object-store.h

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