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