Re: [PATCH] pack-objects: turn off bitmaps when skipping objects

From: Jeff King <peff@peff.net>
Date: Jan 24, 2014, 02:26 UTC
Message-ID: <20140124022621.GB4521@sigill.intra.peff.net>
In-Reply-To: <CAFFjANQ6JkxqSfQaOXF29ETW9ecMXVQTz3x86h_tDjsRdT80HQ@mail.gmail.com>

On Fri, Jan 24, 2014 at 12:56:17AM +0100, Vicent Martí wrote:

Show 10 quoted lines

> On Fri, Jan 24, 2014 at 12:45 AM, Siddharth Agarwal <sid0@fb.com> wrote:
> > Yes, we'd prefer to do that too. How do you actually do this, though? I
> > don't see a way to pass `--honor-pack-keep` (shouldn't I pass in its
> > inverse?) down to `git-pack-objects`.
> 
> We run with this patch in production, it may be of use to you:
> https://gist.github.com/vmg/8589317
> 
> In fact, it may be worth upstreaming too. I'll kindly ask peff to do
> it when he has a moment.

I was actually looking at it earlier when I sent this message. The tricky thing about the patch is that it turns off --honor-pack-keep, but does _not_ teach git-repack to clean up the .keep file.

Which I think is the right and safe thing to do, as otherwise you might blow away a pack with .keep, even though you did not just pack its objects (i.e., because it was written by a fetch or push which did not yet update the refs). So the safe thing is to actually duplicate those objects, leave the .keep pack around, and then assume it will get cleaned up on the next repack.

If you _do_ have a stale .keep file, though, then that stale pack will hang around forever (presumably with its objects duplicated in the "real" pack).

So I think the patch is doing the right thing, but I was still figuring out how to explain it (and I hope I just did). I'll post it with a full commit message tomorrow.

-Peff