Adapted from git://people.freedesktop.org/~anholt/hash_table.dev
Kristian Høgsberg
15 years ago
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/*
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* Copyright © 2009 Intel Corporation |
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* Copyright © 1988-2004 Keith Packard and Bart Massey. |
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* |
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* Permission is hereby granted, free of charge, to any person obtaining a |
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* copy of this software and associated documentation files (the "Software"), |
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* to deal in the Software without restriction, including without limitation |
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* the rights to use, copy, modify, merge, publish, distribute, sublicense, |
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* and/or sell copies of the Software, and to permit persons to whom the |
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* Software is furnished to do so, subject to the following conditions: |
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* |
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* The above copyright notice and this permission notice (including the next |
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* paragraph) shall be included in all copies or substantial portions of the |
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* Software. |
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* |
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR |
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, |
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL |
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* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER |
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING |
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* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS |
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* IN THE SOFTWARE. |
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* |
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* Except as contained in this notice, the names of the authors |
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* or their institutions shall not be used in advertising or |
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* otherwise to promote the sale, use or other dealings in this |
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* Software without prior written authorization from the |
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* authors. |
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* |
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* Authors: |
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* Eric Anholt <eric@anholt.net> |
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* Keith Packard <keithp@keithp.com> |
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*/ |
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#include <stdlib.h> |
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#include "wayland-util.h" |
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struct hash_entry { |
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uint32_t hash; |
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void *data; |
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}; |
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struct wl_hash_table { |
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struct hash_entry *table; |
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uint32_t size; |
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uint32_t rehash; |
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uint32_t max_entries; |
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uint32_t size_index; |
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uint32_t entries; |
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uint32_t deleted_entries; |
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}; |
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#define ARRAY_SIZE(array) (sizeof(array) / sizeof(array[0])) |
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/*
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* From Knuth -- a good choice for hash/rehash values is p, p-2 where |
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* p and p-2 are both prime. These tables are sized to have an extra 10% |
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* free to avoid exponential performance degradation as the hash table fills |
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*/ |
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static const uint32_t deleted_data; |
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static const struct { |
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uint32_t max_entries, size, rehash; |
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} hash_sizes[] = { |
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{ 2, 5, 3 }, |
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{ 4, 7, 5 }, |
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{ 8, 13, 11 }, |
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{ 16, 19, 17 }, |
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{ 32, 43, 41 }, |
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{ 64, 73, 71 }, |
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{ 128, 151, 149 }, |
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{ 256, 283, 281 }, |
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{ 512, 571, 569 }, |
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{ 1024, 1153, 1151 }, |
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{ 2048, 2269, 2267 }, |
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{ 4096, 4519, 4517 }, |
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{ 8192, 9013, 9011 }, |
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{ 16384, 18043, 18041 }, |
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{ 32768, 36109, 36107 }, |
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{ 65536, 72091, 72089 }, |
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{ 131072, 144409, 144407 }, |
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{ 262144, 288361, 288359 }, |
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{ 524288, 576883, 576881 }, |
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{ 1048576, 1153459, 1153457 }, |
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{ 2097152, 2307163, 2307161 }, |
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{ 4194304, 4613893, 4613891 }, |
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{ 8388608, 9227641, 9227639 }, |
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{ 16777216, 18455029, 18455027 }, |
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{ 33554432, 36911011, 36911009 }, |
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{ 67108864, 73819861, 73819859 }, |
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{ 134217728, 147639589, 147639587 }, |
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{ 268435456, 295279081, 295279079 }, |
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{ 536870912, 590559793, 590559791 }, |
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{ 1073741824, 1181116273, 1181116271}, |
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{ 2147483648ul, 2362232233ul, 2362232231ul} |
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}; |
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static int |
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entry_is_free(struct hash_entry *entry) |
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{ |
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return entry->data == NULL; |
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} |
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static int |
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entry_is_deleted(struct hash_entry *entry) |
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{ |
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return entry->data == &deleted_data; |
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} |
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static int |
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entry_is_present(struct hash_entry *entry) |
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{ |
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return entry->data != NULL && entry->data != &deleted_data; |
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} |
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WL_EXPORT struct wl_hash_table * |
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wl_hash_table_create(void) |
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{ |
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struct wl_hash_table *ht; |
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ht = malloc(sizeof(*ht)); |
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if (ht == NULL) |
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return NULL; |
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ht->size_index = 0; |
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ht->size = hash_sizes[ht->size_index].size; |
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ht->rehash = hash_sizes[ht->size_index].rehash; |
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ht->max_entries = hash_sizes[ht->size_index].max_entries; |
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ht->table = calloc(ht->size, sizeof(*ht->table)); |
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ht->entries = 0; |
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ht->deleted_entries = 0; |
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if (ht->table == NULL) { |
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free(ht); |
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return NULL; |
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} |
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return ht; |
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} |
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/**
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* Frees the given hash table. |
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*/ |
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WL_EXPORT void |
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wl_hash_table_destroy(struct wl_hash_table *ht) |
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{ |
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if (!ht) |
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return; |
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free(ht->table); |
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free(ht); |
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} |
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/**
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* Finds a hash table entry with the given key and hash of that key. |
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* |
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* Returns NULL if no entry is found. Note that the data pointer may be |
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* modified by the user. |
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*/ |
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static void * |
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hash_table_search(struct wl_hash_table *ht, uint32_t hash) |
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{ |
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uint32_t hash_address; |
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hash_address = hash % ht->size; |
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do { |
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uint32_t double_hash; |
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struct hash_entry *entry = ht->table + hash_address; |
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if (entry_is_free(entry)) { |
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return NULL; |
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} else if (entry_is_present(entry) && entry->hash == hash) { |
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return entry; |
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} |
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double_hash = hash % ht->rehash; |
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if (double_hash == 0) |
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double_hash = 1; |
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hash_address = (hash_address + double_hash) % ht->size; |
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} while (hash_address != hash % ht->size); |
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return NULL; |
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} |
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WL_EXPORT void * |
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wl_hash_table_lookup(struct wl_hash_table *ht, uint32_t hash) |
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{ |
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struct hash_entry *entry; |
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entry = hash_table_search(ht, hash); |
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if (entry != NULL) |
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return entry->data; |
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return NULL; |
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} |
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static void |
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hash_table_rehash(struct wl_hash_table *ht, int new_size_index) |
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{ |
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struct wl_hash_table old_ht; |
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struct hash_entry *table, *entry; |
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if (new_size_index >= ARRAY_SIZE(hash_sizes)) |
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return; |
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table = calloc(hash_sizes[new_size_index].size, sizeof(*ht->table)); |
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if (table == NULL) |
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return; |
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old_ht = *ht; |
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ht->table = table; |
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ht->size_index = new_size_index; |
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ht->size = hash_sizes[ht->size_index].size; |
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ht->rehash = hash_sizes[ht->size_index].rehash; |
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ht->max_entries = hash_sizes[ht->size_index].max_entries; |
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ht->entries = 0; |
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ht->deleted_entries = 0; |
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for (entry = old_ht.table; |
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entry != old_ht.table + old_ht.size; |
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entry++) { |
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if (entry_is_present(entry)) { |
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wl_hash_table_insert(ht, entry->hash, entry->data); |
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} |
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} |
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free(old_ht.table); |
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} |
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/**
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* Inserts the data with the given hash into the table. |
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* |
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* Note that insertion may rearrange the table on a resize or rehash, |
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* so previously found hash_entries are no longer valid after this function. |
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*/ |
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WL_EXPORT int |
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wl_hash_table_insert(struct wl_hash_table *ht, uint32_t hash, void *data) |
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{ |
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uint32_t hash_address; |
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if (ht->entries >= ht->max_entries) { |
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hash_table_rehash(ht, ht->size_index + 1); |
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} else if (ht->deleted_entries + ht->entries >= ht->max_entries) { |
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hash_table_rehash(ht, ht->size_index); |
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} |
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hash_address = hash % ht->size; |
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do { |
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struct hash_entry *entry = ht->table + hash_address; |
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uint32_t double_hash; |
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if (!entry_is_present(entry)) { |
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if (entry_is_deleted(entry)) |
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ht->deleted_entries--; |
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entry->hash = hash; |
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entry->data = data; |
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ht->entries++; |
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return 0; |
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} |
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double_hash = hash % ht->rehash; |
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if (double_hash == 0) |
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double_hash = 1; |
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hash_address = (hash_address + double_hash) % ht->size; |
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} while (hash_address != hash % ht->size); |
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/* We could hit here if a required resize failed. An unchecked-malloc
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* application could ignore this result. |
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*/ |
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return -1; |
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} |
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/**
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* This function deletes the given hash table entry. |
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* |
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* Note that deletion doesn't otherwise modify the table, so an iteration over |
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* the table deleting entries is safe. |
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*/ |
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WL_EXPORT void |
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wl_hash_table_remove(struct wl_hash_table *ht, uint32_t hash) |
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{ |
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struct hash_entry *entry; |
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entry = hash_table_search(ht, hash); |
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if (entry != NULL) { |
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entry->data = (void *) &deleted_data; |
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ht->entries--; |
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ht->deleted_entries++; |
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} |
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} |
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