src/util/hash_table.c

   1 /*
   2  * Copyright © 2009,2012 Intel Corporation
   3  * Copyright © 1988-2004 Keith Packard and Bart Massey.
   4  *
   5  * Permission is hereby granted, free of charge, to any person obtaining a
   6  * copy of this software and associated documentation files (the "Software"),
   7  * to deal in the Software without restriction, including without limitation
   8  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
   9  * and/or sell copies of the Software, and to permit persons to whom the
  10  * Software is furnished to do so, subject to the following conditions:
  11  *
  12  * The above copyright notice and this permission notice (including the next
  13  * paragraph) shall be included in all copies or substantial portions of the
  14  * Software.
  15  *
  16  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  17  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  18  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
  19  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  20  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
  21  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
  22  * IN THE SOFTWARE.
  23  *
  24  * Except as contained in this notice, the names of the authors
  25  * or their institutions shall not be used in advertising or
  26  * otherwise to promote the sale, use or other dealings in this
  27  * Software without prior written authorization from the
  28  * authors.
  29  *
  30  * Authors:
  31  *    Eric Anholt <eric@anholt.net>
  32  *    Keith Packard <keithp@keithp.com>
  33  */
  34
  35 /**
  36  * Implements an open-addressing, linear-reprobing hash table.
  37  *
  38  * For more information, see:
  39  *
  40  * http://cgit.freedesktop.org/~anholt/hash_table/tree/README
  41  */
  42
  43 #include <stdlib.h>
  44 #include <string.h>
  45 #include <assert.h>
  46
  47 #include "hash_table.h"
  48 #include "ralloc.h"
  49 #include "macros.h"
  50 #include "main/hash.h"
  51
  52 static const uint32_t deleted_key_value;
  53
  54 /**
  55  * From Knuth -- a good choice for hash/rehash values is p, p-2 where
  56  * p and p-2 are both prime.  These tables are sized to have an extra 10%
  57  * free to avoid exponential performance degradation as the hash table fills
  58  */
  59 static const struct {
  60    uint32_t max_entries, size, rehash;
  61 } hash_sizes[] = {
  62    { 2,                 5,              3         },
  63    { 4,                 7,              5         },
  64    { 8,                 13,             11        },
  65    { 16,                19,             17        },
  66    { 32,                43,             41        },
  67    { 64,                73,             71        },
  68    { 128,               151,            149       },
  69    { 256,               283,            281       },
  70    { 512,               571,            569       },
  71    { 1024,              1153,           1151      },
  72    { 2048,              2269,           2267      },
  73    { 4096,              4519,           4517      },
  74    { 8192,              9013,           9011      },
  75    { 16384,             18043,          18041     },
  76    { 32768,             36109,          36107     },
  77    { 65536,             72091,          72089     },
  78    { 131072,            144409,         144407    },
  79    { 262144,            288361,         288359    },
  80    { 524288,            576883,         576881    },
  81    { 1048576,           1153459,        1153457   },
  82    { 2097152,           2307163,        2307161   },
  83    { 4194304,           4613893,        4613891   },
  84    { 8388608,           9227641,        9227639   },
  85    { 16777216,          18455029,       18455027  },
  86    { 33554432,          36911011,       36911009  },
  87    { 67108864,          73819861,       73819859  },
  88    { 134217728,         147639589,      147639587 },
  89    { 268435456,         295279081,      295279079 },
  90    { 536870912,         590559793,      590559791 },
  91    { 1073741824,        1181116273,     1181116271},
  92    { 2147483648ul,      2362232233ul,   2362232231ul}
  93 };
  94
  95 static int
  96 entry_is_free(const struct hash_entry *entry)
  97 {
  98    return entry->key == NULL;
  99 }
 100
 101 static int
 102 entry_is_deleted(const struct hash_table *ht, struct hash_entry *entry)
 103 {
 104    return entry->key == ht->deleted_key;
 105 }
 106
 107 static int
 108 entry_is_present(const struct hash_table *ht, struct hash_entry *entry)
 109 {
 110    return entry->key != NULL && entry->key != ht->deleted_key;
 111 }
 112
 113 struct hash_table *
 114 _mesa_hash_table_create(void *mem_ctx,
 115                         uint32_t (*key_hash_function)(const void *key),
 116                         bool (*key_equals_function)(const void *a,
 117                                                     const void *b))
 118 {
 119    struct hash_table *ht;
 120
 121    ht = ralloc(mem_ctx, struct hash_table);
 122    if (ht == NULL)
 123       return NULL;
 124
 125    ht->size_index = 0;
 126    ht->size = hash_sizes[ht->size_index].size;
 127    ht->rehash = hash_sizes[ht->size_index].rehash;
 128    ht->max_entries = hash_sizes[ht->size_index].max_entries;
 129    ht->key_hash_function = key_hash_function;
 130    ht->key_equals_function = key_equals_function;
 131    ht->table = rzalloc_array(ht, struct hash_entry, ht->size);
 132    ht->entries = 0;
 133    ht->deleted_entries = 0;
 134    ht->deleted_key = &deleted_key_value;
 135
 136    if (ht->table == NULL) {
 137       ralloc_free(ht);
 138       return NULL;
 139    }
 140
 141    return ht;
 142 }
 143
 144 /**
 145  * Frees the given hash table.
 146  *
 147  * If delete_function is passed, it gets called on each entry present before
 148  * freeing.
 149  */
 150 void
 151 _mesa_hash_table_destroy(struct hash_table *ht,
 152                          void (*delete_function)(struct hash_entry *entry))
 153 {
 154    if (!ht)
 155       return;
 156
 157    if (delete_function) {
 158       struct hash_entry *entry;
 159
 160       hash_table_foreach(ht, entry) {
 161          delete_function(entry);
 162       }
 163    }
 164    ralloc_free(ht);
 165 }
 166
 167 /**
 168  * Deletes all entries of the given hash table without deleting the table
 169  * itself or changing its structure.
 170  *
 171  * If delete_function is passed, it gets called on each entry present.
 172  */
 173 void
 174 _mesa_hash_table_clear(struct hash_table *ht,
 175                        void (*delete_function)(struct hash_entry *entry))
 176 {
 177    struct hash_entry *entry;
 178
 179    for (entry = ht->table; entry != ht->table + ht->size; entry++) {
 180       if (entry->key == NULL)
 181          continue;
 182
 183       if (delete_function != NULL && entry->key != ht->deleted_key)
 184          delete_function(entry);
 185
 186       entry->key = NULL;
 187    }
 188
 189    ht->entries = 0;
 190    ht->deleted_entries = 0;
 191 }
 192
 193 /** Sets the value of the key pointer used for deleted entries in the table.
 194  *
 195  * The assumption is that usually keys are actual pointers, so we use a
 196  * default value of a pointer to an arbitrary piece of storage in the library.
 197  * But in some cases a consumer wants to store some other sort of value in the
 198  * table, like a uint32_t, in which case that pointer may conflict with one of
 199  * their valid keys.  This lets that user select a safe value.
 200  *
 201  * This must be called before any keys are actually deleted from the table.
 202  */
 203 void
 204 _mesa_hash_table_set_deleted_key(struct hash_table *ht, const void *deleted_key)
 205 {
 206    ht->deleted_key = deleted_key;
 207 }
 208
 209 static struct hash_entry *
 210 hash_table_search(struct hash_table *ht, uint32_t hash, const void *key)
 211 {
 212    uint32_t start_hash_address = hash % ht->size;
 213    uint32_t hash_address = start_hash_address;
 214
 215    do {
 216       uint32_t double_hash;
 217
 218       struct hash_entry *entry = ht->table + hash_address;
 219
 220       if (entry_is_free(entry)) {
 221          return NULL;
 222       } else if (entry_is_present(ht, entry) && entry->hash == hash) {
 223          if (ht->key_equals_function(key, entry->key)) {
 224             return entry;
 225          }
 226       }
 227
 228       double_hash = 1 + hash % ht->rehash;
 229
 230       hash_address = (hash_address + double_hash) % ht->size;
 231    } while (hash_address != start_hash_address);
 232
 233    return NULL;
 234 }
 235
 236 /**
 237  * Finds a hash table entry with the given key and hash of that key.
 238  *
 239  * Returns NULL if no entry is found.  Note that the data pointer may be
 240  * modified by the user.
 241  */
 242 struct hash_entry *
 243 _mesa_hash_table_search(struct hash_table *ht, const void *key)
 244 {
 245    assert(ht->key_hash_function);
 246    return hash_table_search(ht, ht->key_hash_function(key), key);
 247 }
 248
 249 struct hash_entry *
 250 _mesa_hash_table_search_pre_hashed(struct hash_table *ht, uint32_t hash,
 251                                   const void *key)
 252 {
 253    assert(ht->key_hash_function == NULL || hash == ht->key_hash_function(key));
 254    return hash_table_search(ht, hash, key);
 255 }
 256
 257 static struct hash_entry *
 258 hash_table_insert(struct hash_table *ht, uint32_t hash,
 259                   const void *key, void *data);
 260
 261 static void
 262 _mesa_hash_table_rehash(struct hash_table *ht, unsigned new_size_index)
 263 {
 264    struct hash_table old_ht;
 265    struct hash_entry *table, *entry;
 266
 267    if (new_size_index >= ARRAY_SIZE(hash_sizes))
 268       return;
 269
 270    table = rzalloc_array(ht, struct hash_entry,
 271                          hash_sizes[new_size_index].size);
 272    if (table == NULL)
 273       return;
 274
 275    old_ht = *ht;
 276
 277    ht->table = table;
 278    ht->size_index = new_size_index;
 279    ht->size = hash_sizes[ht->size_index].size;
 280    ht->rehash = hash_sizes[ht->size_index].rehash;
 281    ht->max_entries = hash_sizes[ht->size_index].max_entries;
 282    ht->entries = 0;
 283    ht->deleted_entries = 0;
 284
 285    hash_table_foreach(&old_ht, entry) {
 286       hash_table_insert(ht, entry->hash, entry->key, entry->data);
 287    }
 288
 289    ralloc_free(old_ht.table);
 290 }
 291
 292 static struct hash_entry *
 293 hash_table_insert(struct hash_table *ht, uint32_t hash,
 294                   const void *key, void *data)
 295 {
 296    uint32_t start_hash_address, hash_address;
 297    struct hash_entry *available_entry = NULL;
 298
 299    assert(key != NULL);
 300
 301    if (ht->entries >= ht->max_entries) {
 302       _mesa_hash_table_rehash(ht, ht->size_index + 1);
 303    } else if (ht->deleted_entries + ht->entries >= ht->max_entries) {
 304       _mesa_hash_table_rehash(ht, ht->size_index);
 305    }
 306
 307    start_hash_address = hash % ht->size;
 308    hash_address = start_hash_address;
 309    do {
 310       struct hash_entry *entry = ht->table + hash_address;
 311       uint32_t double_hash;
 312
 313       if (!entry_is_present(ht, entry)) {
 314          /* Stash the first available entry we find */
 315          if (available_entry == NULL)
 316             available_entry = entry;
 317          if (entry_is_free(entry))
 318             break;
 319       }
 320
 321       /* Implement replacement when another insert happens
 322        * with a matching key.  This is a relatively common
 323        * feature of hash tables, with the alternative
 324        * generally being "insert the new value as well, and
 325        * return it first when the key is searched for".
 326        *
 327        * Note that the hash table doesn't have a delete
 328        * callback.  If freeing of old data pointers is
 329        * required to avoid memory leaks, perform a search
 330        * before inserting.
 331        */
 332       if (!entry_is_deleted(ht, entry) &&
 333           entry->hash == hash &&
 334           ht->key_equals_function(key, entry->key)) {
 335          entry->key = key;
 336          entry->data = data;
 337          return entry;
 338       }
 339
 340
 341       double_hash = 1 + hash % ht->rehash;
 342
 343       hash_address = (hash_address + double_hash) % ht->size;
 344    } while (hash_address != start_hash_address);
 345
 346    if (available_entry) {
 347       if (entry_is_deleted(ht, available_entry))
 348          ht->deleted_entries--;
 349       available_entry->hash = hash;
 350       available_entry->key = key;
 351       available_entry->data = data;
 352       ht->entries++;
 353       return available_entry;
 354    }
 355
 356    /* We could hit here if a required resize failed. An unchecked-malloc
 357     * application could ignore this result.
 358     */
 359    return NULL;
 360 }
 361
 362 /**
 363  * Inserts the key with the given hash into the table.
 364  *
 365  * Note that insertion may rearrange the table on a resize or rehash,
 366  * so previously found hash_entries are no longer valid after this function.
 367  */
 368 struct hash_entry *
 369 _mesa_hash_table_insert(struct hash_table *ht, const void *key, void *data)
 370 {
 371    assert(ht->key_hash_function);
 372    return hash_table_insert(ht, ht->key_hash_function(key), key, data);
 373 }
 374
 375 struct hash_entry *
 376 _mesa_hash_table_insert_pre_hashed(struct hash_table *ht, uint32_t hash,
 377                                    const void *key, void *data)
 378 {
 379    assert(ht->key_hash_function == NULL || hash == ht->key_hash_function(key));
 380    return hash_table_insert(ht, hash, key, data);
 381 }
 382
 383 /**
 384  * This function deletes the given hash table entry.
 385  *
 386  * Note that deletion doesn't otherwise modify the table, so an iteration over
 387  * the table deleting entries is safe.
 388  */
 389 void
 390 _mesa_hash_table_remove(struct hash_table *ht,
 391                         struct hash_entry *entry)
 392 {
 393    if (!entry)
 394       return;
 395
 396    entry->key = ht->deleted_key;
 397    ht->entries--;
 398    ht->deleted_entries++;
 399 }
 400
 401 /**
 402  * This function is an iterator over the hash table.
 403  *
 404  * Pass in NULL for the first entry, as in the start of a for loop.  Note that
 405  * an iteration over the table is O(table_size) not O(entries).
 406  */
 407 struct hash_entry *
 408 _mesa_hash_table_next_entry(struct hash_table *ht,
 409                             struct hash_entry *entry)
 410 {
 411    if (entry == NULL)
 412       entry = ht->table;
 413    else
 414       entry = entry + 1;
 415
 416    for (; entry != ht->table + ht->size; entry++) {
 417       if (entry_is_present(ht, entry)) {
 418          return entry;
 419       }
 420    }
 421
 422    return NULL;
 423 }
 424
 425 /**
 426  * Returns a random entry from the hash table.
 427  *
 428  * This may be useful in implementing random replacement (as opposed
 429  * to just removing everything) in caches based on this hash table
 430  * implementation.  @predicate may be used to filter entries, or may
 431  * be set to NULL for no filtering.
 432  */
 433 struct hash_entry *
 434 _mesa_hash_table_random_entry(struct hash_table *ht,
 435                               bool (*predicate)(struct hash_entry *entry))
 436 {
 437    struct hash_entry *entry;
 438    uint32_t i = rand() % ht->size;
 439
 440    if (ht->entries == 0)
 441       return NULL;
 442
 443    for (entry = ht->table + i; entry != ht->table + ht->size; entry++) {
 444       if (entry_is_present(ht, entry) &&
 445           (!predicate || predicate(entry))) {
 446          return entry;
 447       }
 448    }
 449
 450    for (entry = ht->table; entry != ht->table + i; entry++) {
 451       if (entry_is_present(ht, entry) &&
 452           (!predicate || predicate(entry))) {
 453          return entry;
 454       }
 455    }
 456
 457    return NULL;
 458 }
 459
 460
 461 /**
 462  * Quick FNV-1a hash implementation based on:
 463  * http://www.isthe.com/chongo/tech/comp/fnv/
 464  *
 465  * FNV-1a is not be the best hash out there -- Jenkins's lookup3 is supposed
 466  * to be quite good, and it probably beats FNV.  But FNV has the advantage
 467  * that it involves almost no code.  For an improvement on both, see Paul
 468  * Hsieh's http://www.azillionmonkeys.com/qed/hash.html
 469  */
 470 uint32_t
 471 _mesa_hash_data(const void *data, size_t size)
 472 {
 473    return _mesa_fnv32_1a_accumulate_block(_mesa_fnv32_1a_offset_bias,
 474                                           data, size);
 475 }
 476
 477 /** FNV-1a string hash implementation */
 478 uint32_t
 479 _mesa_hash_string(const char *key)
 480 {
 481    uint32_t hash = _mesa_fnv32_1a_offset_bias;
 482
 483    while (*key != 0) {
 484       hash = _mesa_fnv32_1a_accumulate(hash, *key);
 485       key++;
 486    }
 487
 488    return hash;
 489 }
 490
 491 /**
 492  * String compare function for use as the comparison callback in
 493  * _mesa_hash_table_create().
 494  */
 495 bool
 496 _mesa_key_string_equal(const void *a, const void *b)
 497 {
 498    return strcmp(a, b) == 0;
 499 }
 500
 501 bool
 502 _mesa_key_pointer_equal(const void *a, const void *b)
 503 {
 504    return a == b;
 505 }
 506
 507 /**
 508  * Hash table wrapper which supports 64-bit keys.
 509  *
 510  * TODO: unify all hash table implementations.
 511  */
 512
 513 struct hash_key_u64 {
 514    uint64_t value;
 515 };
 516
 517 static uint32_t
 518 key_u64_hash(const void *key)
 519 {
 520    return _mesa_hash_data(key, sizeof(struct hash_key_u64));
 521 }
 522
 523 static bool
 524 key_u64_equals(const void *a, const void *b)
 525 {
 526    const struct hash_key_u64 *aa = a;
 527    const struct hash_key_u64 *bb = b;
 528
 529    return aa->value == bb->value;
 530 }
 531
 532 struct hash_table_u64 *
 533 _mesa_hash_table_u64_create(void *mem_ctx)
 534 {
 535    struct hash_table_u64 *ht;
 536
 537    ht = CALLOC_STRUCT(hash_table_u64);
 538    if (!ht)
 539       return NULL;
 540
 541    if (sizeof(void *) == 8) {
 542       ht->table = _mesa_hash_table_create(mem_ctx, _mesa_hash_pointer,
 543                                           _mesa_key_pointer_equal);
 544    } else {
 545       ht->table = _mesa_hash_table_create(mem_ctx, key_u64_hash,
 546                                           key_u64_equals);
 547    }
 548
 549    if (ht->table)
 550       _mesa_hash_table_set_deleted_key(ht->table, uint_key(DELETED_KEY_VALUE));
 551
 552    return ht;
 553 }
 554
 555 void
 556 _mesa_hash_table_u64_destroy(struct hash_table_u64 *ht,
 557                              void (*delete_function)(struct hash_entry *entry))
 558 {
 559    if (!ht)
 560       return;
 561
 562    if (ht->deleted_key_data) {
 563       if (delete_function) {
 564          struct hash_table *table = ht->table;
 565          struct hash_entry deleted_entry;
 566
 567          /* Create a fake entry for the delete function. */
 568          deleted_entry.hash = table->key_hash_function(table->deleted_key);
 569          deleted_entry.key = table->deleted_key;
 570          deleted_entry.data = ht->deleted_key_data;
 571
 572          delete_function(&deleted_entry);
 573       }
 574       ht->deleted_key_data = NULL;
 575    }
 576
 577    _mesa_hash_table_destroy(ht->table, delete_function);
 578    free(ht);
 579 }
 580
 581 void
 582 _mesa_hash_table_u64_insert(struct hash_table_u64 *ht, uint64_t key,
 583                             void *data)
 584 {
 585    if (key == DELETED_KEY_VALUE) {
 586       ht->deleted_key_data = data;
 587       return;
 588    }
 589
 590    if (sizeof(void *) == 8) {
 591       _mesa_hash_table_insert(ht->table, (void *)(uintptr_t)key, data);
 592    } else {
 593       struct hash_key_u64 *_key = CALLOC_STRUCT(hash_key_u64);
 594
 595       if (!_key)
 596          return;
 597       _key->value = key;
 598
 599       _mesa_hash_table_insert(ht->table, _key, data);
 600    }
 601 }
 602
 603 static struct hash_entry *
 604 hash_table_u64_search(struct hash_table_u64 *ht, uint64_t key)
 605 {
 606    if (sizeof(void *) == 8) {
 607       return _mesa_hash_table_search(ht->table, (void *)(uintptr_t)key);
 608    } else {
 609       struct hash_key_u64 _key = { .value = key };
 610       return _mesa_hash_table_search(ht->table, &_key);
 611    }
 612 }
 613
 614 void *
 615 _mesa_hash_table_u64_search(struct hash_table_u64 *ht, uint64_t key)
 616 {
 617    struct hash_entry *entry;
 618
 619    if (key == DELETED_KEY_VALUE)
 620       return ht->deleted_key_data;
 621
 622    entry = hash_table_u64_search(ht, key);
 623    if (!entry)
 624       return NULL;
 625
 626    return entry->data;
 627 }
 628
 629 void
 630 _mesa_hash_table_u64_remove(struct hash_table_u64 *ht, uint64_t key)
 631 {
 632    struct hash_entry *entry;
 633
 634    if (key == DELETED_KEY_VALUE) {
 635       ht->deleted_key_data = NULL;
 636       return;
 637    }
 638
 639    entry = hash_table_u64_search(ht, key);
 640    if (!entry)
 641       return;
 642
 643    if (sizeof(void *) == 8) {
 644       _mesa_hash_table_remove(ht->table, entry);
 645    } else {
 646       struct hash_key *_key = (struct hash_key *)entry->key;
 647
 648       _mesa_hash_table_remove(ht->table, entry);
 649       free(_key);
 650    }
 651 }