[PATCH 05/10] pack-bitmap: use object_id when loading on-disk bitmaps
- From
Jeff King <peff@peff.net>
- Date
- Feb 24, 2020, 04:32 UTC
- Message-ID
- <20200224043227.GE1018190@coredump.intra.peff.net>
- In-Reply-To
- <20200224042625.GA1015553@coredump.intra.peff.net>
A pack bitmap file contains the index position of the commit for each bitmap, which we then translate into an object id via nth_packed_object_sha1(). In preparation for that function going away, we can switch to the more type-safe nth_packed_object_id().
Note that even though the result ends up in an object_id this does incur an extra copy of the hash (into our temporary object_id, and then into the final malloc'd stored_bitmap struct). This shouldn't make any measurable difference. If it did, we could avoid this copy _and_ the copy of the rest of the items by allocating the stored_bitmap struct beforehand and reading directly into it from the bitmap file. Or better still, if this is a bottleneck, we could introduce an on-disk index to the bitmap file so we don't have to read every single entry to use just one of them. So it's not worth worrying about micro-optimizing out this one hash copy.
Signed-off-by: Jeff King <peff@peff.net> --- pack-bitmap.c | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-)
diff --git a/pack-bitmap.c b/pack-bitmap.c index c81d323329..1a067885a1 100644 --- a/pack-bitmap.c +++ b/pack-bitmap.c @@ -169,7 +169,7 @@ static int load_bitmap_header(struct bitmap_index *index) static struct stored_bitmap *store_bitmap(struct bitmap_index *index, struct ewah_bitmap *root, - const unsigned char *hash, + const struct object_id *oid, struct stored_bitmap *xor_with, int flags) { @@ -181,15 +181,15 @@ static struct stored_bitmap *store_bitmap(struct bitmap_index *index, stored->root = root; stored->xor = xor_with; stored->flags = flags; - oidread(&stored->oid, hash); + oidcpy(&stored->oid, oid); hash_pos = kh_put_oid_map(index->bitmaps, stored->oid, &ret); /* a 0 return code means the insertion succeeded with no changes, * because the SHA1 already existed on the map. this is bad, there * shouldn't be duplicated commits in the index */ if (ret == 0) { - error("Duplicate entry in bitmap index: %s", hash_to_hex(hash)); + error("Duplicate entry in bitmap index: %s", oid_to_hex(oid)); return NULL; } @@ -221,13 +221,13 @@ static int load_bitmap_entries_v1(struct bitmap_index *index) struct ewah_bitmap *bitmap = NULL; struct stored_bitmap *xor_bitmap = NULL; uint32_t commit_idx_pos; - const unsigned char *sha1; + struct object_id oid; commit_idx_pos = read_be32(index->map, &index->map_pos); xor_offset = read_u8(index->map, &index->map_pos); flags = read_u8(index->map, &index->map_pos); - sha1 = nth_packed_object_sha1(index->pack, commit_idx_pos); + nth_packed_object_id(&oid, index->pack, commit_idx_pos); bitmap = read_bitmap_1(index); if (!bitmap) @@ -244,7 +244,7 @@ static int load_bitmap_entries_v1(struct bitmap_index *index) } recent_bitmaps[i % MAX_XOR_OFFSET] = store_bitmap( - index, bitmap, sha1, xor_bitmap, flags); + index, bitmap, &oid, xor_bitmap, flags); } return 0;
-- 2.25.1.823.g95c5488cf7