name-hash.con commit commit: add generation number to struct commit (83073cc)
   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
  11struct 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
  19static 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
  32static 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
  41static 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
  47static 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
  81static 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
  89static 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
 104static 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
 116static 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
 131static int lazy_try_threaded = 1;
 132static int lazy_nr_dir_threads;
 133
 134#ifdef NO_PTHREADS
 135
 136static inline int lookup_lazy_params(struct index_state *istate)
 137{
 138        return 0;
 139}
 140
 141static inline void threaded_lazy_init_name_hash(
 142        struct index_state *istate)
 143{
 144}
 145
 146#else
 147
 148#include "thread-utils.h"
 149
 150/*
 151 * Set a minimum number of cache_entries that we will handle per
 152 * thread and use that to decide how many threads to run (upto
 153 * the number on the system).
 154 *
 155 * For guidance setting the lower per-thread bound, see:
 156 *     t/helper/test-lazy-init-name-hash --analyze
 157 */
 158#define LAZY_THREAD_COST (2000)
 159
 160/*
 161 * We use n mutexes to guard n partitions of the "istate->dir_hash"
 162 * hashtable.  Since "find" and "insert" operations will hash to a
 163 * particular bucket and modify/search a single chain, we can say
 164 * that "all chains mod n" are guarded by the same mutex -- rather
 165 * than having a single mutex to guard the entire table.  (This does
 166 * require that we disable "rehashing" on the hashtable.)
 167 *
 168 * So, a larger value here decreases the probability of a collision
 169 * and the time that each thread must wait for the mutex.
 170 */
 171#define LAZY_MAX_MUTEX   (32)
 172
 173static pthread_mutex_t *lazy_dir_mutex_array;
 174
 175/*
 176 * An array of lazy_entry items is used by the n threads in
 177 * the directory parse (first) phase to (lock-free) store the
 178 * intermediate results.  These values are then referenced by
 179 * the 2 threads in the second phase.
 180 */
 181struct lazy_entry {
 182        struct dir_entry *dir;
 183        unsigned int hash_dir;
 184        unsigned int hash_name;
 185};
 186
 187/*
 188 * Decide if we want to use threads (if available) to load
 189 * the hash tables.  We set "lazy_nr_dir_threads" to zero when
 190 * it is not worth it.
 191 */
 192static int lookup_lazy_params(struct index_state *istate)
 193{
 194        int nr_cpus;
 195
 196        lazy_nr_dir_threads = 0;
 197
 198        if (!lazy_try_threaded)
 199                return 0;
 200
 201        /*
 202         * If we are respecting case, just use the original
 203         * code to build the "istate->name_hash".  We don't
 204         * need the complexity here.
 205         */
 206        if (!ignore_case)
 207                return 0;
 208
 209        nr_cpus = online_cpus();
 210        if (nr_cpus < 2)
 211                return 0;
 212
 213        if (istate->cache_nr < 2 * LAZY_THREAD_COST)
 214                return 0;
 215
 216        if (istate->cache_nr < nr_cpus * LAZY_THREAD_COST)
 217                nr_cpus = istate->cache_nr / LAZY_THREAD_COST;
 218        lazy_nr_dir_threads = nr_cpus;
 219        return lazy_nr_dir_threads;
 220}
 221
 222/*
 223 * Initialize n mutexes for use when searching and inserting
 224 * into "istate->dir_hash".  All "dir" threads are trying
 225 * to insert partial pathnames into the hash as they iterate
 226 * over their portions of the index, so lock contention is
 227 * high.
 228 *
 229 * However, the hashmap is going to put items into bucket
 230 * chains based on their hash values.  Use that to create n
 231 * mutexes and lock on mutex[bucket(hash) % n].  This will
 232 * decrease the collision rate by (hopefully) by a factor of n.
 233 */
 234static void init_dir_mutex(void)
 235{
 236        int j;
 237
 238        lazy_dir_mutex_array = xcalloc(LAZY_MAX_MUTEX, sizeof(pthread_mutex_t));
 239
 240        for (j = 0; j < LAZY_MAX_MUTEX; j++)
 241                init_recursive_mutex(&lazy_dir_mutex_array[j]);
 242}
 243
 244static void cleanup_dir_mutex(void)
 245{
 246        int j;
 247
 248        for (j = 0; j < LAZY_MAX_MUTEX; j++)
 249                pthread_mutex_destroy(&lazy_dir_mutex_array[j]);
 250
 251        free(lazy_dir_mutex_array);
 252}
 253
 254static void lock_dir_mutex(int j)
 255{
 256        pthread_mutex_lock(&lazy_dir_mutex_array[j]);
 257}
 258
 259static void unlock_dir_mutex(int j)
 260{
 261        pthread_mutex_unlock(&lazy_dir_mutex_array[j]);
 262}
 263
 264static inline int compute_dir_lock_nr(
 265        const struct hashmap *map,
 266        unsigned int hash)
 267{
 268        return hashmap_bucket(map, hash) % LAZY_MAX_MUTEX;
 269}
 270
 271static struct dir_entry *hash_dir_entry_with_parent_and_prefix(
 272        struct index_state *istate,
 273        struct dir_entry *parent,
 274        struct strbuf *prefix)
 275{
 276        struct dir_entry *dir;
 277        unsigned int hash;
 278        int lock_nr;
 279
 280        /*
 281         * Either we have a parent directory and path with slash(es)
 282         * or the directory is an immediate child of the root directory.
 283         */
 284        assert((parent != NULL) ^ (strchr(prefix->buf, '/') == NULL));
 285
 286        if (parent)
 287                hash = memihash_cont(parent->ent.hash,
 288                        prefix->buf + parent->namelen,
 289                        prefix->len - parent->namelen);
 290        else
 291                hash = memihash(prefix->buf, prefix->len);
 292
 293        lock_nr = compute_dir_lock_nr(&istate->dir_hash, hash);
 294        lock_dir_mutex(lock_nr);
 295
 296        dir = find_dir_entry__hash(istate, prefix->buf, prefix->len, hash);
 297        if (!dir) {
 298                FLEX_ALLOC_MEM(dir, name, prefix->buf, prefix->len);
 299                hashmap_entry_init(dir, hash);
 300                dir->namelen = prefix->len;
 301                dir->parent = parent;
 302                hashmap_add(&istate->dir_hash, dir);
 303
 304                if (parent) {
 305                        unlock_dir_mutex(lock_nr);
 306
 307                        /* All I really need here is an InterlockedIncrement(&(parent->nr)) */
 308                        lock_nr = compute_dir_lock_nr(&istate->dir_hash, parent->ent.hash);
 309                        lock_dir_mutex(lock_nr);
 310                        parent->nr++;
 311                }
 312        }
 313
 314        unlock_dir_mutex(lock_nr);
 315
 316        return dir;
 317}
 318
 319/*
 320 * handle_range_1() and handle_range_dir() are derived from
 321 * clear_ce_flags_1() and clear_ce_flags_dir() in unpack-trees.c
 322 * and handle the iteration over the entire array of index entries.
 323 * They use recursion for adjacent entries in the same parent
 324 * directory.
 325 */
 326static int handle_range_1(
 327        struct index_state *istate,
 328        int k_start,
 329        int k_end,
 330        struct dir_entry *parent,
 331        struct strbuf *prefix,
 332        struct lazy_entry *lazy_entries);
 333
 334static int handle_range_dir(
 335        struct index_state *istate,
 336        int k_start,
 337        int k_end,
 338        struct dir_entry *parent,
 339        struct strbuf *prefix,
 340        struct lazy_entry *lazy_entries,
 341        struct dir_entry **dir_new_out)
 342{
 343        int rc, k;
 344        int input_prefix_len = prefix->len;
 345        struct dir_entry *dir_new;
 346
 347        dir_new = hash_dir_entry_with_parent_and_prefix(istate, parent, prefix);
 348
 349        strbuf_addch(prefix, '/');
 350
 351        /*
 352         * Scan forward in the index array for index entries having the same
 353         * path prefix (that are also in this directory).
 354         */
 355        if (k_start + 1 >= k_end)
 356                k = k_end;
 357        else if (strncmp(istate->cache[k_start + 1]->name, prefix->buf, prefix->len) > 0)
 358                k = k_start + 1;
 359        else if (strncmp(istate->cache[k_end - 1]->name, prefix->buf, prefix->len) == 0)
 360                k = k_end;
 361        else {
 362                int begin = k_start;
 363                int end = k_end;
 364                while (begin < end) {
 365                        int mid = (begin + end) >> 1;
 366                        int cmp = strncmp(istate->cache[mid]->name, prefix->buf, prefix->len);
 367                        if (cmp == 0) /* mid has same prefix; look in second part */
 368                                begin = mid + 1;
 369                        else if (cmp > 0) /* mid is past group; look in first part */
 370                                end = mid;
 371                        else
 372                                die("cache entry out of order");
 373                }
 374                k = begin;
 375        }
 376
 377        /*
 378         * Recurse and process what we can of this subset [k_start, k).
 379         */
 380        rc = handle_range_1(istate, k_start, k, dir_new, prefix, lazy_entries);
 381
 382        strbuf_setlen(prefix, input_prefix_len);
 383
 384        *dir_new_out = dir_new;
 385        return rc;
 386}
 387
 388static int handle_range_1(
 389        struct index_state *istate,
 390        int k_start,
 391        int k_end,
 392        struct dir_entry *parent,
 393        struct strbuf *prefix,
 394        struct lazy_entry *lazy_entries)
 395{
 396        int input_prefix_len = prefix->len;
 397        int k = k_start;
 398
 399        while (k < k_end) {
 400                struct cache_entry *ce_k = istate->cache[k];
 401                const char *name, *slash;
 402
 403                if (prefix->len && strncmp(ce_k->name, prefix->buf, prefix->len))
 404                        break;
 405
 406                name = ce_k->name + prefix->len;
 407                slash = strchr(name, '/');
 408
 409                if (slash) {
 410                        int len = slash - name;
 411                        int processed;
 412                        struct dir_entry *dir_new;
 413
 414                        strbuf_add(prefix, name, len);
 415                        processed = handle_range_dir(istate, k, k_end, parent, prefix, lazy_entries, &dir_new);
 416                        if (processed) {
 417                                k += processed;
 418                                strbuf_setlen(prefix, input_prefix_len);
 419                                continue;
 420                        }
 421
 422                        strbuf_addch(prefix, '/');
 423                        processed = handle_range_1(istate, k, k_end, dir_new, prefix, lazy_entries);
 424                        k += processed;
 425                        strbuf_setlen(prefix, input_prefix_len);
 426                        continue;
 427                }
 428
 429                /*
 430                 * It is too expensive to take a lock to insert "ce_k"
 431                 * into "istate->name_hash" and increment the ref-count
 432                 * on the "parent" dir.  So we defer actually updating
 433                 * permanent data structures until phase 2 (where we
 434                 * can change the locking requirements) and simply
 435                 * accumulate our current results into the lazy_entries
 436                 * data array).
 437                 *
 438                 * We do not need to lock the lazy_entries array because
 439                 * we have exclusive access to the cells in the range
 440                 * [k_start,k_end) that this thread was given.
 441                 */
 442                lazy_entries[k].dir = parent;
 443                if (parent) {
 444                        lazy_entries[k].hash_name = memihash_cont(
 445                                parent->ent.hash,
 446                                ce_k->name + parent->namelen,
 447                                ce_namelen(ce_k) - parent->namelen);
 448                        lazy_entries[k].hash_dir = parent->ent.hash;
 449                } else {
 450                        lazy_entries[k].hash_name = memihash(ce_k->name, ce_namelen(ce_k));
 451                }
 452
 453                k++;
 454        }
 455
 456        return k - k_start;
 457}
 458
 459struct lazy_dir_thread_data {
 460        pthread_t pthread;
 461        struct index_state *istate;
 462        struct lazy_entry *lazy_entries;
 463        int k_start;
 464        int k_end;
 465};
 466
 467static void *lazy_dir_thread_proc(void *_data)
 468{
 469        struct lazy_dir_thread_data *d = _data;
 470        struct strbuf prefix = STRBUF_INIT;
 471        handle_range_1(d->istate, d->k_start, d->k_end, NULL, &prefix, d->lazy_entries);
 472        strbuf_release(&prefix);
 473        return NULL;
 474}
 475
 476struct lazy_name_thread_data {
 477        pthread_t pthread;
 478        struct index_state *istate;
 479        struct lazy_entry *lazy_entries;
 480};
 481
 482static void *lazy_name_thread_proc(void *_data)
 483{
 484        struct lazy_name_thread_data *d = _data;
 485        int k;
 486
 487        for (k = 0; k < d->istate->cache_nr; k++) {
 488                struct cache_entry *ce_k = d->istate->cache[k];
 489                ce_k->ce_flags |= CE_HASHED;
 490                hashmap_entry_init(ce_k, d->lazy_entries[k].hash_name);
 491                hashmap_add(&d->istate->name_hash, ce_k);
 492        }
 493
 494        return NULL;
 495}
 496
 497static inline void lazy_update_dir_ref_counts(
 498        struct index_state *istate,
 499        struct lazy_entry *lazy_entries)
 500{
 501        int k;
 502
 503        for (k = 0; k < istate->cache_nr; k++) {
 504                if (lazy_entries[k].dir)
 505                        lazy_entries[k].dir->nr++;
 506        }
 507}
 508
 509static void threaded_lazy_init_name_hash(
 510        struct index_state *istate)
 511{
 512        int nr_each;
 513        int k_start;
 514        int t;
 515        struct lazy_entry *lazy_entries;
 516        struct lazy_dir_thread_data *td_dir;
 517        struct lazy_name_thread_data *td_name;
 518
 519        k_start = 0;
 520        nr_each = DIV_ROUND_UP(istate->cache_nr, lazy_nr_dir_threads);
 521
 522        lazy_entries = xcalloc(istate->cache_nr, sizeof(struct lazy_entry));
 523        td_dir = xcalloc(lazy_nr_dir_threads, sizeof(struct lazy_dir_thread_data));
 524        td_name = xcalloc(1, sizeof(struct lazy_name_thread_data));
 525
 526        init_dir_mutex();
 527
 528        /*
 529         * Phase 1:
 530         * Build "istate->dir_hash" using n "dir" threads (and a read-only index).
 531         */
 532        for (t = 0; t < lazy_nr_dir_threads; t++) {
 533                struct lazy_dir_thread_data *td_dir_t = td_dir + t;
 534                td_dir_t->istate = istate;
 535                td_dir_t->lazy_entries = lazy_entries;
 536                td_dir_t->k_start = k_start;
 537                k_start += nr_each;
 538                if (k_start > istate->cache_nr)
 539                        k_start = istate->cache_nr;
 540                td_dir_t->k_end = k_start;
 541                if (pthread_create(&td_dir_t->pthread, NULL, lazy_dir_thread_proc, td_dir_t))
 542                        die("unable to create lazy_dir_thread");
 543        }
 544        for (t = 0; t < lazy_nr_dir_threads; t++) {
 545                struct lazy_dir_thread_data *td_dir_t = td_dir + t;
 546                if (pthread_join(td_dir_t->pthread, NULL))
 547                        die("unable to join lazy_dir_thread");
 548        }
 549
 550        /*
 551         * Phase 2:
 552         * Iterate over all index entries and add them to the "istate->name_hash"
 553         * using a single "name" background thread.
 554         * (Testing showed it wasn't worth running more than 1 thread for this.)
 555         *
 556         * Meanwhile, finish updating the parent directory ref-counts for each
 557         * index entry using the current thread.  (This step is very fast and
 558         * doesn't need threading.)
 559         */
 560        td_name->istate = istate;
 561        td_name->lazy_entries = lazy_entries;
 562        if (pthread_create(&td_name->pthread, NULL, lazy_name_thread_proc, td_name))
 563                die("unable to create lazy_name_thread");
 564
 565        lazy_update_dir_ref_counts(istate, lazy_entries);
 566
 567        if (pthread_join(td_name->pthread, NULL))
 568                die("unable to join lazy_name_thread");
 569
 570        cleanup_dir_mutex();
 571
 572        free(td_name);
 573        free(td_dir);
 574        free(lazy_entries);
 575}
 576
 577#endif
 578
 579static void lazy_init_name_hash(struct index_state *istate)
 580{
 581        uint64_t start = getnanotime();
 582
 583        if (istate->name_hash_initialized)
 584                return;
 585        hashmap_init(&istate->name_hash, cache_entry_cmp, NULL, istate->cache_nr);
 586        hashmap_init(&istate->dir_hash, dir_entry_cmp, NULL, istate->cache_nr);
 587
 588        if (lookup_lazy_params(istate)) {
 589                /*
 590                 * Disable item counting and automatic rehashing because
 591                 * we do per-chain (mod n) locking rather than whole hashmap
 592                 * locking and we need to prevent the table-size from changing
 593                 * and bucket items from being redistributed.
 594                 */
 595                hashmap_disable_item_counting(&istate->dir_hash);
 596                threaded_lazy_init_name_hash(istate);
 597                hashmap_enable_item_counting(&istate->dir_hash);
 598        } else {
 599                int nr;
 600                for (nr = 0; nr < istate->cache_nr; nr++)
 601                        hash_index_entry(istate, istate->cache[nr]);
 602        }
 603
 604        istate->name_hash_initialized = 1;
 605        trace_performance_since(start, "initialize name hash");
 606}
 607
 608/*
 609 * A test routine for t/helper/ sources.
 610 *
 611 * Returns the number of threads used or 0 when
 612 * the non-threaded code path was used.
 613 *
 614 * Requesting threading WILL NOT override guards
 615 * in lookup_lazy_params().
 616 */
 617int test_lazy_init_name_hash(struct index_state *istate, int try_threaded)
 618{
 619        lazy_nr_dir_threads = 0;
 620        lazy_try_threaded = try_threaded;
 621
 622        lazy_init_name_hash(istate);
 623
 624        return lazy_nr_dir_threads;
 625}
 626
 627void add_name_hash(struct index_state *istate, struct cache_entry *ce)
 628{
 629        if (istate->name_hash_initialized)
 630                hash_index_entry(istate, ce);
 631}
 632
 633void remove_name_hash(struct index_state *istate, struct cache_entry *ce)
 634{
 635        if (!istate->name_hash_initialized || !(ce->ce_flags & CE_HASHED))
 636                return;
 637        ce->ce_flags &= ~CE_HASHED;
 638        hashmap_remove(&istate->name_hash, ce, ce);
 639
 640        if (ignore_case)
 641                remove_dir_entry(istate, ce);
 642}
 643
 644static int slow_same_name(const char *name1, int len1, const char *name2, int len2)
 645{
 646        if (len1 != len2)
 647                return 0;
 648
 649        while (len1) {
 650                unsigned char c1 = *name1++;
 651                unsigned char c2 = *name2++;
 652                len1--;
 653                if (c1 != c2) {
 654                        c1 = toupper(c1);
 655                        c2 = toupper(c2);
 656                        if (c1 != c2)
 657                                return 0;
 658                }
 659        }
 660        return 1;
 661}
 662
 663static int same_name(const struct cache_entry *ce, const char *name, int namelen, int icase)
 664{
 665        int len = ce_namelen(ce);
 666
 667        /*
 668         * Always do exact compare, even if we want a case-ignoring comparison;
 669         * we do the quick exact one first, because it will be the common case.
 670         */
 671        if (len == namelen && !memcmp(name, ce->name, len))
 672                return 1;
 673
 674        if (!icase)
 675                return 0;
 676
 677        return slow_same_name(name, namelen, ce->name, len);
 678}
 679
 680int index_dir_exists(struct index_state *istate, const char *name, int namelen)
 681{
 682        struct dir_entry *dir;
 683
 684        lazy_init_name_hash(istate);
 685        dir = find_dir_entry(istate, name, namelen);
 686        return dir && dir->nr;
 687}
 688
 689void adjust_dirname_case(struct index_state *istate, char *name)
 690{
 691        const char *startPtr = name;
 692        const char *ptr = startPtr;
 693
 694        lazy_init_name_hash(istate);
 695        while (*ptr) {
 696                while (*ptr && *ptr != '/')
 697                        ptr++;
 698
 699                if (*ptr == '/') {
 700                        struct dir_entry *dir;
 701
 702                        ptr++;
 703                        dir = find_dir_entry(istate, name, ptr - name + 1);
 704                        if (dir) {
 705                                memcpy((void *)startPtr, dir->name + (startPtr - name), ptr - startPtr);
 706                                startPtr = ptr;
 707                        }
 708                }
 709        }
 710}
 711
 712struct cache_entry *index_file_exists(struct index_state *istate, const char *name, int namelen, int icase)
 713{
 714        struct cache_entry *ce;
 715
 716        lazy_init_name_hash(istate);
 717
 718        ce = hashmap_get_from_hash(&istate->name_hash,
 719                                   memihash(name, namelen), NULL);
 720        while (ce) {
 721                if (same_name(ce, name, namelen, icase))
 722                        return ce;
 723                ce = hashmap_get_next(&istate->name_hash, ce);
 724        }
 725        return NULL;
 726}
 727
 728void free_name_hash(struct index_state *istate)
 729{
 730        if (!istate->name_hash_initialized)
 731                return;
 732        istate->name_hash_initialized = 0;
 733
 734        hashmap_free(&istate->name_hash, 0);
 735        hashmap_free(&istate->dir_hash, 1);
 736}