Separate `ref_cache` into a separate module

This is v3 of a patch series to separate the reference caching code into a separate module that interacts with files_ref_cache more at arm's length. Thanks to Stefan and Duy for their feedback about v2 [1].

This version has only minor changes since v2 (and indeed since v1 [2]):

* Rebased onto the current nd/files-backend-git-dir (there were no conflicts).

* Removed redundant assignment in

refs_verify_refname_available(): implement once for all backends

* Improved two commit messages.

This patch series is also available from my GitHub fork [3] as branch "separate-ref-cache". These patches depend on Duy's nd/files-backend-git-dir branch.

[1] http://public-inbox.org/git/[email protected]/
[2] http://public-inbox.org/git/[email protected]/
[3] https://github.com/mhagger/git

Michael Haggerty (20):
get_ref_dir(): don't call read_loose_refs() for "refs/bisect" refs_read_raw_ref(): new function refs_ref_iterator_begin(): new function refs_verify_refname_available(): implement once for all backends refs_verify_refname_available(): use function in more places
ref-cache: rename add_ref() to add_ref_entry()
ref-cache: rename find_ref() to find_ref_entry()
ref-cache: rename remove_entry() to remove_entry_from_dir()
refs: split ref_cache code into separate files
ref-cache: introduce a new type, ref_cache
refs: record the ref_store in ref_cache, not ref_dir
ref-cache: use a callback function to fill the cache
refs: handle "refs/bisect/" in loose_fill_ref_dir() do_for_each_entry_in_dir(): eliminate offset argument get_loose_ref_dir(): function renamed from get_loose_refs() get_loose_ref_cache(): new function cache_ref_iterator_begin(): make function smarter commit_packed_refs(): use reference iteration files_pack_refs(): use reference iteration do_for_each_entry_in_dir(): delete function

 Makefile             |    1 +
 refs.c               |  111 ++++-
 refs.h               |    2 +-
 refs/files-backend.c | 1229 +++++++-------------------------------------------
 refs/ref-cache.c     |  523 +++++++++++++++++++++
 refs/ref-cache.h     |  267 +++++++++++
 refs/refs-internal.h |   22 +-
 7 files changed, 1066 insertions(+), 1089 deletions(-)
 create mode 100644 refs/ref-cache.c
 create mode 100644 refs/ref-cache.h

2.11.0