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 struct 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  */
  29 enum 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  */
  87 struct 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 struct packing_data {
 122         struct repository *repo;
 123         struct object_entry *objects;
 124         uint32_t nr_objects, nr_alloc;
 125
 126         int32_t *index;
 127         uint32_t index_size;
 128
 129         unsigned int *in_pack_pos;
 130         unsigned long *delta_size;
 131
 132         /*
 133          * Only one of these can be non-NULL and they have different
 134          * sizes. if in_pack_by_idx is allocated, oe_in_pack() returns
 135          * the pack of an object using in_pack_idx field. If not,
 136          * in_pack[] array is used the same way as in_pack_pos[]
 137          */
 138         struct packed_git **in_pack_by_idx;
 139         struct packed_git **in_pack;
 140
 141         /*
 142          * During packing with multiple threads, protect the in-core
 143          * object database from concurrent accesses.
 144          */
 145         pthread_mutex_t odb_lock;
 146
 147         /*
 148          * This list contains entries for bases which we know the other side
 149          * has (e.g., via reachability bitmaps), but which aren't in our
 150          * "objects" list.
 151          */
 152         struct object_entry *ext_bases;
 153         uint32_t nr_ext, alloc_ext;
 154
 155         uintmax_t oe_size_limit;
 156         uintmax_t oe_delta_size_limit;
 157
 158         /* delta islands */
 159         unsigned int *tree_depth;
 160         unsigned char *layer;
 161
 162         /*
 163          * Used when writing cruft packs.
 164          *
 165          * Object mtimes are stored in pack order when writing, but
 166          * written out in lexicographic (index) order.
 167          */
 168         uint32_t *cruft_mtime;
 169 };
 170
 171 void prepare_packing_data(struct repository *r, struct packing_data *pdata);
 172
 173 /* Protect access to object database */
 174 static inline void packing_data_lock(struct packing_data *pdata)
 175 {
 176         pthread_mutex_lock(&pdata->odb_lock);
 177 }
 178 static inline void packing_data_unlock(struct packing_data *pdata)
 179 {
 180         pthread_mutex_unlock(&pdata->odb_lock);
 181 }
 182
 183 struct object_entry *packlist_alloc(struct packing_data *pdata,
 184                                     const struct object_id *oid);
 185
 186 struct object_entry *packlist_find(struct packing_data *pdata,
 187                                    const struct object_id *oid);
 188
 189 static inline uint32_t pack_name_hash(const char *name)
 190 {
 191         uint32_t c, hash = 0;
 192
 193         if (!name)
 194                 return 0;
 195
 196         /*
 197          * This effectively just creates a sortable number from the
 198          * last sixteen non-whitespace characters. Last characters
 199          * count "most", so things that end in ".c" sort together.
 200          */
 201         while ((c = *name++) != 0) {
 202                 if (isspace(c))
 203                         continue;
 204                 hash = (hash >> 2) + (c << 24);
 205         }
 206         return hash;
 207 }
 208
 209 static inline enum object_type oe_type(const struct object_entry *e)
 210 {
 211         return e->type_valid ? e->type_ : OBJ_BAD;
 212 }
 213
 214 static inline void oe_set_type(struct object_entry *e,
 215                                enum object_type type)
 216 {
 217         if (type >= OBJ_ANY)
 218                 BUG("OBJ_ANY cannot be set in pack-objects code");
 219
 220         e->type_valid = type >= OBJ_NONE;
 221         e->type_ = (unsigned)type;
 222 }
 223
 224 static inline unsigned int oe_in_pack_pos(const struct packing_data *pack,
 225                                           const struct object_entry *e)
 226 {
 227         return pack->in_pack_pos[e - pack->objects];
 228 }
 229
 230 static inline void oe_set_in_pack_pos(const struct packing_data *pack,
 231                                       const struct object_entry *e,
 232                                       unsigned int pos)
 233 {
 234         pack->in_pack_pos[e - pack->objects] = pos;
 235 }
 236
 237 static inline struct packed_git *oe_in_pack(const struct packing_data *pack,
 238                                             const struct object_entry *e)
 239 {
 240         if (pack->in_pack_by_idx)
 241                 return pack->in_pack_by_idx[e->in_pack_idx];
 242         else
 243                 return pack->in_pack[e - pack->objects];
 244 }
 245
 246 void oe_map_new_pack(struct packing_data *pack);
 247
 248 static inline void oe_set_in_pack(struct packing_data *pack,
 249                                   struct object_entry *e,
 250                                   struct packed_git *p)
 251 {
 252         if (pack->in_pack_by_idx) {
 253                 if (p->index) {
 254                         e->in_pack_idx = p->index;
 255                         return;
 256                 }
 257                 /*
 258                  * We're accessing packs by index, but this pack doesn't have
 259                  * an index (e.g., because it was added since we created the
 260                  * in_pack_by_idx array). Bail to oe_map_new_pack(), which
 261                  * will convert us to using the full in_pack array, and then
 262                  * fall through to our in_pack handling.
 263                  */
 264                 oe_map_new_pack(pack);
 265         }
 266         pack->in_pack[e - pack->objects] = p;
 267 }
 268
 269 void oe_set_delta_ext(struct packing_data *pack,
 270                       struct object_entry *e,
 271                       const struct object_id *oid);
 272
 273 static inline unsigned int oe_tree_depth(struct packing_data *pack,
 274                                          struct object_entry *e)
 275 {
 276         if (!pack->tree_depth)
 277                 return 0;
 278         return pack->tree_depth[e - pack->objects];
 279 }
 280
 281 static inline void oe_set_layer(struct packing_data *pack,
 282                                 struct object_entry *e,
 283                                 unsigned char layer)
 284 {
 285         if (!pack->layer)
 286                 CALLOC_ARRAY(pack->layer, pack->nr_alloc);
 287         pack->layer[e - pack->objects] = layer;
 288 }
 289
 290 static inline uint32_t oe_cruft_mtime(struct packing_data *pack,
 291                                       struct object_entry *e)
 292 {
 293         if (!pack->cruft_mtime)
 294                 return 0;
 295         return pack->cruft_mtime[e - pack->objects];
 296 }
 297
 298 static inline void oe_set_cruft_mtime(struct packing_data *pack,
 299                                       struct object_entry *e,
 300                                       uint32_t mtime)
 301 {
 302         if (!pack->cruft_mtime)
 303                 CALLOC_ARRAY(pack->cruft_mtime, pack->nr_alloc);
 304         pack->cruft_mtime[e - pack->objects] = mtime;
 305 }
 306
 307 #endif