[PATCH 0/6] Push negotiation

[Jonathan Tan <jonathantanmy@google.com>]

Here are patches for push negotiation. The basic idea is that we can
reuse part of the fetch protocol (and code) to find out what is in
common between the client and server, and then use that information to
further narrow the objects sent in the packfile during a push.

Patch 1 is a bug fix that probably should be merged even if the rest
aren't. Patches 2-4 are refactorings in preparation for the future
patches. Patches 5-6 contain the actual logic and documentation.

I have written more about it in my prior work [1], although the commit
messages and documentation in patches 5-6 should be enough to explain
what's going on. (If they're not, feel free to make review comments.)

The main change from [1] is that the client-side code that used to be in
builtin/fetch-pack.c is now in builtin/fetch.c, because I realized that
builtin/fetch-pack.c does not support HTTP. Other than that, all the
"what hasn't been done yet" items have been done except for statistics
in the commit message.

[1] https://lore.kernel.org/git/20210218012100.928957-1-jonathantanmy@google.com/

Jonathan Tan (6):
  fetch-pack: buffer object-format with other args
  fetch-pack: refactor process_acks()
  fetch-pack: refactor add_haves()
  fetch-pack: refactor command and capability write
  fetch: teach independent negotiation (no packfile)
  send-pack: support push negotiation

 Documentation/config/push.txt           |   7 +
 Documentation/technical/protocol-v2.txt |   8 +
 builtin/fetch.c                         |  27 ++-
 fetch-pack.c                            | 224 +++++++++++++++---------
 fetch-pack.h                            |  11 ++
 object.h                                |   2 +-
 send-pack.c                             |  61 ++++++-
 t/t5516-fetch-push.sh                   |  35 ++++
 t/t5701-git-serve.sh                    |   2 +-
 t/t5702-protocol-v2.sh                  |  89 ++++++++++
 transport-helper.c                      |  10 ++
 transport.c                             |  30 +++-
 transport.h                             |   6 +
 upload-pack.c                           |  18 +-
 14 files changed, 430 insertions(+), 100 deletions(-)

-- 
2.31.1.295.g9ea45b61b8-goog