[PATCH 0/6] Push negotiation

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(-)