Fix CAA_BITS_PER_lONG typo
[urcu.git] / urcu / rculfhash.h
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1#ifndef _URCU_RCULFHASH_H
2#define _URCU_RCULFHASH_H
ab7d5fc6 3
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4/*
5 * urcu/rculfhash.h
6 *
7 * Userspace RCU library - Lock-Free RCU Hash Table
8 *
9 * Copyright 2011 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
10 *
11 * This library is free software; you can redistribute it and/or
12 * modify it under the terms of the GNU Lesser General Public
13 * License as published by the Free Software Foundation; either
14 * version 2.1 of the License, or (at your option) any later version.
15 *
16 * This library is distributed in the hope that it will be useful,
17 * but WITHOUT ANY WARRANTY; without even the implied warranty of
18 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
19 * Lesser General Public License for more details.
20 *
21 * You should have received a copy of the GNU Lesser General Public
22 * License along with this library; if not, write to the Free Software
23 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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24 *
25 * Include this file _after_ including your URCU flavor.
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26 */
27
674f7a69 28#include <stdint.h>
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29#include <urcu-call-rcu.h>
30
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31#ifdef __cplusplus
32extern "C" {
33#endif
34
7f61a77f 35/*
14044b37 36 * struct cds_lfht_node and struct _cds_lfht_node should be aligned on
b198f0fd 37 * 4-bytes boundaries because the two lower bits are used as flags.
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38 */
39
14044b37 40struct _cds_lfht_node {
b198f0fd 41 struct cds_lfht_node *next; /* ptr | DUMMY_FLAG | REMOVED_FLAG */
abc490a1 42 unsigned long reverse_hash;
58ca0741 43} __attribute__((aligned(4)));
cc4fcb10 44
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45/*
46 * struct cds_lfht_node can be embedded into a structure (as a field).
47 * caa_container_of() can be used to get the structure from the struct
48 * cds_lfht_node after a lookup.
49 */
14044b37 50struct cds_lfht_node {
cc4fcb10 51 /* cache-hot for iteration */
14044b37 52 struct _cds_lfht_node p; /* needs to be first field */
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53 void *key;
54 unsigned int key_len;
9b35f1e4 55 /* cache-cold for iteration */
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56 struct rcu_head head;
57};
58
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59struct cds_lfht_iter {
60 struct cds_lfht_node *node, *next;
61};
62
63static inline
64struct cds_lfht_node *cds_lfht_iter_get_node(struct cds_lfht_iter *iter)
65{
66 return iter->node;
67}
68
14044b37 69struct cds_lfht;
ab7d5fc6 70
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71/*
72 * Caution !
abc490a1 73 * Ensure reader and writer threads are registered as urcu readers.
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74 */
75
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76typedef unsigned long (*cds_lfht_hash_fct)(void *key, size_t length,
77 unsigned long seed);
78typedef unsigned long (*cds_lfht_compare_fct)(void *key1, size_t key1_len,
79 void *key2, size_t key2_len);
abc490a1 80
f0c29ed7 81/*
14044b37 82 * cds_lfht_node_init - initialize a hash table node
f0c29ed7 83 */
abc490a1 84static inline
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85void cds_lfht_node_init(struct cds_lfht_node *node, void *key,
86 size_t key_len)
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87{
88 node->key = key;
732ad076 89 node->key_len = key_len;
abc490a1 90}
674f7a69 91
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92/*
93 * Hash table creation flags.
94 */
95enum {
96 CDS_LFHT_AUTO_RESIZE = (1U << 0),
5afadd12 97 CDS_LFHT_ACCOUNTING = (1U << 1),
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98};
99
674f7a69 100/*
7a9dcf9b 101 * _cds_lfht_new - API used by cds_lfht_new wrapper. Do not use directly.
674f7a69 102 */
7a9dcf9b 103struct cds_lfht *_cds_lfht_new(cds_lfht_hash_fct hash_fct,
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104 cds_lfht_compare_fct compare_fct,
105 unsigned long hash_seed,
106 unsigned long init_size,
5488222b 107 unsigned long min_alloc_size,
b8af5011 108 int flags,
14044b37 109 void (*cds_lfht_call_rcu)(struct rcu_head *head,
1475579c 110 void (*func)(struct rcu_head *head)),
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111 void (*cds_lfht_synchronize_rcu)(void),
112 void (*cds_lfht_rcu_read_lock)(void),
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113 void (*cds_lfht_rcu_read_unlock)(void),
114 void (*cds_lfht_rcu_thread_offline)(void),
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115 void (*cds_lfht_rcu_thread_online)(void),
116 void (*cds_lfht_rcu_register_thread)(void),
117 void (*cds_lfht_rcu_unregister_thread)(void),
118 pthread_attr_t *attr);
ab7d5fc6 119
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120/*
121 * cds_lfht_new - allocate a hash table.
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122 * @hash_fct: the hashing function.
123 * @compare_fct: the key comparison function.
124 * @hash_seed: the seed for hash function.
125 * @init_size: number of nodes to allocate initially. Must be power of two.
5488222b 126 * @min_alloc_size: the smallest allocation size to use. Must be power of two.
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127 * @flags: hash table creation flags (can be combined with bitwise or: '|').
128 * 0: no flags.
129 * CDS_LFHT_AUTO_RESIZE: automatically resize hash table.
b7d619b0 130 * @attr: optional resize worker thread attributes. NULL for default.
7a9dcf9b 131 *
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132 * Return NULL on error.
133 * Note: the RCU flavor must be already included before the hash table header.
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134 *
135 * The programmer is responsible for ensuring that resize operation has a
136 * priority equal to hash table updater threads. It should be performed by
137 * specifying the appropriate priority in the pthread "attr" argument, and,
138 * for CDS_LFHT_AUTO_RESIZE, by ensuring that call_rcu worker threads also have
139 * this priority level. Having lower priority for call_rcu and resize threads
140 * does not pose any correctness issue, but the resize operations could be
141 * starved by updates, thus leading to long hash table bucket chains.
3df0c49c 142 * Threads calling this API need to be registered RCU read-side threads.
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143 */
144static inline
145struct cds_lfht *cds_lfht_new(cds_lfht_hash_fct hash_fct,
146 cds_lfht_compare_fct compare_fct,
147 unsigned long hash_seed,
148 unsigned long init_size,
5488222b 149 unsigned long min_alloc_size,
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150 int flags,
151 pthread_attr_t *attr)
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152{
153 return _cds_lfht_new(hash_fct, compare_fct, hash_seed,
5488222b 154 init_size, min_alloc_size, flags,
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155 call_rcu, synchronize_rcu, rcu_read_lock,
156 rcu_read_unlock, rcu_thread_offline,
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157 rcu_thread_online, rcu_register_thread,
158 rcu_unregister_thread, attr);
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159}
160
f0c29ed7 161/*
14044b37 162 * cds_lfht_destroy - destroy a hash table.
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163 * @ht: the hash table to destroy.
164 * @attr: (output) resize worker thread attributes, as received by cds_lfht_new.
165 * The caller will typically want to free this pointer if dynamically
166 * allocated.
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167 *
168 * Return 0 on success, negative error value on error.
3df0c49c 169 * Threads calling this API need to be registered RCU read-side threads.
f0c29ed7 170 */
b7d619b0 171int cds_lfht_destroy(struct cds_lfht *ht, pthread_attr_t **attr);
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172
173/*
14044b37 174 * cds_lfht_count_nodes - count the number of nodes in the hash table.
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175 *
176 * Call with rcu_read_lock held.
3df0c49c 177 * Threads calling this API need to be registered RCU read-side threads.
f0c29ed7 178 */
14044b37 179void cds_lfht_count_nodes(struct cds_lfht *ht,
d933dd0e 180 long *approx_before,
adc0de68 181 unsigned long *count,
973e5e1b 182 unsigned long *removed,
d933dd0e 183 long *approx_after);
ab7d5fc6 184
f0c29ed7 185/*
14044b37 186 * cds_lfht_lookup - lookup a node by key.
f0c29ed7 187 *
adc0de68 188 * Output in "*iter". *iter->node set to NULL if not found.
f0c29ed7 189 * Call with rcu_read_lock held.
3df0c49c 190 * Threads calling this API need to be registered RCU read-side threads.
f0c29ed7 191 */
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192void cds_lfht_lookup(struct cds_lfht *ht, void *key, size_t key_len,
193 struct cds_lfht_iter *iter);
ab7d5fc6 194
f0c29ed7 195/*
3883c0e5 196 * cds_lfht_next_duplicate - get the next item with same key (after a lookup).
f0c29ed7 197 *
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198 * Uses an iterator initialized by a lookup.
199 * Sets *iter-node to the following node with same key.
200 * Sets *iter->node to NULL if no following node exists with same key.
201 * RCU read-side lock must be held across cds_lfht_lookup and
202 * cds_lfht_next calls, and also between cds_lfht_next calls using the
203 * node returned by a previous cds_lfht_next.
204 * Call with rcu_read_lock held.
3df0c49c 205 * Threads calling this API need to be registered RCU read-side threads.
f0c29ed7 206 */
3883c0e5 207void cds_lfht_next_duplicate(struct cds_lfht *ht, struct cds_lfht_iter *iter);
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208
209/*
210 * cds_lfht_first - get the first node in the table.
211 *
212 * Output in "*iter". *iter->node set to NULL if table is empty.
213 * Call with rcu_read_lock held.
3df0c49c 214 * Threads calling this API need to be registered RCU read-side threads.
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215 */
216void cds_lfht_first(struct cds_lfht *ht, struct cds_lfht_iter *iter);
217
218/*
219 * cds_lfht_next - get the next node in the table.
220 *
221 * Input/Output in "*iter". *iter->node set to NULL if *iter was
222 * pointing to the last table node.
223 * Call with rcu_read_lock held.
3df0c49c 224 * Threads calling this API need to be registered RCU read-side threads.
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225 */
226void cds_lfht_next(struct cds_lfht *ht, struct cds_lfht_iter *iter);
ab7d5fc6 227
18117871 228/*
14044b37 229 * cds_lfht_add - add a node to the hash table.
f0c29ed7 230 *
48ed1c18 231 * This function supports adding redundant keys into the table.
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232 * Call with rcu_read_lock held.
233 * Threads calling this API need to be registered RCU read-side threads.
f0c29ed7 234 */
14044b37 235void cds_lfht_add(struct cds_lfht *ht, struct cds_lfht_node *node);
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236
237/*
14044b37 238 * cds_lfht_add_unique - add a node to hash table, if key is not present.
f0c29ed7 239 *
6878c72b 240 * Return the node added upon success.
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241 * Return the unique node already present upon failure. If
242 * cds_lfht_add_unique fails, the node passed as parameter should be
243 * freed by the caller.
f0c29ed7 244 * Call with rcu_read_lock held.
3df0c49c 245 * Threads calling this API need to be registered RCU read-side threads.
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246 *
247 * The semantic of this function is that if only this function is used
248 * to add keys into the table, no duplicated keys should ever be
249 * observable in the table. The same guarantee apply for combination of
9357c415 250 * add_unique and add_replace (see below).
18117871 251 */
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252struct cds_lfht_node *cds_lfht_add_unique(struct cds_lfht *ht,
253 struct cds_lfht_node *node);
3eca1b8c 254
48ed1c18 255/*
9357c415 256 * cds_lfht_add_replace - replace or add a node within hash table.
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257 *
258 * Return the node replaced upon success. If no node matching the key
259 * was present, return NULL, which also means the operation succeeded.
260 * This replacement operation should never fail.
261 * Call with rcu_read_lock held.
3df0c49c 262 * Threads calling this API need to be registered RCU read-side threads.
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263 * After successful replacement, a grace period must be waited for before
264 * freeing the memory reserved for the returned node.
265 *
266 * The semantic of replacement vs lookups is the following: if lookups
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267 * are performed between a key unique insertion and its removal, we
268 * guarantee that the lookups and get next will always find exactly one
269 * instance of the key if it is replaced concurrently with the lookups.
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270 *
271 * Providing this semantic allows us to ensure that replacement-only
272 * schemes will never generate duplicated keys. It also allows us to
9357c415 273 * guarantee that a combination of add_replace and add_unique updates
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274 * will never generate duplicated keys.
275 */
9357c415 276struct cds_lfht_node *cds_lfht_add_replace(struct cds_lfht *ht,
adc0de68 277 struct cds_lfht_node *node);
48ed1c18 278
f0c29ed7 279/*
9357c415 280 * cds_lfht_replace - replace a node pointer to by iter within hash table.
f0c29ed7 281 *
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282 * Return 0 if replacement is successful, negative value otherwise.
283 * Replacing a NULL old node or an already removed node will fail with a
284 * negative value.
285 * Old node can be looked up with cds_lfht_lookup and cds_lfht_next.
286 * RCU read-side lock must be held between lookup and replacement.
287 * Call with rcu_read_lock held.
3df0c49c 288 * Threads calling this API need to be registered RCU read-side threads.
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289 * After successful replacement, a grace period must be waited for before
290 * freeing the memory reserved for the old node (which can be accessed
291 * with cds_lfht_iter_get_node).
292 *
293 * The semantic of replacement vs lookups is the following: if lookups
294 * are performed between a key unique insertion and its removal, we
295 * guarantee that the lookups and get next will always find exactly one
296 * instance of the key if it is replaced concurrently with the lookups.
297 *
298 * Providing this semantic allows us to ensure that replacement-only
299 * schemes will never generate duplicated keys. It also allows us to
300 * guarantee that a combination of add_replace and add_unique updates
301 * will never generate duplicated keys.
302 */
303int cds_lfht_replace(struct cds_lfht *ht, struct cds_lfht_iter *old_iter,
304 struct cds_lfht_node *new_node);
305
306/*
307 * cds_lfht_del - remove node pointed to by iterator from hash table.
308 *
309 * Return 0 if the node is successfully removed, negative value
310 * otherwise.
311 * Replacing a NULL node or an already removed node will fail with a
312 * negative value.
313 * Node can be looked up with cds_lfht_lookup and cds_lfht_next.
314 * cds_lfht_iter_get_node.
315 * RCU read-side lock must be held between lookup and removal.
f0c29ed7 316 * Call with rcu_read_lock held.
3df0c49c 317 * Threads calling this API need to be registered RCU read-side threads.
48ed1c18 318 * After successful removal, a grace period must be waited for before
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319 * freeing the memory reserved for old node (which can be accessed with
320 * cds_lfht_iter_get_node).
f0c29ed7 321 */
9357c415 322int cds_lfht_del(struct cds_lfht *ht, struct cds_lfht_iter *iter);
ab7d5fc6 323
f0c29ed7 324/*
14044b37 325 * cds_lfht_resize - Force a hash table resize
1475579c 326 * @new_size: update to this hash table size.
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327 *
328 * Threads calling this API need to be registered RCU read-side threads.
f0c29ed7 329 */
1475579c 330void cds_lfht_resize(struct cds_lfht *ht, unsigned long new_size);
464a1ec9 331
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332#ifdef __cplusplus
333}
334#endif
335
a42cc659 336#endif /* _URCU_RCULFHASH_H */
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