src/mesa/main/set.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 #include <stdlib.h>
  36
  37 #include "macros.h"
  38 #include "set.h"
  39 #include "ralloc.h"
  40
  41 /*
  42  * From Knuth -- a good choice for hash/rehash values is p, p-2 where
  43  * p and p-2 are both prime.  These tables are sized to have an extra 10%
  44  * free to avoid exponential performance degradation as the hash table fills
  45  */
  46
  47 uint32_t deleted_key_value;
  48 const void *deleted_key = &deleted_key_value;
  49
  50 static const struct {
  51    uint32_t max_entries, size, rehash;
  52 } hash_sizes[] = {
  53    { 2,            5,            3            },
  54    { 4,            7,            5            },
  55    { 8,            13,           11           },
  56    { 16,           19,           17           },
  57    { 32,           43,           41           },
  58    { 64,           73,           71           },
  59    { 128,          151,          149          },
  60    { 256,          283,          281          },
  61    { 512,          571,          569          },
  62    { 1024,         1153,         1151         },
  63    { 2048,         2269,         2267         },
  64    { 4096,         4519,         4517         },
  65    { 8192,         9013,         9011         },
  66    { 16384,        18043,        18041        },
  67    { 32768,        36109,        36107        },
  68    { 65536,        72091,        72089        },
  69    { 131072,       144409,       144407       },
  70    { 262144,       288361,       288359       },
  71    { 524288,       576883,       576881       },
  72    { 1048576,      1153459,      1153457      },
  73    { 2097152,      2307163,      2307161      },
  74    { 4194304,      4613893,      4613891      },
  75    { 8388608,      9227641,      9227639      },
  76    { 16777216,     18455029,     18455027     },
  77    { 33554432,     36911011,     36911009     },
  78    { 67108864,     73819861,     73819859     },
  79    { 134217728,    147639589,    147639587    },
  80    { 268435456,    295279081,    295279079    },
  81    { 536870912,    590559793,    590559791    },
  82    { 1073741824,   1181116273,   1181116271   },
  83    { 2147483648ul, 2362232233ul, 2362232231ul }
  84 };
  85
  86 static int
  87 entry_is_free(struct set_entry *entry)
  88 {
  89    return entry->key == NULL;
  90 }
  91
  92 static int
  93 entry_is_deleted(struct set_entry *entry)
  94 {
  95    return entry->key == deleted_key;
  96 }
  97
  98 static int
  99 entry_is_present(struct set_entry *entry)
 100 {
 101    return entry->key != NULL && entry->key != deleted_key;
 102 }
 103
 104 struct set *
 105 _mesa_set_create(void *mem_ctx,
 106                  bool (*key_equals_function)(const void *a,
 107                                              const void *b))
 108 {
 109    struct set *ht;
 110
 111    ht = ralloc(mem_ctx, struct set);
 112    if (ht == NULL)
 113       return NULL;
 114
 115    ht->mem_ctx = mem_ctx;
 116    ht->size_index = 0;
 117    ht->size = hash_sizes[ht->size_index].size;
 118    ht->rehash = hash_sizes[ht->size_index].rehash;
 119    ht->max_entries = hash_sizes[ht->size_index].max_entries;
 120    ht->key_equals_function = key_equals_function;
 121    ht->table = rzalloc_array(ht, struct set_entry, ht->size);
 122    ht->entries = 0;
 123    ht->deleted_entries = 0;
 124
 125    if (ht->table == NULL) {
 126       ralloc_free(ht);
 127       return NULL;
 128    }
 129
 130    return ht;
 131 }
 132
 133 /**
 134  * Frees the given set.
 135  *
 136  * If delete_function is passed, it gets called on each entry present before
 137  * freeing.
 138  */
 139 void
 140 _mesa_set_destroy(struct set *ht, void (*delete_function)(struct set_entry *entry))
 141 {
 142    if (!ht)
 143       return;
 144
 145    if (delete_function) {
 146       struct set_entry *entry;
 147
 148       set_foreach (ht, entry) {
 149          delete_function(entry);
 150       }
 151    }
 152    ralloc_free(ht->table);
 153    ralloc_free(ht);
 154 }
 155
 156 /**
 157  * Finds a set entry with the given key and hash of that key.
 158  *
 159  * Returns NULL if no entry is found.
 160  */
 161 struct set_entry *
 162 _mesa_set_search(const struct set *ht, uint32_t hash, const void *key)
 163 {
 164    uint32_t hash_address;
 165
 166    hash_address = hash % ht->size;
 167    do {
 168       uint32_t double_hash;
 169
 170       struct set_entry *entry = ht->table + hash_address;
 171
 172       if (entry_is_free(entry)) {
 173          return NULL;
 174       } else if (entry_is_present(entry) && entry->hash == hash) {
 175          if (ht->key_equals_function(key, entry->key)) {
 176             return entry;
 177          }
 178       }
 179
 180       double_hash = 1 + hash % ht->rehash;
 181
 182       hash_address = (hash_address + double_hash) % ht->size;
 183    } while (hash_address != hash % ht->size);
 184
 185    return NULL;
 186 }
 187
 188 static void
 189 set_rehash(struct set *ht, int new_size_index)
 190 {
 191    struct set old_ht;
 192    struct set_entry *table, *entry;
 193
 194    if (new_size_index >= ARRAY_SIZE(hash_sizes))
 195       return;
 196
 197    table = rzalloc_array(ht, struct set_entry,
 198                          hash_sizes[new_size_index].size);
 199    if (table == NULL)
 200       return;
 201
 202    old_ht = *ht;
 203
 204    ht->table = table;
 205    ht->size_index = new_size_index;
 206    ht->size = hash_sizes[ht->size_index].size;
 207    ht->rehash = hash_sizes[ht->size_index].rehash;
 208    ht->max_entries = hash_sizes[ht->size_index].max_entries;
 209    ht->entries = 0;
 210    ht->deleted_entries = 0;
 211
 212    for (entry = old_ht.table;
 213         entry != old_ht.table + old_ht.size;
 214         entry++) {
 215       if (entry_is_present(entry)) {
 216          _mesa_set_add(ht, entry->hash, entry->key);
 217       }
 218    }
 219
 220    ralloc_free(old_ht.table);
 221 }
 222
 223 /**
 224  * Inserts the key with the given hash into the table.
 225  *
 226  * Note that insertion may rearrange the table on a resize or rehash,
 227  * so previously found hash_entries are no longer valid after this function.
 228  */
 229 struct set_entry *
 230 _mesa_set_add(struct set *ht, uint32_t hash, const void *key)
 231 {
 232    uint32_t hash_address;
 233
 234    if (ht->entries >= ht->max_entries) {
 235       set_rehash(ht, ht->size_index + 1);
 236    } else if (ht->deleted_entries + ht->entries >= ht->max_entries) {
 237       set_rehash(ht, ht->size_index);
 238    }
 239
 240    hash_address = hash % ht->size;
 241    do {
 242       struct set_entry *entry = ht->table + hash_address;
 243       uint32_t double_hash;
 244
 245       if (!entry_is_present(entry)) {
 246          if (entry_is_deleted(entry))
 247             ht->deleted_entries--;
 248          entry->hash = hash;
 249          entry->key = key;
 250          ht->entries++;
 251          return entry;
 252       }
 253
 254       /* Implement replacement when another insert happens
 255        * with a matching key.  This is a relatively common
 256        * feature of hash tables, with the alternative
 257        * generally being "insert the new value as well, and
 258        * return it first when the key is searched for".
 259        *
 260        * Note that the hash table doesn't have a delete callback.
 261        * If freeing of old keys is required to avoid memory leaks,
 262        * perform a search before inserting.
 263        */
 264       if (entry->hash == hash &&
 265           ht->key_equals_function(key, entry->key)) {
 266          entry->key = key;
 267          return entry;
 268       }
 269
 270       double_hash = 1 + hash % ht->rehash;
 271
 272       hash_address = (hash_address + double_hash) % ht->size;
 273    } while (hash_address != hash % ht->size);
 274
 275    /* We could hit here if a required resize failed. An unchecked-malloc
 276     * application could ignore this result.
 277     */
 278    return NULL;
 279 }
 280
 281 /**
 282  * This function deletes the given hash table entry.
 283  *
 284  * Note that deletion doesn't otherwise modify the table, so an iteration over
 285  * the table deleting entries is safe.
 286  */
 287 void
 288 _mesa_set_remove(struct set *ht, struct set_entry *entry)
 289 {
 290    if (!entry)
 291       return;
 292
 293    entry->key = deleted_key;
 294    ht->entries--;
 295    ht->deleted_entries++;
 296 }
 297
 298 /**
 299  * This function is an iterator over the hash table.
 300  *
 301  * Pass in NULL for the first entry, as in the start of a for loop.  Note that
 302  * an iteration over the table is O(table_size) not O(entries).
 303  */
 304 struct set_entry *
 305 _mesa_set_next_entry(const struct set *ht, struct set_entry *entry)
 306 {
 307    if (entry == NULL)
 308       entry = ht->table;
 309    else
 310       entry = entry + 1;
 311
 312    for (; entry != ht->table + ht->size; entry++) {
 313       if (entry_is_present(entry)) {
 314          return entry;
 315       }
 316    }
 317
 318    return NULL;
 319 }
 320
 321 struct set_entry *
 322 _mesa_set_random_entry(struct set *ht,
 323                        int (*predicate)(struct set_entry *entry))
 324 {
 325    struct set_entry *entry;
 326    uint32_t i = rand() % ht->size;
 327
 328    if (ht->entries == 0)
 329       return NULL;
 330
 331    for (entry = ht->table + i; entry != ht->table + ht->size; entry++) {
 332       if (entry_is_present(entry) &&
 333           (!predicate || predicate(entry))) {
 334          return entry;
 335       }
 336    }
 337
 338    for (entry = ht->table; entry != ht->table + i; entry++) {
 339       if (entry_is_present(entry) &&
 340           (!predicate || predicate(entry))) {
 341          return entry;
 342       }
 343    }
 344
 345    return NULL;
 346 }
 347