Merge branch 'master' into urcu/ht-shrink
[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
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40/*
41 * _cds_lfht_node: Contains the internal pointers and reverse-hash
42 * value required for lookup and traversal of the hash table.
43 */
14044b37 44struct _cds_lfht_node {
b198f0fd 45 struct cds_lfht_node *next; /* ptr | DUMMY_FLAG | REMOVED_FLAG */
abc490a1 46 unsigned long reverse_hash;
58ca0741 47} __attribute__((aligned(4)));
cc4fcb10 48
ae62aa6a 49/*
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50 * cds_lfht_node: Contains the full key and length required to check for
51 * an actual match, and also contains an rcu_head structure that is used
52 * by RCU to track a node through a given RCU grace period. There is an
53 * instance of _cds_lfht_node enclosed as a field within each
54 * _cds_lfht_node structure.
55 *
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56 * struct cds_lfht_node can be embedded into a structure (as a field).
57 * caa_container_of() can be used to get the structure from the struct
58 * cds_lfht_node after a lookup.
59 */
14044b37 60struct cds_lfht_node {
cc4fcb10 61 /* cache-hot for iteration */
14044b37 62 struct _cds_lfht_node p; /* needs to be first field */
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63 void *key;
64 unsigned int key_len;
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65};
66
7f52427b 67/* cds_lfht_iter: Used to track state while traversing a hash chain. */
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68struct cds_lfht_iter {
69 struct cds_lfht_node *node, *next;
70};
71
72static inline
73struct cds_lfht_node *cds_lfht_iter_get_node(struct cds_lfht_iter *iter)
74{
75 return iter->node;
76}
77
14044b37 78struct cds_lfht;
ab7d5fc6 79
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80/*
81 * Caution !
abc490a1 82 * Ensure reader and writer threads are registered as urcu readers.
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83 */
84
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85typedef unsigned long (*cds_lfht_hash_fct)(void *key, size_t length,
86 unsigned long seed);
87typedef unsigned long (*cds_lfht_compare_fct)(void *key1, size_t key1_len,
88 void *key2, size_t key2_len);
abc490a1 89
f0c29ed7 90/*
14044b37 91 * cds_lfht_node_init - initialize a hash table node
f0c29ed7 92 */
abc490a1 93static inline
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94void cds_lfht_node_init(struct cds_lfht_node *node, void *key,
95 size_t key_len)
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96{
97 node->key = key;
732ad076 98 node->key_len = key_len;
abc490a1 99}
674f7a69 100
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101/*
102 * Hash table creation flags.
103 */
104enum {
105 CDS_LFHT_AUTO_RESIZE = (1U << 0),
5afadd12 106 CDS_LFHT_ACCOUNTING = (1U << 1),
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107};
108
674f7a69 109/*
7a9dcf9b 110 * _cds_lfht_new - API used by cds_lfht_new wrapper. Do not use directly.
674f7a69 111 */
7a9dcf9b 112struct cds_lfht *_cds_lfht_new(cds_lfht_hash_fct hash_fct,
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113 cds_lfht_compare_fct compare_fct,
114 unsigned long hash_seed,
115 unsigned long init_size,
5488222b 116 unsigned long min_alloc_size,
b8af5011 117 int flags,
14044b37 118 void (*cds_lfht_call_rcu)(struct rcu_head *head,
1475579c 119 void (*func)(struct rcu_head *head)),
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120 void (*cds_lfht_synchronize_rcu)(void),
121 void (*cds_lfht_rcu_read_lock)(void),
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122 void (*cds_lfht_rcu_read_unlock)(void),
123 void (*cds_lfht_rcu_thread_offline)(void),
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124 void (*cds_lfht_rcu_thread_online)(void),
125 void (*cds_lfht_rcu_register_thread)(void),
126 void (*cds_lfht_rcu_unregister_thread)(void),
127 pthread_attr_t *attr);
ab7d5fc6 128
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129/*
130 * cds_lfht_new - allocate a hash table.
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131 * @hash_fct: the hashing function.
132 * @compare_fct: the key comparison function.
133 * @hash_seed: the seed for hash function.
134 * @init_size: number of nodes to allocate initially. Must be power of two.
5488222b 135 * @min_alloc_size: the smallest allocation size to use. Must be power of two.
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136 * @flags: hash table creation flags (can be combined with bitwise or: '|').
137 * 0: no flags.
138 * CDS_LFHT_AUTO_RESIZE: automatically resize hash table.
b7d619b0 139 * @attr: optional resize worker thread attributes. NULL for default.
7a9dcf9b 140 *
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141 * Return NULL on error.
142 * Note: the RCU flavor must be already included before the hash table header.
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143 *
144 * The programmer is responsible for ensuring that resize operation has a
145 * priority equal to hash table updater threads. It should be performed by
146 * specifying the appropriate priority in the pthread "attr" argument, and,
147 * for CDS_LFHT_AUTO_RESIZE, by ensuring that call_rcu worker threads also have
148 * this priority level. Having lower priority for call_rcu and resize threads
149 * does not pose any correctness issue, but the resize operations could be
150 * starved by updates, thus leading to long hash table bucket chains.
3df0c49c 151 * Threads calling this API need to be registered RCU read-side threads.
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152 */
153static inline
154struct cds_lfht *cds_lfht_new(cds_lfht_hash_fct hash_fct,
155 cds_lfht_compare_fct compare_fct,
156 unsigned long hash_seed,
157 unsigned long init_size,
5488222b 158 unsigned long min_alloc_size,
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159 int flags,
160 pthread_attr_t *attr)
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161{
162 return _cds_lfht_new(hash_fct, compare_fct, hash_seed,
5488222b 163 init_size, min_alloc_size, flags,
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164 call_rcu, synchronize_rcu, rcu_read_lock,
165 rcu_read_unlock, rcu_thread_offline,
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166 rcu_thread_online, rcu_register_thread,
167 rcu_unregister_thread, attr);
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168}
169
f0c29ed7 170/*
14044b37 171 * cds_lfht_destroy - destroy a hash table.
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172 * @ht: the hash table to destroy.
173 * @attr: (output) resize worker thread attributes, as received by cds_lfht_new.
174 * The caller will typically want to free this pointer if dynamically
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175 * allocated. The attr point can be NULL if the caller does not
176 * need to be informed of the value passed to cds_lfht_new().
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177 *
178 * Return 0 on success, negative error value on error.
3df0c49c 179 * Threads calling this API need to be registered RCU read-side threads.
f0c29ed7 180 */
b7d619b0 181int cds_lfht_destroy(struct cds_lfht *ht, pthread_attr_t **attr);
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182
183/*
14044b37 184 * cds_lfht_count_nodes - count the number of nodes in the hash table.
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185 * @ht: the hash table.
186 * @split_count_before: Sample the node count split-counter before traversal.
187 * @count: Traverse the hash table, count the number of nodes observed.
188 * @removed: Number of logically removed nodes observed during traversal.
189 * @split_count_after: Sample the node count split-counter after traversal.
f0c29ed7 190 * Call with rcu_read_lock held.
3df0c49c 191 * Threads calling this API need to be registered RCU read-side threads.
f0c29ed7 192 */
14044b37 193void cds_lfht_count_nodes(struct cds_lfht *ht,
7f52427b 194 long *split_count_before,
adc0de68 195 unsigned long *count,
973e5e1b 196 unsigned long *removed,
7f52427b 197 long *split_count_after);
ab7d5fc6 198
f0c29ed7 199/*
14044b37 200 * cds_lfht_lookup - lookup a node by key.
f0c29ed7 201 *
adc0de68 202 * Output in "*iter". *iter->node set to NULL if not found.
f0c29ed7 203 * Call with rcu_read_lock held.
3df0c49c 204 * Threads calling this API need to be registered RCU read-side threads.
f0c29ed7 205 */
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206void cds_lfht_lookup(struct cds_lfht *ht, void *key, size_t key_len,
207 struct cds_lfht_iter *iter);
ab7d5fc6 208
f0c29ed7 209/*
3883c0e5 210 * cds_lfht_next_duplicate - get the next item with same key (after a lookup).
f0c29ed7 211 *
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212 * Uses an iterator initialized by a lookup.
213 * Sets *iter-node to the following node with same key.
214 * Sets *iter->node to NULL if no following node exists with same key.
215 * RCU read-side lock must be held across cds_lfht_lookup and
216 * cds_lfht_next calls, and also between cds_lfht_next calls using the
217 * node returned by a previous cds_lfht_next.
218 * Call with rcu_read_lock held.
3df0c49c 219 * Threads calling this API need to be registered RCU read-side threads.
f0c29ed7 220 */
3883c0e5 221void cds_lfht_next_duplicate(struct cds_lfht *ht, struct cds_lfht_iter *iter);
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222
223/*
224 * cds_lfht_first - get the first node in the table.
225 *
226 * Output in "*iter". *iter->node set to NULL if table is empty.
227 * Call with rcu_read_lock held.
3df0c49c 228 * Threads calling this API need to be registered RCU read-side threads.
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229 */
230void cds_lfht_first(struct cds_lfht *ht, struct cds_lfht_iter *iter);
231
232/*
233 * cds_lfht_next - get the next node in the table.
234 *
235 * Input/Output in "*iter". *iter->node set to NULL if *iter was
236 * pointing to the last table node.
237 * Call with rcu_read_lock held.
3df0c49c 238 * Threads calling this API need to be registered RCU read-side threads.
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239 */
240void cds_lfht_next(struct cds_lfht *ht, struct cds_lfht_iter *iter);
ab7d5fc6 241
18117871 242/*
14044b37 243 * cds_lfht_add - add a node to the hash table.
f0c29ed7 244 *
48ed1c18 245 * This function supports adding redundant keys into the table.
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246 * Call with rcu_read_lock held.
247 * Threads calling this API need to be registered RCU read-side threads.
f0c29ed7 248 */
14044b37 249void cds_lfht_add(struct cds_lfht *ht, struct cds_lfht_node *node);
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250
251/*
14044b37 252 * cds_lfht_add_unique - add a node to hash table, if key is not present.
f0c29ed7 253 *
6878c72b 254 * Return the node added upon success.
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255 * Return the unique node already present upon failure. If
256 * cds_lfht_add_unique fails, the node passed as parameter should be
257 * freed by the caller.
f0c29ed7 258 * Call with rcu_read_lock held.
3df0c49c 259 * Threads calling this API need to be registered RCU read-side threads.
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260 *
261 * The semantic of this function is that if only this function is used
262 * to add keys into the table, no duplicated keys should ever be
263 * observable in the table. The same guarantee apply for combination of
9357c415 264 * add_unique and add_replace (see below).
18117871 265 */
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266struct cds_lfht_node *cds_lfht_add_unique(struct cds_lfht *ht,
267 struct cds_lfht_node *node);
3eca1b8c 268
48ed1c18 269/*
9357c415 270 * cds_lfht_add_replace - replace or add a node within hash table.
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271 *
272 * Return the node replaced upon success. If no node matching the key
273 * was present, return NULL, which also means the operation succeeded.
274 * This replacement operation should never fail.
275 * Call with rcu_read_lock held.
3df0c49c 276 * Threads calling this API need to be registered RCU read-side threads.
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277 * After successful replacement, a grace period must be waited for before
278 * freeing the memory reserved for the returned node.
279 *
280 * The semantic of replacement vs lookups is the following: if lookups
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281 * are performed between a key unique insertion and its removal, we
282 * guarantee that the lookups and get next will always find exactly one
283 * instance of the key if it is replaced concurrently with the lookups.
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284 *
285 * Providing this semantic allows us to ensure that replacement-only
286 * schemes will never generate duplicated keys. It also allows us to
9357c415 287 * guarantee that a combination of add_replace and add_unique updates
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288 * will never generate duplicated keys.
289 */
9357c415 290struct cds_lfht_node *cds_lfht_add_replace(struct cds_lfht *ht,
adc0de68 291 struct cds_lfht_node *node);
48ed1c18 292
f0c29ed7 293/*
9357c415 294 * cds_lfht_replace - replace a node pointer to by iter within hash table.
f0c29ed7 295 *
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296 * Return 0 if replacement is successful, negative value otherwise.
297 * Replacing a NULL old node or an already removed node will fail with a
298 * negative value.
299 * Old node can be looked up with cds_lfht_lookup and cds_lfht_next.
300 * RCU read-side lock must be held between lookup and replacement.
301 * Call with rcu_read_lock held.
3df0c49c 302 * Threads calling this API need to be registered RCU read-side threads.
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303 * After successful replacement, a grace period must be waited for before
304 * freeing the memory reserved for the old node (which can be accessed
305 * with cds_lfht_iter_get_node).
306 *
307 * The semantic of replacement vs lookups is the following: if lookups
308 * are performed between a key unique insertion and its removal, we
309 * guarantee that the lookups and get next will always find exactly one
310 * instance of the key if it is replaced concurrently with the lookups.
311 *
312 * Providing this semantic allows us to ensure that replacement-only
313 * schemes will never generate duplicated keys. It also allows us to
314 * guarantee that a combination of add_replace and add_unique updates
315 * will never generate duplicated keys.
316 */
317int cds_lfht_replace(struct cds_lfht *ht, struct cds_lfht_iter *old_iter,
318 struct cds_lfht_node *new_node);
319
320/*
321 * cds_lfht_del - remove node pointed to by iterator from hash table.
322 *
323 * Return 0 if the node is successfully removed, negative value
324 * otherwise.
325 * Replacing a NULL node or an already removed node will fail with a
326 * negative value.
327 * Node can be looked up with cds_lfht_lookup and cds_lfht_next.
328 * cds_lfht_iter_get_node.
329 * RCU read-side lock must be held between lookup and removal.
f0c29ed7 330 * Call with rcu_read_lock held.
3df0c49c 331 * Threads calling this API need to be registered RCU read-side threads.
48ed1c18 332 * After successful removal, a grace period must be waited for before
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333 * freeing the memory reserved for old node (which can be accessed with
334 * cds_lfht_iter_get_node).
f0c29ed7 335 */
9357c415 336int cds_lfht_del(struct cds_lfht *ht, struct cds_lfht_iter *iter);
ab7d5fc6 337
f0c29ed7 338/*
14044b37 339 * cds_lfht_resize - Force a hash table resize
1475579c 340 * @new_size: update to this hash table size.
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341 *
342 * Threads calling this API need to be registered RCU read-side threads.
f0c29ed7 343 */
1475579c 344void cds_lfht_resize(struct cds_lfht *ht, unsigned long new_size);
464a1ec9 345
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346#ifdef __cplusplus
347}
348#endif
349
a42cc659 350#endif /* _URCU_RCULFHASH_H */
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