RCU hash table API documentation
[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
24 */
25
674f7a69 26#include <stdint.h>
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27#include <urcu-call-rcu.h>
28
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29#ifdef __cplusplus
30extern "C" {
31#endif
32
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33/*
34 * struct rcu_ht_node and struct _rcu_ht_node should be aligned on
35 * 4-bytes boundaries because the two lower bits are used as flags.
36 */
37
cc4fcb10 38struct _rcu_ht_node {
d95bd160 39 struct rcu_ht_node *next; /* ptr | DUMMY_FLAG | REMOVED_FLAG */
abc490a1 40 unsigned long reverse_hash;
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41};
42
43struct rcu_ht_node {
44 /* cache-hot for iteration */
45 struct _rcu_ht_node p; /* needs to be first field */
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46 void *key;
47 unsigned int key_len;
9b35f1e4 48 /* cache-cold for iteration */
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49 struct rcu_head head;
50};
51
52struct rcu_ht;
ab7d5fc6 53
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54/*
55 * Caution !
abc490a1 56 * Ensure reader and writer threads are registered as urcu readers.
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57 */
58
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59typedef unsigned long (*ht_hash_fct)(void *key, size_t length,
60 unsigned long seed);
61typedef unsigned long (*ht_compare_fct)(void *key1, size_t key1_len,
62 void *key2, size_t key2_len);
abc490a1 63
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64/*
65 * ht_node_init - initialize a hash table node
66 */
abc490a1 67static inline
732ad076 68void ht_node_init(struct rcu_ht_node *node, void *key,
cb233752 69 size_t key_len)
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70{
71 node->key = key;
732ad076 72 node->key_len = key_len;
abc490a1 73}
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74
75/*
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76 * ht_new - allocate a hash table.
77 *
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78 * init_size must be power of two.
79 */
abc490a1 80struct rcu_ht *ht_new(ht_hash_fct hash_fct,
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81 ht_compare_fct compare_fct,
82 unsigned long hash_seed,
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83 unsigned long init_size,
84 void (*ht_call_rcu)(struct rcu_head *head,
85 void (*func)(struct rcu_head *head)));
ab7d5fc6 86
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87/*
88 * ht_destroy - destroy a hash table.
89 */
5e28c532 90int ht_destroy(struct rcu_ht *ht);
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91
92/*
93 * ht_count_nodes - count the number of nodes in the hash table.
94 *
95 * Call with rcu_read_lock held.
96 */
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97void ht_count_nodes(struct rcu_ht *ht,
98 unsigned long *count,
99 unsigned long *removed);
ab7d5fc6 100
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101/*
102 * ht_lookup - lookup a node by key.
103 *
104 * Returns NULL if not found.
105 * Call with rcu_read_lock held.
106 */
732ad076 107struct rcu_ht_node *ht_lookup(struct rcu_ht *ht, void *key, size_t key_len);
ab7d5fc6 108
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109/*
110 * ht_next - get the next item with same key (after a lookup).
111 *
112 * Returns NULL if no following node exists with same key.
113 * RCU read-side lock must be held across ht_lookup and ht_next calls, and also
114 * between ht_next calls using the node returned by a previous ht_next.
115 * Call with rcu_read_lock held.
116 */
117struct rcu_ht_node *ht_next(struct rcu_ht *ht, struct rcu_ht_node *node);
ab7d5fc6 118
18117871 119/*
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120 * ht_add - add a node to the hash table.
121 *
18117871 122 * Call with rcu_read_lock held.
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123 */
124void ht_add(struct rcu_ht *ht, struct rcu_ht_node *node);
125
126/*
127 * ht_add_unique - add a node to hash table, if key is not present.
128 *
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129 * Returns the node added upon success.
130 * Returns the unique node already present upon failure. If ht_add_unique fails,
131 * the node passed as parameter should be freed by the caller.
f0c29ed7 132 * Call with rcu_read_lock held.
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133 */
134struct rcu_ht_node *ht_add_unique(struct rcu_ht *ht, struct rcu_ht_node *node);
3eca1b8c 135
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136/*
137 * ht_remove - remove node from hash table.
138 *
139 * Node can be looked up with ht_lookup. RCU read-side lock must be held between
140 * lookup and removal.
141 * Call with rcu_read_lock held.
142 */
abc490a1 143int ht_remove(struct rcu_ht *ht, struct rcu_ht_node *node);
ab7d5fc6 144
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145/*
146 * ht_resize - Force a hash table resize
147 * @growth: growth order (current size is multiplied by 2^growth)
148 *
149 * Currently, only expand operation is supported (growth >= 0).
150 */
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151void ht_resize(struct rcu_ht *ht, int growth);
152
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153#ifdef __cplusplus
154}
155#endif
156
a42cc659 157#endif /* _URCU_RCULFHASH_H */
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