 ± 0.01 times faster than meson compile (version = HEAD~)
>
> Signed-off-by: Patrick Steinhardt <ps@pks.im>
> ---
>  meson.build | 11 +++++++----
>  1 file changed, 7 insertions(+), 4 deletions(-)
>
> diff --git a/meson.build b/meson.build
> index 0a95d90d21..4fdb4c5405 100644
> --- a/meson.build
> +++ b/meson.build
> @@ -1925,10 +1925,13 @@ bin_wrappers += executable('scalar',
>
>  if curl.found()
>    libgit_curl = declare_dependency(
> -    sources: [
> -      'http.c',
> -      'http-walker.c',
> -    ],
> +    link_with: static_library('git-curl',
> +      sources: [
> +        'http.c',
> +        'http-walker.c',
> +      ],
> +      dependencies: [libgit_commonmain, curl],
> +    ),

So there are 7 locations which mark `libgit_curl` as a dependency,
earlier this would have recompiled the two sources here each time for
each of the 7 locations.

Now we build a static library and declare the dependency to be linked
with the static library. Looks good.

>      dependencies: [libgit_commonmain, curl],
>    )
>
>
> --
> 2.56.0.rc2.329.gd58861e689.dirty