midx: introduce `bsearch_one_midx()`

The `bsearch_midx()` function will be extended in a following commit to
search for the location of a given object ID across all MIDXs in a chain
(or the single non-chain MIDX if no chain is available).

While most callers will naturally want to use the updated
`bsearch_midx()` function, there are a handful of special cases that
will want finer control and will only want to search through a single
MIDX.

For instance, the object abbreviation code, which cares about object IDs
near to where we'd expect to find a match in a MIDX. In that case, we
want to look at the nearby matches in each layer of the MIDX chain, not
just a single one).

Split the more fine-grained control out into a separate function called
`bsearch_one_midx()` which searches only a single MIDX.

At present both `bsearch_midx()` and `bsearch_one_midx()` have identical
behavior, but the following commit will rewrite the former to be aware
of incremental MIDXs for the remaining non-special case callers.

Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 4 insertions, 1 deletions

diff --git a/midx.h b/midx.h
index 020e49f77c..46c53d69ff 100644
--- a/midx.h
+++ b/midx.h
@@ -90,7 +90,10 @@ struct multi_pack_index *load_multi_pack_index(const char *object_dir, int local
 int prepare_midx_pack(struct repository *r, struct multi_pack_index *m, uint32_t pack_int_id);
 int nth_bitmapped_pack(struct repository *r, struct multi_pack_index *m,
 		       struct bitmapped_pack *bp, uint32_t pack_int_id);
-int bsearch_midx(const struct object_id *oid, struct multi_pack_index *m, uint32_t *result);
+int bsearch_one_midx(const struct object_id *oid, struct multi_pack_index *m,
+		     uint32_t *result);
+int bsearch_midx(const struct object_id *oid, struct multi_pack_index *m,
+		 uint32_t *result);
 off_t nth_midxed_offset(struct multi_pack_index *m, uint32_t pos);
 uint32_t nth_midxed_pack_int_id(struct multi_pack_index *m, uint32_t pos);
 struct object_id *nth_midxed_object_oid(struct object_id *oid,