object-store.h

   1 #ifndef OBJECT_STORE_H
   2 #define OBJECT_STORE_H
   3
   4 #include "cache.h"
   5 #include "oidmap.h"
   6 #include "list.h"
   7 #include "oid-array.h"
   8 #include "strbuf.h"
   9 #include "thread-utils.h"
  10 #include "khash.h"
  11 #include "dir.h"
  12 #include "oidtree.h"
  13 #include "oidset.h"
  14
  15 struct object_directory {
  16         struct object_directory *next;
  17
  18         /*
  19          * Used to store the results of readdir(3) calls when we are OK
  20          * sacrificing accuracy due to races for speed. That includes
  21          * object existence with OBJECT_INFO_QUICK, as well as
  22          * our search for unique abbreviated hashes. Don't use it for tasks
  23          * requiring greater accuracy!
  24          *
  25          * Be sure to call odb_load_loose_cache() before using.
  26          */
  27         uint32_t loose_objects_subdir_seen[8]; /* 256 bits */
  28         struct oidtree *loose_objects_cache;
  29
  30         /*
  31          * This is a temporary object store created by the tmp_objdir
  32          * facility. Disable ref updates since the objects in the store
  33          * might be discarded on rollback.
  34          */
  35         int disable_ref_updates;
  36
  37         /*
  38          * This object store is ephemeral, so there is no need to fsync.
  39          */
  40         int will_destroy;
  41
  42         /*
  43          * Path to the alternative object store. If this is a relative path,
  44          * it is relative to the current working directory.
  45          */
  46         char *path;
  47 };
  48
  49 KHASH_INIT(odb_path_map, const char * /* key: odb_path */,
  50         struct object_directory *, 1, fspathhash, fspatheq)
  51
  52 void prepare_alt_odb(struct repository *r);
  53 char *compute_alternate_path(const char *path, struct strbuf *err);
  54 struct object_directory *find_odb(struct repository *r, const char *obj_dir);
  55 typedef int alt_odb_fn(struct object_directory *, void *);
  56 int foreach_alt_odb(alt_odb_fn, void*);
  57 typedef void alternate_ref_fn(const struct object_id *oid, void *);
  58 void for_each_alternate_ref(alternate_ref_fn, void *);
  59
  60 /*
  61  * Add the directory to the on-disk alternates file; the new entry will also
  62  * take effect in the current process.
  63  */
  64 void add_to_alternates_file(const char *dir);
  65
  66 /*
  67  * Add the directory to the in-memory list of alternates (along with any
  68  * recursive alternates it points to), but do not modify the on-disk alternates
  69  * file.
  70  */
  71 void add_to_alternates_memory(const char *dir);
  72
  73 /*
  74  * Replace the current writable object directory with the specified temporary
  75  * object directory; returns the former primary object directory.
  76  */
  77 struct object_directory *set_temporary_primary_odb(const char *dir, int will_destroy);
  78
  79 /*
  80  * Restore a previous ODB replaced by set_temporary_main_odb.
  81  */
  82 void restore_primary_odb(struct object_directory *restore_odb, const char *old_path);
  83
  84 /*
  85  * Populate and return the loose object cache array corresponding to the
  86  * given object ID.
  87  */
  88 struct oidtree *odb_loose_cache(struct object_directory *odb,
  89                                   const struct object_id *oid);
  90
  91 /* Empty the loose object cache for the specified object directory. */
  92 void odb_clear_loose_cache(struct object_directory *odb);
  93
  94 /* Clear and free the specified object directory */
  95 void free_object_directory(struct object_directory *odb);
  96
  97 struct packed_git {
  98         struct hashmap_entry packmap_ent;
  99         struct packed_git *next;
 100         struct list_head mru;
 101         struct pack_window *windows;
 102         off_t pack_size;
 103         const void *index_data;
 104         size_t index_size;
 105         uint32_t num_objects;
 106         uint32_t crc_offset;
 107         struct oidset bad_objects;
 108         int index_version;
 109         time_t mtime;
 110         int pack_fd;
 111         int index;              /* for builtin/pack-objects.c */
 112         unsigned pack_local:1,
 113                  pack_keep:1,
 114                  pack_keep_in_core:1,
 115                  freshened:1,
 116                  do_not_close:1,
 117                  pack_promisor:1,
 118                  multi_pack_index:1,
 119                  is_cruft:1;
 120         unsigned char hash[GIT_MAX_RAWSZ];
 121         struct revindex_entry *revindex;
 122         const uint32_t *revindex_data;
 123         const uint32_t *revindex_map;
 124         size_t revindex_size;
 125         /*
 126          * mtimes_map points at the beginning of the memory mapped region of
 127          * this pack's corresponding .mtimes file, and mtimes_size is the size
 128          * of that .mtimes file
 129          */
 130         const uint32_t *mtimes_map;
 131         size_t mtimes_size;
 132         /* something like ".git/objects/pack/xxxxx.pack" */
 133         char pack_name[FLEX_ARRAY]; /* more */
 134 };
 135
 136 struct multi_pack_index;
 137
 138 static inline int pack_map_entry_cmp(const void *unused_cmp_data,
 139                                      const struct hashmap_entry *entry,
 140                                      const struct hashmap_entry *entry2,
 141                                      const void *keydata)
 142 {
 143         const char *key = keydata;
 144         const struct packed_git *pg1, *pg2;
 145
 146         pg1 = container_of(entry, const struct packed_git, packmap_ent);
 147         pg2 = container_of(entry2, const struct packed_git, packmap_ent);
 148
 149         return strcmp(pg1->pack_name, key ? key : pg2->pack_name);
 150 }
 151
 152 struct raw_object_store {
 153         /*
 154          * Set of all object directories; the main directory is first (and
 155          * cannot be NULL after initialization). Subsequent directories are
 156          * alternates.
 157          */
 158         struct object_directory *odb;
 159         struct object_directory **odb_tail;
 160         kh_odb_path_map_t *odb_by_path;
 161
 162         int loaded_alternates;
 163
 164         /*
 165          * A list of alternate object directories loaded from the environment;
 166          * this should not generally need to be accessed directly, but will
 167          * populate the "odb" list when prepare_alt_odb() is run.
 168          */
 169         char *alternate_db;
 170
 171         /*
 172          * Objects that should be substituted by other objects
 173          * (see git-replace(1)).
 174          */
 175         struct oidmap *replace_map;
 176         unsigned replace_map_initialized : 1;
 177         pthread_mutex_t replace_mutex; /* protect object replace functions */
 178
 179         struct commit_graph *commit_graph;
 180         unsigned commit_graph_attempted : 1; /* if loading has been attempted */
 181
 182         /*
 183          * private data
 184          *
 185          * should only be accessed directly by packfile.c and midx.c
 186          */
 187         struct multi_pack_index *multi_pack_index;
 188
 189         /*
 190          * private data
 191          *
 192          * should only be accessed directly by packfile.c
 193          */
 194
 195         struct packed_git *packed_git;
 196         /* A most-recently-used ordered version of the packed_git list. */
 197         struct list_head packed_git_mru;
 198
 199         struct {
 200                 struct packed_git **packs;
 201                 unsigned flags;
 202         } kept_pack_cache;
 203
 204         /*
 205          * A map of packfiles to packed_git structs for tracking which
 206          * packs have been loaded already.
 207          */
 208         struct hashmap pack_map;
 209
 210         /*
 211          * A fast, rough count of the number of objects in the repository.
 212          * These two fields are not meant for direct access. Use
 213          * approximate_object_count() instead.
 214          */
 215         unsigned long approximate_object_count;
 216         unsigned approximate_object_count_valid : 1;
 217
 218         /*
 219          * Whether packed_git has already been populated with this repository's
 220          * packs.
 221          */
 222         unsigned packed_git_initialized : 1;
 223 };
 224
 225 struct raw_object_store *raw_object_store_new(void);
 226 void raw_object_store_clear(struct raw_object_store *o);
 227
 228 /*
 229  * Put in `buf` the name of the file in the local object database that
 230  * would be used to store a loose object with the specified oid.
 231  */
 232 const char *loose_object_path(struct repository *r, struct strbuf *buf,
 233                               const struct object_id *oid);
 234
 235 void *map_loose_object(struct repository *r, const struct object_id *oid,
 236                        unsigned long *size);
 237
 238 void *read_object_file_extended(struct repository *r,
 239                                 const struct object_id *oid,
 240                                 enum object_type *type,
 241                                 unsigned long *size, int lookup_replace);
 242 static inline void *repo_read_object_file(struct repository *r,
 243                                           const struct object_id *oid,
 244                                           enum object_type *type,
 245                                           unsigned long *size)
 246 {
 247         return read_object_file_extended(r, oid, type, size, 1);
 248 }
 249 #ifndef NO_THE_REPOSITORY_COMPATIBILITY_MACROS
 250 #define read_object_file(oid, type, size) repo_read_object_file(the_repository, oid, type, size)
 251 #endif
 252
 253 /* Read and unpack an object file into memory, write memory to an object file */
 254 int oid_object_info(struct repository *r, const struct object_id *, unsigned long *);
 255
 256 void hash_object_file(const struct git_hash_algo *algo, const void *buf,
 257                       unsigned long len, enum object_type type,
 258                       struct object_id *oid);
 259
 260 int write_object_file_flags(const void *buf, unsigned long len,
 261                             enum object_type type, struct object_id *oid,
 262                             unsigned flags);
 263 static inline int write_object_file(const void *buf, unsigned long len,
 264                                     enum object_type type, struct object_id *oid)
 265 {
 266         return write_object_file_flags(buf, len, type, oid, 0);
 267 }
 268
 269 int write_object_file_literally(const void *buf, unsigned long len,
 270                                 const char *type, struct object_id *oid,
 271                                 unsigned flags);
 272
 273 /*
 274  * Add an object file to the in-memory object store, without writing it
 275  * to disk.
 276  *
 277  * Callers are responsible for calling write_object_file to record the
 278  * object in persistent storage before writing any other new objects
 279  * that reference it.
 280  */
 281 int pretend_object_file(void *, unsigned long, enum object_type,
 282                         struct object_id *oid);
 283
 284 int force_object_loose(const struct object_id *oid, time_t mtime);
 285
 286 /*
 287  * Open the loose object at path, check its hash, and return the contents,
 288  * use the "oi" argument to assert things about the object, or e.g. populate its
 289  * type, and size. If the object is a blob, then "contents" may return NULL,
 290  * to allow streaming of large blobs.
 291  *
 292  * Returns 0 on success, negative on error (details may be written to stderr).
 293  */
 294 int read_loose_object(const char *path,
 295                       const struct object_id *expected_oid,
 296                       struct object_id *real_oid,
 297                       void **contents,
 298                       struct object_info *oi);
 299
 300 /* Retry packed storage after checking packed and loose storage */
 301 #define HAS_OBJECT_RECHECK_PACKED 1
 302
 303 /*
 304  * Returns 1 if the object exists. This function will not lazily fetch objects
 305  * in a partial clone.
 306  */
 307 int has_object(struct repository *r, const struct object_id *oid,
 308                unsigned flags);
 309
 310 /*
 311  * These macros and functions are deprecated. If checking existence for an
 312  * object that is likely to be missing and/or whose absence is relatively
 313  * inconsequential (or is consequential but the caller is prepared to handle
 314  * it), use has_object(), which has better defaults (no lazy fetch in a partial
 315  * clone and no rechecking of packed storage). In the unlikely event that a
 316  * caller needs to assert existence of an object that it fully expects to
 317  * exist, and wants to trigger a lazy fetch in a partial clone, use
 318  * oid_object_info_extended() with a NULL struct object_info.
 319  *
 320  * These functions can be removed once all callers have migrated to
 321  * has_object() and/or oid_object_info_extended().
 322  */
 323 int repo_has_object_file(struct repository *r, const struct object_id *oid);
 324 int repo_has_object_file_with_flags(struct repository *r,
 325                                     const struct object_id *oid, int flags);
 326 #ifndef NO_THE_REPOSITORY_COMPATIBILITY_MACROS
 327 #define has_object_file(oid) repo_has_object_file(the_repository, oid)
 328 #define has_object_file_with_flags(oid, flags) repo_has_object_file_with_flags(the_repository, oid, flags)
 329 #endif
 330
 331 /*
 332  * Return true iff an alternate object database has a loose object
 333  * with the specified name.  This function does not respect replace
 334  * references.
 335  */
 336 int has_loose_object_nonlocal(const struct object_id *);
 337
 338 int has_loose_object(const struct object_id *);
 339
 340 /**
 341  * format_object_header() is a thin wrapper around s xsnprintf() that
 342  * writes the initial "<type> <obj-len>" part of the loose object
 343  * header. It returns the size that snprintf() returns + 1.
 344  */
 345 int format_object_header(char *str, size_t size, enum object_type type,
 346                          size_t objsize);
 347
 348 void assert_oid_type(const struct object_id *oid, enum object_type expect);
 349
 350 /*
 351  * Enabling the object read lock allows multiple threads to safely call the
 352  * following functions in parallel: repo_read_object_file(), read_object_file(),
 353  * read_object_file_extended(), read_object_with_reference(), read_object(),
 354  * oid_object_info() and oid_object_info_extended().
 355  *
 356  * obj_read_lock() and obj_read_unlock() may also be used to protect other
 357  * section which cannot execute in parallel with object reading. Since the used
 358  * lock is a recursive mutex, these sections can even contain calls to object
 359  * reading functions. However, beware that in these cases zlib inflation won't
 360  * be performed in parallel, losing performance.
 361  *
 362  * TODO: oid_object_info_extended()'s call stack has a recursive behavior. If
 363  * any of its callees end up calling it, this recursive call won't benefit from
 364  * parallel inflation.
 365  */
 366 void enable_obj_read_lock(void);
 367 void disable_obj_read_lock(void);
 368
 369 extern int obj_read_use_lock;
 370 extern pthread_mutex_t obj_read_mutex;
 371
 372 static inline void obj_read_lock(void)
 373 {
 374         if(obj_read_use_lock)
 375                 pthread_mutex_lock(&obj_read_mutex);
 376 }
 377
 378 static inline void obj_read_unlock(void)
 379 {
 380         if(obj_read_use_lock)
 381                 pthread_mutex_unlock(&obj_read_mutex);
 382 }
 383
 384 struct object_info {
 385         /* Request */
 386         enum object_type *typep;
 387         unsigned long *sizep;
 388         off_t *disk_sizep;
 389         struct object_id *delta_base_oid;
 390         struct strbuf *type_name;
 391         void **contentp;
 392
 393         /* Response */
 394         enum {
 395                 OI_CACHED,
 396                 OI_LOOSE,
 397                 OI_PACKED,
 398                 OI_DBCACHED
 399         } whence;
 400         union {
 401                 /*
 402                  * struct {
 403                  *      ... Nothing to expose in this case
 404                  * } cached;
 405                  * struct {
 406                  *      ... Nothing to expose in this case
 407                  * } loose;
 408                  */
 409                 struct {
 410                         struct packed_git *pack;
 411                         off_t offset;
 412                         unsigned int is_delta;
 413                 } packed;
 414         } u;
 415 };
 416
 417 /*
 418  * Initializer for a "struct object_info" that wants no items. You may
 419  * also memset() the memory to all-zeroes.
 420  */
 421 #define OBJECT_INFO_INIT { 0 }
 422
 423 /* Invoke lookup_replace_object() on the given hash */
 424 #define OBJECT_INFO_LOOKUP_REPLACE 1
 425 /* Allow reading from a loose object file of unknown/bogus type */
 426 #define OBJECT_INFO_ALLOW_UNKNOWN_TYPE 2
 427 /* Do not retry packed storage after checking packed and loose storage */
 428 #define OBJECT_INFO_QUICK 8
 429 /* Do not check loose object */
 430 #define OBJECT_INFO_IGNORE_LOOSE 16
 431 /*
 432  * Do not attempt to fetch the object if missing (even if fetch_is_missing is
 433  * nonzero).
 434  */
 435 #define OBJECT_INFO_SKIP_FETCH_OBJECT 32
 436 /*
 437  * This is meant for bulk prefetching of missing blobs in a partial
 438  * clone. Implies OBJECT_INFO_SKIP_FETCH_OBJECT and OBJECT_INFO_QUICK
 439  */
 440 #define OBJECT_INFO_FOR_PREFETCH (OBJECT_INFO_SKIP_FETCH_OBJECT | OBJECT_INFO_QUICK)
 441
 442 int oid_object_info_extended(struct repository *r,
 443                              const struct object_id *,
 444                              struct object_info *, unsigned flags);
 445
 446 /*
 447  * Iterate over the files in the loose-object parts of the object
 448  * directory "path", triggering the following callbacks:
 449  *
 450  *  - loose_object is called for each loose object we find.
 451  *
 452  *  - loose_cruft is called for any files that do not appear to be
 453  *    loose objects. Note that we only look in the loose object
 454  *    directories "objects/[0-9a-f]{2}/", so we will not report
 455  *    "objects/foobar" as cruft.
 456  *
 457  *  - loose_subdir is called for each top-level hashed subdirectory
 458  *    of the object directory (e.g., "$OBJDIR/f0"). It is called
 459  *    after the objects in the directory are processed.
 460  *
 461  * Any callback that is NULL will be ignored. Callbacks returning non-zero
 462  * will end the iteration.
 463  *
 464  * In the "buf" variant, "path" is a strbuf which will also be used as a
 465  * scratch buffer, but restored to its original contents before
 466  * the function returns.
 467  */
 468 typedef int each_loose_object_fn(const struct object_id *oid,
 469                                  const char *path,
 470                                  void *data);
 471 typedef int each_loose_cruft_fn(const char *basename,
 472                                 const char *path,
 473                                 void *data);
 474 typedef int each_loose_subdir_fn(unsigned int nr,
 475                                  const char *path,
 476                                  void *data);
 477 int for_each_file_in_obj_subdir(unsigned int subdir_nr,
 478                                 struct strbuf *path,
 479                                 each_loose_object_fn obj_cb,
 480                                 each_loose_cruft_fn cruft_cb,
 481                                 each_loose_subdir_fn subdir_cb,
 482                                 void *data);
 483 int for_each_loose_file_in_objdir(const char *path,
 484                                   each_loose_object_fn obj_cb,
 485                                   each_loose_cruft_fn cruft_cb,
 486                                   each_loose_subdir_fn subdir_cb,
 487                                   void *data);
 488 int for_each_loose_file_in_objdir_buf(struct strbuf *path,
 489                                       each_loose_object_fn obj_cb,
 490                                       each_loose_cruft_fn cruft_cb,
 491                                       each_loose_subdir_fn subdir_cb,
 492                                       void *data);
 493
 494 /* Flags for for_each_*_object() below. */
 495 enum for_each_object_flags {
 496         /* Iterate only over local objects, not alternates. */
 497         FOR_EACH_OBJECT_LOCAL_ONLY = (1<<0),
 498
 499         /* Only iterate over packs obtained from the promisor remote. */
 500         FOR_EACH_OBJECT_PROMISOR_ONLY = (1<<1),
 501
 502         /*
 503          * Visit objects within a pack in packfile order rather than .idx order
 504          */
 505         FOR_EACH_OBJECT_PACK_ORDER = (1<<2),
 506
 507         /* Only iterate over packs that are not marked as kept in-core. */
 508         FOR_EACH_OBJECT_SKIP_IN_CORE_KEPT_PACKS = (1<<3),
 509
 510         /* Only iterate over packs that do not have .keep files. */
 511         FOR_EACH_OBJECT_SKIP_ON_DISK_KEPT_PACKS = (1<<4),
 512 };
 513
 514 /*
 515  * Iterate over all accessible loose objects without respect to
 516  * reachability. By default, this includes both local and alternate objects.
 517  * The order in which objects are visited is unspecified.
 518  *
 519  * Any flags specific to packs are ignored.
 520  */
 521 int for_each_loose_object(each_loose_object_fn, void *,
 522                           enum for_each_object_flags flags);
 523
 524 /*
 525  * Iterate over all accessible packed objects without respect to reachability.
 526  * By default, this includes both local and alternate packs.
 527  *
 528  * Note that some objects may appear twice if they are found in multiple packs.
 529  * Each pack is visited in an unspecified order. By default, objects within a
 530  * pack are visited in pack-idx order (i.e., sorted by oid).
 531  */
 532 typedef int each_packed_object_fn(const struct object_id *oid,
 533                                   struct packed_git *pack,
 534                                   uint32_t pos,
 535                                   void *data);
 536 int for_each_object_in_pack(struct packed_git *p,
 537                             each_packed_object_fn, void *data,
 538                             enum for_each_object_flags flags);
 539 int for_each_packed_object(each_packed_object_fn, void *,
 540                            enum for_each_object_flags flags);
 541
 542 #endif /* OBJECT_STORE_H */