[PATCH 0/5] Store submodules in a hash, not a linked list

[Michael Haggerty <mhagger@alum.mit.edu>]

I have mentioned this patch series on the mailing list a couple of
time [1,2] but haven't submitted it before. I just rebased it to
current master. It is available from my Git fork [3] as branch
"submodule-hash".

The first point of this patch series is to optimize submodule
`ref_store` lookup by storing the `ref_store`s in a hashmap rather
than a linked list. But a more interesting second point is to weaken
the 1:1 relationship between submodules and `ref_stores` a little bit
more.

A `files_ref_store` would be perfectly happy to represent, say, the
references *physically* stored in a linked worktree (e.g., `HEAD`,
`refs/bisect/*`, etc) even though that is not the complete collection
of refs that are *logically* visible from that worktree (which
includes references from the main repository, too). But the old code
was confusing the two things by storing "submodule" in every
`ref_store` instance.

So push the submodule attribute down to the `files_ref_store` class
(but continue to let the `ref_store`s be looked up by submodule).

The last commit is relatively orthogonal to the others; it simplifies
read_loose_refs() by calling resolve_ref_recursively() directly using
the `ref_store` instance that it already has in hand, rather than
indirectly via the public wrappers.

Michael

[1] http://public-inbox.org/git/341999fc-4496-b974-c117-c18a2fca1358@alum.mit.edu/
[2] http://public-inbox.org/git/37fe2024-0378-a974-a28d-18a89d3e2312@alum.mit.edu/
[3] https://github.com/mhagger/git

Michael Haggerty (5):
  refs: store submodule ref stores in a hashmap
  refs: push the submodule attribute down
  register_ref_store(): new function
  files_ref_store::submodule: use NULL for the main repository
  read_loose_refs(): read refs using resolve_ref_recursively()

 refs.c               | 93 ++++++++++++++++++++++++++++++++++------------------
 refs/files-backend.c | 77 +++++++++++++++++++++++++------------------
 refs/refs-internal.h | 37 ++++++++-------------
 3 files changed, 122 insertions(+), 85 deletions(-)

-- 
2.9.3