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