sha1_object_info_extended(): hint about objects in delta-base cache

An object found in the delta-base cache is not guaranteed to
stay there, but we know it came from a pack and it is likely
to give us a quick access if we read_sha1_file() it right now,
which is a piece of useful information.

Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/cache.h b/cache.h
index 9fbc07e976e1fc904f4e53072ddab74b20277588..3a1af9d958bfc5c6c0dbdd1dd1a5907c032a032d 100644 (file)
--- a/cache.h
+++ b/cache.h
@@ -1030,7 +1030,8 @@ struct object_info {
        enum {
                OI_CACHED,
                OI_LOOSE,
-               OI_PACKED
+               OI_PACKED,
+               OI_DBCACHED
        } whence;
        union {
                /*

diff --git a/sha1_file.c b/sha1_file.c
index 7eed3166717f9ec1606cc683b916027474e83007..1d6f93d5d323818753c81b790dc48469f21ef8a5 100644 (file)
--- a/sha1_file.c
+++ b/sha1_file.c
@@ -1697,6 +1697,13 @@ static unsigned long pack_entry_hash(struct packed_git *p, off_t base_offset)
        return hash % MAX_DELTA_CACHE;
 }
 
+static int in_delta_base_cache(struct packed_git *p, off_t base_offset)
+{
+       unsigned long hash = pack_entry_hash(p, base_offset);
+       struct delta_base_cache_entry *ent = delta_base_cache + hash;
+       return (ent->data && ent->p == p && ent->base_offset == base_offset);
+}
+
 static void *cache_or_unpack_entry(struct packed_git *p, off_t base_offset,
        unsigned long *base_size, enum object_type *type, int keep_cache)
 {
@@ -2128,6 +2135,8 @@ int sha1_object_info_extended(const unsigned char *sha1, struct object_info *oi)
        if (status < 0) {
                mark_bad_packed_object(e.p, sha1);
                status = sha1_object_info_extended(sha1, oi);
+       } else if (in_delta_base_cache(e.p, e.offset)) {
+               oi->whence = OI_DBCACHED;
        } else {
                oi->whence = OI_PACKED;
                oi->u.packed.offset = e.offset;