Re: [gentoo-portage-dev] [RFC] New file layout for PKGDIR and binhosts

[Zac Medico <zmedico@gentoo.org>]

On 12/23/2014 09:16 PM, Matthew Thode wrote:
> I like this (and it has been a long time coming).  What format are we
> going to store the metadata of the use flag combinations and the rest?

The current approach is to store the data in an xpak segment that is
appended to the end of the tbz2 file. The $PKGDIR/Packages files serves
as a cache for the essential parts of the xpak data that are used in
dependency calculations.

> I guess that's already stored since portage knows not to use binpkgs if
> those change.
> 
> Also, would this change be a good time to change to store that metadata
> externally?

That's why we have the $PKGDIR/Packages cache, which is validated using
stat.st_size and stat.st_mtime

> Running portage over NFS with binpkgs takes forever, I

It's probably all of the readdir and stat calls. If we simply assumed
that $PKGDIR/Packages was valid, we could eliminate the readdir and stat
calls. Binhost clients operate under this assumption.

> don't think a binhost makes it faster either.  If there were some way to
> get all the info for the binpkgs into one file (so it could be run on
> cron or something), this could mean that I'd only have to do one file
> request for all that metadata and would be much quicker than inspecting
> all those files.

That's what $PKGDIR/Packages is.
-- 
Thanks,
Zac