rculfhash: document flags
[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
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37 * 4-bytes boundaries because the two lower bits are used as flags.
38 */
39
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40struct _cds_lfht_node {
41 struct cds_lfht_node *next; /* ptr | DUMMY_FLAG | REMOVED_FLAG */
abc490a1 42 unsigned long reverse_hash;
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43};
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
14044b37 54struct cds_lfht;
ab7d5fc6 55
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56/*
57 * Caution !
abc490a1 58 * Ensure reader and writer threads are registered as urcu readers.
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59 */
60
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61typedef unsigned long (*cds_lfht_hash_fct)(void *key, size_t length,
62 unsigned long seed);
63typedef unsigned long (*cds_lfht_compare_fct)(void *key1, size_t key1_len,
64 void *key2, size_t key2_len);
abc490a1 65
f0c29ed7 66/*
14044b37 67 * cds_lfht_node_init - initialize a hash table node
f0c29ed7 68 */
abc490a1 69static inline
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70void cds_lfht_node_init(struct cds_lfht_node *node, void *key,
71 size_t key_len)
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72{
73 node->key = key;
732ad076 74 node->key_len = key_len;
abc490a1 75}
674f7a69 76
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77/*
78 * Hash table creation flags.
79 */
80enum {
81 CDS_LFHT_AUTO_RESIZE = (1U << 0),
82};
83
674f7a69 84/*
7a9dcf9b 85 * _cds_lfht_new - API used by cds_lfht_new wrapper. Do not use directly.
674f7a69 86 */
7a9dcf9b 87struct cds_lfht *_cds_lfht_new(cds_lfht_hash_fct hash_fct,
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88 cds_lfht_compare_fct compare_fct,
89 unsigned long hash_seed,
90 unsigned long init_size,
b8af5011 91 int flags,
14044b37 92 void (*cds_lfht_call_rcu)(struct rcu_head *head,
1475579c 93 void (*func)(struct rcu_head *head)),
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94 void (*cds_lfht_synchronize_rcu)(void),
95 void (*cds_lfht_rcu_read_lock)(void),
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96 void (*cds_lfht_rcu_read_unlock)(void),
97 void (*cds_lfht_rcu_thread_offline)(void),
98 void (*cds_lfht_rcu_thread_online)(void));
ab7d5fc6 99
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100/*
101 * cds_lfht_new - allocate a hash table.
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102 * @hash_fct: the hashing function.
103 * @compare_fct: the key comparison function.
104 * @hash_seed: the seed for hash function.
105 * @init_size: number of nodes to allocate initially. Must be power of two.
106 * @flags: hash table creation flags (can be combined with bitwise or: '|').
107 * 0: no flags.
108 * CDS_LFHT_AUTO_RESIZE: automatically resize hash table.
7a9dcf9b 109 *
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110 * Return NULL on error.
111 * Note: the RCU flavor must be already included before the hash table header.
112 */
113static inline
114struct cds_lfht *cds_lfht_new(cds_lfht_hash_fct hash_fct,
115 cds_lfht_compare_fct compare_fct,
116 unsigned long hash_seed,
117 unsigned long init_size,
118 int flags)
119{
120 return _cds_lfht_new(hash_fct, compare_fct, hash_seed,
121 init_size, flags,
122 call_rcu, synchronize_rcu, rcu_read_lock,
123 rcu_read_unlock, rcu_thread_offline,
124 rcu_thread_online);
125}
126
f0c29ed7 127/*
14044b37 128 * cds_lfht_destroy - destroy a hash table.
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129 *
130 * Return 0 on success, negative error value on error.
f0c29ed7 131 */
14044b37 132int cds_lfht_destroy(struct cds_lfht *ht);
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133
134/*
14044b37 135 * cds_lfht_count_nodes - count the number of nodes in the hash table.
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136 *
137 * Call with rcu_read_lock held.
138 */
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139void cds_lfht_count_nodes(struct cds_lfht *ht,
140 unsigned long *count,
141 unsigned long *removed);
ab7d5fc6 142
f0c29ed7 143/*
14044b37 144 * cds_lfht_lookup - lookup a node by key.
f0c29ed7 145 *
6878c72b 146 * Return NULL if not found.
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147 * Call with rcu_read_lock held.
148 */
14044b37 149struct cds_lfht_node *cds_lfht_lookup(struct cds_lfht *ht, void *key, size_t key_len);
ab7d5fc6 150
f0c29ed7 151/*
14044b37 152 * cds_lfht_next - get the next item with same key (after a lookup).
f0c29ed7 153 *
6878c72b 154 * Return NULL if no following node exists with same key.
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155 * RCU read-side lock must be held across cds_lfht_lookup and cds_lfht_next calls, and also
156 * between cds_lfht_next calls using the node returned by a previous cds_lfht_next.
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157 * Call with rcu_read_lock held.
158 */
14044b37 159struct cds_lfht_node *cds_lfht_next(struct cds_lfht *ht, struct cds_lfht_node *node);
ab7d5fc6 160
18117871 161/*
14044b37 162 * cds_lfht_add - add a node to the hash table.
f0c29ed7 163 *
18117871 164 * Call with rcu_read_lock held.
f0c29ed7 165 */
14044b37 166void cds_lfht_add(struct cds_lfht *ht, struct cds_lfht_node *node);
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167
168/*
14044b37 169 * cds_lfht_add_unique - add a node to hash table, if key is not present.
f0c29ed7 170 *
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171 * Return the node added upon success.
172 * Return the unique node already present upon failure. If cds_lfht_add_unique fails,
18117871 173 * the node passed as parameter should be freed by the caller.
f0c29ed7 174 * Call with rcu_read_lock held.
18117871 175 */
14044b37 176struct cds_lfht_node *cds_lfht_add_unique(struct cds_lfht *ht, struct cds_lfht_node *node);
3eca1b8c 177
f0c29ed7 178/*
14044b37 179 * cds_lfht_remove - remove node from hash table.
f0c29ed7 180 *
14044b37 181 * Node can be looked up with cds_lfht_lookup. RCU read-side lock must be held between
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182 * lookup and removal.
183 * Call with rcu_read_lock held.
184 */
14044b37 185int cds_lfht_remove(struct cds_lfht *ht, struct cds_lfht_node *node);
ab7d5fc6 186
f0c29ed7 187/*
14044b37 188 * cds_lfht_resize - Force a hash table resize
1475579c 189 * @new_size: update to this hash table size.
f0c29ed7 190 */
1475579c 191void cds_lfht_resize(struct cds_lfht *ht, unsigned long new_size);
464a1ec9 192
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193#ifdef __cplusplus
194}
195#endif
196
a42cc659 197#endif /* _URCU_RCULFHASH_H */
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