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