tb/cruft-packs (was Re: What's cooking in git.git (May 2022, #07; Wed, 25))

[Taylor Blau <me@ttaylorr.com>]

On Thu, May 26, 2022 at 01:41:25AM -0700, Junio C Hamano wrote:
> * tb/cruft-packs (2022-05-25) 18 commits
>  - sha1-file.c: don't freshen cruft packs
>  - builtin/gc.c: conditionally avoid pruning objects via loose
>  - builtin/repack.c: add cruft packs to MIDX during geometric repack
>  - builtin/repack.c: use named flags for existing_packs
>  - builtin/repack.c: allow configuring cruft pack generation
>  - builtin/repack.c: support generating a cruft pack
>  - builtin/pack-objects.c: --cruft with expiration
>  - reachable: report precise timestamps from objects in cruft packs
>  - reachable: add options to add_unseen_recent_objects_to_traversal
>  - builtin/pack-objects.c: --cruft without expiration
>  - builtin/pack-objects.c: return from create_object_entry()
>  - t/helper: add 'pack-mtimes' test-tool
>  - pack-mtimes: support writing pack .mtimes files
>  - chunk-format.h: extract oid_version()
>  - pack-write: pass 'struct packing_data' to 'stage_tmp_packfiles'
>  - fixup! pack-mtimes: support reading .mtimes files
>  - pack-mtimes: support reading .mtimes files
>  - Documentation/technical: add cruft-packs.txt
>
>  A mechanism to pack unreachable objects into a "cruft pack",
>  instead of ejecting them into loose form to be reclaimed later, has
>  been introduced.
>
>  Will merge to 'next' after squashing fixup! in???
>  source: <cover.1653088640.git.me@ttaylorr.com>

I think this is ready. This topic has been thoroughly reviewed, and the
outstanding topics:

  - user-facing documentation cautioning about mixed-version cruft GCs
    (similar to what I added in Documentation/technical/cruft-packs.txt
    in v4)

  - 64-bit timestamps, if desired

Can easily be done on top. The first one is trivial, and I'll send
some patches before getting too close to the -rc phase. The latter is
more substantial, but isn't a requirement for merging this (and the
format is extensible so this could be done on top if there is
significant interest).

Thanks,
Taylor