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@xxxxxxxxxxxx>
---
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
