Service disruption: git converter currently down

[Warner Losh]

On Mon, Sep 23, 2019, 8:42 PM Ulrich Spörlein <uspoerlein at gmail.com> wrote:

> Am Mo., 23. Sept. 2019 um 20:34 Uhr schrieb Shawn Webb
> <shawn.webb at hardenedbsd.org>:
> >
> > Hey Ulrich,
> >
> > I appreciate your hard work in maintaining the git mirror. Work like
> > this can sometimes go unthanked. I want to take a moment to show
> > appreciation for you and the FreeBSD project in maintaining the git
> > mirror.
> >
> > I do have a few concerns with what was stated in your email. I've
> > written my concerns inline. I hope this discussion is a positive one,
> > wherein upstream and downstream can effectively come to a conclusion.
> >
> > On Mon, Sep 23, 2019 at 08:16:25PM +0200, Ulrich Sp??rlein wrote:
> > > Am Mo., 23. Sept. 2019 um 19:51 Uhr schrieb Sean Chittenden
> > > <sean at chittenden.org>:
> > > >>
> > > >> Please note however, that more "garbage" metadata escaped from SVN
> into
> > > >> github, meaning 3rd parties have a hard time re-running the
> conversion and
> > > >> making sure that it matches SVN down to the metadata (i.e.
> timestamps).
> > > >>
> > > >> Eventually, this will have to be re-rolled and a new "master"
> branch will
> > > >> be force-pushed into github. There's no timeline for this yet.
> > > >
> > > >
> > > > Wait, what?  Can you elaborate?
> > > >
> > > > Discussion of a force-push to github has occurred a few times and
> been explicitly ruled out because most of our corporate citizens use github
> to integrate changes from FreeBSD.  Rerolling master was universally
> rejected when we socialized wanting to do this due to the level of
> disruption this would cause.  The feedback was that this would be a
> high-cost, low-value operation.  In the tradeoffs of purity vs pragmatism,
> pragmatism wins every time (that is the FreeBSD way).
> > > >
> > > > -sc
> > >
> > >
> > > This is not just about pragmatism and the disruption it would cause is
> > > vastly overblown by people who don't seem to know much about the git
> > > storage model.
> > >
> > > There *is* garbage metadata in the published version on github, there
> > > *is* a disclaimer on https://wiki.freebsd.org/GitWorkflow since
> > > forever, and the cost of switching from 1 published branch to another
> > > is literally:
> > >
> > > - git diff origin/broken_master mybranch > mybranch.patch
> > > - git checkout -b fixed_branch origin/fixed_master
> > > - patch < mybranch.patch
> >
> > Such a workflow breaks historical accuracy. Instead of `git annotate`
> > showing the history properly, it's now based on an "epoch commit".
> > Sure such a commit brings the branch to a working condition, but at
> > the cost of history.
>
> Is there really that much value in having "git blame" work in that
> environment?
> My mental model is of short-lived branches that get upstreamed, so I'm
> biased
> towards this not being all that big of a problem (for some at least).
>

Yes. There absolutely is.

> >
> > > It should also be possible to merge both broken and fixed master into
> > > your branch (at the exact same SVN revision in time) and then you can
> > > follow fixed_master going forward. You'll schlepp around double the
> > > commit history, but not tree objects.
> > > If you want to retain history, you can upstream the changes prior to
> > > the switch
> >
> > I so wish that were possible for certain downstream projects. We're
> > unable to upstream the majority of our work. To argue "upstream your
> > work and you won't be affected" is to choose an argument that does not
> > reflect the reality of a growing portion of FreeBSD's downstream
> > consumers: the inability to work effectively with upstream.
>
> :/
>
> I'm 80% sure that you can just merge both branches and things will be fine
> (though the exact incantation will surely be black magic). I'd love to
> try this on
> an actual repo though, I don't have the time to craft some test repo to
> verify
> this assumption, and then find out that other repos are different).
>

One might be able to do this, but this is really quite a lot to ask. I've
done a lot of git rebase in connection with qemu. The hard part us knowing
hash X is for rev r123 in branch 1, but hash Y In branch 2. Once you can
automate that, for various mappings, a script to rebase old to new becomes
possible which will lessen the impact, but not eliminate it.

Also, I'll be offline in the coming weeks, so don't expect immediate
> responses
> from me going forward. I already had to spent most of my weekend to patch
> things up and had to cancel other plans.
>

I think it is safe to view this discussion as just don't force push yet as
we are in no position to mitigate the large disruption this would cause. If
you aren't force pushing master, there is no time urgency to solve this.

Finally, and most importantly, thank you for all your time and efforts
here. They are much appreciated. Any quibbling over future plans shouldn't
detract from that.

Warner


Cheers,
> Uli
> _______________________________________________
> freebsd-git at freebsd.org mailing list
> https://lists.freebsd.org/mailman/listinfo/freebsd-git
> To unsubscribe, send any mail to "freebsd-git-unsubscribe at freebsd.org"
>