[PATCH 00/26] Clean up update-refs --stdin and implement ref_transaction

I just sent an email to the list [1] describing how I want to decouple reference-handling code from the rest of Git, and implement pluggable reference storage backends. This patch series is the first movement in that direction.

update_refs() and "update-ref --stdin" implement the beginning of transactions for git references, by allowing a group of reference changes to be done in an all-or-nothing fashion. The main point of this patch series is to increase the abstraction level of the API for dealing with reference transactions, by moving the handling of the transaction to refs.c. The new API for dealing with reference transactions is

    ref_transaction *transaction = create_ref_transaction();
    queue_create_ref(transaction, refname, new_sha1, ...);
    queue_update_ref(transaction, refname, new_sha1, old_sha1, ...);
    queue_delete_ref(transaction, refname, old_sha1, ...);
    ...
    if (commit_ref_transaction(transaction, msg, ...))
        die(...);

When implementing this I found a number of minor problems in the implementation of "git update-ref --stdin", not to mention that it used "struct ref_update" all the way up and down its parser call stack. So most of the commits in this series are actually cleanups in builtin/update-ref.c. I also spend some time making the error messages emitted by that command more uniform.

Then, in just a couple of commits, the ref_transaction abstraction is introduced, update-ref is changed to use it, and update_refs() is removed from the refs API (it was only used by this one caller).

Finally, now that refs.c owns the data structures for dealing with transactions, it is possible to make a few simplifications. More changes in this neighborhood will be coming in future patches.

[1] http://article.gmane.org/gmane.comp.version-control.git/243726

Michael Haggerty (26):
  t1400: Fix name and expected result of one test
  t1400: Provide sensible input to the command
  t1400: Pass a legitimate <newvalue> to update command
  parse_arg(): Really test that argument is properly terminated
  t1400: Add some more tests involving quoted arguments
  refs.h: Rename the action_on_err constants
  update_refs(): Fix constness
  update-ref --stdin: Read the whole input at once
  parse_cmd_verify(): Copy old_sha1 instead of evaluating <oldvalue>
    twice
  update-ref.c: Extract a new function, parse_refname()
  update-ref --stdin: Improve error messages for invalid values
  update-ref --stdin: Make error messages more consistent
  update-ref --stdin: Simplify error messages for missing oldvalues
  update-ref.c: Extract a new function, parse_next_sha1()
  update-ref --stdin: Improve the error message for unexpected EOF
  update-ref --stdin: Harmonize error messages
  refs: Add a concept of a reference transaction
  update-ref --stdin: Reimplement using reference transactions
  refs: Remove API function update_refs()
  struct ref_update: Rename field "ref_name" to "refname"
  struct ref_update: Store refname as a FLEX_ARRAY.
  commit_ref_transaction(): Introduce temporary variables
  struct ref_update: Add a lock member
  struct ref_update: Add type field
  commit_ref_transaction(): Also free the ref_transaction
  commit_ref_transaction(): Work with transaction->updates in place

 builtin/checkout.c                     |   2 +-
 builtin/clone.c                        |   9 +-
 builtin/merge.c                        |   6 +-
 builtin/notes.c                        |   6 +-
 builtin/reset.c                        |   6 +-
 builtin/update-ref.c                   | 402 +++++++++++++++++++--------------
 contrib/examples/builtin-fetch--tool.c |   3 +-
 notes-cache.c                          |   2 +-
 notes-utils.c                          |   3 +-
 refs.c                                 | 184 +++++++++++----
 refs.h                                 |  93 ++++++--
 t/t1400-update-ref.sh                  |  86 ++++---
 12 files changed, 524 insertions(+), 278 deletions(-)