Andrew's git - gitweb.git/blob

   1#ifndef PACK_OBJECTS_H
   2#define PACK_OBJECTS_H
   3
   4#include "object-store.h"
   5
   6#define OE_DFS_STATE_BITS       2
   7#define OE_DEPTH_BITS           12
   8#define OE_IN_PACK_BITS         10
   9#define OE_Z_DELTA_BITS         20
  10/*
  11 * Note that oe_set_size() becomes expensive when the given size is
  12 * above this limit. Don't lower it too much.
  13 */
  14#define OE_SIZE_BITS            31
  15
  16/*
  17 * State flags for depth-first search used for analyzing delta cycles.
  18 *
  19 * The depth is measured in delta-links to the base (so if A is a delta
  20 * against B, then A has a depth of 1, and B a depth of 0).
  21 */
  22enum dfs_state {
  23        DFS_NONE = 0,
  24        DFS_ACTIVE,
  25        DFS_DONE,
  26        DFS_NUM_STATES
  27};
  28
  29/*
  30 * basic object info
  31 * -----------------
  32 * idx.oid is filled up before delta searching starts. idx.crc32 is
  33 * only valid after the object is written out and will be used for
  34 * generating the index. idx.offset will be both gradually set and
  35 * used in writing phase (base objects get offset first, then deltas
  36 * refer to them)
  37 *
  38 * "size" is the uncompressed object size. Compressed size of the raw
  39 * data for an object in a pack is not stored anywhere but is computed
  40 * and made available when reverse .idx is made. Note that when a
  41 * delta is reused, "size" is the uncompressed _delta_ size, not the
  42 * canonical one after the delta has been applied.
  43 *
  44 * "hash" contains a path name hash which is used for sorting the
  45 * delta list and also during delta searching. Once prepare_pack()
  46 * returns it's no longer needed.
  47 *
  48 * source pack info
  49 * ----------------
  50 * The (in_pack, in_pack_offset) tuple contains the location of the
  51 * object in the source pack. in_pack_header_size allows quickly
  52 * skipping the header and going straight to the zlib stream.
  53 *
  54 * "type" and "in_pack_type" both describe object type. in_pack_type
  55 * may contain a delta type, while type is always the canonical type.
  56 *
  57 * deltas
  58 * ------
  59 * Delta links (delta, delta_child and delta_sibling) are created to
  60 * reflect that delta graph from the source pack then updated or added
  61 * during delta searching phase when we find better deltas.
  62 *
  63 * delta_child and delta_sibling are last needed in
  64 * compute_write_order(). "delta" and "delta_size" must remain valid
  65 * at object writing phase in case the delta is not cached.
  66 *
  67 * If a delta is cached in memory and is compressed, delta_data points
  68 * to the data and z_delta_size contains the compressed size. If it's
  69 * uncompressed [1], z_delta_size must be zero. delta_size is always
  70 * the uncompressed size and must be valid even if the delta is not
  71 * cached.
  72 *
  73 * [1] during try_delta phase we don't bother with compressing because
  74 * the delta could be quickly replaced with a better one.
  75 */
  76struct object_entry {
  77        struct pack_idx_entry idx;
  78        unsigned size_:OE_SIZE_BITS;
  79        unsigned size_valid:1;
  80        unsigned in_pack_idx:OE_IN_PACK_BITS;   /* already in pack */
  81        off_t in_pack_offset;
  82        uint32_t delta_idx;     /* delta base object */
  83        uint32_t delta_child_idx; /* deltified objects who bases me */
  84        uint32_t delta_sibling_idx; /* other deltified objects who
  85                                     * uses the same base as me
  86                                     */
  87        void *delta_data;       /* cached delta (uncompressed) */
  88        unsigned long delta_size;       /* delta data size (uncompressed) */
  89        unsigned z_delta_size:OE_Z_DELTA_BITS;
  90        unsigned type_:TYPE_BITS;
  91        unsigned in_pack_type:TYPE_BITS; /* could be delta */
  92        unsigned type_valid:1;
  93        uint32_t hash;                  /* name hint hash */
  94        unsigned char in_pack_header_size;
  95        unsigned preferred_base:1; /*
  96                                    * we do not pack this, but is available
  97                                    * to be used as the base object to delta
  98                                    * objects against.
  99                                    */
 100        unsigned no_try_delta:1;
 101        unsigned tagged:1; /* near the very tip of refs */
 102        unsigned filled:1; /* assigned write-order */
 103        unsigned dfs_state:OE_DFS_STATE_BITS;
 104        unsigned depth:OE_DEPTH_BITS;
 105};
 106
 107struct packing_data {
 108        struct object_entry *objects;
 109        uint32_t nr_objects, nr_alloc;
 110
 111        int32_t *index;
 112        uint32_t index_size;
 113
 114        unsigned int *in_pack_pos;
 115
 116        /*
 117         * Only one of these can be non-NULL and they have different
 118         * sizes. if in_pack_by_idx is allocated, oe_in_pack() returns
 119         * the pack of an object using in_pack_idx field. If not,
 120         * in_pack[] array is used the same way as in_pack_pos[]
 121         */
 122        struct packed_git **in_pack_by_idx;
 123        struct packed_git **in_pack;
 124
 125        uintmax_t oe_size_limit;
 126};
 127
 128void prepare_packing_data(struct packing_data *pdata);
 129struct object_entry *packlist_alloc(struct packing_data *pdata,
 130                                    const unsigned char *sha1,
 131                                    uint32_t index_pos);
 132
 133struct object_entry *packlist_find(struct packing_data *pdata,
 134                                   const unsigned char *sha1,
 135                                   uint32_t *index_pos);
 136
 137static inline uint32_t pack_name_hash(const char *name)
 138{
 139        uint32_t c, hash = 0;
 140
 141        if (!name)
 142                return 0;
 143
 144        /*
 145         * This effectively just creates a sortable number from the
 146         * last sixteen non-whitespace characters. Last characters
 147         * count "most", so things that end in ".c" sort together.
 148         */
 149        while ((c = *name++) != 0) {
 150                if (isspace(c))
 151                        continue;
 152                hash = (hash >> 2) + (c << 24);
 153        }
 154        return hash;
 155}
 156
 157static inline enum object_type oe_type(const struct object_entry *e)
 158{
 159        return e->type_valid ? e->type_ : OBJ_BAD;
 160}
 161
 162static inline void oe_set_type(struct object_entry *e,
 163                               enum object_type type)
 164{
 165        if (type >= OBJ_ANY)
 166                BUG("OBJ_ANY cannot be set in pack-objects code");
 167
 168        e->type_valid = type >= OBJ_NONE;
 169        e->type_ = (unsigned)type;
 170}
 171
 172static inline unsigned int oe_in_pack_pos(const struct packing_data *pack,
 173                                          const struct object_entry *e)
 174{
 175        return pack->in_pack_pos[e - pack->objects];
 176}
 177
 178static inline void oe_set_in_pack_pos(const struct packing_data *pack,
 179                                      const struct object_entry *e,
 180                                      unsigned int pos)
 181{
 182        pack->in_pack_pos[e - pack->objects] = pos;
 183}
 184
 185static inline struct packed_git *oe_in_pack(const struct packing_data *pack,
 186                                            const struct object_entry *e)
 187{
 188        if (pack->in_pack_by_idx)
 189                return pack->in_pack_by_idx[e->in_pack_idx];
 190        else
 191                return pack->in_pack[e - pack->objects];
 192}
 193
 194void oe_map_new_pack(struct packing_data *pack,
 195                     struct packed_git *p);
 196static inline void oe_set_in_pack(struct packing_data *pack,
 197                                  struct object_entry *e,
 198                                  struct packed_git *p)
 199{
 200        if (!p->index)
 201                oe_map_new_pack(pack, p);
 202        if (pack->in_pack_by_idx)
 203                e->in_pack_idx = p->index;
 204        else
 205                pack->in_pack[e - pack->objects] = p;
 206}
 207
 208static inline struct object_entry *oe_delta(
 209                const struct packing_data *pack,
 210                const struct object_entry *e)
 211{
 212        if (e->delta_idx)
 213                return &pack->objects[e->delta_idx - 1];
 214        return NULL;
 215}
 216
 217static inline void oe_set_delta(struct packing_data *pack,
 218                                struct object_entry *e,
 219                                struct object_entry *delta)
 220{
 221        if (delta)
 222                e->delta_idx = (delta - pack->objects) + 1;
 223        else
 224                e->delta_idx = 0;
 225}
 226
 227static inline struct object_entry *oe_delta_child(
 228                const struct packing_data *pack,
 229                const struct object_entry *e)
 230{
 231        if (e->delta_child_idx)
 232                return &pack->objects[e->delta_child_idx - 1];
 233        return NULL;
 234}
 235
 236static inline void oe_set_delta_child(struct packing_data *pack,
 237                                      struct object_entry *e,
 238                                      struct object_entry *delta)
 239{
 240        if (delta)
 241                e->delta_child_idx = (delta - pack->objects) + 1;
 242        else
 243                e->delta_child_idx = 0;
 244}
 245
 246static inline struct object_entry *oe_delta_sibling(
 247                const struct packing_data *pack,
 248                const struct object_entry *e)
 249{
 250        if (e->delta_sibling_idx)
 251                return &pack->objects[e->delta_sibling_idx - 1];
 252        return NULL;
 253}
 254
 255static inline void oe_set_delta_sibling(struct packing_data *pack,
 256                                        struct object_entry *e,
 257                                        struct object_entry *delta)
 258{
 259        if (delta)
 260                e->delta_sibling_idx = (delta - pack->objects) + 1;
 261        else
 262                e->delta_sibling_idx = 0;
 263}
 264
 265unsigned long oe_get_size_slow(struct packing_data *pack,
 266                               const struct object_entry *e);
 267static inline unsigned long oe_size(struct packing_data *pack,
 268                                    const struct object_entry *e)
 269{
 270        if (e->size_valid)
 271                return e->size_;
 272
 273        return oe_get_size_slow(pack, e);
 274}
 275
 276static inline int oe_size_less_than(struct packing_data *pack,
 277                                    const struct object_entry *lhs,
 278                                    unsigned long rhs)
 279{
 280        if (lhs->size_valid)
 281                return lhs->size_ < rhs;
 282        if (rhs < pack->oe_size_limit) /* rhs < 2^x <= lhs ? */
 283                return 0;
 284        return oe_get_size_slow(pack, lhs) < rhs;
 285}
 286
 287static inline int oe_size_greater_than(struct packing_data *pack,
 288                                       const struct object_entry *lhs,
 289                                       unsigned long rhs)
 290{
 291        if (lhs->size_valid)
 292                return lhs->size_ > rhs;
 293        if (rhs < pack->oe_size_limit) /* rhs < 2^x <= lhs ? */
 294                return 1;
 295        return oe_get_size_slow(pack, lhs) > rhs;
 296}
 297
 298static inline void oe_set_size(struct packing_data *pack,
 299                               struct object_entry *e,
 300                               unsigned long size)
 301{
 302        if (size < pack->oe_size_limit) {
 303                e->size_ = size;
 304                e->size_valid = 1;
 305        } else {
 306                e->size_valid = 0;
 307                if (oe_get_size_slow(pack, e) != size)
 308                        BUG("'size' is supposed to be the object size!");
 309        }
 310}
 311
 312#endif