/* * Copyright © 2009-2012 Intel Corporation * Copyright © 1988-2004 Keith Packard and Bart Massey. * * Permission is hereby granted, free of charge, to any person obtaining a * copy of this software and associated documentation files (the "Software"), * to deal in the Software without restriction, including without limitation * the rights to use, copy, modify, merge, publish, distribute, sublicense, * and/or sell copies of the Software, and to permit persons to whom the * Software is furnished to do so, subject to the following conditions: * * The above copyright notice and this permission notice (including the next * paragraph) shall be included in all copies or substantial portions of the * Software. * * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS * IN THE SOFTWARE. * * Except as contained in this notice, the names of the authors * or their institutions shall not be used in advertising or * otherwise to promote the sale, use or other dealings in this * Software without prior written authorization from the * authors. * * Authors: * Eric Anholt <eric@anholt.net> * Keith Packard <keithp@keithp.com> */ #include <stdlib.h> #include "macros.h" #include "set.h" #include "ralloc.h" /* * From Knuth -- a good choice for hash/rehash values is p, p-2 where * p and p-2 are both prime. These tables are sized to have an extra 10% * free to avoid exponential performance degradation as the hash table fills */ uint32_t deleted_key_value; const void *deleted_key = &deleted_key_value; static const struct { uint32_t max_entries, size, rehash; } hash_sizes[] = { { 2, 5, 3 }, { 4, 7, 5 }, { 8, 13, 11 }, { 16, 19, 17 }, { 32, 43, 41 }, { 64, 73, 71 }, { 128, 151, 149 }, { 256, 283, 281 }, { 512, 571, 569 }, { 1024, 1153, 1151 }, { 2048, 2269, 2267 }, { 4096, 4519, 4517 }, { 8192, 9013, 9011 }, { 16384, 18043, 18041 }, { 32768, 36109, 36107 }, { 65536, 72091, 72089 }, { 131072, 144409, 144407 }, { 262144, 288361, 288359 }, { 524288, 576883, 576881 }, { 1048576, 1153459, 1153457 }, { 2097152, 2307163, 2307161 }, { 4194304, 4613893, 4613891 }, { 8388608, 9227641, 9227639 }, { 16777216, 18455029, 18455027 }, { 33554432, 36911011, 36911009 }, { 67108864, 73819861, 73819859 }, { 134217728, 147639589, 147639587 }, { 268435456, 295279081, 295279079 }, { 536870912, 590559793, 590559791 }, { 1073741824, 1181116273, 1181116271 }, { 2147483648ul, 2362232233ul, 2362232231ul } }; static int entry_is_free(struct set_entry *entry) { return entry->key == NULL; } static int entry_is_deleted(struct set_entry *entry) { return entry->key == deleted_key; } static int entry_is_present(struct set_entry *entry) { return entry->key != NULL && entry->key != deleted_key; } struct set * _mesa_set_create(void *mem_ctx, bool key_equals_function(const void *a, const void *b)) { struct set *ht; ht = ralloc(mem_ctx, struct set); if (ht == NULL) return NULL; ht->mem_ctx = mem_ctx; ht->size_index = 0; ht->size = hash_sizes[ht->size_index].size; ht->rehash = hash_sizes[ht->size_index].rehash; ht->max_entries = hash_sizes[ht->size_index].max_entries; ht->key_equals_function = key_equals_function; ht->table = rzalloc_array(ht, struct set_entry, ht->size); ht->entries = 0; ht->deleted_entries = 0; if (ht->table == NULL) { ralloc_free(ht); return NULL; } return ht; } /** * Frees the given set. * * If delete_function is passed, it gets called on each entry present before * freeing. */ void _mesa_set_destroy(struct set *ht, void (*delete_function)(struct set_entry *entry)) { if (!ht) return; if (delete_function) { struct set_entry *entry; set_foreach (ht, entry) { delete_function(entry); } } ralloc_free(ht->table); ralloc_free(ht); } /** * Finds a set entry with the given key and hash of that key. * * Returns NULL if no entry is found. */ struct set_entry * _mesa_set_search(const struct set *ht, uint32_t hash, const void *key) { uint32_t hash_address; hash_address = hash % ht->size; do { uint32_t double_hash; struct set_entry *entry = ht->table + hash_address; if (entry_is_free(entry)) { return NULL; } else if (entry_is_present(entry) && entry->hash == hash) { if (ht->key_equals_function(key, entry->key)) { return entry; } } double_hash = 1 + hash % ht->rehash; hash_address = (hash_address + double_hash) % ht->size; } while (hash_address != hash % ht->size); return NULL; } static void set_rehash(struct set *ht, int new_size_index) { struct set old_ht; struct set_entry *table, *entry; if (new_size_index >= ARRAY_SIZE(hash_sizes)) return; table = rzalloc_array(ht, struct set_entry, hash_sizes[new_size_index].size); if (table == NULL) return; old_ht = *ht; ht->table = table; ht->size_index = new_size_index; ht->size = hash_sizes[ht->size_index].size; ht->rehash = hash_sizes[ht->size_index].rehash; ht->max_entries = hash_sizes[ht->size_index].max_entries; ht->entries = 0; ht->deleted_entries = 0; for (entry = old_ht.table; entry != old_ht.table + old_ht.size; entry++) { if (entry_is_present(entry)) { _mesa_set_add(ht, entry->hash, entry->key); } } ralloc_free(old_ht.table); } /** * Inserts the key with the given hash into the table. * * Note that insertion may rearrange the table on a resize or rehash, * so previously found hash_entries are no longer valid after this function. */ struct set_entry * _mesa_set_add(struct set *ht, uint32_t hash, const void *key) { uint32_t hash_address; if (ht->entries >= ht->max_entries) { set_rehash(ht, ht->size_index + 1); } else if (ht->deleted_entries + ht->entries >= ht->max_entries) { set_rehash(ht, ht->size_index); } hash_address = hash % ht->size; do { struct set_entry *entry = ht->table + hash_address; uint32_t double_hash; if (!entry_is_present(entry)) { if (entry_is_deleted(entry)) ht->deleted_entries--; entry->hash = hash; entry->key = key; ht->entries++; return entry; } /* Implement replacement when another insert happens * with a matching key. This is a relatively common * feature of hash tables, with the alternative * generally being "insert the new value as well, and * return it first when the key is searched for". * * Note that the hash table doesn't have a delete callback. * If freeing of old keys is required to avoid memory leaks, * perform a search before inserting. */ if (entry->hash == hash && ht->key_equals_function(key, entry->key)) { entry->key = key; return entry; } double_hash = 1 + hash % ht->rehash; hash_address = (hash_address + double_hash) % ht->size; } while (hash_address != hash % ht->size); /* We could hit here if a required resize failed. An unchecked-malloc * application could ignore this result. */ return NULL; } /** * This function deletes the given hash table entry. * * Note that deletion doesn't otherwise modify the table, so an iteration over * the table deleting entries is safe. */ void _mesa_set_remove(struct set *ht, struct set_entry *entry) { if (!entry) return; entry->key = deleted_key; ht->entries--; ht->deleted_entries++; } /** * This function is an iterator over the hash table. * * Pass in NULL for the first entry, as in the start of a for loop. Note that * an iteration over the table is O(table_size) not O(entries). */ struct set_entry * _mesa_set_next_entry(const struct set *ht, struct set_entry *entry) { if (entry == NULL) entry = ht->table; else entry = entry + 1; for (; entry != ht->table + ht->size; entry++) { if (entry_is_present(entry)) { return entry; } } return NULL; } struct set_entry * _mesa_set_random_entry(struct set *ht, int (*predicate)(struct set_entry *entry)) { struct set_entry *entry; uint32_t i = rand() % ht->size; if (ht->entries == 0) return NULL; for (entry = ht->table + i; entry != ht->table + ht->size; entry++) { if (entry_is_present(entry) && (!predicate || predicate(entry))) { return entry; } } for (entry = ht->table; entry != ht->table + i; entry++) { if (entry_is_present(entry) && (!predicate || predicate(entry))) { return entry; } } return NULL; }