Re: [PATCHv11 20/20] builtin-gc: Teach the new --notes option to garbage-collect notes

From: Junio C Hamano <gitster@pobox.com>
Date: Jan 21, 2010, 20:01 UTC
Message-ID: <7vtyufp6r9.fsf@alter.siamese.dyndns.org>
In-Reply-To: <780e0a6b1001211127u6304546ej4e5bffbceca12e0b@mail.gmail.com>

Stephen Boyd <bebarino@gmail.com> writes:

Show 8 quoted lines

> On Sun, Jan 17, 2010 at 1:04 PM, Johan Herland <johan@herland.net> wrote:
>> The new --notes option triggers a call to gc_notes(), which removes note
>> objects that reference non-existing objects.
>>
>
> Shouldn't notes be unconditionally garbage collected? Or maybe there's
> a reason why notes should be treated differently that isn't written
> here.

A few thoughts, inspired by this patch, but on other things around "notes":

 - This is more about pruning notes regarding objects that are no longer
   availabe from _the tip_ of the notes tree.  It doesn't run (and I am
   not suggesting to make it it to run) filter-branch to eradicate all
   such stale notes from the notes commit ancestry, so in that sense this
   is not really a garbage collection.

 - We would want to have "notes prune" subcommand that lets us do the
   pruning without all the other "gc" operation.  "git gc" would of course
   call the same underlying code "notes prune" would use if we want to
   be able to trigger "notes prune" from it.

 - Because there is no public interface to list objects that are annotated
   with the most recent notes tree, the only thing this pruning affects is
   the look-up overhead of "log --show-notes".  As such, it might be
   better to later add tree rebalancing in "notes prune" and at that
   point, it will become even less about garbage collection and more about
   performance ("notes optimize?").

 - Do we want to have a public interface to list objects that are
   annotated with notes?  "git notes" probably deserves a bit more
   subcommands other than "(edit|show)" to help users, e.g. "list" and
   "remove".

 - If this were "notes optimize" (this is just me thinking aloud), perhaps
   we would want to do this at some key places (e.g. when you
   automatically rebalance the tree).