[OE-core] Meson support in oe-core

[Alexander Kanavin]

On 08/10/2017 12:10 AM, Randy MacLeod wrote:
> Yep, total time for 'without gtk-doc' is *more* than cut in half!
> 
> The drop in configure time is certainly expected but the compilation
> stage should be dominated by the compiler rather than make or ninja.
> The 'without gtk-doc' compile difference mostly confirms that
> but the 9% drop is odd. A couple of sources I've found assert that
> for large projects and parallel builds a full build time is essentially
> the same with ninja:
>     http://david.rothlis.net/ninja-benchmark/
> That work was done on a MacBook (!!) so it would be interesting to
> see what the results are on a 24+ core Linux system. I might
> give that a try tonight if there's nothing good on NetFlix.

To be honest, achieving faster build times is secondary in importance to 
me. The important part is that autotools is one of the most awful pieces 
of software ever written, and the less we have to deal with it in Yocto, 
the happier we all will be. Upstreans generally share that POV.

Read this:
http://blog.nirbheek.in/2016/05/gstreamer-and-meson-new-hope.html
and this:
http://voices.canonical.com/jussi.pakkanen/2011/09/13/autotools/

> By the way, systemd-234 has meson support and you (Alex) have sent
> a patch update to 242 to the oe-core list but without switching to meson
> as is reasonable. Anyway, 232 takes 51 seconds on my 16+16 core machine
> so it would be a useful benchmark as well. Want to take a stab at that?

Oe-core master does not yet have any support for meson. We've done some 
private work to bring it in, but it's not ready for submission yet. I 
also want to build a few different recipes with it to make sure it 
'basically works' for several different things.

After meson support is in master, we can start converting recipes from 
autotools to meson. That requires careful manual work, but the good news 
is that it can be done piece-meal; there's no need to switch everything 
at once.

My plan is to try gstreamer next, and after that, implement meson 
support for gettext. It's a notorious bottleneck in many builds, due to 
inexplicably slow autoconf (that even RP couldn't get down to the root 
cause of).

Alex