[PATCH v2 3/5] make object_directory.loose_objects_subdir_seen a bitmap
- From
- Eric Wong <e@80x24.org>
- Date
- Jun 29, 2021, 20:53 UTC
- Message-ID
- <20210629205305.7100-4-e@80x24.org>
- In-Reply-To
- <20210627024718.25383-1-e@80x24.org>
There's no point in using 8 bits per-directory when 1 bit will do. This saves us 224 bytes per object directory, which ends up being 22MB when dealing with 100K alternates.
v2: use bitsizeof() macro and better variable names
Signed-off-by: Eric Wong <e@80x24.org> --- object-file.c | 11 ++++++++--- object-store.h | 2 +- 2 files changed, 9 insertions(+), 4 deletions(-)
diff --git a/object-file.c b/object-file.c index 6be43c2b60..91183d1297 100644 --- a/object-file.c +++ b/object-file.c @@ -2463,12 +2463,17 @@ struct oid_array *odb_loose_cache(struct object_directory *odb, { int subdir_nr = oid->hash[0]; struct strbuf buf = STRBUF_INIT; + size_t word_bits = bitsizeof(odb->loose_objects_subdir_seen[0]); + size_t word_index = subdir_nr / word_bits; + size_t mask = 1 << (subdir_nr % word_bits); + uint32_t *bitmap; if (subdir_nr < 0 || - subdir_nr >= ARRAY_SIZE(odb->loose_objects_subdir_seen)) + subdir_nr >= bitsizeof(odb->loose_objects_subdir_seen)) BUG("subdir_nr out of range"); - if (odb->loose_objects_subdir_seen[subdir_nr]) + bitmap = &odb->loose_objects_subdir_seen[word_index]; + if (*bitmap & mask) return &odb->loose_objects_cache[subdir_nr]; strbuf_addstr(&buf, odb->path); @@ -2476,7 +2481,7 @@ struct oid_array *odb_loose_cache(struct object_directory *odb, append_loose_object, NULL, NULL, &odb->loose_objects_cache[subdir_nr]); - odb->loose_objects_subdir_seen[subdir_nr] = 1; + *bitmap |= mask; strbuf_release(&buf); return &odb->loose_objects_cache[subdir_nr]; } diff --git a/object-store.h b/object-store.h index 20c1cedb75..8fcddf3e65 100644 --- a/object-store.h +++ b/object-store.h @@ -22,7 +22,7 @@ struct object_directory { * * Be sure to call odb_load_loose_cache() before using. */ - char loose_objects_subdir_seen[256]; + uint32_t loose_objects_subdir_seen[8]; /* 256 bits */ struct oid_array loose_objects_cache[256]; /*