pack-objects.h

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