rculfhash: add TODO for resize worker threads
[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
7f61a77f 33/*
14044b37 34 * struct cds_lfht_node and struct _cds_lfht_node should be aligned on
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35 * 4-bytes boundaries because the two lower bits are used as flags.
36 */
37
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38struct _cds_lfht_node {
39 struct cds_lfht_node *next; /* ptr | DUMMY_FLAG | REMOVED_FLAG */
abc490a1 40 unsigned long reverse_hash;
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41};
42
14044b37 43struct cds_lfht_node {
cc4fcb10 44 /* cache-hot for iteration */
14044b37 45 struct _cds_lfht_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
14044b37 52struct cds_lfht;
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 (*cds_lfht_hash_fct)(void *key, size_t length,
60 unsigned long seed);
61typedef unsigned long (*cds_lfht_compare_fct)(void *key1, size_t key1_len,
62 void *key2, size_t key2_len);
abc490a1 63
f0c29ed7 64/*
14044b37 65 * cds_lfht_node_init - initialize a hash table node
f0c29ed7 66 */
abc490a1 67static inline
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68void cds_lfht_node_init(struct cds_lfht_node *node, void *key,
69 size_t key_len)
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70{
71 node->key = key;
732ad076 72 node->key_len = key_len;
abc490a1 73}
674f7a69 74
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75/*
76 * Hash table creation flags.
77 */
78enum {
79 CDS_LFHT_AUTO_RESIZE = (1U << 0),
80};
81
674f7a69 82/*
14044b37 83 * cds_lfht_new - allocate a hash table.
f0c29ed7 84 *
674f7a69 85 * init_size must be power of two.
6878c72b 86 * Return NULL on error.
674f7a69 87 */
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88struct cds_lfht *cds_lfht_new(cds_lfht_hash_fct hash_fct,
89 cds_lfht_compare_fct compare_fct,
90 unsigned long hash_seed,
91 unsigned long init_size,
b8af5011 92 int flags,
14044b37 93 void (*cds_lfht_call_rcu)(struct rcu_head *head,
1475579c 94 void (*func)(struct rcu_head *head)),
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95 void (*cds_lfht_synchronize_rcu)(void),
96 void (*cds_lfht_rcu_read_lock)(void),
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97 void (*cds_lfht_rcu_read_unlock)(void),
98 void (*cds_lfht_rcu_thread_offline)(void),
99 void (*cds_lfht_rcu_thread_online)(void));
ab7d5fc6 100
f0c29ed7 101/*
14044b37 102 * cds_lfht_destroy - destroy a hash table.
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103 *
104 * Return 0 on success, negative error value on error.
f0c29ed7 105 */
14044b37 106int cds_lfht_destroy(struct cds_lfht *ht);
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107
108/*
14044b37 109 * cds_lfht_count_nodes - count the number of nodes in the hash table.
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110 *
111 * Call with rcu_read_lock held.
112 */
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113void cds_lfht_count_nodes(struct cds_lfht *ht,
114 unsigned long *count,
115 unsigned long *removed);
ab7d5fc6 116
f0c29ed7 117/*
14044b37 118 * cds_lfht_lookup - lookup a node by key.
f0c29ed7 119 *
6878c72b 120 * Return NULL if not found.
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121 * Call with rcu_read_lock held.
122 */
14044b37 123struct cds_lfht_node *cds_lfht_lookup(struct cds_lfht *ht, void *key, size_t key_len);
ab7d5fc6 124
f0c29ed7 125/*
14044b37 126 * cds_lfht_next - get the next item with same key (after a lookup).
f0c29ed7 127 *
6878c72b 128 * Return NULL if no following node exists with same key.
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129 * RCU read-side lock must be held across cds_lfht_lookup and cds_lfht_next calls, and also
130 * between cds_lfht_next calls using the node returned by a previous cds_lfht_next.
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131 * Call with rcu_read_lock held.
132 */
14044b37 133struct cds_lfht_node *cds_lfht_next(struct cds_lfht *ht, struct cds_lfht_node *node);
ab7d5fc6 134
18117871 135/*
14044b37 136 * cds_lfht_add - add a node to the hash table.
f0c29ed7 137 *
18117871 138 * Call with rcu_read_lock held.
f0c29ed7 139 */
14044b37 140void cds_lfht_add(struct cds_lfht *ht, struct cds_lfht_node *node);
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141
142/*
14044b37 143 * cds_lfht_add_unique - add a node to hash table, if key is not present.
f0c29ed7 144 *
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145 * Return the node added upon success.
146 * Return the unique node already present upon failure. If cds_lfht_add_unique fails,
18117871 147 * the node passed as parameter should be freed by the caller.
f0c29ed7 148 * Call with rcu_read_lock held.
18117871 149 */
14044b37 150struct cds_lfht_node *cds_lfht_add_unique(struct cds_lfht *ht, struct cds_lfht_node *node);
3eca1b8c 151
f0c29ed7 152/*
14044b37 153 * cds_lfht_remove - remove node from hash table.
f0c29ed7 154 *
14044b37 155 * Node can be looked up with cds_lfht_lookup. RCU read-side lock must be held between
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156 * lookup and removal.
157 * Call with rcu_read_lock held.
158 */
14044b37 159int cds_lfht_remove(struct cds_lfht *ht, struct cds_lfht_node *node);
ab7d5fc6 160
f0c29ed7 161/*
14044b37 162 * cds_lfht_resize - Force a hash table resize
1475579c 163 * @new_size: update to this hash table size.
f0c29ed7 164 */
1475579c 165void cds_lfht_resize(struct cds_lfht *ht, unsigned long new_size);
464a1ec9 166
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167#ifdef __cplusplus
168}
169#endif
170
a42cc659 171#endif /* _URCU_RCULFHASH_H */
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