diff options
author | Eric Anholt <[email protected]> | 2012-11-06 23:18:41 -0800 |
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committer | Chad Versace <[email protected]> | 2012-11-12 15:52:42 -0800 |
commit | 35fd61bd99c15c2e13d3945b41c4db7df6e64319 (patch) | |
tree | 23771a21726cb11bd292ba51a5e95022032c7af6 /src/mesa/main/hash_table.c | |
parent | 1e8dd15311dab217d74c7c5d5a2dee6f6d7bf95e (diff) |
mesa: Import a copy of the open-addressing hash table code I wrote.
Mesa's chaining hash table for object names is slow, and this should be much
faster. I namespaced the functions under _mesa_*, to avoid visibility
troubles that we may have had before with hash_table_* functions.
v2: Move .c file to main/, const a few things, clean up loop conditions,
add/extend some comments.
Reviewed-by: Brian Paul <[email protected]>
Reviewed-by: Chad Versace <[email protected]>
Acked-by: Kenneth Graunke <[email protected]> (v1)
Diffstat (limited to 'src/mesa/main/hash_table.c')
-rw-r--r-- | src/mesa/main/hash_table.c | 442 |
1 files changed, 442 insertions, 0 deletions
diff --git a/src/mesa/main/hash_table.c b/src/mesa/main/hash_table.c new file mode 100644 index 00000000000..1e4561e6caf --- /dev/null +++ b/src/mesa/main/hash_table.c @@ -0,0 +1,442 @@ +/* + * 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 <[email protected]> + * Keith Packard <[email protected]> + */ + +/** + * Implements an open-addressing, linear-reprobing hash table. + * + * For more information, see: + * + * http://cgit.freedesktop.org/~anholt/hash_table/tree/README + */ + +#include <stdlib.h> +#include <string.h> + +#include "main/hash_table.h" +#include "ralloc.h" + +#define ARRAY_SIZE(array) (sizeof(array) / sizeof(array[0])) + +static const uint32_t deleted_key_value; + +/** + * 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 + */ +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(const struct hash_entry *entry) +{ + return entry->key == NULL; +} + +static int +entry_is_deleted(const struct hash_table *ht, struct hash_entry *entry) +{ + return entry->key == ht->deleted_key; +} + +static int +entry_is_present(const struct hash_table *ht, struct hash_entry *entry) +{ + return entry->key != NULL && entry->key != ht->deleted_key; +} + +struct hash_table * +_mesa_hash_table_create(void *mem_ctx, + bool key_equals_function(const void *a, + const void *b)) +{ + struct hash_table *ht; + + ht = ralloc(mem_ctx, struct hash_table); + 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 hash_entry, ht->size); + ht->entries = 0; + ht->deleted_entries = 0; + ht->deleted_key = &deleted_key_value; + + if (ht->table == NULL) { + ralloc_free(ht); + return NULL; + } + + return ht; +} + +/** + * Frees the given hash table. + * + * If delete_function is passed, it gets called on each entry present before + * freeing. + */ +void +_mesa_hash_table_destroy(struct hash_table *ht, + void (*delete_function)(struct hash_entry *entry)) +{ + if (!ht) + return; + + if (delete_function) { + struct hash_entry *entry; + + hash_table_foreach(ht, entry) { + delete_function(entry); + } + } + ralloc_free(ht); +} + +/** Sets the value of the key pointer used for deleted entries in the table. + * + * The assumption is that usually keys are actual pointers, so we use a + * default value of a pointer to an arbitrary piece of storage in the library. + * But in some cases a consumer wants to store some other sort of value in the + * table, like a uint32_t, in which case that pointer may conflict with one of + * their valid keys. This lets that user select a safe value. + * + * This must be called before any keys are actually deleted from the table. + */ +void +_mesa_hash_table_set_deleted_key(struct hash_table *ht, const void *deleted_key) +{ + ht->deleted_key = deleted_key; +} + +/** + * Finds a hash table entry with the given key and hash of that key. + * + * Returns NULL if no entry is found. Note that the data pointer may be + * modified by the user. + */ +struct hash_entry * +_mesa_hash_table_search(struct hash_table *ht, uint32_t hash, + const void *key) +{ + uint32_t start_hash_address = hash % ht->size; + uint32_t hash_address = start_hash_address; + + do { + uint32_t double_hash; + + struct hash_entry *entry = ht->table + hash_address; + + if (entry_is_free(entry)) { + return NULL; + } else if (entry_is_present(ht, 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 != start_hash_address); + + return NULL; +} + +static void +_mesa_hash_table_rehash(struct hash_table *ht, int new_size_index) +{ + struct hash_table old_ht; + struct hash_entry *table, *entry; + + if (new_size_index >= ARRAY_SIZE(hash_sizes)) + return; + + table = rzalloc_array(ht, struct hash_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; + + hash_table_foreach(&old_ht, entry) { + _mesa_hash_table_insert(ht, entry->hash, + entry->key, entry->data); + } + + 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 hash_entry * +_mesa_hash_table_insert(struct hash_table *ht, uint32_t hash, + const void *key, void *data) +{ + uint32_t start_hash_address, hash_address; + + if (ht->entries >= ht->max_entries) { + _mesa_hash_table_rehash(ht, ht->size_index + 1); + } else if (ht->deleted_entries + ht->entries >= ht->max_entries) { + _mesa_hash_table_rehash(ht, ht->size_index); + } + + start_hash_address = hash % ht->size; + hash_address = start_hash_address; + do { + struct hash_entry *entry = ht->table + hash_address; + uint32_t double_hash; + + if (!entry_is_present(ht, entry)) { + if (entry_is_deleted(ht, entry)) + ht->deleted_entries--; + entry->hash = hash; + entry->key = key; + entry->data = data; + 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 data pointers 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; + entry->data = data; + return entry; + } + + + double_hash = 1 + hash % ht->rehash; + + hash_address = (hash_address + double_hash) % ht->size; + } while (hash_address != start_hash_address); + + /* 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_hash_table_remove(struct hash_table *ht, + struct hash_entry *entry) +{ + if (!entry) + return; + + entry->key = ht->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 hash_entry * +_mesa_hash_table_next_entry(struct hash_table *ht, + struct hash_entry *entry) +{ + if (entry == NULL) + entry = ht->table; + else + entry = entry + 1; + + for (; entry != ht->table + ht->size; entry++) { + if (entry_is_present(ht, entry)) { + return entry; + } + } + + return NULL; +} + +/** + * Returns a random entry from the hash table. + * + * This may be useful in implementing random replacement (as opposed + * to just removing everything) in caches based on this hash table + * implementation. @predicate may be used to filter entries, or may + * be set to NULL for no filtering. + */ +struct hash_entry * +_mesa_hash_table_random_entry(struct hash_table *ht, + bool (*predicate)(struct hash_entry *entry)) +{ + struct hash_entry *entry; + uint32_t i = random() % ht->size; + + if (ht->entries == 0) + return NULL; + + for (entry = ht->table + i; entry != ht->table + ht->size; entry++) { + if (entry_is_present(ht, entry) && + (!predicate || predicate(entry))) { + return entry; + } + } + + for (entry = ht->table; entry != ht->table + i; entry++) { + if (entry_is_present(ht, entry) && + (!predicate || predicate(entry))) { + return entry; + } + } + + return NULL; +} + + +/** + * Quick FNV-1 hash implementation based on: + * http://www.isthe.com/chongo/tech/comp/fnv/ + * + * FNV-1 is not be the best hash out there -- Jenkins's lookup3 is supposed to + * be quite good, and it probably beats FNV. But FNV has the advantage that + * it involves almost no code. For an improvement on both, see Paul + * Hsieh's http://www.azillionmonkeys.com/qed/hash.html + */ +uint32_t +_mesa_hash_data(const void *data, size_t size) +{ + uint32_t hash = 2166136261ul; + const uint8_t *bytes = data; + + while (size-- != 0) { + hash ^= *bytes; + hash = hash * 0x01000193; + bytes++; + } + + return hash; +} + +/** FNV-1 string hash implementation */ +uint32_t +_mesa_hash_string(const char *key) +{ + uint32_t hash = 2166136261ul; + + while (*key != 0) { + hash ^= *key; + hash = hash * 0x01000193; + key++; + } + + return hash; +} + +/** + * String compare function for use as the comparison callback in + * _mesa_hash_table_create(). + */ +bool +_mesa_key_string_equal(const void *a, const void *b) +{ + return strcmp(a, b) == 0; +} + +bool +_mesa_key_pointer_equal(const void *a, const void *b) +{ + return a == b; +} |