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 "set.h"
  38 #include "ralloc.h"
  39
  40 #define ARRAY_SIZE(array) (sizeof(array) / sizeof(array[0]))
  41
  42 /*
  43  * From Knuth -- a good choice for hash/rehash values is p, p-2 where
  44  * p and p-2 are both prime.  These tables are sized to have an extra 10%
  45  * free to avoid exponential performance degradation as the hash table fills
  46  */
  47
  48 uint32_t deleted_key_value;
  49 const void *deleted_key = &deleted_key_value;
  50
  51 static const struct {
  52    uint32_t max_entries, size, rehash;
  53 } hash_sizes[] = {
  54    { 2,            5,            3            },
  55    { 4,            7,            5            },
  56    { 8,            13,           11           },
  57    { 16,           19,           17           },
  58    { 32,           43,           41           },
  59    { 64,           73,           71           },
  60    { 128,          151,          149          },
  61    { 256,          283,          281          },
  62    { 512,          571,          569          },
  63    { 1024,         1153,         1151         },
  64    { 2048,         2269,         2267         },
  65    { 4096,         4519,         4517         },
  66    { 8192,         9013,         9011         },
  67    { 16384,        18043,        18041        },
  68    { 32768,        36109,        36107        },
  69    { 65536,        72091,        72089        },
  70    { 131072,       144409,       144407       },
  71    { 262144,       288361,       288359       },
  72    { 524288,       576883,       576881       },
  73    { 1048576,      1153459,      1153457      },
  74    { 2097152,      2307163,      2307161      },
  75    { 4194304,      4613893,      4613891      },
  76    { 8388608,      9227641,      9227639      },
  77    { 16777216,     18455029,     18455027     },
  78    { 33554432,     36911011,     36911009     },
  79    { 67108864,     73819861,     73819859     },
  80    { 134217728,    147639589,    147639587    },
  81    { 268435456,    295279081,    295279079    },
  82    { 536870912,    590559793,    590559791    },
  83    { 1073741824,   1181116273,   1181116271   },
  84    { 2147483648ul, 2362232233ul, 2362232231ul }
  85 };
  86
  87 static int
  88 entry_is_free(struct set_entry *entry)
  89 {
  90    return entry->key == NULL;
  91 }
  92
  93 static int
  94 entry_is_deleted(struct set_entry *entry)
  95 {
  96    return entry->key == deleted_key;
  97 }
  98
  99 static int
 100 entry_is_present(struct set_entry *entry)
 101 {
 102    return entry->key != NULL && entry->key != deleted_key;
 103 }
 104
 105 struct set *
 106 _mesa_set_create(void *mem_ctx,
 107                  bool key_equals_function(const void *a,
 108                                           const void *b))
 109 {
 110    struct set *ht;
 111
 112    ht = ralloc(mem_ctx, struct set);
 113    if (ht == NULL)
 114       return NULL;
 115
 116    ht->mem_ctx = mem_ctx;
 117    ht->size_index = 0;
 118    ht->size = hash_sizes[ht->size_index].size;
 119    ht->rehash = hash_sizes[ht->size_index].rehash;
 120    ht->max_entries = hash_sizes[ht->size_index].max_entries;
 121    ht->key_equals_function = key_equals_function;
 122    ht->table = rzalloc_array(ht, struct set_entry, ht->size);
 123    ht->entries = 0;
 124    ht->deleted_entries = 0;
 125
 126    if (ht->table == NULL) {
 127       ralloc_free(ht);
 128       return NULL;
 129    }
 130
 131    return ht;
 132 }
 133
 134 /**
 135  * Frees the given set.
 136  *
 137  * If delete_function is passed, it gets called on each entry present before
 138  * freeing.
 139  */
 140 void
 141 _mesa_set_destroy(struct set *ht, void (*delete_function)(struct set_entry *entry))
 142 {
 143    if (!ht)
 144       return;
 145
 146    if (delete_function) {
 147       struct set_entry *entry;
 148
 149       set_foreach (ht, entry) {
 150          delete_function(entry);
 151       }
 152    }
 153    ralloc_free(ht->table);
 154    ralloc_free(ht);
 155 }
 156
 157 /**
 158  * Finds a set entry with the given key and hash of that key.
 159  *
 160  * Returns NULL if no entry is found.
 161  */
 162 struct set_entry *
 163 _mesa_set_search(const struct set *ht, uint32_t hash, const void *key)
 164 {
 165    uint32_t hash_address;
 166
 167    hash_address = hash % ht->size;
 168    do {
 169       uint32_t double_hash;
 170
 171       struct set_entry *entry = ht->table + hash_address;
 172
 173       if (entry_is_free(entry)) {
 174          return NULL;
 175       } else if (entry_is_present(entry) && entry->hash == hash) {
 176          if (ht->key_equals_function(key, entry->key)) {
 177             return entry;
 178          }
 179       }
 180
 181       double_hash = 1 + hash % ht->rehash;
 182
 183       hash_address = (hash_address + double_hash) % ht->size;
 184    } while (hash_address != hash % ht->size);
 185
 186    return NULL;
 187 }
 188
 189 static void
 190 set_rehash(struct set *ht, int new_size_index)
 191 {
 192    struct set old_ht;
 193    struct set_entry *table, *entry;
 194
 195    if (new_size_index >= ARRAY_SIZE(hash_sizes))
 196       return;
 197
 198    table = rzalloc_array(ht, struct set_entry,
 199                          hash_sizes[new_size_index].size);
 200    if (table == NULL)
 201       return;
 202
 203    old_ht = *ht;
 204
 205    ht->table = table;
 206    ht->size_index = new_size_index;
 207    ht->size = hash_sizes[ht->size_index].size;
 208    ht->rehash = hash_sizes[ht->size_index].rehash;
 209    ht->max_entries = hash_sizes[ht->size_index].max_entries;
 210    ht->entries = 0;
 211    ht->deleted_entries = 0;
 212
 213    for (entry = old_ht.table;
 214         entry != old_ht.table + old_ht.size;
 215         entry++) {
 216       if (entry_is_present(entry)) {
 217          _mesa_set_add(ht, entry->hash, entry->key);
 218       }
 219    }
 220
 221    ralloc_free(old_ht.table);
 222 }
 223
 224 /**
 225  * Inserts the key with the given hash into the table.
 226  *
 227  * Note that insertion may rearrange the table on a resize or rehash,
 228  * so previously found hash_entries are no longer valid after this function.
 229  */
 230 struct set_entry *
 231 _mesa_set_add(struct set *ht, uint32_t hash, const void *key)
 232 {
 233    uint32_t hash_address;
 234
 235    if (ht->entries >= ht->max_entries) {
 236       set_rehash(ht, ht->size_index + 1);
 237    } else if (ht->deleted_entries + ht->entries >= ht->max_entries) {
 238       set_rehash(ht, ht->size_index);
 239    }
 240
 241    hash_address = hash % ht->size;
 242    do {
 243       struct set_entry *entry = ht->table + hash_address;
 244       uint32_t double_hash;
 245
 246       if (!entry_is_present(entry)) {
 247          if (entry_is_deleted(entry))
 248             ht->deleted_entries--;
 249          entry->hash = hash;
 250          entry->key = key;
 251          ht->entries++;
 252          return entry;
 253       }
 254
 255       /* Implement replacement when another insert happens
 256        * with a matching key.  This is a relatively common
 257        * feature of hash tables, with the alternative
 258        * generally being "insert the new value as well, and
 259        * return it first when the key is searched for".
 260        *
 261        * Note that the hash table doesn't have a delete callback.
 262        * If freeing of old keys is required to avoid memory leaks,
 263        * perform a search before inserting.
 264        */
 265       if (entry->hash == hash &&
 266           ht->key_equals_function(key, entry->key)) {
 267          entry->key = key;
 268          return entry;
 269       }
 270
 271       double_hash = 1 + hash % ht->rehash;
 272
 273       hash_address = (hash_address + double_hash) % ht->size;
 274    } while (hash_address != hash % ht->size);
 275
 276    /* We could hit here if a required resize failed. An unchecked-malloc
 277     * application could ignore this result.
 278     */
 279    return NULL;
 280 }
 281
 282 /**
 283  * This function deletes the given hash table entry.
 284  *
 285  * Note that deletion doesn't otherwise modify the table, so an iteration over
 286  * the table deleting entries is safe.
 287  */
 288 void
 289 _mesa_set_remove(struct set *ht, struct set_entry *entry)
 290 {
 291    if (!entry)
 292       return;
 293
 294    entry->key = deleted_key;
 295    ht->entries--;
 296    ht->deleted_entries++;
 297 }
 298
 299 /**
 300  * This function is an iterator over the hash table.
 301  *
 302  * Pass in NULL for the first entry, as in the start of a for loop.  Note that
 303  * an iteration over the table is O(table_size) not O(entries).
 304  */
 305 struct set_entry *
 306 _mesa_set_next_entry(const struct set *ht, struct set_entry *entry)
 307 {
 308    if (entry == NULL)
 309       entry = ht->table;
 310    else
 311       entry = entry + 1;
 312
 313    for (; entry != ht->table + ht->size; entry++) {
 314       if (entry_is_present(entry)) {
 315          return entry;
 316       }
 317    }
 318
 319    return NULL;
 320 }
 321
 322 struct set_entry *
 323 _mesa_set_random_entry(struct set *ht,
 324                        int (*predicate)(struct set_entry *entry))
 325 {
 326    struct set_entry *entry;
 327    uint32_t i = rand() % ht->size;
 328
 329    if (ht->entries == 0)
 330       return NULL;
 331
 332    for (entry = ht->table + i; entry != ht->table + ht->size; entry++) {
 333       if (entry_is_present(entry) &&
 334           (!predicate || predicate(entry))) {
 335          return entry;
 336       }
 337    }
 338
 339    for (entry = ht->table; entry != ht->table + i; entry++) {
 340       if (entry_is_present(entry) &&
 341           (!predicate || predicate(entry))) {
 342          return entry;
 343       }
 344    }
 345
 346    return NULL;
 347 }
 348