/*
* 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;
}