0,0 → 1,475 |
/* |
* 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> |
*/ |
|
/** |
* 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 <assert.h> |
|
#include "hash_table.h" |
#include "ralloc.h" |
#include "macros.h" |
|
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, |
uint32_t (*key_hash_function)(const void *key), |
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->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_hash_function = key_hash_function; |
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; |
} |
|
static struct hash_entry * |
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; |
} |
|
/** |
* 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, const void *key) |
{ |
assert(ht->key_hash_function); |
return hash_table_search(ht, ht->key_hash_function(key), key); |
} |
|
struct hash_entry * |
_mesa_hash_table_search_pre_hashed(struct hash_table *ht, uint32_t hash, |
const void *key) |
{ |
assert(ht->key_hash_function == NULL || hash == ht->key_hash_function(key)); |
return hash_table_search(ht, hash, key); |
} |
|
static struct hash_entry * |
hash_table_insert(struct hash_table *ht, uint32_t hash, |
const void *key, void *data); |
|
static void |
_mesa_hash_table_rehash(struct hash_table *ht, unsigned 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) { |
hash_table_insert(ht, entry->hash, entry->key, entry->data); |
} |
|
ralloc_free(old_ht.table); |
} |
|
static struct hash_entry * |
hash_table_insert(struct hash_table *ht, uint32_t hash, |
const void *key, void *data) |
{ |
uint32_t start_hash_address, hash_address; |
struct hash_entry *available_entry = NULL; |
|
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)) { |
/* Stash the first available entry we find */ |
if (available_entry == NULL) |
available_entry = entry; |
if (entry_is_free(entry)) |
break; |
} |
|
/* 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); |
|
if (available_entry) { |
if (entry_is_deleted(ht, available_entry)) |
ht->deleted_entries--; |
available_entry->hash = hash; |
available_entry->key = key; |
available_entry->data = data; |
ht->entries++; |
return available_entry; |
} |
|
/* We could hit here if a required resize failed. An unchecked-malloc |
* application could ignore this result. |
*/ |
return NULL; |
} |
|
/** |
* 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, const void *key, void *data) |
{ |
assert(ht->key_hash_function); |
return hash_table_insert(ht, ht->key_hash_function(key), key, data); |
} |
|
struct hash_entry * |
_mesa_hash_table_insert_pre_hashed(struct hash_table *ht, uint32_t hash, |
const void *key, void *data) |
{ |
assert(ht->key_hash_function == NULL || hash == ht->key_hash_function(key)); |
return hash_table_insert(ht, hash, key, data); |
} |
|
/** |
* 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 = rand() % 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-1a hash implementation based on: |
* http://www.isthe.com/chongo/tech/comp/fnv/ |
* |
* FNV-1a 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) |
{ |
return _mesa_fnv32_1a_accumulate_block(_mesa_fnv32_1a_offset_bias, |
data, size); |
} |
|
/** FNV-1a string hash implementation */ |
uint32_t |
_mesa_hash_string(const char *key) |
{ |
uint32_t hash = _mesa_fnv32_1a_offset_bias; |
|
while (*key != 0) { |
hash = _mesa_fnv32_1a_accumulate(hash, *key); |
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; |
} |