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a42cc659 MD |
1 | #ifndef _URCU_RCULFHASH_H |
2 | #define _URCU_RCULFHASH_H | |
ab7d5fc6 | 3 | |
f0c29ed7 MD |
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 | |
cf77d1fa MD |
24 | * |
25 | * Include this file _after_ including your URCU flavor. | |
f0c29ed7 MD |
26 | */ |
27 | ||
674f7a69 | 28 | #include <stdint.h> |
abc490a1 MD |
29 | #include <urcu-call-rcu.h> |
30 | ||
01389791 MD |
31 | #ifdef __cplusplus |
32 | extern "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. |
7f61a77f MD |
38 | */ |
39 | ||
14044b37 | 40 | struct _cds_lfht_node { |
b198f0fd | 41 | struct cds_lfht_node *next; /* ptr | DUMMY_FLAG | REMOVED_FLAG */ |
abc490a1 | 42 | unsigned long reverse_hash; |
58ca0741 | 43 | } __attribute__((aligned(4))); |
cc4fcb10 | 44 | |
14044b37 | 45 | struct cds_lfht_node { |
cc4fcb10 | 46 | /* cache-hot for iteration */ |
14044b37 | 47 | struct _cds_lfht_node p; /* needs to be first field */ |
9b35f1e4 MD |
48 | void *key; |
49 | unsigned int key_len; | |
9b35f1e4 | 50 | /* cache-cold for iteration */ |
abc490a1 MD |
51 | struct rcu_head head; |
52 | }; | |
53 | ||
adc0de68 MD |
54 | struct cds_lfht_iter { |
55 | struct cds_lfht_node *node, *next; | |
56 | }; | |
57 | ||
58 | static inline | |
59 | struct cds_lfht_node *cds_lfht_iter_get_node(struct cds_lfht_iter *iter) | |
60 | { | |
61 | return iter->node; | |
62 | } | |
63 | ||
14044b37 | 64 | struct cds_lfht; |
ab7d5fc6 | 65 | |
5e28c532 MD |
66 | /* |
67 | * Caution ! | |
abc490a1 | 68 | * Ensure reader and writer threads are registered as urcu readers. |
5e28c532 MD |
69 | */ |
70 | ||
14044b37 MD |
71 | typedef unsigned long (*cds_lfht_hash_fct)(void *key, size_t length, |
72 | unsigned long seed); | |
73 | typedef 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 | 79 | static inline |
14044b37 MD |
80 | void cds_lfht_node_init(struct cds_lfht_node *node, void *key, |
81 | size_t key_len) | |
abc490a1 MD |
82 | { |
83 | node->key = key; | |
732ad076 | 84 | node->key_len = key_len; |
abc490a1 | 85 | } |
674f7a69 | 86 | |
b8af5011 MD |
87 | /* |
88 | * Hash table creation flags. | |
89 | */ | |
90 | enum { | |
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 | 97 | struct cds_lfht *_cds_lfht_new(cds_lfht_hash_fct hash_fct, |
14044b37 MD |
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)), |
01dbfa62 MD |
104 | void (*cds_lfht_synchronize_rcu)(void), |
105 | void (*cds_lfht_rcu_read_lock)(void), | |
5f511391 MD |
106 | void (*cds_lfht_rcu_read_unlock)(void), |
107 | void (*cds_lfht_rcu_thread_offline)(void), | |
b7d619b0 MD |
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 | |
7a9dcf9b MD |
113 | /* |
114 | * cds_lfht_new - allocate a hash table. | |
f22dd01d MD |
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 | * |
7a9dcf9b MD |
124 | * Return NULL on error. |
125 | * Note: the RCU flavor must be already included before the hash table header. | |
b7d619b0 MD |
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. | |
7a9dcf9b MD |
134 | */ |
135 | static inline | |
136 | struct 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, | |
b7d619b0 MD |
140 | int flags, |
141 | pthread_attr_t *attr) | |
7a9dcf9b MD |
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, | |
b7d619b0 MD |
147 | rcu_thread_online, rcu_register_thread, |
148 | rcu_unregister_thread, attr); | |
7a9dcf9b MD |
149 | } |
150 | ||
f0c29ed7 | 151 | /* |
14044b37 | 152 | * cds_lfht_destroy - destroy a hash table. |
b7d619b0 MD |
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. | |
6878c72b MD |
157 | * |
158 | * Return 0 on success, negative error value on error. | |
f0c29ed7 | 159 | */ |
b7d619b0 | 160 | int cds_lfht_destroy(struct cds_lfht *ht, pthread_attr_t **attr); |
f0c29ed7 MD |
161 | |
162 | /* | |
14044b37 | 163 | * cds_lfht_count_nodes - count the number of nodes in the hash table. |
f0c29ed7 MD |
164 | * |
165 | * Call with rcu_read_lock held. | |
166 | */ | |
14044b37 | 167 | void cds_lfht_count_nodes(struct cds_lfht *ht, |
adc0de68 MD |
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. |
f0c29ed7 MD |
175 | * Call with rcu_read_lock held. |
176 | */ | |
adc0de68 MD |
177 | void 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 | * |
adc0de68 MD |
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 | 191 | void 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 | 199 | void cds_lfht_add(struct cds_lfht *ht, struct cds_lfht_node *node); |
f0c29ed7 MD |
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. |
860d07e8 MD |
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. |
48ed1c18 MD |
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 | */ |
adc0de68 MD |
215 | struct cds_lfht_node *cds_lfht_add_unique(struct cds_lfht *ht, |
216 | struct cds_lfht_node *node); | |
3eca1b8c | 217 | |
48ed1c18 MD |
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. |
48ed1c18 MD |
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 | */ | |
adc0de68 MD |
238 | struct 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. |
860d07e8 MD |
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. |
48ed1c18 MD |
248 | * After successful removal, a grace period must be waited for before |
249 | * freeing the memory reserved for node. | |
f0c29ed7 | 250 | */ |
860d07e8 | 251 | int 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 | 257 | void cds_lfht_resize(struct cds_lfht *ht, unsigned long new_size); |
464a1ec9 | 258 | |
01389791 MD |
259 | #ifdef __cplusplus |
260 | } | |
261 | #endif | |
262 | ||
a42cc659 | 263 | #endif /* _URCU_RCULFHASH_H */ |