[devel] RFC: girar: optimize rebuild

[Gleb Fotengauer-Malinovskiy]

Hi,

On Sat, Apr 11, 2020 at 02:10:42AM +0300, Vladimir D. Seleznev wrote:
> 
> Hi!
> 
> The first part of rebuilt packages optimization for girar. It introduces
> pkg_identity() and simple optimization of the rebuilt sourcerpm.

Why do we rebuild source rpm at all when we already have one?  I mean,
when we use hasher with --query-repackage this new rebuilt source rpm is
no better then original one.

I think we can always save the original source rpm when we rebuild
a package or copy it from branch to branch (like we actually do for
packages originally built from src.rpm-s).

> pkg_identity() takes RPM package and returns a value called package identity,
> a hash of subset of RPM package header. That subset is the entire header
> without some nonessential artifacts like buildhost, buildtime, header hashsum,
> etc.
> 
> The two package builds of the same NEVR might have equal or different
> package identities. The equal identities mean that build results of these
> packages are equal too, that allows build optimization. The practical
> example of simple rebuilt sourcerpm optimization also introduced.

Did you consider adding all this identity logic on the rpm's side (as a
standalone helper may be)?  I personally don't like the whole idea
of tracking rpm tags status on girar side.  Also, this helper may be
useful outside of girar.

> The future work can be about optimization of "copied" to another branch
> sourcerpm with retrieved from archive sourcerpm, and binary packages
> optimization (this case has an issue when binary subpackages are mixed
> archs, i.e. arch and noarch, this probably could work only with single-arch
> builds).

Looks like a good plan.  I think optimization of binary packages is more
important then optimization which looks for archived packages.
We may want to take binary packages from archive too anyway.

-- 
glebfm
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