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         unsigned char hash[GIT_MAX_RAWSZ];
 120         struct revindex_entry *revindex;
 121         const uint32_t *revindex_data;
 122         const uint32_t *revindex_map;
 123         size_t revindex_size;
 124         /* something like ".git/objects/pack/xxxxx.pack" */
 125         char pack_name[FLEX_ARRAY]; /* more */
 126 };
 127
 128 struct multi_pack_index;
 129
 130 static inline int pack_map_entry_cmp(const void *unused_cmp_data,
 131                                      const struct hashmap_entry *entry,
 132                                      const struct hashmap_entry *entry2,
 133                                      const void *keydata)
 134 {
 135         const char *key = keydata;
 136         const struct packed_git *pg1, *pg2;
 137
 138         pg1 = container_of(entry, const struct packed_git, packmap_ent);
 139         pg2 = container_of(entry2, const struct packed_git, packmap_ent);
 140
 141         return strcmp(pg1->pack_name, key ? key : pg2->pack_name);
 142 }
 143
 144 struct raw_object_store {
 145         /*
 146          * Set of all object directories; the main directory is first (and
 147          * cannot be NULL after initialization). Subsequent directories are
 148          * alternates.
 149          */
 150         struct object_directory *odb;
 151         struct object_directory **odb_tail;
 152         kh_odb_path_map_t *odb_by_path;
 153
 154         int loaded_alternates;
 155
 156         /*
 157          * A list of alternate object directories loaded from the environment;
 158          * this should not generally need to be accessed directly, but will
 159          * populate the "odb" list when prepare_alt_odb() is run.
 160          */
 161         char *alternate_db;
 162
 163         /*
 164          * Objects that should be substituted by other objects
 165          * (see git-replace(1)).
 166          */
 167         struct oidmap *replace_map;
 168         unsigned replace_map_initialized : 1;
 169         pthread_mutex_t replace_mutex; /* protect object replace functions */
 170
 171         struct commit_graph *commit_graph;
 172         unsigned commit_graph_attempted : 1; /* if loading has been attempted */
 173
 174         /*
 175          * private data
 176          *
 177          * should only be accessed directly by packfile.c and midx.c
 178          */
 179         struct multi_pack_index *multi_pack_index;
 180
 181         /*
 182          * private data
 183          *
 184          * should only be accessed directly by packfile.c
 185          */
 186
 187         struct packed_git *packed_git;
 188         /* A most-recently-used ordered version of the packed_git list. */
 189         struct list_head packed_git_mru;
 190
 191         struct {
 192                 struct packed_git **packs;
 193                 unsigned flags;
 194         } kept_pack_cache;
 195
 196         /*
 197          * A map of packfiles to packed_git structs for tracking which
 198          * packs have been loaded already.
 199          */
 200         struct hashmap pack_map;
 201
 202         /*
 203          * A fast, rough count of the number of objects in the repository.
 204          * These two fields are not meant for direct access. Use
 205          * approximate_object_count() instead.
 206          */
 207         unsigned long approximate_object_count;
 208         unsigned approximate_object_count_valid : 1;
 209
 210         /*
 211          * Whether packed_git has already been populated with this repository's
 212          * packs.
 213          */
 214         unsigned packed_git_initialized : 1;
 215 };
 216
 217 struct raw_object_store *raw_object_store_new(void);
 218 void raw_object_store_clear(struct raw_object_store *o);
 219
 220 /*
 221  * Put in `buf` the name of the file in the local object database that
 222  * would be used to store a loose object with the specified oid.
 223  */
 224 const char *loose_object_path(struct repository *r, struct strbuf *buf,
 225                               const struct object_id *oid);
 226
 227 void *map_loose_object(struct repository *r, const struct object_id *oid,
 228                        unsigned long *size);
 229
 230 void *read_object_file_extended(struct repository *r,
 231                                 const struct object_id *oid,
 232                                 enum object_type *type,
 233                                 unsigned long *size, int lookup_replace);
 234 static inline void *repo_read_object_file(struct repository *r,
 235                                           const struct object_id *oid,
 236                                           enum object_type *type,
 237                                           unsigned long *size)
 238 {
 239         return read_object_file_extended(r, oid, type, size, 1);
 240 }
 241 #ifndef NO_THE_REPOSITORY_COMPATIBILITY_MACROS
 242 #define read_object_file(oid, type, size) repo_read_object_file(the_repository, oid, type, size)
 243 #endif
 244
 245 /* Read and unpack an object file into memory, write memory to an object file */
 246 int oid_object_info(struct repository *r, const struct object_id *, unsigned long *);
 247
 248 void hash_object_file(const struct git_hash_algo *algo, const void *buf,
 249                       unsigned long len, enum object_type type,
 250                       struct object_id *oid);
 251
 252 int write_object_file_flags(const void *buf, unsigned long len,
 253                             enum object_type type, struct object_id *oid,
 254                             unsigned flags);
 255 static inline int write_object_file(const void *buf, unsigned long len,
 256                                     enum object_type type, struct object_id *oid)
 257 {
 258         return write_object_file_flags(buf, len, type, oid, 0);
 259 }
 260
 261 int write_object_file_literally(const void *buf, unsigned long len,
 262                                 const char *type, struct object_id *oid,
 263                                 unsigned flags);
 264
 265 /*
 266  * Add an object file to the in-memory object store, without writing it
 267  * to disk.
 268  *
 269  * Callers are responsible for calling write_object_file to record the
 270  * object in persistent storage before writing any other new objects
 271  * that reference it.
 272  */
 273 int pretend_object_file(void *, unsigned long, enum object_type,
 274                         struct object_id *oid);
 275
 276 int force_object_loose(const struct object_id *oid, time_t mtime);
 277
 278 /*
 279  * Open the loose object at path, check its hash, and return the contents,
 280  * use the "oi" argument to assert things about the object, or e.g. populate its
 281  * type, and size. If the object is a blob, then "contents" may return NULL,
 282  * to allow streaming of large blobs.
 283  *
 284  * Returns 0 on success, negative on error (details may be written to stderr).
 285  */
 286 int read_loose_object(const char *path,
 287                       const struct object_id *expected_oid,
 288                       struct object_id *real_oid,
 289                       void **contents,
 290                       struct object_info *oi);
 291
 292 /* Retry packed storage after checking packed and loose storage */
 293 #define HAS_OBJECT_RECHECK_PACKED 1
 294
 295 /*
 296  * Returns 1 if the object exists. This function will not lazily fetch objects
 297  * in a partial clone.
 298  */
 299 int has_object(struct repository *r, const struct object_id *oid,
 300                unsigned flags);
 301
 302 /*
 303  * These macros and functions are deprecated. If checking existence for an
 304  * object that is likely to be missing and/or whose absence is relatively
 305  * inconsequential (or is consequential but the caller is prepared to handle
 306  * it), use has_object(), which has better defaults (no lazy fetch in a partial
 307  * clone and no rechecking of packed storage). In the unlikely event that a
 308  * caller needs to assert existence of an object that it fully expects to
 309  * exist, and wants to trigger a lazy fetch in a partial clone, use
 310  * oid_object_info_extended() with a NULL struct object_info.
 311  *
 312  * These functions can be removed once all callers have migrated to
 313  * has_object() and/or oid_object_info_extended().
 314  */
 315 int repo_has_object_file(struct repository *r, const struct object_id *oid);
 316 int repo_has_object_file_with_flags(struct repository *r,
 317                                     const struct object_id *oid, int flags);
 318 #ifndef NO_THE_REPOSITORY_COMPATIBILITY_MACROS
 319 #define has_object_file(oid) repo_has_object_file(the_repository, oid)
 320 #define has_object_file_with_flags(oid, flags) repo_has_object_file_with_flags(the_repository, oid, flags)
 321 #endif
 322
 323 /*
 324  * Return true iff an alternate object database has a loose object
 325  * with the specified name.  This function does not respect replace
 326  * references.
 327  */
 328 int has_loose_object_nonlocal(const struct object_id *);
 329
 330 /**
 331  * format_object_header() is a thin wrapper around s xsnprintf() that
 332  * writes the initial "<type> <obj-len>" part of the loose object
 333  * header. It returns the size that snprintf() returns + 1.
 334  */
 335 int format_object_header(char *str, size_t size, enum object_type type,
 336                          size_t objsize);
 337
 338 void assert_oid_type(const struct object_id *oid, enum object_type expect);
 339
 340 /*
 341  * Enabling the object read lock allows multiple threads to safely call the
 342  * following functions in parallel: repo_read_object_file(), read_object_file(),
 343  * read_object_file_extended(), read_object_with_reference(), read_object(),
 344  * oid_object_info() and oid_object_info_extended().
 345  *
 346  * obj_read_lock() and obj_read_unlock() may also be used to protect other
 347  * section which cannot execute in parallel with object reading. Since the used
 348  * lock is a recursive mutex, these sections can even contain calls to object
 349  * reading functions. However, beware that in these cases zlib inflation won't
 350  * be performed in parallel, losing performance.
 351  *
 352  * TODO: oid_object_info_extended()'s call stack has a recursive behavior. If
 353  * any of its callees end up calling it, this recursive call won't benefit from
 354  * parallel inflation.
 355  */
 356 void enable_obj_read_lock(void);
 357 void disable_obj_read_lock(void);
 358
 359 extern int obj_read_use_lock;
 360 extern pthread_mutex_t obj_read_mutex;
 361
 362 static inline void obj_read_lock(void)
 363 {
 364         if(obj_read_use_lock)
 365                 pthread_mutex_lock(&obj_read_mutex);
 366 }
 367
 368 static inline void obj_read_unlock(void)
 369 {
 370         if(obj_read_use_lock)
 371                 pthread_mutex_unlock(&obj_read_mutex);
 372 }
 373
 374 struct object_info {
 375         /* Request */
 376         enum object_type *typep;
 377         unsigned long *sizep;
 378         off_t *disk_sizep;
 379         struct object_id *delta_base_oid;
 380         struct strbuf *type_name;
 381         void **contentp;
 382
 383         /* Response */
 384         enum {
 385                 OI_CACHED,
 386                 OI_LOOSE,
 387                 OI_PACKED,
 388                 OI_DBCACHED
 389         } whence;
 390         union {
 391                 /*
 392                  * struct {
 393                  *      ... Nothing to expose in this case
 394                  * } cached;
 395                  * struct {
 396                  *      ... Nothing to expose in this case
 397                  * } loose;
 398                  */
 399                 struct {
 400                         struct packed_git *pack;
 401                         off_t offset;
 402                         unsigned int is_delta;
 403                 } packed;
 404         } u;
 405 };
 406
 407 /*
 408  * Initializer for a "struct object_info" that wants no items. You may
 409  * also memset() the memory to all-zeroes.
 410  */
 411 #define OBJECT_INFO_INIT { 0 }
 412
 413 /* Invoke lookup_replace_object() on the given hash */
 414 #define OBJECT_INFO_LOOKUP_REPLACE 1
 415 /* Allow reading from a loose object file of unknown/bogus type */
 416 #define OBJECT_INFO_ALLOW_UNKNOWN_TYPE 2
 417 /* Do not retry packed storage after checking packed and loose storage */
 418 #define OBJECT_INFO_QUICK 8
 419 /* Do not check loose object */
 420 #define OBJECT_INFO_IGNORE_LOOSE 16
 421 /*
 422  * Do not attempt to fetch the object if missing (even if fetch_is_missing is
 423  * nonzero).
 424  */
 425 #define OBJECT_INFO_SKIP_FETCH_OBJECT 32
 426 /*
 427  * This is meant for bulk prefetching of missing blobs in a partial
 428  * clone. Implies OBJECT_INFO_SKIP_FETCH_OBJECT and OBJECT_INFO_QUICK
 429  */
 430 #define OBJECT_INFO_FOR_PREFETCH (OBJECT_INFO_SKIP_FETCH_OBJECT | OBJECT_INFO_QUICK)
 431
 432 int oid_object_info_extended(struct repository *r,
 433                              const struct object_id *,
 434                              struct object_info *, unsigned flags);
 435
 436 /*
 437  * Iterate over the files in the loose-object parts of the object
 438  * directory "path", triggering the following callbacks:
 439  *
 440  *  - loose_object is called for each loose object we find.
 441  *
 442  *  - loose_cruft is called for any files that do not appear to be
 443  *    loose objects. Note that we only look in the loose object
 444  *    directories "objects/[0-9a-f]{2}/", so we will not report
 445  *    "objects/foobar" as cruft.
 446  *
 447  *  - loose_subdir is called for each top-level hashed subdirectory
 448  *    of the object directory (e.g., "$OBJDIR/f0"). It is called
 449  *    after the objects in the directory are processed.
 450  *
 451  * Any callback that is NULL will be ignored. Callbacks returning non-zero
 452  * will end the iteration.
 453  *
 454  * In the "buf" variant, "path" is a strbuf which will also be used as a
 455  * scratch buffer, but restored to its original contents before
 456  * the function returns.
 457  */
 458 typedef int each_loose_object_fn(const struct object_id *oid,
 459                                  const char *path,
 460                                  void *data);
 461 typedef int each_loose_cruft_fn(const char *basename,
 462                                 const char *path,
 463                                 void *data);
 464 typedef int each_loose_subdir_fn(unsigned int nr,
 465                                  const char *path,
 466                                  void *data);
 467 int for_each_file_in_obj_subdir(unsigned int subdir_nr,
 468                                 struct strbuf *path,
 469                                 each_loose_object_fn obj_cb,
 470                                 each_loose_cruft_fn cruft_cb,
 471                                 each_loose_subdir_fn subdir_cb,
 472                                 void *data);
 473 int for_each_loose_file_in_objdir(const char *path,
 474                                   each_loose_object_fn obj_cb,
 475                                   each_loose_cruft_fn cruft_cb,
 476                                   each_loose_subdir_fn subdir_cb,
 477                                   void *data);
 478 int for_each_loose_file_in_objdir_buf(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
 484 /* Flags for for_each_*_object() below. */
 485 enum for_each_object_flags {
 486         /* Iterate only over local objects, not alternates. */
 487         FOR_EACH_OBJECT_LOCAL_ONLY = (1<<0),
 488
 489         /* Only iterate over packs obtained from the promisor remote. */
 490         FOR_EACH_OBJECT_PROMISOR_ONLY = (1<<1),
 491
 492         /*
 493          * Visit objects within a pack in packfile order rather than .idx order
 494          */
 495         FOR_EACH_OBJECT_PACK_ORDER = (1<<2),
 496
 497         /* Only iterate over packs that are not marked as kept in-core. */
 498         FOR_EACH_OBJECT_SKIP_IN_CORE_KEPT_PACKS = (1<<3),
 499
 500         /* Only iterate over packs that do not have .keep files. */
 501         FOR_EACH_OBJECT_SKIP_ON_DISK_KEPT_PACKS = (1<<4),
 502 };
 503
 504 /*
 505  * Iterate over all accessible loose objects without respect to
 506  * reachability. By default, this includes both local and alternate objects.
 507  * The order in which objects are visited is unspecified.
 508  *
 509  * Any flags specific to packs are ignored.
 510  */
 511 int for_each_loose_object(each_loose_object_fn, void *,
 512                           enum for_each_object_flags flags);
 513
 514 /*
 515  * Iterate over all accessible packed objects without respect to reachability.
 516  * By default, this includes both local and alternate packs.
 517  *
 518  * Note that some objects may appear twice if they are found in multiple packs.
 519  * Each pack is visited in an unspecified order. By default, objects within a
 520  * pack are visited in pack-idx order (i.e., sorted by oid).
 521  */
 522 typedef int each_packed_object_fn(const struct object_id *oid,
 523                                   struct packed_git *pack,
 524                                   uint32_t pos,
 525                                   void *data);
 526 int for_each_object_in_pack(struct packed_git *p,
 527                             each_packed_object_fn, void *data,
 528                             enum for_each_object_flags flags);
 529 int for_each_packed_object(each_packed_object_fn, void *,
 530                            enum for_each_object_flags flags);
 531
 532 #endif /* OBJECT_STORE_H */