[PATCH v2 19/26] pack-revindex: factor out `midx_key_to_pack_pos()` helper
- From
Taylor Blau <me@ttaylorr.com>
- Date
- Dec 14, 2023, 22:24 UTC
- Message-ID
- <14b054d27283ffdda1d3f2a4078a4dae54868bfa.1702592604.git.me@ttaylorr.com>
- In-Reply-To
- <cover.1702592603.git.me@ttaylorr.com>
The `midx_to_pack_pos()` function implements a binary search over objects in the MIDX between lexical and pseudo-pack order. It does this by taking in an index into the lexical order (i.e. the same argument you'd use for `nth_midxed_object_id()` and similar) and spits out a position in the pseudo-pack order.
This works for all callers, since they currently all are translating from lexical order to pseudo-pack order. But future callers may want to translate a known (offset, pack_id) tuple into an index into the psuedo-pack order, without knowing where that (offset, pack_id) tuple appears in lexical order.
Prepare for implementing a function that translates between a (offset, pack_id) tuple into an index into the psuedo-pack order by extracting a helper function which does just that, and then reimplementing midx_to_pack_pos() in terms of it.
Signed-off-by: Taylor Blau <me@ttaylorr.com> --- pack-revindex.c | 39 ++++++++++++++++++++++++--------------- 1 file changed, 24 insertions(+), 15 deletions(-)
diff --git a/pack-revindex.c b/pack-revindex.c index 7dc6c776d5..baa4657ed3 100644 --- a/pack-revindex.c +++ b/pack-revindex.c @@ -520,19 +520,12 @@ static int midx_pack_order_cmp(const void *va, const void *vb) return 0; } -int midx_to_pack_pos(struct multi_pack_index *m, uint32_t at, uint32_t *pos) +static int midx_key_to_pack_pos(struct multi_pack_index *m, + struct midx_pack_key *key, + uint32_t *pos) { - struct midx_pack_key key; uint32_t *found; - if (!m->revindex_data) - BUG("midx_to_pack_pos: reverse index not yet loaded"); - if (m->num_objects <= at) - BUG("midx_to_pack_pos: out-of-bounds object at %"PRIu32, at); - - key.pack = nth_midxed_pack_int_id(m, at); - key.offset = nth_midxed_offset(m, at); - key.midx = m; /* * The preferred pack sorts first, so determine its identifier by * looking at the first object in pseudo-pack order. @@ -542,16 +535,32 @@ int midx_to_pack_pos(struct multi_pack_index *m, uint32_t at, uint32_t *pos) * implicitly is preferred (and includes all its objects, since ties are * broken first by pack identifier). */ - if (midx_preferred_pack(key.midx, &key.preferred_pack) < 0) + if (midx_preferred_pack(key->midx, &key->preferred_pack) < 0) return error(_("could not determine preferred pack")); - - found = bsearch(&key, m->revindex_data, m->num_objects, - sizeof(*m->revindex_data), midx_pack_order_cmp); + found = bsearch(key, m->revindex_data, m->num_objects, + sizeof(*m->revindex_data), + midx_pack_order_cmp); if (!found) - return error("bad offset for revindex"); + return -1; *pos = found - m->revindex_data; return 0; } + +int midx_to_pack_pos(struct multi_pack_index *m, uint32_t at, uint32_t *pos) +{ + struct midx_pack_key key; + + if (!m->revindex_data) + BUG("midx_to_pack_pos: reverse index not yet loaded"); + if (m->num_objects <= at) + BUG("midx_to_pack_pos: out-of-bounds object at %"PRIu32, at); + + key.pack = nth_midxed_pack_int_id(m, at); + key.offset = nth_midxed_offset(m, at); + key.midx = m; + + return midx_key_to_pack_pos(m, &key, pos); +}
-- 2.43.0.102.ga31d690331.dirty