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 struct hash_table *
 145 _mesa_hash_table_clone(struct hash_table *src, void *dst_mem_ctx)
 146 {
 147    struct hash_table *ht;
 148
 149    ht = ralloc(dst_mem_ctx, struct hash_table);
 150    if (ht == NULL)
 151       return NULL;
 152
 153    memcpy(ht, src, sizeof(struct hash_table));
 154
 155    ht->table = ralloc_array(ht, struct hash_entry, ht->size);
 156    if (ht->table == NULL) {
 157       ralloc_free(ht);
 158       return NULL;
 159    }
 160
 161    memcpy(ht->table, src->table, ht->size * sizeof(struct hash_entry));
 162
 163    return ht;
 164 }
 165
 166 /**
 167  * Frees the given hash table.
 168  *
 169  * If delete_function is passed, it gets called on each entry present before
 170  * freeing.
 171  */
 172 void
 173 _mesa_hash_table_destroy(struct hash_table *ht,
 174                          void (*delete_function)(struct hash_entry *entry))
 175 {
 176    if (!ht)
 177       return;
 178
 179    if (delete_function) {
 180       struct hash_entry *entry;
 181
 182       hash_table_foreach(ht, entry) {
 183          delete_function(entry);
 184       }
 185    }
 186    ralloc_free(ht);
 187 }
 188
 189 /**
 190  * Deletes all entries of the given hash table without deleting the table
 191  * itself or changing its structure.
 192  *
 193  * If delete_function is passed, it gets called on each entry present.
 194  */
 195 void
 196 _mesa_hash_table_clear(struct hash_table *ht,
 197                        void (*delete_function)(struct hash_entry *entry))
 198 {
 199    struct hash_entry *entry;
 200
 201    for (entry = ht->table; entry != ht->table + ht->size; entry++) {
 202       if (entry->key == NULL)
 203          continue;
 204
 205       if (delete_function != NULL && entry->key != ht->deleted_key)
 206          delete_function(entry);
 207
 208       entry->key = NULL;
 209    }
 210
 211    ht->entries = 0;
 212    ht->deleted_entries = 0;
 213 }
 214
 215 /** Sets the value of the key pointer used for deleted entries in the table.
 216  *
 217  * The assumption is that usually keys are actual pointers, so we use a
 218  * default value of a pointer to an arbitrary piece of storage in the library.
 219  * But in some cases a consumer wants to store some other sort of value in the
 220  * table, like a uint32_t, in which case that pointer may conflict with one of
 221  * their valid keys.  This lets that user select a safe value.
 222  *
 223  * This must be called before any keys are actually deleted from the table.
 224  */
 225 void
 226 _mesa_hash_table_set_deleted_key(struct hash_table *ht, const void *deleted_key)
 227 {
 228    ht->deleted_key = deleted_key;
 229 }
 230
 231 static struct hash_entry *
 232 hash_table_search(struct hash_table *ht, uint32_t hash, const void *key)
 233 {
 234    uint32_t start_hash_address = hash % ht->size;
 235    uint32_t hash_address = start_hash_address;
 236
 237    do {
 238       uint32_t double_hash;
 239
 240       struct hash_entry *entry = ht->table + hash_address;
 241
 242       if (entry_is_free(entry)) {
 243          return NULL;
 244       } else if (entry_is_present(ht, entry) && entry->hash == hash) {
 245          if (ht->key_equals_function(key, entry->key)) {
 246             return entry;
 247          }
 248       }
 249
 250       double_hash = 1 + hash % ht->rehash;
 251
 252       hash_address = (hash_address + double_hash) % ht->size;
 253    } while (hash_address != start_hash_address);
 254
 255    return NULL;
 256 }
 257
 258 /**
 259  * Finds a hash table entry with the given key and hash of that key.
 260  *
 261  * Returns NULL if no entry is found.  Note that the data pointer may be
 262  * modified by the user.
 263  */
 264 struct hash_entry *
 265 _mesa_hash_table_search(struct hash_table *ht, const void *key)
 266 {
 267    assert(ht->key_hash_function);
 268    return hash_table_search(ht, ht->key_hash_function(key), key);
 269 }
 270
 271 struct hash_entry *
 272 _mesa_hash_table_search_pre_hashed(struct hash_table *ht, uint32_t hash,
 273                                   const void *key)
 274 {
 275    assert(ht->key_hash_function == NULL || hash == ht->key_hash_function(key));
 276    return hash_table_search(ht, hash, key);
 277 }
 278
 279 static struct hash_entry *
 280 hash_table_insert(struct hash_table *ht, uint32_t hash,
 281                   const void *key, void *data);
 282
 283 static void
 284 _mesa_hash_table_rehash(struct hash_table *ht, unsigned new_size_index)
 285 {
 286    struct hash_table old_ht;
 287    struct hash_entry *table, *entry;
 288
 289    if (new_size_index >= ARRAY_SIZE(hash_sizes))
 290       return;
 291
 292    table = rzalloc_array(ht, struct hash_entry,
 293                          hash_sizes[new_size_index].size);
 294    if (table == NULL)
 295       return;
 296
 297    old_ht = *ht;
 298
 299    ht->table = table;
 300    ht->size_index = new_size_index;
 301    ht->size = hash_sizes[ht->size_index].size;
 302    ht->rehash = hash_sizes[ht->size_index].rehash;
 303    ht->max_entries = hash_sizes[ht->size_index].max_entries;
 304    ht->entries = 0;
 305    ht->deleted_entries = 0;
 306
 307    hash_table_foreach(&old_ht, entry) {
 308       hash_table_insert(ht, entry->hash, entry->key, entry->data);
 309    }
 310
 311    ralloc_free(old_ht.table);
 312 }
 313
 314 static struct hash_entry *
 315 hash_table_insert(struct hash_table *ht, uint32_t hash,
 316                   const void *key, void *data)
 317 {
 318    uint32_t start_hash_address, hash_address;
 319    struct hash_entry *available_entry = NULL;
 320
 321    assert(key != NULL);
 322
 323    if (ht->entries >= ht->max_entries) {
 324       _mesa_hash_table_rehash(ht, ht->size_index + 1);
 325    } else if (ht->deleted_entries + ht->entries >= ht->max_entries) {
 326       _mesa_hash_table_rehash(ht, ht->size_index);
 327    }
 328
 329    start_hash_address = hash % ht->size;
 330    hash_address = start_hash_address;
 331    do {
 332       struct hash_entry *entry = ht->table + hash_address;
 333       uint32_t double_hash;
 334
 335       if (!entry_is_present(ht, entry)) {
 336          /* Stash the first available entry we find */
 337          if (available_entry == NULL)
 338             available_entry = entry;
 339          if (entry_is_free(entry))
 340             break;
 341       }
 342
 343       /* Implement replacement when another insert happens
 344        * with a matching key.  This is a relatively common
 345        * feature of hash tables, with the alternative
 346        * generally being "insert the new value as well, and
 347        * return it first when the key is searched for".
 348        *
 349        * Note that the hash table doesn't have a delete
 350        * callback.  If freeing of old data pointers is
 351        * required to avoid memory leaks, perform a search
 352        * before inserting.
 353        */
 354       if (!entry_is_deleted(ht, entry) &&
 355           entry->hash == hash &&
 356           ht->key_equals_function(key, entry->key)) {
 357          entry->key = key;
 358          entry->data = data;
 359          return entry;
 360       }
 361
 362
 363       double_hash = 1 + hash % ht->rehash;
 364
 365       hash_address = (hash_address + double_hash) % ht->size;
 366    } while (hash_address != start_hash_address);
 367
 368    if (available_entry) {
 369       if (entry_is_deleted(ht, available_entry))
 370          ht->deleted_entries--;
 371       available_entry->hash = hash;
 372       available_entry->key = key;
 373       available_entry->data = data;
 374       ht->entries++;
 375       return available_entry;
 376    }
 377
 378    /* We could hit here if a required resize failed. An unchecked-malloc
 379     * application could ignore this result.
 380     */
 381    return NULL;
 382 }
 383
 384 /**
 385  * Inserts the key with the given hash into the table.
 386  *
 387  * Note that insertion may rearrange the table on a resize or rehash,
 388  * so previously found hash_entries are no longer valid after this function.
 389  */
 390 struct hash_entry *
 391 _mesa_hash_table_insert(struct hash_table *ht, const void *key, void *data)
 392 {
 393    assert(ht->key_hash_function);
 394    return hash_table_insert(ht, ht->key_hash_function(key), key, data);
 395 }
 396
 397 struct hash_entry *
 398 _mesa_hash_table_insert_pre_hashed(struct hash_table *ht, uint32_t hash,
 399                                    const void *key, void *data)
 400 {
 401    assert(ht->key_hash_function == NULL || hash == ht->key_hash_function(key));
 402    return hash_table_insert(ht, hash, key, data);
 403 }
 404
 405 /**
 406  * This function deletes the given hash table entry.
 407  *
 408  * Note that deletion doesn't otherwise modify the table, so an iteration over
 409  * the table deleting entries is safe.
 410  */
 411 void
 412 _mesa_hash_table_remove(struct hash_table *ht,
 413                         struct hash_entry *entry)
 414 {
 415    if (!entry)
 416       return;
 417
 418    entry->key = ht->deleted_key;
 419    ht->entries--;
 420    ht->deleted_entries++;
 421 }
 422
 423 /**
 424  * Removes the entry with the corresponding key, if exists.
 425  */
 426 void _mesa_hash_table_remove_key(struct hash_table *ht,
 427                                  const void *key)
 428 {
 429    _mesa_hash_table_remove(ht, _mesa_hash_table_search(ht, key));
 430 }
 431
 432 /**
 433  * This function is an iterator over the hash table.
 434  *
 435  * Pass in NULL for the first entry, as in the start of a for loop.  Note that
 436  * an iteration over the table is O(table_size) not O(entries).
 437  */
 438 struct hash_entry *
 439 _mesa_hash_table_next_entry(struct hash_table *ht,
 440                             struct hash_entry *entry)
 441 {
 442    if (entry == NULL)
 443       entry = ht->table;
 444    else
 445       entry = entry + 1;
 446
 447    for (; entry != ht->table + ht->size; entry++) {
 448       if (entry_is_present(ht, entry)) {
 449          return entry;
 450       }
 451    }
 452
 453    return NULL;
 454 }
 455
 456 /**
 457  * Returns a random entry from the hash table.
 458  *
 459  * This may be useful in implementing random replacement (as opposed
 460  * to just removing everything) in caches based on this hash table
 461  * implementation.  @predicate may be used to filter entries, or may
 462  * be set to NULL for no filtering.
 463  */
 464 struct hash_entry *
 465 _mesa_hash_table_random_entry(struct hash_table *ht,
 466                               bool (*predicate)(struct hash_entry *entry))
 467 {
 468    struct hash_entry *entry;
 469    uint32_t i = rand() % ht->size;
 470
 471    if (ht->entries == 0)
 472       return NULL;
 473
 474    for (entry = ht->table + i; entry != ht->table + ht->size; entry++) {
 475       if (entry_is_present(ht, entry) &&
 476           (!predicate || predicate(entry))) {
 477          return entry;
 478       }
 479    }
 480
 481    for (entry = ht->table; entry != ht->table + i; entry++) {
 482       if (entry_is_present(ht, entry) &&
 483           (!predicate || predicate(entry))) {
 484          return entry;
 485       }
 486    }
 487
 488    return NULL;
 489 }
 490
 491
 492 /**
 493  * Quick FNV-1a hash implementation based on:
 494  * http://www.isthe.com/chongo/tech/comp/fnv/
 495  *
 496  * FNV-1a is not be the best hash out there -- Jenkins's lookup3 is supposed
 497  * to be quite good, and it probably beats FNV.  But FNV has the advantage
 498  * that it involves almost no code.  For an improvement on both, see Paul
 499  * Hsieh's http://www.azillionmonkeys.com/qed/hash.html
 500  */
 501 uint32_t
 502 _mesa_hash_data(const void *data, size_t size)
 503 {
 504    return _mesa_fnv32_1a_accumulate_block(_mesa_fnv32_1a_offset_bias,
 505                                           data, size);
 506 }
 507
 508 /** FNV-1a string hash implementation */
 509 uint32_t
 510 _mesa_hash_string(const void *_key)
 511 {
 512    uint32_t hash = _mesa_fnv32_1a_offset_bias;
 513    const char *key = _key;
 514
 515    while (*key != 0) {
 516       hash = _mesa_fnv32_1a_accumulate(hash, *key);
 517       key++;
 518    }
 519
 520    return hash;
 521 }
 522
 523 /**
 524  * String compare function for use as the comparison callback in
 525  * _mesa_hash_table_create().
 526  */
 527 bool
 528 _mesa_key_string_equal(const void *a, const void *b)
 529 {
 530    return strcmp(a, b) == 0;
 531 }
 532
 533 bool
 534 _mesa_key_pointer_equal(const void *a, const void *b)
 535 {
 536    return a == b;
 537 }
 538
 539 /**
 540  * Hash table wrapper which supports 64-bit keys.
 541  *
 542  * TODO: unify all hash table implementations.
 543  */
 544
 545 struct hash_key_u64 {
 546    uint64_t value;
 547 };
 548
 549 static uint32_t
 550 key_u64_hash(const void *key)
 551 {
 552    return _mesa_hash_data(key, sizeof(struct hash_key_u64));
 553 }
 554
 555 static bool
 556 key_u64_equals(const void *a, const void *b)
 557 {
 558    const struct hash_key_u64 *aa = a;
 559    const struct hash_key_u64 *bb = b;
 560
 561    return aa->value == bb->value;
 562 }
 563
 564 struct hash_table_u64 *
 565 _mesa_hash_table_u64_create(void *mem_ctx)
 566 {
 567    struct hash_table_u64 *ht;
 568
 569    ht = CALLOC_STRUCT(hash_table_u64);
 570    if (!ht)
 571       return NULL;
 572
 573    if (sizeof(void *) == 8) {
 574       ht->table = _mesa_hash_table_create(mem_ctx, _mesa_hash_pointer,
 575                                           _mesa_key_pointer_equal);
 576    } else {
 577       ht->table = _mesa_hash_table_create(mem_ctx, key_u64_hash,
 578                                           key_u64_equals);
 579    }
 580
 581    if (ht->table)
 582       _mesa_hash_table_set_deleted_key(ht->table, uint_key(DELETED_KEY_VALUE));
 583
 584    return ht;
 585 }
 586
 587 void
 588 _mesa_hash_table_u64_destroy(struct hash_table_u64 *ht,
 589                              void (*delete_function)(struct hash_entry *entry))
 590 {
 591    if (!ht)
 592       return;
 593
 594    if (ht->deleted_key_data) {
 595       if (delete_function) {
 596          struct hash_table *table = ht->table;
 597          struct hash_entry deleted_entry;
 598
 599          /* Create a fake entry for the delete function. */
 600          deleted_entry.hash = table->key_hash_function(table->deleted_key);
 601          deleted_entry.key = table->deleted_key;
 602          deleted_entry.data = ht->deleted_key_data;
 603
 604          delete_function(&deleted_entry);
 605       }
 606       ht->deleted_key_data = NULL;
 607    }
 608
 609    _mesa_hash_table_destroy(ht->table, delete_function);
 610    free(ht);
 611 }
 612
 613 void
 614 _mesa_hash_table_u64_insert(struct hash_table_u64 *ht, uint64_t key,
 615                             void *data)
 616 {
 617    if (key == DELETED_KEY_VALUE) {
 618       ht->deleted_key_data = data;
 619       return;
 620    }
 621
 622    if (sizeof(void *) == 8) {
 623       _mesa_hash_table_insert(ht->table, (void *)(uintptr_t)key, data);
 624    } else {
 625       struct hash_key_u64 *_key = CALLOC_STRUCT(hash_key_u64);
 626
 627       if (!_key)
 628          return;
 629       _key->value = key;
 630
 631       _mesa_hash_table_insert(ht->table, _key, data);
 632    }
 633 }
 634
 635 static struct hash_entry *
 636 hash_table_u64_search(struct hash_table_u64 *ht, uint64_t key)
 637 {
 638    if (sizeof(void *) == 8) {
 639       return _mesa_hash_table_search(ht->table, (void *)(uintptr_t)key);
 640    } else {
 641       struct hash_key_u64 _key = { .value = key };
 642       return _mesa_hash_table_search(ht->table, &_key);
 643    }
 644 }
 645
 646 void *
 647 _mesa_hash_table_u64_search(struct hash_table_u64 *ht, uint64_t key)
 648 {
 649    struct hash_entry *entry;
 650
 651    if (key == DELETED_KEY_VALUE)
 652       return ht->deleted_key_data;
 653
 654    entry = hash_table_u64_search(ht, key);
 655    if (!entry)
 656       return NULL;
 657
 658    return entry->data;
 659 }
 660
 661 void
 662 _mesa_hash_table_u64_remove(struct hash_table_u64 *ht, uint64_t key)
 663 {
 664    struct hash_entry *entry;
 665
 666    if (key == DELETED_KEY_VALUE) {
 667       ht->deleted_key_data = NULL;
 668       return;
 669    }
 670
 671    entry = hash_table_u64_search(ht, key);
 672    if (!entry)
 673       return;
 674
 675    if (sizeof(void *) == 8) {
 676       _mesa_hash_table_remove(ht->table, entry);
 677    } else {
 678       struct hash_key *_key = (struct hash_key *)entry->key;
 679
 680       _mesa_hash_table_remove(ht->table, entry);
 681       free(_key);
 682    }
 683 }