name-hash.c

   1 /*
   2  * name-hash.c
   3  *
   4  * Hashing names in the index state
   5  *
   6  * Copyright (C) 2008 Linus Torvalds
   7  */
   8 #include "cache.h"
   9 #include "thread-utils.h"
  10
  11 struct dir_entry {
  12         struct hashmap_entry ent;
  13         struct dir_entry *parent;
  14         int nr;
  15         unsigned int namelen;
  16         char name[FLEX_ARRAY];
  17 };
  18
  19 static int dir_entry_cmp(const void *unused_cmp_data,
  20                          const struct hashmap_entry *eptr,
  21                          const struct hashmap_entry *entry_or_key,
  22                          const void *keydata)
  23 {
  24         const struct dir_entry *e1, *e2;
  25         const char *name = keydata;
  26
  27         e1 = container_of(eptr, const struct dir_entry, ent);
  28         e2 = container_of(entry_or_key, const struct dir_entry, ent);
  29
  30         return e1->namelen != e2->namelen || strncasecmp(e1->name,
  31                         name ? name : e2->name, e1->namelen);
  32 }
  33
  34 static struct dir_entry *find_dir_entry__hash(struct index_state *istate,
  35                 const char *name, unsigned int namelen, unsigned int hash)
  36 {
  37         struct dir_entry key;
  38         hashmap_entry_init(&key.ent, hash);
  39         key.namelen = namelen;
  40         return hashmap_get_entry(&istate->dir_hash, &key, ent, name);
  41 }
  42
  43 static struct dir_entry *find_dir_entry(struct index_state *istate,
  44                 const char *name, unsigned int namelen)
  45 {
  46         return find_dir_entry__hash(istate, name, namelen, memihash(name, namelen));
  47 }
  48
  49 static struct dir_entry *hash_dir_entry(struct index_state *istate,
  50                 struct cache_entry *ce, int namelen)
  51 {
  52         /*
  53          * Throw each directory component in the hash for quick lookup
  54          * during a git status. Directory components are stored without their
  55          * closing slash.  Despite submodules being a directory, they never
  56          * reach this point, because they are stored
  57          * in index_state.name_hash (as ordinary cache_entries).
  58          */
  59         struct dir_entry *dir;
  60
  61         /* get length of parent directory */
  62         while (namelen > 0 && !is_dir_sep(ce->name[namelen - 1]))
  63                 namelen--;
  64         if (namelen <= 0)
  65                 return NULL;
  66         namelen--;
  67
  68         /* lookup existing entry for that directory */
  69         dir = find_dir_entry(istate, ce->name, namelen);
  70         if (!dir) {
  71                 /* not found, create it and add to hash table */
  72                 FLEX_ALLOC_MEM(dir, name, ce->name, namelen);
  73                 hashmap_entry_init(&dir->ent, memihash(ce->name, namelen));
  74                 dir->namelen = namelen;
  75                 hashmap_add(&istate->dir_hash, &dir->ent);
  76
  77                 /* recursively add missing parent directories */
  78                 dir->parent = hash_dir_entry(istate, ce, namelen);
  79         }
  80         return dir;
  81 }
  82
  83 static void add_dir_entry(struct index_state *istate, struct cache_entry *ce)
  84 {
  85         /* Add reference to the directory entry (and parents if 0). */
  86         struct dir_entry *dir = hash_dir_entry(istate, ce, ce_namelen(ce));
  87         while (dir && !(dir->nr++))
  88                 dir = dir->parent;
  89 }
  90
  91 static void remove_dir_entry(struct index_state *istate, struct cache_entry *ce)
  92 {
  93         /*
  94          * Release reference to the directory entry. If 0, remove and continue
  95          * with parent directory.
  96          */
  97         struct dir_entry *dir = hash_dir_entry(istate, ce, ce_namelen(ce));
  98         while (dir && !(--dir->nr)) {
  99                 struct dir_entry *parent = dir->parent;
 100                 hashmap_remove(&istate->dir_hash, &dir->ent, NULL);
 101                 free(dir);
 102                 dir = parent;
 103         }
 104 }
 105
 106 static void hash_index_entry(struct index_state *istate, struct cache_entry *ce)
 107 {
 108         if (ce->ce_flags & CE_HASHED)
 109                 return;
 110         ce->ce_flags |= CE_HASHED;
 111         hashmap_entry_init(&ce->ent, memihash(ce->name, ce_namelen(ce)));
 112         hashmap_add(&istate->name_hash, &ce->ent);
 113
 114         if (ignore_case)
 115                 add_dir_entry(istate, ce);
 116 }
 117
 118 static int cache_entry_cmp(const void *unused_cmp_data,
 119                            const struct hashmap_entry *eptr,
 120                            const struct hashmap_entry *entry_or_key,
 121                            const void *remove)
 122 {
 123         const struct cache_entry *ce1, *ce2;
 124
 125         ce1 = container_of(eptr, const struct cache_entry, ent);
 126         ce2 = container_of(entry_or_key, const struct cache_entry, ent);
 127
 128         /*
 129          * For remove_name_hash, find the exact entry (pointer equality); for
 130          * index_file_exists, find all entries with matching hash code and
 131          * decide whether the entry matches in same_name.
 132          */
 133         return remove ? !(ce1 == ce2) : 0;
 134 }
 135
 136 static int lazy_try_threaded = 1;
 137 static int lazy_nr_dir_threads;
 138
 139 /*
 140  * Set a minimum number of cache_entries that we will handle per
 141  * thread and use that to decide how many threads to run (upto
 142  * the number on the system).
 143  *
 144  * For guidance setting the lower per-thread bound, see:
 145  *     t/helper/test-lazy-init-name-hash --analyze
 146  */
 147 #define LAZY_THREAD_COST (2000)
 148
 149 /*
 150  * We use n mutexes to guard n partitions of the "istate->dir_hash"
 151  * hashtable.  Since "find" and "insert" operations will hash to a
 152  * particular bucket and modify/search a single chain, we can say
 153  * that "all chains mod n" are guarded by the same mutex -- rather
 154  * than having a single mutex to guard the entire table.  (This does
 155  * require that we disable "rehashing" on the hashtable.)
 156  *
 157  * So, a larger value here decreases the probability of a collision
 158  * and the time that each thread must wait for the mutex.
 159  */
 160 #define LAZY_MAX_MUTEX   (32)
 161
 162 static pthread_mutex_t *lazy_dir_mutex_array;
 163
 164 /*
 165  * An array of lazy_entry items is used by the n threads in
 166  * the directory parse (first) phase to (lock-free) store the
 167  * intermediate results.  These values are then referenced by
 168  * the 2 threads in the second phase.
 169  */
 170 struct lazy_entry {
 171         struct dir_entry *dir;
 172         unsigned int hash_dir;
 173         unsigned int hash_name;
 174 };
 175
 176 /*
 177  * Decide if we want to use threads (if available) to load
 178  * the hash tables.  We set "lazy_nr_dir_threads" to zero when
 179  * it is not worth it.
 180  */
 181 static int lookup_lazy_params(struct index_state *istate)
 182 {
 183         int nr_cpus;
 184
 185         lazy_nr_dir_threads = 0;
 186
 187         if (!lazy_try_threaded)
 188                 return 0;
 189
 190         /*
 191          * If we are respecting case, just use the original
 192          * code to build the "istate->name_hash".  We don't
 193          * need the complexity here.
 194          */
 195         if (!ignore_case)
 196                 return 0;
 197
 198         nr_cpus = online_cpus();
 199         if (nr_cpus < 2)
 200                 return 0;
 201
 202         if (istate->cache_nr < 2 * LAZY_THREAD_COST)
 203                 return 0;
 204
 205         if (istate->cache_nr < nr_cpus * LAZY_THREAD_COST)
 206                 nr_cpus = istate->cache_nr / LAZY_THREAD_COST;
 207         lazy_nr_dir_threads = nr_cpus;
 208         return lazy_nr_dir_threads;
 209 }
 210
 211 /*
 212  * Initialize n mutexes for use when searching and inserting
 213  * into "istate->dir_hash".  All "dir" threads are trying
 214  * to insert partial pathnames into the hash as they iterate
 215  * over their portions of the index, so lock contention is
 216  * high.
 217  *
 218  * However, the hashmap is going to put items into bucket
 219  * chains based on their hash values.  Use that to create n
 220  * mutexes and lock on mutex[bucket(hash) % n].  This will
 221  * decrease the collision rate by (hopefully) by a factor of n.
 222  */
 223 static void init_dir_mutex(void)
 224 {
 225         int j;
 226
 227         lazy_dir_mutex_array = xcalloc(LAZY_MAX_MUTEX, sizeof(pthread_mutex_t));
 228
 229         for (j = 0; j < LAZY_MAX_MUTEX; j++)
 230                 init_recursive_mutex(&lazy_dir_mutex_array[j]);
 231 }
 232
 233 static void cleanup_dir_mutex(void)
 234 {
 235         int j;
 236
 237         for (j = 0; j < LAZY_MAX_MUTEX; j++)
 238                 pthread_mutex_destroy(&lazy_dir_mutex_array[j]);
 239
 240         free(lazy_dir_mutex_array);
 241 }
 242
 243 static void lock_dir_mutex(int j)
 244 {
 245         pthread_mutex_lock(&lazy_dir_mutex_array[j]);
 246 }
 247
 248 static void unlock_dir_mutex(int j)
 249 {
 250         pthread_mutex_unlock(&lazy_dir_mutex_array[j]);
 251 }
 252
 253 static inline int compute_dir_lock_nr(
 254         const struct hashmap *map,
 255         unsigned int hash)
 256 {
 257         return hashmap_bucket(map, hash) % LAZY_MAX_MUTEX;
 258 }
 259
 260 static struct dir_entry *hash_dir_entry_with_parent_and_prefix(
 261         struct index_state *istate,
 262         struct dir_entry *parent,
 263         struct strbuf *prefix)
 264 {
 265         struct dir_entry *dir;
 266         unsigned int hash;
 267         int lock_nr;
 268
 269         /*
 270          * Either we have a parent directory and path with slash(es)
 271          * or the directory is an immediate child of the root directory.
 272          */
 273         assert((parent != NULL) ^ (strchr(prefix->buf, '/') == NULL));
 274
 275         if (parent)
 276                 hash = memihash_cont(parent->ent.hash,
 277                         prefix->buf + parent->namelen,
 278                         prefix->len - parent->namelen);
 279         else
 280                 hash = memihash(prefix->buf, prefix->len);
 281
 282         lock_nr = compute_dir_lock_nr(&istate->dir_hash, hash);
 283         lock_dir_mutex(lock_nr);
 284
 285         dir = find_dir_entry__hash(istate, prefix->buf, prefix->len, hash);
 286         if (!dir) {
 287                 FLEX_ALLOC_MEM(dir, name, prefix->buf, prefix->len);
 288                 hashmap_entry_init(&dir->ent, hash);
 289                 dir->namelen = prefix->len;
 290                 dir->parent = parent;
 291                 hashmap_add(&istate->dir_hash, &dir->ent);
 292
 293                 if (parent) {
 294                         unlock_dir_mutex(lock_nr);
 295
 296                         /* All I really need here is an InterlockedIncrement(&(parent->nr)) */
 297                         lock_nr = compute_dir_lock_nr(&istate->dir_hash, parent->ent.hash);
 298                         lock_dir_mutex(lock_nr);
 299                         parent->nr++;
 300                 }
 301         }
 302
 303         unlock_dir_mutex(lock_nr);
 304
 305         return dir;
 306 }
 307
 308 /*
 309  * handle_range_1() and handle_range_dir() are derived from
 310  * clear_ce_flags_1() and clear_ce_flags_dir() in unpack-trees.c
 311  * and handle the iteration over the entire array of index entries.
 312  * They use recursion for adjacent entries in the same parent
 313  * directory.
 314  */
 315 static int handle_range_1(
 316         struct index_state *istate,
 317         int k_start,
 318         int k_end,
 319         struct dir_entry *parent,
 320         struct strbuf *prefix,
 321         struct lazy_entry *lazy_entries);
 322
 323 static int handle_range_dir(
 324         struct index_state *istate,
 325         int k_start,
 326         int k_end,
 327         struct dir_entry *parent,
 328         struct strbuf *prefix,
 329         struct lazy_entry *lazy_entries,
 330         struct dir_entry **dir_new_out)
 331 {
 332         int rc, k;
 333         int input_prefix_len = prefix->len;
 334         struct dir_entry *dir_new;
 335
 336         dir_new = hash_dir_entry_with_parent_and_prefix(istate, parent, prefix);
 337
 338         strbuf_addch(prefix, '/');
 339
 340         /*
 341          * Scan forward in the index array for index entries having the same
 342          * path prefix (that are also in this directory).
 343          */
 344         if (k_start + 1 >= k_end)
 345                 k = k_end;
 346         else if (strncmp(istate->cache[k_start + 1]->name, prefix->buf, prefix->len) > 0)
 347                 k = k_start + 1;
 348         else if (strncmp(istate->cache[k_end - 1]->name, prefix->buf, prefix->len) == 0)
 349                 k = k_end;
 350         else {
 351                 int begin = k_start;
 352                 int end = k_end;
 353                 assert(begin >= 0);
 354                 while (begin < end) {
 355                         int mid = begin + ((end - begin) >> 1);
 356                         int cmp = strncmp(istate->cache[mid]->name, prefix->buf, prefix->len);
 357                         if (cmp == 0) /* mid has same prefix; look in second part */
 358                                 begin = mid + 1;
 359                         else if (cmp > 0) /* mid is past group; look in first part */
 360                                 end = mid;
 361                         else
 362                                 die("cache entry out of order");
 363                 }
 364                 k = begin;
 365         }
 366
 367         /*
 368          * Recurse and process what we can of this subset [k_start, k).
 369          */
 370         rc = handle_range_1(istate, k_start, k, dir_new, prefix, lazy_entries);
 371
 372         strbuf_setlen(prefix, input_prefix_len);
 373
 374         *dir_new_out = dir_new;
 375         return rc;
 376 }
 377
 378 static int handle_range_1(
 379         struct index_state *istate,
 380         int k_start,
 381         int k_end,
 382         struct dir_entry *parent,
 383         struct strbuf *prefix,
 384         struct lazy_entry *lazy_entries)
 385 {
 386         int input_prefix_len = prefix->len;
 387         int k = k_start;
 388
 389         while (k < k_end) {
 390                 struct cache_entry *ce_k = istate->cache[k];
 391                 const char *name, *slash;
 392
 393                 if (prefix->len && strncmp(ce_k->name, prefix->buf, prefix->len))
 394                         break;
 395
 396                 name = ce_k->name + prefix->len;
 397                 slash = strchr(name, '/');
 398
 399                 if (slash) {
 400                         int len = slash - name;
 401                         int processed;
 402                         struct dir_entry *dir_new;
 403
 404                         strbuf_add(prefix, name, len);
 405                         processed = handle_range_dir(istate, k, k_end, parent, prefix, lazy_entries, &dir_new);
 406                         if (processed) {
 407                                 k += processed;
 408                                 strbuf_setlen(prefix, input_prefix_len);
 409                                 continue;
 410                         }
 411
 412                         strbuf_addch(prefix, '/');
 413                         processed = handle_range_1(istate, k, k_end, dir_new, prefix, lazy_entries);
 414                         k += processed;
 415                         strbuf_setlen(prefix, input_prefix_len);
 416                         continue;
 417                 }
 418
 419                 /*
 420                  * It is too expensive to take a lock to insert "ce_k"
 421                  * into "istate->name_hash" and increment the ref-count
 422                  * on the "parent" dir.  So we defer actually updating
 423                  * permanent data structures until phase 2 (where we
 424                  * can change the locking requirements) and simply
 425                  * accumulate our current results into the lazy_entries
 426                  * data array).
 427                  *
 428                  * We do not need to lock the lazy_entries array because
 429                  * we have exclusive access to the cells in the range
 430                  * [k_start,k_end) that this thread was given.
 431                  */
 432                 lazy_entries[k].dir = parent;
 433                 if (parent) {
 434                         lazy_entries[k].hash_name = memihash_cont(
 435                                 parent->ent.hash,
 436                                 ce_k->name + parent->namelen,
 437                                 ce_namelen(ce_k) - parent->namelen);
 438                         lazy_entries[k].hash_dir = parent->ent.hash;
 439                 } else {
 440                         lazy_entries[k].hash_name = memihash(ce_k->name, ce_namelen(ce_k));
 441                 }
 442
 443                 k++;
 444         }
 445
 446         return k - k_start;
 447 }
 448
 449 struct lazy_dir_thread_data {
 450         pthread_t pthread;
 451         struct index_state *istate;
 452         struct lazy_entry *lazy_entries;
 453         int k_start;
 454         int k_end;
 455 };
 456
 457 static void *lazy_dir_thread_proc(void *_data)
 458 {
 459         struct lazy_dir_thread_data *d = _data;
 460         struct strbuf prefix = STRBUF_INIT;
 461         handle_range_1(d->istate, d->k_start, d->k_end, NULL, &prefix, d->lazy_entries);
 462         strbuf_release(&prefix);
 463         return NULL;
 464 }
 465
 466 struct lazy_name_thread_data {
 467         pthread_t pthread;
 468         struct index_state *istate;
 469         struct lazy_entry *lazy_entries;
 470 };
 471
 472 static void *lazy_name_thread_proc(void *_data)
 473 {
 474         struct lazy_name_thread_data *d = _data;
 475         int k;
 476
 477         for (k = 0; k < d->istate->cache_nr; k++) {
 478                 struct cache_entry *ce_k = d->istate->cache[k];
 479                 ce_k->ce_flags |= CE_HASHED;
 480                 hashmap_entry_init(&ce_k->ent, d->lazy_entries[k].hash_name);
 481                 hashmap_add(&d->istate->name_hash, &ce_k->ent);
 482         }
 483
 484         return NULL;
 485 }
 486
 487 static inline void lazy_update_dir_ref_counts(
 488         struct index_state *istate,
 489         struct lazy_entry *lazy_entries)
 490 {
 491         int k;
 492
 493         for (k = 0; k < istate->cache_nr; k++) {
 494                 if (lazy_entries[k].dir)
 495                         lazy_entries[k].dir->nr++;
 496         }
 497 }
 498
 499 static void threaded_lazy_init_name_hash(
 500         struct index_state *istate)
 501 {
 502         int err;
 503         int nr_each;
 504         int k_start;
 505         int t;
 506         struct lazy_entry *lazy_entries;
 507         struct lazy_dir_thread_data *td_dir;
 508         struct lazy_name_thread_data *td_name;
 509
 510         if (!HAVE_THREADS)
 511                 return;
 512
 513         k_start = 0;
 514         nr_each = DIV_ROUND_UP(istate->cache_nr, lazy_nr_dir_threads);
 515
 516         lazy_entries = xcalloc(istate->cache_nr, sizeof(struct lazy_entry));
 517         td_dir = xcalloc(lazy_nr_dir_threads, sizeof(struct lazy_dir_thread_data));
 518         td_name = xcalloc(1, sizeof(struct lazy_name_thread_data));
 519
 520         init_dir_mutex();
 521
 522         /*
 523          * Phase 1:
 524          * Build "istate->dir_hash" using n "dir" threads (and a read-only index).
 525          */
 526         for (t = 0; t < lazy_nr_dir_threads; t++) {
 527                 struct lazy_dir_thread_data *td_dir_t = td_dir + t;
 528                 td_dir_t->istate = istate;
 529                 td_dir_t->lazy_entries = lazy_entries;
 530                 td_dir_t->k_start = k_start;
 531                 k_start += nr_each;
 532                 if (k_start > istate->cache_nr)
 533                         k_start = istate->cache_nr;
 534                 td_dir_t->k_end = k_start;
 535                 err = pthread_create(&td_dir_t->pthread, NULL, lazy_dir_thread_proc, td_dir_t);
 536                 if (err)
 537                         die(_("unable to create lazy_dir thread: %s"), strerror(err));
 538         }
 539         for (t = 0; t < lazy_nr_dir_threads; t++) {
 540                 struct lazy_dir_thread_data *td_dir_t = td_dir + t;
 541                 if (pthread_join(td_dir_t->pthread, NULL))
 542                         die("unable to join lazy_dir_thread");
 543         }
 544
 545         /*
 546          * Phase 2:
 547          * Iterate over all index entries and add them to the "istate->name_hash"
 548          * using a single "name" background thread.
 549          * (Testing showed it wasn't worth running more than 1 thread for this.)
 550          *
 551          * Meanwhile, finish updating the parent directory ref-counts for each
 552          * index entry using the current thread.  (This step is very fast and
 553          * doesn't need threading.)
 554          */
 555         td_name->istate = istate;
 556         td_name->lazy_entries = lazy_entries;
 557         err = pthread_create(&td_name->pthread, NULL, lazy_name_thread_proc, td_name);
 558         if (err)
 559                 die(_("unable to create lazy_name thread: %s"), strerror(err));
 560
 561         lazy_update_dir_ref_counts(istate, lazy_entries);
 562
 563         err = pthread_join(td_name->pthread, NULL);
 564         if (err)
 565                 die(_("unable to join lazy_name thread: %s"), strerror(err));
 566
 567         cleanup_dir_mutex();
 568
 569         free(td_name);
 570         free(td_dir);
 571         free(lazy_entries);
 572 }
 573
 574 static void lazy_init_name_hash(struct index_state *istate)
 575 {
 576
 577         if (istate->name_hash_initialized)
 578                 return;
 579         trace_performance_enter();
 580         hashmap_init(&istate->name_hash, cache_entry_cmp, NULL, istate->cache_nr);
 581         hashmap_init(&istate->dir_hash, dir_entry_cmp, NULL, istate->cache_nr);
 582
 583         if (lookup_lazy_params(istate)) {
 584                 /*
 585                  * Disable item counting and automatic rehashing because
 586                  * we do per-chain (mod n) locking rather than whole hashmap
 587                  * locking and we need to prevent the table-size from changing
 588                  * and bucket items from being redistributed.
 589                  */
 590                 hashmap_disable_item_counting(&istate->dir_hash);
 591                 threaded_lazy_init_name_hash(istate);
 592                 hashmap_enable_item_counting(&istate->dir_hash);
 593         } else {
 594                 int nr;
 595                 for (nr = 0; nr < istate->cache_nr; nr++)
 596                         hash_index_entry(istate, istate->cache[nr]);
 597         }
 598
 599         istate->name_hash_initialized = 1;
 600         trace_performance_leave("initialize name hash");
 601 }
 602
 603 /*
 604  * A test routine for t/helper/ sources.
 605  *
 606  * Returns the number of threads used or 0 when
 607  * the non-threaded code path was used.
 608  *
 609  * Requesting threading WILL NOT override guards
 610  * in lookup_lazy_params().
 611  */
 612 int test_lazy_init_name_hash(struct index_state *istate, int try_threaded)
 613 {
 614         lazy_nr_dir_threads = 0;
 615         lazy_try_threaded = try_threaded;
 616
 617         lazy_init_name_hash(istate);
 618
 619         return lazy_nr_dir_threads;
 620 }
 621
 622 void add_name_hash(struct index_state *istate, struct cache_entry *ce)
 623 {
 624         if (istate->name_hash_initialized)
 625                 hash_index_entry(istate, ce);
 626 }
 627
 628 void remove_name_hash(struct index_state *istate, struct cache_entry *ce)
 629 {
 630         if (!istate->name_hash_initialized || !(ce->ce_flags & CE_HASHED))
 631                 return;
 632         ce->ce_flags &= ~CE_HASHED;
 633         hashmap_remove(&istate->name_hash, &ce->ent, ce);
 634
 635         if (ignore_case)
 636                 remove_dir_entry(istate, ce);
 637 }
 638
 639 static int slow_same_name(const char *name1, int len1, const char *name2, int len2)
 640 {
 641         if (len1 != len2)
 642                 return 0;
 643
 644         while (len1) {
 645                 unsigned char c1 = *name1++;
 646                 unsigned char c2 = *name2++;
 647                 len1--;
 648                 if (c1 != c2) {
 649                         c1 = toupper(c1);
 650                         c2 = toupper(c2);
 651                         if (c1 != c2)
 652                                 return 0;
 653                 }
 654         }
 655         return 1;
 656 }
 657
 658 static int same_name(const struct cache_entry *ce, const char *name, int namelen, int icase)
 659 {
 660         int len = ce_namelen(ce);
 661
 662         /*
 663          * Always do exact compare, even if we want a case-ignoring comparison;
 664          * we do the quick exact one first, because it will be the common case.
 665          */
 666         if (len == namelen && !memcmp(name, ce->name, len))
 667                 return 1;
 668
 669         if (!icase)
 670                 return 0;
 671
 672         return slow_same_name(name, namelen, ce->name, len);
 673 }
 674
 675 int index_dir_exists(struct index_state *istate, const char *name, int namelen)
 676 {
 677         struct dir_entry *dir;
 678
 679         lazy_init_name_hash(istate);
 680         dir = find_dir_entry(istate, name, namelen);
 681         return dir && dir->nr;
 682 }
 683
 684 void adjust_dirname_case(struct index_state *istate, char *name)
 685 {
 686         const char *startPtr = name;
 687         const char *ptr = startPtr;
 688
 689         lazy_init_name_hash(istate);
 690         while (*ptr) {
 691                 while (*ptr && *ptr != '/')
 692                         ptr++;
 693
 694                 if (*ptr == '/') {
 695                         struct dir_entry *dir;
 696
 697                         dir = find_dir_entry(istate, name, ptr - name);
 698                         if (dir) {
 699                                 memcpy((void *)startPtr, dir->name + (startPtr - name), ptr - startPtr);
 700                                 startPtr = ptr + 1;
 701                         }
 702                         ptr++;
 703                 }
 704         }
 705 }
 706
 707 struct cache_entry *index_file_exists(struct index_state *istate, const char *name, int namelen, int icase)
 708 {
 709         struct cache_entry *ce;
 710         unsigned int hash = memihash(name, namelen);
 711
 712         lazy_init_name_hash(istate);
 713
 714         ce = hashmap_get_entry_from_hash(&istate->name_hash, hash, NULL,
 715                                          struct cache_entry, ent);
 716         hashmap_for_each_entry_from(&istate->name_hash, ce, ent) {
 717                 if (same_name(ce, name, namelen, icase))
 718                         return ce;
 719         }
 720         return NULL;
 721 }
 722
 723 void free_name_hash(struct index_state *istate)
 724 {
 725         if (!istate->name_hash_initialized)
 726                 return;
 727         istate->name_hash_initialized = 0;
 728
 729         hashmap_free(&istate->name_hash);
 730         hashmap_free_entries(&istate->dir_hash, struct dir_entry, ent);
 731 }