[PATCH 0/8] update-ref: add support for update-symref option

[Karthik Nayak <karthik.188@gmail.com>]

From: Karthik Nayak <karthik.188@gmail.com>

The 'git-update-ref(1)' command allows transactional reference updates.
But currently only supports regular reference updates. Meaning, if one
wants to update HEAD (symbolic ref) in a transaction, there is no tool
to do so.

One option to obtain transactional updates for the HEAD ref is to
manually create the HEAD.lock file and commit. This is intrusive, where
the user needs to mimic internal git behavior. Also, this only works
when using the files backend.

At GitLab, we've been using the manual process till date, to allow users
to set and change their default branch. But with the introduction of
reftables as a reference backend, this becomes a necessity to be solved
within git.

This patch series goes about introducing 'update-symref' command for
'git-update-ref(1)'. This command allows the user to create symref in a
transaction similar to the 'update' command of 'git-update-ref(1)'. This
command also works well with the existing 'no-deref' option.

We don't create a dedicated 'create-symref' since 'update-symref' can
also create symrefs. We don't create 'delete-symref', since the 'delete'
command can also delete symrefs.

Karthik Nayak (8):
  files-backend: extract out `create_symref_lock`
  reftable-backend: extract out `write_symref_with_log`
  reftable-backend: move `write_symref_with_log` up
  refs: accept symref in `ref_transaction_add_update`
  refs/files-backend: add support for symref updates
  refs/reftable-backend: add support for symref updates
  refs: add 'update-symref' command to 'update-ref'
  refs: support symrefs in 'reference-transaction' hook

 Documentation/git-update-ref.txt |  11 ++-
 Documentation/githooks.txt       |  13 ++-
 branch.c                         |   2 +-
 builtin/fast-import.c            |   6 +-
 builtin/fetch.c                  |   2 +-
 builtin/receive-pack.c           |   2 +-
 builtin/replace.c                |   2 +-
 builtin/tag.c                    |   2 +-
 builtin/update-ref.c             |  63 +++++++++++---
 refs.c                           |  37 ++++++---
 refs.h                           |   9 +-
 refs/files-backend.c             |  95 ++++++++++++++++-----
 refs/refs-internal.h             |  12 ++-
 refs/reftable-backend.c          | 136 ++++++++++++++++++-------------
 sequencer.c                      |   6 +-
 t/t0600-reffiles-backend.sh      |  30 +++++++
 t/t1400-update-ref.sh            | 127 +++++++++++++++++++++++++++++
 t/t1416-ref-transaction-hooks.sh |  27 ++++++
 walker.c                         |   2 +-
 19 files changed, 464 insertions(+), 120 deletions(-)

-- 
2.43.GIT