[Buildroot] [PATCH 1/4] pkg-infra: introduce pre/post-step hooks

[Yann E. MORIN <yann.morin.1998@free.fr>]

On 2013-10-14 09:16 +0200, Thomas Petazzoni spake thusly:
> Dear Yann E. MORIN,
> 
> On Mon, 14 Oct 2013 01:11:25 +0200, Yann E. MORIN wrote:
> > From: "Yann E. MORIN" <yann.morin.1998@free.fr>
> > 
> > This hooks will let us instrument the build process in many ways:
> >   - log current step to see what broke
> >   - time each step to see what is worth optimising
> >   - sanity-check installed files (rpath, overwritten files...)
> >   - call user-provided script
> >   - ...
> > 
> > The steps are fine-grain, and all have a 'start' and a 'end' hooks.
> > Here is the list of available steps (19 total):
> >   - extract, post-extract
> >   - pre-patch, patch, post-patch
> >   - pre-configure, configure, post-configure
> >   - build, post-build
> >   - install-host, post-install-host
> >   - install-staging, post-install-staging, pkg-config-staging
> >   - install-image, post-install-image
> >   - install-target, post-install-target
> > 
> > The download, clean, uninstall steps are not instrumented on purpose.
> > 
> > Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
> 
> I am not sure to follow why we're introducing additional hooks here.
> Why don't we generalize the existing pre/post hooks mechanism to *all*
> steps (by all I mean the steps you are interested in instrumenting),
> and use that to hook the different things you introduce in patch 2, 3,
> 4 ?

I'm not sure I understand what you suggest, so I'll try to explain what
I understood (in a series-like order):

  - add missing pre/post hooks to all steps
  - have the pkg-infra internally register pre/post hooks for each
    package
  - add and register the time/user hooks

Is that what you meant?

> Also, do we really need to have hook points for the pre-hooks and
> post-hooks each time?

Yes, I wan't to be able to instrument them. Especially, I want to be
able to check that pre/post hook are not messing with target/ in crazy
way. I also want to be able to time them (heck, I've seen a hook takes
orders of magnitude longer than the corresponding action).

With your suggestion, I don't know how we can instrument the pre/post
hooks.

Note: However, I agree that we could reduce the number of steps by
squashing, for example, end-pre-configure with start-configure, or
end-configure with start-post-configure (and so on). But having both
start/end be separate barriers is cleaner and more systematic; it helps
reviewing a log of the build without constantly wondering what frontier
a specific step is.

Regards,
Yann E. MORIN.

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