Re: [gentoo-portage-dev] [PATCH] egencache: add --stable-mtime option

[Michał Górny]

On Sat, 19 Dec 2015 15:51:29 -0800
Zac Medico <zmedico@g.o> wrote:

> On 12/16/2015 09:49 AM, Michał Górny wrote:
> > On Wed, 16 Dec 2015 14:38:03 +0100
> > Alexander Berntsen <bernalex@g.o> wrote:
> >
> >> -----BEGIN PGP SIGNED MESSAGE-----
> >> Hash: SHA512
> >>
> >> On 16/12/15 06:33, Zac Medico wrote:
> >>> Disable Manifest "stable mtime" behavior by default, and add a
> >>> corresponding egencache option.
> >> This message tells me nothing about why we need to do this.
> >
> > We need do this because we changed the behavior and the new behavior is
> > counter-intuitive. We already had a number of bugs caused by it,
> > and while it's used by Infra, it's at least unexpected when someone
> > manually runs 'repoman manifest'.
>
> Just because it was historically buggy does not mean that it will always
> be that way. I believe that it will be very safe once we've fixed it to
> include the mtimes of all relevant directories in the max mtime calculation.
>
> > I mean, before this all started 'repoman manifest' just updated
> > the Manifest which meant it's mtime changed. Nowadays, it also sets
> > mtime to some value in the past, which means running 'repoman manifest'
> > may result in updated Manifest having mtime older than the old
> > Manifest. As a result, people using rsync are in trouble. And this has
> > been reported too by overlay owners.
>
> We should get our facts straight. It's not possible for the updated
> Manifest to have an older mtime than the old manifest, because the mtime
> of the old Manfiest is included in the max mtime calculation.

Unless you remove the old Manifest (and distfiles) to have Portage
refetch the files and recalc the digests.

-- 
Best regards,
Michał Górny
<http://dev.gentoo.org/~mgorny/>