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Diffstat (limited to 'pack-objects.h')
| -rw-r--r-- | pack-objects.h | 45 |
1 files changed, 45 insertions, 0 deletions
diff --git a/pack-objects.h b/pack-objects.h index 03f1191659..c0a1f61aac 100644 --- a/pack-objects.h +++ b/pack-objects.h @@ -1,6 +1,51 @@ #ifndef PACK_OBJECTS_H #define PACK_OBJECTS_H +/* + * basic object info + * ----------------- + * idx.oid is filled up before delta searching starts. idx.crc32 is + * only valid after the object is written out and will be used for + * generating the index. idx.offset will be both gradually set and + * used in writing phase (base objects get offset first, then deltas + * refer to them) + * + * "size" is the uncompressed object size. Compressed size of the raw + * data for an object in a pack is not stored anywhere but is computed + * and made available when reverse .idx is made. + * + * "hash" contains a path name hash which is used for sorting the + * delta list and also during delta searching. Once prepare_pack() + * returns it's no longer needed. + * + * source pack info + * ---------------- + * The (in_pack, in_pack_offset) tuple contains the location of the + * object in the source pack. in_pack_header_size allows quickly + * skipping the header and going straight to the zlib stream. + * + * "type" and "in_pack_type" both describe object type. in_pack_type + * may contain a delta type, while type is always the canonical type. + * + * deltas + * ------ + * Delta links (delta, delta_child and delta_sibling) are created to + * reflect that delta graph from the source pack then updated or added + * during delta searching phase when we find better deltas. + * + * delta_child and delta_sibling are last needed in + * compute_write_order(). "delta" and "delta_size" must remain valid + * at object writing phase in case the delta is not cached. + * + * If a delta is cached in memory and is compressed, delta_data points + * to the data and z_delta_size contains the compressed size. If it's + * uncompressed [1], z_delta_size must be zero. delta_size is always + * the uncompressed size and must be valid even if the delta is not + * cached. + * + * [1] during try_delta phase we don't bother with compressing because + * the delta could be quickly replaced with a better one. + */ struct object_entry { struct pack_idx_entry idx; unsigned long size; /* uncompressed size */ |