diff options
Diffstat (limited to 'pack-objects.h')
| -rw-r--r-- | pack-objects.h | 316 |
1 files changed, 292 insertions, 24 deletions
diff --git a/pack-objects.h b/pack-objects.h index 03f1191..edf74da 100644 --- a/pack-objects.h +++ b/pack-objects.h @@ -1,45 +1,125 @@ #ifndef PACK_OBJECTS_H #define PACK_OBJECTS_H +#include "object-store.h" + +#define DEFAULT_DELTA_CACHE_SIZE (256 * 1024 * 1024) + +#define OE_DFS_STATE_BITS 2 +#define OE_DEPTH_BITS 12 +#define OE_IN_PACK_BITS 10 +#define OE_Z_DELTA_BITS 20 +/* + * Note that oe_set_size() becomes expensive when the given size is + * above this limit. Don't lower it too much. + */ +#define OE_SIZE_BITS 31 +#define OE_DELTA_SIZE_BITS 20 + +/* + * State flags for depth-first search used for analyzing delta cycles. + * + * The depth is measured in delta-links to the base (so if A is a delta + * against B, then A has a depth of 1, and B a depth of 0). + */ +enum dfs_state { + DFS_NONE = 0, + DFS_ACTIVE, + DFS_DONE, + DFS_NUM_STATES +}; + +/* + * The size of struct nearly determines pack-objects's memory + * consumption. This struct is packed tight for that reason. When you + * add or reorder something in this struct, think a bit about this. + * + * 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. Note that when a + * delta is reused, "size" is the uncompressed _delta_ size, not the + * canonical one after the delta has been applied. + * + * "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 */ - struct packed_git *in_pack; /* already in pack */ - off_t in_pack_offset; - struct object_entry *delta; /* delta base object */ - struct object_entry *delta_child; /* deltified objects who bases me */ - struct object_entry *delta_sibling; /* other deltified objects who - * uses the same base as me - */ void *delta_data; /* cached delta (uncompressed) */ - unsigned long delta_size; /* delta data size (uncompressed) */ - unsigned long z_delta_size; /* delta data size (compressed) */ - enum object_type type; - enum object_type in_pack_type; /* could be delta */ + off_t in_pack_offset; uint32_t hash; /* name hint hash */ - unsigned int in_pack_pos; - unsigned char in_pack_header_size; + unsigned size_:OE_SIZE_BITS; + unsigned size_valid:1; + uint32_t delta_idx; /* delta base object */ + uint32_t delta_child_idx; /* deltified objects who bases me */ + uint32_t delta_sibling_idx; /* other deltified objects who + * uses the same base as me + */ + unsigned delta_size_:OE_DELTA_SIZE_BITS; /* delta data size (uncompressed) */ + unsigned delta_size_valid:1; + unsigned in_pack_idx:OE_IN_PACK_BITS; /* already in pack */ + unsigned z_delta_size:OE_Z_DELTA_BITS; + unsigned type_valid:1; + unsigned type_:TYPE_BITS; + unsigned no_try_delta:1; + unsigned in_pack_type:TYPE_BITS; /* could be delta */ unsigned preferred_base:1; /* * we do not pack this, but is available * to be used as the base object to delta * objects against. */ - unsigned no_try_delta:1; unsigned tagged:1; /* near the very tip of refs */ unsigned filled:1; /* assigned write-order */ + unsigned dfs_state:OE_DFS_STATE_BITS; + unsigned char in_pack_header_size; + unsigned depth:OE_DEPTH_BITS; /* - * State flags for depth-first search used for analyzing delta cycles. + * pahole results on 64-bit linux (gcc and clang) + * + * size: 80, bit_padding: 20 bits, holes: 8 bits + * + * and on 32-bit (gcc) * - * The depth is measured in delta-links to the base (so if A is a delta - * against B, then A has a depth of 1, and B a depth of 0). + * size: 76, bit_padding: 20 bits, holes: 8 bits */ - enum { - DFS_NONE = 0, - DFS_ACTIVE, - DFS_DONE - } dfs_state; - int depth; }; struct packing_data { @@ -48,8 +128,22 @@ struct packing_data { int32_t *index; uint32_t index_size; + + unsigned int *in_pack_pos; + + /* + * Only one of these can be non-NULL and they have different + * sizes. if in_pack_by_idx is allocated, oe_in_pack() returns + * the pack of an object using in_pack_idx field. If not, + * in_pack[] array is used the same way as in_pack_pos[] + */ + struct packed_git **in_pack_by_idx; + struct packed_git **in_pack; + + uintmax_t oe_size_limit; }; +void prepare_packing_data(struct packing_data *pdata); struct object_entry *packlist_alloc(struct packing_data *pdata, const unsigned char *sha1, uint32_t index_pos); @@ -78,4 +172,178 @@ static inline uint32_t pack_name_hash(const char *name) return hash; } +static inline enum object_type oe_type(const struct object_entry *e) +{ + return e->type_valid ? e->type_ : OBJ_BAD; +} + +static inline void oe_set_type(struct object_entry *e, + enum object_type type) +{ + if (type >= OBJ_ANY) + BUG("OBJ_ANY cannot be set in pack-objects code"); + + e->type_valid = type >= OBJ_NONE; + e->type_ = (unsigned)type; +} + +static inline unsigned int oe_in_pack_pos(const struct packing_data *pack, + const struct object_entry *e) +{ + return pack->in_pack_pos[e - pack->objects]; +} + +static inline void oe_set_in_pack_pos(const struct packing_data *pack, + const struct object_entry *e, + unsigned int pos) +{ + pack->in_pack_pos[e - pack->objects] = pos; +} + +static inline struct packed_git *oe_in_pack(const struct packing_data *pack, + const struct object_entry *e) +{ + if (pack->in_pack_by_idx) + return pack->in_pack_by_idx[e->in_pack_idx]; + else + return pack->in_pack[e - pack->objects]; +} + +void oe_map_new_pack(struct packing_data *pack, + struct packed_git *p); +static inline void oe_set_in_pack(struct packing_data *pack, + struct object_entry *e, + struct packed_git *p) +{ + if (!p->index) + oe_map_new_pack(pack, p); + if (pack->in_pack_by_idx) + e->in_pack_idx = p->index; + else + pack->in_pack[e - pack->objects] = p; +} + +static inline struct object_entry *oe_delta( + const struct packing_data *pack, + const struct object_entry *e) +{ + if (e->delta_idx) + return &pack->objects[e->delta_idx - 1]; + return NULL; +} + +static inline void oe_set_delta(struct packing_data *pack, + struct object_entry *e, + struct object_entry *delta) +{ + if (delta) + e->delta_idx = (delta - pack->objects) + 1; + else + e->delta_idx = 0; +} + +static inline struct object_entry *oe_delta_child( + const struct packing_data *pack, + const struct object_entry *e) +{ + if (e->delta_child_idx) + return &pack->objects[e->delta_child_idx - 1]; + return NULL; +} + +static inline void oe_set_delta_child(struct packing_data *pack, + struct object_entry *e, + struct object_entry *delta) +{ + if (delta) + e->delta_child_idx = (delta - pack->objects) + 1; + else + e->delta_child_idx = 0; +} + +static inline struct object_entry *oe_delta_sibling( + const struct packing_data *pack, + const struct object_entry *e) +{ + if (e->delta_sibling_idx) + return &pack->objects[e->delta_sibling_idx - 1]; + return NULL; +} + +static inline void oe_set_delta_sibling(struct packing_data *pack, + struct object_entry *e, + struct object_entry *delta) +{ + if (delta) + e->delta_sibling_idx = (delta - pack->objects) + 1; + else + e->delta_sibling_idx = 0; +} + +unsigned long oe_get_size_slow(struct packing_data *pack, + const struct object_entry *e); +static inline unsigned long oe_size(struct packing_data *pack, + const struct object_entry *e) +{ + if (e->size_valid) + return e->size_; + + return oe_get_size_slow(pack, e); +} + +static inline int oe_size_less_than(struct packing_data *pack, + const struct object_entry *lhs, + unsigned long rhs) +{ + if (lhs->size_valid) + return lhs->size_ < rhs; + if (rhs < pack->oe_size_limit) /* rhs < 2^x <= lhs ? */ + return 0; + return oe_get_size_slow(pack, lhs) < rhs; +} + +static inline int oe_size_greater_than(struct packing_data *pack, + const struct object_entry *lhs, + unsigned long rhs) +{ + if (lhs->size_valid) + return lhs->size_ > rhs; + if (rhs < pack->oe_size_limit) /* rhs < 2^x <= lhs ? */ + return 1; + return oe_get_size_slow(pack, lhs) > rhs; +} + +static inline void oe_set_size(struct packing_data *pack, + struct object_entry *e, + unsigned long size) +{ + if (size < pack->oe_size_limit) { + e->size_ = size; + e->size_valid = 1; + } else { + e->size_valid = 0; + if (oe_get_size_slow(pack, e) != size) + BUG("'size' is supposed to be the object size!"); + } +} + +static inline unsigned long oe_delta_size(struct packing_data *pack, + const struct object_entry *e) +{ + if (e->delta_size_valid) + return e->delta_size_; + return oe_size(pack, e); +} + +static inline void oe_set_delta_size(struct packing_data *pack, + struct object_entry *e, + unsigned long size) +{ + e->delta_size_ = size; + e->delta_size_valid = e->delta_size_ == size; + if (!e->delta_size_valid && size != oe_size(pack, e)) + BUG("this can only happen in check_object() " + "where delta size is the same as entry size"); +} + #endif |