rculfhash: remove now unneeded gc flag (combine with removed)
[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;
48ed1c18 43} __attribute__((aligned(8)));
cc4fcb10 44
14044b37 45struct cds_lfht_node {
cc4fcb10 46 /* cache-hot for iteration */
14044b37 47 struct _cds_lfht_node p; /* needs to be first field */
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48 void *key;
49 unsigned int key_len;
9b35f1e4 50 /* cache-cold for iteration */
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51 struct rcu_head head;
52};
53
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54struct cds_lfht_iter {
55 struct cds_lfht_node *node, *next;
56};
57
58static inline
59struct cds_lfht_node *cds_lfht_iter_get_node(struct cds_lfht_iter *iter)
60{
61 return iter->node;
62}
63
14044b37 64struct cds_lfht;
ab7d5fc6 65
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66/*
67 * Caution !
abc490a1 68 * Ensure reader and writer threads are registered as urcu readers.
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69 */
70
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71typedef unsigned long (*cds_lfht_hash_fct)(void *key, size_t length,
72 unsigned long seed);
73typedef unsigned long (*cds_lfht_compare_fct)(void *key1, size_t key1_len,
74 void *key2, size_t key2_len);
abc490a1 75
f0c29ed7 76/*
14044b37 77 * cds_lfht_node_init - initialize a hash table node
f0c29ed7 78 */
abc490a1 79static inline
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80void cds_lfht_node_init(struct cds_lfht_node *node, void *key,
81 size_t key_len)
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82{
83 node->key = key;
732ad076 84 node->key_len = key_len;
abc490a1 85}
674f7a69 86
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87/*
88 * Hash table creation flags.
89 */
90enum {
91 CDS_LFHT_AUTO_RESIZE = (1U << 0),
92};
93
674f7a69 94/*
7a9dcf9b 95 * _cds_lfht_new - API used by cds_lfht_new wrapper. Do not use directly.
674f7a69 96 */
7a9dcf9b 97struct cds_lfht *_cds_lfht_new(cds_lfht_hash_fct hash_fct,
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98 cds_lfht_compare_fct compare_fct,
99 unsigned long hash_seed,
100 unsigned long init_size,
b8af5011 101 int flags,
14044b37 102 void (*cds_lfht_call_rcu)(struct rcu_head *head,
1475579c 103 void (*func)(struct rcu_head *head)),
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104 void (*cds_lfht_synchronize_rcu)(void),
105 void (*cds_lfht_rcu_read_lock)(void),
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106 void (*cds_lfht_rcu_read_unlock)(void),
107 void (*cds_lfht_rcu_thread_offline)(void),
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108 void (*cds_lfht_rcu_thread_online)(void),
109 void (*cds_lfht_rcu_register_thread)(void),
110 void (*cds_lfht_rcu_unregister_thread)(void),
111 pthread_attr_t *attr);
ab7d5fc6 112
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113/*
114 * cds_lfht_new - allocate a hash table.
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115 * @hash_fct: the hashing function.
116 * @compare_fct: the key comparison function.
117 * @hash_seed: the seed for hash function.
118 * @init_size: number of nodes to allocate initially. Must be power of two.
119 * @flags: hash table creation flags (can be combined with bitwise or: '|').
120 * 0: no flags.
121 * CDS_LFHT_AUTO_RESIZE: automatically resize hash table.
b7d619b0 122 * @attr: optional resize worker thread attributes. NULL for default.
7a9dcf9b 123 *
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124 * Return NULL on error.
125 * Note: the RCU flavor must be already included before the hash table header.
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126 *
127 * The programmer is responsible for ensuring that resize operation has a
128 * priority equal to hash table updater threads. It should be performed by
129 * specifying the appropriate priority in the pthread "attr" argument, and,
130 * for CDS_LFHT_AUTO_RESIZE, by ensuring that call_rcu worker threads also have
131 * this priority level. Having lower priority for call_rcu and resize threads
132 * does not pose any correctness issue, but the resize operations could be
133 * starved by updates, thus leading to long hash table bucket chains.
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134 */
135static inline
136struct cds_lfht *cds_lfht_new(cds_lfht_hash_fct hash_fct,
137 cds_lfht_compare_fct compare_fct,
138 unsigned long hash_seed,
139 unsigned long init_size,
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140 int flags,
141 pthread_attr_t *attr)
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142{
143 return _cds_lfht_new(hash_fct, compare_fct, hash_seed,
144 init_size, flags,
145 call_rcu, synchronize_rcu, rcu_read_lock,
146 rcu_read_unlock, rcu_thread_offline,
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147 rcu_thread_online, rcu_register_thread,
148 rcu_unregister_thread, attr);
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149}
150
f0c29ed7 151/*
14044b37 152 * cds_lfht_destroy - destroy a hash table.
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153 * @ht: the hash table to destroy.
154 * @attr: (output) resize worker thread attributes, as received by cds_lfht_new.
155 * The caller will typically want to free this pointer if dynamically
156 * allocated.
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157 *
158 * Return 0 on success, negative error value on error.
f0c29ed7 159 */
b7d619b0 160int cds_lfht_destroy(struct cds_lfht *ht, pthread_attr_t **attr);
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161
162/*
14044b37 163 * cds_lfht_count_nodes - count the number of nodes in the hash table.
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164 *
165 * Call with rcu_read_lock held.
166 */
14044b37 167void cds_lfht_count_nodes(struct cds_lfht *ht,
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168 unsigned long *count,
169 unsigned long *removed);
ab7d5fc6 170
f0c29ed7 171/*
14044b37 172 * cds_lfht_lookup - lookup a node by key.
f0c29ed7 173 *
adc0de68 174 * Output in "*iter". *iter->node set to NULL if not found.
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175 * Call with rcu_read_lock held.
176 */
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177void cds_lfht_lookup(struct cds_lfht *ht, void *key, size_t key_len,
178 struct cds_lfht_iter *iter);
ab7d5fc6 179
f0c29ed7 180/*
14044b37 181 * cds_lfht_next - get the next item with same key (after a lookup).
f0c29ed7 182 *
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183 * Uses an iterator initialized by a lookup.
184 * Sets *iter-node to the following node with same key.
185 * Sets *iter->node to NULL if no following node exists with same key.
186 * RCU read-side lock must be held across cds_lfht_lookup and
187 * cds_lfht_next calls, and also between cds_lfht_next calls using the
188 * node returned by a previous cds_lfht_next.
189 * Call with rcu_read_lock held.
f0c29ed7 190 */
adc0de68 191void cds_lfht_next(struct cds_lfht *ht, struct cds_lfht_iter *iter);
ab7d5fc6 192
18117871 193/*
14044b37 194 * cds_lfht_add - add a node to the hash table.
f0c29ed7 195 *
18117871 196 * Call with rcu_read_lock held.
48ed1c18 197 * This function supports adding redundant keys into the table.
f0c29ed7 198 */
14044b37 199void cds_lfht_add(struct cds_lfht *ht, struct cds_lfht_node *node);
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200
201/*
14044b37 202 * cds_lfht_add_unique - add a node to hash table, if key is not present.
f0c29ed7 203 *
6878c72b 204 * Return the node added upon success.
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205 * Return the unique node already present upon failure. If
206 * cds_lfht_add_unique fails, the node passed as parameter should be
207 * freed by the caller.
f0c29ed7 208 * Call with rcu_read_lock held.
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209 *
210 * The semantic of this function is that if only this function is used
211 * to add keys into the table, no duplicated keys should ever be
212 * observable in the table. The same guarantee apply for combination of
213 * add_unique and replace (see below).
18117871 214 */
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215struct cds_lfht_node *cds_lfht_add_unique(struct cds_lfht *ht,
216 struct cds_lfht_node *node);
3eca1b8c 217
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218/*
219 * cds_lfht_replace - replace a node within hash table.
220 *
221 * Return the node replaced upon success. If no node matching the key
222 * was present, return NULL, which also means the operation succeeded.
223 * This replacement operation should never fail.
224 * Call with rcu_read_lock held.
225 * After successful replacement, a grace period must be waited for before
226 * freeing the memory reserved for the returned node.
227 *
228 * The semantic of replacement vs lookups is the following: if lookups
229 * are performed between a key insertion and its removal, we guarantee
230 * that the lookups will always find the key if it is replaced
adc0de68 231 * concurrently with the lookups.
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232 *
233 * Providing this semantic allows us to ensure that replacement-only
234 * schemes will never generate duplicated keys. It also allows us to
235 * guarantee that a combination of replacement and add_unique updates
236 * will never generate duplicated keys.
237 */
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238struct cds_lfht_node *cds_lfht_replace(struct cds_lfht *ht,
239 struct cds_lfht_node *node);
48ed1c18 240
f0c29ed7 241/*
860d07e8 242 * cds_lfht_del - remove node from hash table.
f0c29ed7 243 *
48ed1c18 244 * Return 0 if the node is successfully removed.
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245 * Node can be looked up with cds_lfht_lookup. RCU read-side lock must
246 * be held between lookup and removal.
f0c29ed7 247 * Call with rcu_read_lock held.
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248 * After successful removal, a grace period must be waited for before
249 * freeing the memory reserved for node.
f0c29ed7 250 */
860d07e8 251int cds_lfht_del(struct cds_lfht *ht, struct cds_lfht_node *node);
ab7d5fc6 252
f0c29ed7 253/*
14044b37 254 * cds_lfht_resize - Force a hash table resize
1475579c 255 * @new_size: update to this hash table size.
f0c29ed7 256 */
1475579c 257void cds_lfht_resize(struct cds_lfht *ht, unsigned long new_size);
464a1ec9 258
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259#ifdef __cplusplus
260}
261#endif
262
a42cc659 263#endif /* _URCU_RCULFHASH_H */
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