Re: fetching packs and storing them as packs

[Eran Tromer <git2eran@tromer.org>]

On 2006-10-27 03:42, Shawn Pearce wrote:
> Nicolas Pitre <nico@cam.org> wrote:
>> On Fri, 27 Oct 2006, Eran Tromer wrote:
>> Well, the race does exist.  Don't do repack -a -d at the same time then.
> 
> This is an issue for "central" repositories that people push into
> and which might be getting repacked according to a cronjob.

AFAICT, the bottom line of the "Re: auto-packing on kernel.org? please?"
thread last October was "sure, go ahead".


> Unfortunately I don't have a solution.  I tried to come up with
> one but didn't.  :-)

Here's one way to do it.
Change git-repack to follow references under $GIT_DIR/tmp/refs/ too.
To receive or fetch a pack:
1. Add references to the new heads in
   `mktemp $GIT_DIR/tmp/refs/XXXXXX`.
2. Put the new .pack under $GIT_DIR/objects/pack/.
3. Put the new .idx under $GIT_DIR/objects/pack/.
4. Update the relevant heads under $GIT_DIR/refs/.
5. Delete the references from step 1.

This is repack-safe and never corrupts the repo. The worst-case failure
mode is if you die before cleaning the refs from $GIT_DIR/tmp/refs. That
may mean some packed objects will never be removed by "repack -a -d"
even if they lose all references from $GIT_DIR/refs, so do "tmpwatch -m
240 $GIT_DIR/tmp/refs" to take care of that.

  Eran