Re: Keep reflogs for deleted (remote tracking) branches?

[Tao Klerks <tao@klerks.biz>]

On Mon, Mar 14, 2022 at 11:52 AM Ævar Arnfjörð Bjarmason
<avarab@gmail.com> wrote:
>
> I think you might find it interesting to have pre-receive hooks
> e.g. reject pushes if you're deleting a topic whose commits aren't
> entirely <your author> i.e. just something like:
>
>     git push -o ireallymeanit=1 --delete topic
>
> I.e. it's an easy to implement extra safety check that people can always
> opt-out of, print a scary message and most people will think twice :)

That is indeed very interesting, thanks! I need to think about exactly
when this is the right thing to do, but it's a tool in the box that I
was not aware of!


> > My question is specifically about the, in my opinion, very surprising
> > behavior of deleting reflogs along with deleted branches - I mainly
> > provided the example use-case for context.
>
> Yes it's quite a mess, e.g. if you follow the rabit hole at the
> recent[1].
>
> One fundimental problem (discussed in various places around the reftable
> backend) is that we carry N meanings for an empty reflog:
>
> A. "This is an active branch, but we have expired the entries".
>
> B. "I manually created this, knowing that the various core.* configs
>    around reflog will say "oh, a reflog exists, let's log to it" (in
>    some cases).
>
> C. Another is: This is "stale" log, i.e. no branch exists, but the log
>    is there.
>
> Which is one reason[2] we'd delete them on branch deletion, because
> otherwise we'd start logging again when a branch is re-created, which
> possibly isn't what we wanted.
>
> 1. https://lore.kernel.org/git/de5e2b0e290791d0a4f58a893d8571b5fc8c4f1a.1646952843.git.avarab@gmail.com
> 2. I'm not saying this was intended, and haven't looked into this case,
>    just that's it it's an emergent effect of how these files are treated
>    now.

Very interesting, thx. Fwiw I would argue that resuming full logging
when a new branch appears with the same name (within the period of
time where the reflog is not empty yet) is a very reasonable thing to
end up doing, but I guess Han-Wen's note about potential path
conflicts on branches *after* a deletion make this a hard thing to
change, even if "accidental logging resuming" were accepted as a
sensible outcome here.