pack-objects.hon commit Fourth batch (bc12974)
   1#ifndef PACK_OBJECTS_H
   2#define PACK_OBJECTS_H
   3
   4#include "object-store.h"
   5#include "thread-utils.h"
   6#include "pack.h"
   7
   8struct repository;
   9
  10#define DEFAULT_DELTA_CACHE_SIZE (256 * 1024 * 1024)
  11
  12#define OE_DFS_STATE_BITS       2
  13#define OE_DEPTH_BITS           12
  14#define OE_IN_PACK_BITS         10
  15#define OE_Z_DELTA_BITS         20
  16/*
  17 * Note that oe_set_size() becomes expensive when the given size is
  18 * above this limit. Don't lower it too much.
  19 */
  20#define OE_SIZE_BITS            31
  21#define OE_DELTA_SIZE_BITS      23
  22
  23/*
  24 * State flags for depth-first search used for analyzing delta cycles.
  25 *
  26 * The depth is measured in delta-links to the base (so if A is a delta
  27 * against B, then A has a depth of 1, and B a depth of 0).
  28 */
  29enum dfs_state {
  30        DFS_NONE = 0,
  31        DFS_ACTIVE,
  32        DFS_DONE,
  33        DFS_NUM_STATES
  34};
  35
  36/*
  37 * The size of struct nearly determines pack-objects's memory
  38 * consumption. This struct is packed tight for that reason. When you
  39 * add or reorder something in this struct, think a bit about this.
  40 *
  41 * basic object info
  42 * -----------------
  43 * idx.oid is filled up before delta searching starts. idx.crc32 is
  44 * only valid after the object is written out and will be used for
  45 * generating the index. idx.offset will be both gradually set and
  46 * used in writing phase (base objects get offset first, then deltas
  47 * refer to them)
  48 *
  49 * "size" is the uncompressed object size. Compressed size of the raw
  50 * data for an object in a pack is not stored anywhere but is computed
  51 * and made available when reverse .idx is made. Note that when a
  52 * delta is reused, "size" is the uncompressed _delta_ size, not the
  53 * canonical one after the delta has been applied.
  54 *
  55 * "hash" contains a path name hash which is used for sorting the
  56 * delta list and also during delta searching. Once prepare_pack()
  57 * returns it's no longer needed.
  58 *
  59 * source pack info
  60 * ----------------
  61 * The (in_pack, in_pack_offset) tuple contains the location of the
  62 * object in the source pack. in_pack_header_size allows quickly
  63 * skipping the header and going straight to the zlib stream.
  64 *
  65 * "type" and "in_pack_type" both describe object type. in_pack_type
  66 * may contain a delta type, while type is always the canonical type.
  67 *
  68 * deltas
  69 * ------
  70 * Delta links (delta, delta_child and delta_sibling) are created to
  71 * reflect that delta graph from the source pack then updated or added
  72 * during delta searching phase when we find better deltas.
  73 *
  74 * delta_child and delta_sibling are last needed in
  75 * compute_write_order(). "delta" and "delta_size" must remain valid
  76 * at object writing phase in case the delta is not cached.
  77 *
  78 * If a delta is cached in memory and is compressed, delta_data points
  79 * to the data and z_delta_size contains the compressed size. If it's
  80 * uncompressed [1], z_delta_size must be zero. delta_size is always
  81 * the uncompressed size and must be valid even if the delta is not
  82 * cached.
  83 *
  84 * [1] during try_delta phase we don't bother with compressing because
  85 * the delta could be quickly replaced with a better one.
  86 */
  87struct object_entry {
  88        struct pack_idx_entry idx;
  89        void *delta_data;       /* cached delta (uncompressed) */
  90        off_t in_pack_offset;
  91        uint32_t hash;                  /* name hint hash */
  92        unsigned size_:OE_SIZE_BITS;
  93        unsigned size_valid:1;
  94        uint32_t delta_idx;     /* delta base object */
  95        uint32_t delta_child_idx; /* deltified objects who bases me */
  96        uint32_t delta_sibling_idx; /* other deltified objects who
  97                                     * uses the same base as me
  98                                     */
  99        unsigned delta_size_:OE_DELTA_SIZE_BITS; /* delta data size (uncompressed) */
 100        unsigned delta_size_valid:1;
 101        unsigned char in_pack_header_size;
 102        unsigned in_pack_idx:OE_IN_PACK_BITS;   /* already in pack */
 103        unsigned z_delta_size:OE_Z_DELTA_BITS;
 104        unsigned type_valid:1;
 105        unsigned no_try_delta:1;
 106        unsigned type_:TYPE_BITS;
 107        unsigned in_pack_type:TYPE_BITS; /* could be delta */
 108
 109        unsigned preferred_base:1; /*
 110                                    * we do not pack this, but is available
 111                                    * to be used as the base object to delta
 112                                    * objects against.
 113                                    */
 114        unsigned tagged:1; /* near the very tip of refs */
 115        unsigned filled:1; /* assigned write-order */
 116        unsigned dfs_state:OE_DFS_STATE_BITS;
 117        unsigned depth:OE_DEPTH_BITS;
 118        unsigned ext_base:1; /* delta_idx points outside packlist */
 119
 120        /*
 121         * pahole results on 64-bit linux (gcc and clang)
 122         *
 123         *   size: 80, bit_padding: 9 bits
 124         *
 125         * and on 32-bit (gcc)
 126         *
 127         *   size: 76, bit_padding: 9 bits
 128         */
 129};
 130
 131struct packing_data {
 132        struct repository *repo;
 133        struct object_entry *objects;
 134        uint32_t nr_objects, nr_alloc;
 135
 136        int32_t *index;
 137        uint32_t index_size;
 138
 139        unsigned int *in_pack_pos;
 140        unsigned long *delta_size;
 141
 142        /*
 143         * Only one of these can be non-NULL and they have different
 144         * sizes. if in_pack_by_idx is allocated, oe_in_pack() returns
 145         * the pack of an object using in_pack_idx field. If not,
 146         * in_pack[] array is used the same way as in_pack_pos[]
 147         */
 148        struct packed_git **in_pack_by_idx;
 149        struct packed_git **in_pack;
 150
 151        /*
 152         * During packing with multiple threads, protect the in-core
 153         * object database from concurrent accesses.
 154         */
 155        pthread_mutex_t odb_lock;
 156
 157        /*
 158         * This list contains entries for bases which we know the other side
 159         * has (e.g., via reachability bitmaps), but which aren't in our
 160         * "objects" list.
 161         */
 162        struct object_entry *ext_bases;
 163        uint32_t nr_ext, alloc_ext;
 164
 165        uintmax_t oe_size_limit;
 166        uintmax_t oe_delta_size_limit;
 167
 168        /* delta islands */
 169        unsigned int *tree_depth;
 170        unsigned char *layer;
 171};
 172
 173void prepare_packing_data(struct repository *r, struct packing_data *pdata);
 174
 175/* Protect access to object database */
 176static inline void packing_data_lock(struct packing_data *pdata)
 177{
 178        pthread_mutex_lock(&pdata->odb_lock);
 179}
 180static inline void packing_data_unlock(struct packing_data *pdata)
 181{
 182        pthread_mutex_unlock(&pdata->odb_lock);
 183}
 184
 185struct object_entry *packlist_alloc(struct packing_data *pdata,
 186                                    const struct object_id *oid);
 187
 188struct object_entry *packlist_find(struct packing_data *pdata,
 189                                   const struct object_id *oid);
 190
 191static inline uint32_t pack_name_hash(const char *name)
 192{
 193        uint32_t c, hash = 0;
 194
 195        if (!name)
 196                return 0;
 197
 198        /*
 199         * This effectively just creates a sortable number from the
 200         * last sixteen non-whitespace characters. Last characters
 201         * count "most", so things that end in ".c" sort together.
 202         */
 203        while ((c = *name++) != 0) {
 204                if (isspace(c))
 205                        continue;
 206                hash = (hash >> 2) + (c << 24);
 207        }
 208        return hash;
 209}
 210
 211static inline enum object_type oe_type(const struct object_entry *e)
 212{
 213        return e->type_valid ? e->type_ : OBJ_BAD;
 214}
 215
 216static inline void oe_set_type(struct object_entry *e,
 217                               enum object_type type)
 218{
 219        if (type >= OBJ_ANY)
 220                BUG("OBJ_ANY cannot be set in pack-objects code");
 221
 222        e->type_valid = type >= OBJ_NONE;
 223        e->type_ = (unsigned)type;
 224}
 225
 226static inline unsigned int oe_in_pack_pos(const struct packing_data *pack,
 227                                          const struct object_entry *e)
 228{
 229        return pack->in_pack_pos[e - pack->objects];
 230}
 231
 232static inline void oe_set_in_pack_pos(const struct packing_data *pack,
 233                                      const struct object_entry *e,
 234                                      unsigned int pos)
 235{
 236        pack->in_pack_pos[e - pack->objects] = pos;
 237}
 238
 239static inline struct packed_git *oe_in_pack(const struct packing_data *pack,
 240                                            const struct object_entry *e)
 241{
 242        if (pack->in_pack_by_idx)
 243                return pack->in_pack_by_idx[e->in_pack_idx];
 244        else
 245                return pack->in_pack[e - pack->objects];
 246}
 247
 248void oe_map_new_pack(struct packing_data *pack);
 249
 250static inline void oe_set_in_pack(struct packing_data *pack,
 251                                  struct object_entry *e,
 252                                  struct packed_git *p)
 253{
 254        if (!p->index)
 255                oe_map_new_pack(pack);
 256        if (pack->in_pack_by_idx)
 257                e->in_pack_idx = p->index;
 258        else
 259                pack->in_pack[e - pack->objects] = p;
 260}
 261
 262static inline struct object_entry *oe_delta(
 263                const struct packing_data *pack,
 264                const struct object_entry *e)
 265{
 266        if (!e->delta_idx)
 267                return NULL;
 268        if (e->ext_base)
 269                return &pack->ext_bases[e->delta_idx - 1];
 270        else
 271                return &pack->objects[e->delta_idx - 1];
 272}
 273
 274static inline void oe_set_delta(struct packing_data *pack,
 275                                struct object_entry *e,
 276                                struct object_entry *delta)
 277{
 278        if (delta)
 279                e->delta_idx = (delta - pack->objects) + 1;
 280        else
 281                e->delta_idx = 0;
 282}
 283
 284void oe_set_delta_ext(struct packing_data *pack,
 285                      struct object_entry *e,
 286                      const unsigned char *sha1);
 287
 288static inline struct object_entry *oe_delta_child(
 289                const struct packing_data *pack,
 290                const struct object_entry *e)
 291{
 292        if (e->delta_child_idx)
 293                return &pack->objects[e->delta_child_idx - 1];
 294        return NULL;
 295}
 296
 297static inline void oe_set_delta_child(struct packing_data *pack,
 298                                      struct object_entry *e,
 299                                      struct object_entry *delta)
 300{
 301        if (delta)
 302                e->delta_child_idx = (delta - pack->objects) + 1;
 303        else
 304                e->delta_child_idx = 0;
 305}
 306
 307static inline struct object_entry *oe_delta_sibling(
 308                const struct packing_data *pack,
 309                const struct object_entry *e)
 310{
 311        if (e->delta_sibling_idx)
 312                return &pack->objects[e->delta_sibling_idx - 1];
 313        return NULL;
 314}
 315
 316static inline void oe_set_delta_sibling(struct packing_data *pack,
 317                                        struct object_entry *e,
 318                                        struct object_entry *delta)
 319{
 320        if (delta)
 321                e->delta_sibling_idx = (delta - pack->objects) + 1;
 322        else
 323                e->delta_sibling_idx = 0;
 324}
 325
 326unsigned long oe_get_size_slow(struct packing_data *pack,
 327                               const struct object_entry *e);
 328static inline unsigned long oe_size(struct packing_data *pack,
 329                                    const struct object_entry *e)
 330{
 331        if (e->size_valid)
 332                return e->size_;
 333
 334        return oe_get_size_slow(pack, e);
 335}
 336
 337static inline int oe_size_less_than(struct packing_data *pack,
 338                                    const struct object_entry *lhs,
 339                                    unsigned long rhs)
 340{
 341        if (lhs->size_valid)
 342                return lhs->size_ < rhs;
 343        if (rhs < pack->oe_size_limit) /* rhs < 2^x <= lhs ? */
 344                return 0;
 345        return oe_get_size_slow(pack, lhs) < rhs;
 346}
 347
 348static inline int oe_size_greater_than(struct packing_data *pack,
 349                                       const struct object_entry *lhs,
 350                                       unsigned long rhs)
 351{
 352        if (lhs->size_valid)
 353                return lhs->size_ > rhs;
 354        if (rhs < pack->oe_size_limit) /* rhs < 2^x <= lhs ? */
 355                return 1;
 356        return oe_get_size_slow(pack, lhs) > rhs;
 357}
 358
 359static inline void oe_set_size(struct packing_data *pack,
 360                               struct object_entry *e,
 361                               unsigned long size)
 362{
 363        if (size < pack->oe_size_limit) {
 364                e->size_ = size;
 365                e->size_valid = 1;
 366        } else {
 367                e->size_valid = 0;
 368                if (oe_get_size_slow(pack, e) != size)
 369                        BUG("'size' is supposed to be the object size!");
 370        }
 371}
 372
 373static inline unsigned long oe_delta_size(struct packing_data *pack,
 374                                          const struct object_entry *e)
 375{
 376        if (e->delta_size_valid)
 377                return e->delta_size_;
 378
 379        /*
 380         * pack->delta_size[] can't be NULL because oe_set_delta_size()
 381         * must have been called when a new delta is saved with
 382         * oe_set_delta().
 383         * If oe_delta() returns NULL (i.e. default state, which means
 384         * delta_size_valid is also false), then the caller must never
 385         * call oe_delta_size().
 386         */
 387        return pack->delta_size[e - pack->objects];
 388}
 389
 390static inline void oe_set_delta_size(struct packing_data *pack,
 391                                     struct object_entry *e,
 392                                     unsigned long size)
 393{
 394        if (size < pack->oe_delta_size_limit) {
 395                e->delta_size_ = size;
 396                e->delta_size_valid = 1;
 397        } else {
 398                packing_data_lock(pack);
 399                if (!pack->delta_size)
 400                        ALLOC_ARRAY(pack->delta_size, pack->nr_alloc);
 401                packing_data_unlock(pack);
 402
 403                pack->delta_size[e - pack->objects] = size;
 404                e->delta_size_valid = 0;
 405        }
 406}
 407
 408static inline unsigned int oe_tree_depth(struct packing_data *pack,
 409                                         struct object_entry *e)
 410{
 411        if (!pack->tree_depth)
 412                return 0;
 413        return pack->tree_depth[e - pack->objects];
 414}
 415
 416static inline void oe_set_tree_depth(struct packing_data *pack,
 417                                     struct object_entry *e,
 418                                     unsigned int tree_depth)
 419{
 420        if (!pack->tree_depth)
 421                CALLOC_ARRAY(pack->tree_depth, pack->nr_alloc);
 422        pack->tree_depth[e - pack->objects] = tree_depth;
 423}
 424
 425static inline unsigned char oe_layer(struct packing_data *pack,
 426                                     struct object_entry *e)
 427{
 428        if (!pack->layer)
 429                return 0;
 430        return pack->layer[e - pack->objects];
 431}
 432
 433static inline void oe_set_layer(struct packing_data *pack,
 434                                struct object_entry *e,
 435                                unsigned char layer)
 436{
 437        if (!pack->layer)
 438                CALLOC_ARRAY(pack->layer, pack->nr_alloc);
 439        pack->layer[e - pack->objects] = layer;
 440}
 441
 442#endif