[Buildroot] [PATCH 2/3] graph-depends: split off get_version/get_depends into pkgutil.py

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

On 2018-11-07 21:41 +0100, Thomas De Schampheleire spake thusly:
> El mi?., 7 nov. 2018 a las 20:39, Yann E. MORIN
> (<yann.morin.1998@free.fr>) escribi?:
> > On 2018-11-07 20:06 +0100, Thomas De Schampheleire spake thusly:
> > > El mi?., 7 nov. 2018 a las 19:07, Yann E. MORIN
> > > (<yann.morin.1998@free.fr>) escribi?:
> > > > On 2017-02-03 21:57 +0100, Thomas De Schampheleire spake thusly:
> > > > > From: Thomas De Schampheleire <thomas.de_schampheleire@nokia.com>
> > > > >
> > > > > Functions to obtain the version and dependencies of a package from Python
> > > > > can be useful for several scripts. Extract this logic out of graph-depends
> > > > > into pkgutil.py.
> > > >
> > > > Coming back to this script, because I'm rewriting the way graph-depends
> > > > gets the dependency tree. When you said "useful for several scripts,"
> > > > did you expect it to be useful to scripts that are not in Buildroot
> > > > (e.g. user-local scripts)?
> > >
> > > Yes, exactly. We are using the logic from pkgutil from another python
> > > script and want to avoid code duplication.
> > > This particular script is not something that upstream accepts, i.e.
> > > generating opkg files for specific packages (and for that, we need to
> > > know the dependencies and versions of each package).
> >
> > So, if you were to get a new function that would return basically the
> > same, but in another format, but much quicker (~4s instead of ~45s),
> > would that be something you could adapt to?
> >
> > I'm changing the way the dependency tree is extracted from the Makefile
> > data, and the function now has this API (function name yet to be
> > bike-shedded about):
> >
> >     dict_deps, dict_types = get_dependency_tree(direction)
> >
> > where:
> >
> >   - direction is either string 'forward' or 'back',
> >
> >   - dict_deps is a dictionnary, which keys are the package names, and
> >     which values are lists of packages that are direct dependencies of
> >     the key package (basically, what get_all_depends() currently
> >     returns, but the whole dependency tree)
> 
> How is dict_deps different from what get_depends in brpkgutil.py
> currently returns? Your statement "but the whole dependency tree" is
> not clear to me.

Currently, brpkgutil.get_depends() takes a list of packages for which
to get the dependencies. The new get_dependency_tree() does not take
such a list; it always returns the whole dependency tree (i.e. from the
'ALL' meta package).

> >   - dict_types is a dictionnary, which keys are the package names, and
> >     the values are string representing whtehr the packages are target or
> >     host, and virtual or not, e.g.: 'target', 'target-virtual', 'host',
> >     'host-virtual'.
> >
> > If needed, I could very easily make it return a three-tuple, with the
> > third one being dict_versions, keyed by package names, with values the
> > package version.
> >
> > Would that be something that would be usable in your use case?
> 
> To help the discussion, here are some snippets from our code:
> 
>         Package.versions = brpkgutil.get_version(list(Package.files.keys()))
>         Package.depends = brpkgutil.get_depends(list(Package.files.keys()))

So you could write:

    Package.depends, Package.versions = brpkgutil.get_dependency_tree('forward')

>         self.version = Package.versions[self.pkg]        # this
> variable will be used in several places, we just need the string
> representing the version
>     ...
>     def get_opkg_depends(self):
>         """Return the dependencies that need to be declared in the opkg"""
>         deps = set(Package.depends[self.pkg]).intersection(set(Package.requested_pkgs))
>         if deps is not None:
>             return ','.join(deps)
>         else:
>             return ''
> 
> The code above is basically all we do with the version and dependencies.
> As long as we can get this info in some way, I'm fine with changes.
> Returning the versions together with the dependencies in one call,
> removing the call to brpkgutil.get_version is fine by me, if it is
> better for the in-tree usage (I'm fine with either way).

OK, good.

Currently, in Buildroot, we use the version string just because we need
to know whether a package is virutal or not. Do you really need the
version string for what it is, or just to test if it is virtual or not?

Regards,
Yann E. MORIN.

> Thanks,
> Thomas

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