Re: [PATCH 4/4] core.abbrev: raise the default abbreviation to 12 hexdigits

[Linus Torvalds <torvalds@linux-foundation.org>]

On Fri, Sep 30, 2016 at 1:06 AM, Jeff King <peff@peff.net> wrote:
>
> I agree that this deals with the performance concerns by caching the
> default_abbrev_len and starting there. I still think it's unnecessarily
> invasive to touch get_short_sha1() at all, which is otherwise only a
> reading function.

So the reason that d oesn't work is that the "disambiguate_state" data
where we keep the number of objects is only visible within
get_short_sha1().

So outside that function, you don't have any sane way to figure out
how many objects. So then you have to do the extra counting function..

> So IMHO, the best combination is the init_default_abbrev() you posted in
> [1], but initialized at the top of find_unique_abbrev(). And cached
> there, obviously, in a similar way.

That's certainly possible, but I'm really not happy with how the
counting function looks.  And nobody actually stood up to say "yeah,
that gets alternate loose objects right" or "if you have tons of those
alternate loose objects you have other issues anyway". I think
somebody would have to "own" that counting function, the advantage of
just putting it into disambiguate_state is that we just get the
counting for free..

                         Linus