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fa68aa62 MD |
1 | #ifndef _URCU_RCULFHASH_H |
2 | #define _URCU_RCULFHASH_H | |
3 | ||
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 | * Include this file _after_ including your URCU flavor. | |
26 | */ | |
27 | ||
28 | #include <stdint.h> | |
29 | #include <urcu-call-rcu.h> | |
30 | ||
31 | #ifdef __cplusplus | |
32 | extern "C" { | |
33 | #endif | |
34 | ||
35 | /* | |
36 | * struct cds_lfht_node and struct _cds_lfht_node should be aligned on | |
37 | * 4-bytes boundaries because the two lower bits are used as flags. | |
38 | */ | |
39 | ||
40 | struct _cds_lfht_node { | |
41 | struct cds_lfht_node *next; /* ptr | DUMMY_FLAG | REMOVED_FLAG */ | |
42 | unsigned long reverse_hash; | |
43 | } __attribute__((aligned(4))); | |
44 | ||
f6a9efaa DG |
45 | /* |
46 | * struct cds_lfht_node can be embedded into a structure (as a field). | |
47 | * caa_container_of() can be used to get the structure from the struct | |
48 | * cds_lfht_node after a lookup. | |
49 | */ | |
fa68aa62 MD |
50 | struct cds_lfht_node { |
51 | /* cache-hot for iteration */ | |
52 | struct _cds_lfht_node p; /* needs to be first field */ | |
53 | void *key; | |
54 | unsigned int key_len; | |
55 | /* cache-cold for iteration */ | |
56 | struct rcu_head head; | |
57 | }; | |
58 | ||
59 | struct cds_lfht_iter { | |
60 | struct cds_lfht_node *node, *next; | |
61 | }; | |
62 | ||
63 | static inline | |
64 | struct cds_lfht_node *cds_lfht_iter_get_node(struct cds_lfht_iter *iter) | |
65 | { | |
66 | return iter->node; | |
67 | } | |
68 | ||
69 | struct cds_lfht; | |
70 | ||
71 | /* | |
72 | * Caution ! | |
73 | * Ensure reader and writer threads are registered as urcu readers. | |
74 | */ | |
75 | ||
76 | typedef unsigned long (*cds_lfht_hash_fct)(void *key, size_t length, | |
77 | unsigned long seed); | |
78 | typedef unsigned long (*cds_lfht_compare_fct)(void *key1, size_t key1_len, | |
79 | void *key2, size_t key2_len); | |
80 | ||
81 | /* | |
82 | * cds_lfht_node_init - initialize a hash table node | |
83 | */ | |
84 | static inline | |
85 | void cds_lfht_node_init(struct cds_lfht_node *node, void *key, | |
86 | size_t key_len) | |
87 | { | |
88 | node->key = key; | |
89 | node->key_len = key_len; | |
90 | } | |
91 | ||
92 | /* | |
93 | * Hash table creation flags. | |
94 | */ | |
95 | enum { | |
96 | CDS_LFHT_AUTO_RESIZE = (1U << 0), | |
97 | }; | |
98 | ||
99 | /* | |
100 | * _cds_lfht_new - API used by cds_lfht_new wrapper. Do not use directly. | |
101 | */ | |
102 | struct cds_lfht *_cds_lfht_new(cds_lfht_hash_fct hash_fct, | |
103 | cds_lfht_compare_fct compare_fct, | |
104 | unsigned long hash_seed, | |
105 | unsigned long init_size, | |
106 | int flags, | |
107 | void (*cds_lfht_call_rcu)(struct rcu_head *head, | |
108 | void (*func)(struct rcu_head *head)), | |
109 | void (*cds_lfht_synchronize_rcu)(void), | |
110 | void (*cds_lfht_rcu_read_lock)(void), | |
111 | void (*cds_lfht_rcu_read_unlock)(void), | |
112 | void (*cds_lfht_rcu_thread_offline)(void), | |
113 | void (*cds_lfht_rcu_thread_online)(void), | |
114 | void (*cds_lfht_rcu_register_thread)(void), | |
115 | void (*cds_lfht_rcu_unregister_thread)(void), | |
116 | pthread_attr_t *attr); | |
117 | ||
118 | /* | |
119 | * cds_lfht_new - allocate a hash table. | |
120 | * @hash_fct: the hashing function. | |
121 | * @compare_fct: the key comparison function. | |
122 | * @hash_seed: the seed for hash function. | |
123 | * @init_size: number of nodes to allocate initially. Must be power of two. | |
124 | * @flags: hash table creation flags (can be combined with bitwise or: '|'). | |
125 | * 0: no flags. | |
126 | * CDS_LFHT_AUTO_RESIZE: automatically resize hash table. | |
127 | * @attr: optional resize worker thread attributes. NULL for default. | |
128 | * | |
129 | * Return NULL on error. | |
130 | * Note: the RCU flavor must be already included before the hash table header. | |
131 | * | |
132 | * The programmer is responsible for ensuring that resize operation has a | |
133 | * priority equal to hash table updater threads. It should be performed by | |
134 | * specifying the appropriate priority in the pthread "attr" argument, and, | |
135 | * for CDS_LFHT_AUTO_RESIZE, by ensuring that call_rcu worker threads also have | |
136 | * this priority level. Having lower priority for call_rcu and resize threads | |
137 | * does not pose any correctness issue, but the resize operations could be | |
138 | * starved by updates, thus leading to long hash table bucket chains. | |
139 | */ | |
140 | static inline | |
141 | struct cds_lfht *cds_lfht_new(cds_lfht_hash_fct hash_fct, | |
142 | cds_lfht_compare_fct compare_fct, | |
143 | unsigned long hash_seed, | |
144 | unsigned long init_size, | |
145 | int flags, | |
146 | pthread_attr_t *attr) | |
147 | { | |
148 | return _cds_lfht_new(hash_fct, compare_fct, hash_seed, | |
149 | init_size, flags, | |
150 | call_rcu, synchronize_rcu, rcu_read_lock, | |
151 | rcu_read_unlock, rcu_thread_offline, | |
152 | rcu_thread_online, rcu_register_thread, | |
153 | rcu_unregister_thread, attr); | |
154 | } | |
155 | ||
156 | /* | |
157 | * cds_lfht_destroy - destroy a hash table. | |
158 | * @ht: the hash table to destroy. | |
159 | * @attr: (output) resize worker thread attributes, as received by cds_lfht_new. | |
160 | * The caller will typically want to free this pointer if dynamically | |
161 | * allocated. | |
162 | * | |
163 | * Return 0 on success, negative error value on error. | |
164 | */ | |
165 | int cds_lfht_destroy(struct cds_lfht *ht, pthread_attr_t **attr); | |
166 | ||
167 | /* | |
168 | * cds_lfht_count_nodes - count the number of nodes in the hash table. | |
169 | * | |
170 | * Call with rcu_read_lock held. | |
171 | */ | |
172 | void cds_lfht_count_nodes(struct cds_lfht *ht, | |
173 | long *approx_before, | |
174 | unsigned long *count, | |
175 | unsigned long *removed, | |
176 | long *approx_after); | |
177 | ||
178 | /* | |
179 | * cds_lfht_lookup - lookup a node by key. | |
180 | * | |
181 | * Output in "*iter". *iter->node set to NULL if not found. | |
182 | * Call with rcu_read_lock held. | |
183 | */ | |
184 | void cds_lfht_lookup(struct cds_lfht *ht, void *key, size_t key_len, | |
185 | struct cds_lfht_iter *iter); | |
186 | ||
187 | /* | |
f6a9efaa | 188 | * cds_lfht_next_duplicate - get the next item with same key (after a lookup). |
fa68aa62 MD |
189 | * |
190 | * Uses an iterator initialized by a lookup. | |
191 | * Sets *iter-node to the following node with same key. | |
192 | * Sets *iter->node to NULL if no following node exists with same key. | |
193 | * RCU read-side lock must be held across cds_lfht_lookup and | |
194 | * cds_lfht_next calls, and also between cds_lfht_next calls using the | |
195 | * node returned by a previous cds_lfht_next. | |
196 | * Call with rcu_read_lock held. | |
197 | */ | |
f6a9efaa DG |
198 | void cds_lfht_next_duplicate(struct cds_lfht *ht, struct cds_lfht_iter *iter); |
199 | ||
200 | /* | |
201 | * cds_lfht_first - get the first node in the table. | |
202 | * | |
203 | * Output in "*iter". *iter->node set to NULL if table is empty. | |
204 | * Call with rcu_read_lock held. | |
205 | */ | |
206 | void cds_lfht_first(struct cds_lfht *ht, struct cds_lfht_iter *iter); | |
207 | ||
208 | /* | |
209 | * cds_lfht_next - get the next node in the table. | |
210 | * | |
211 | * Input/Output in "*iter". *iter->node set to NULL if *iter was | |
212 | * pointing to the last table node. | |
213 | * Call with rcu_read_lock held. | |
214 | */ | |
fa68aa62 MD |
215 | void cds_lfht_next(struct cds_lfht *ht, struct cds_lfht_iter *iter); |
216 | ||
217 | /* | |
218 | * cds_lfht_add - add a node to the hash table. | |
219 | * | |
220 | * Call with rcu_read_lock held. | |
221 | * This function supports adding redundant keys into the table. | |
222 | */ | |
223 | void cds_lfht_add(struct cds_lfht *ht, struct cds_lfht_node *node); | |
224 | ||
225 | /* | |
226 | * cds_lfht_add_unique - add a node to hash table, if key is not present. | |
227 | * | |
228 | * Return the node added upon success. | |
229 | * Return the unique node already present upon failure. If | |
230 | * cds_lfht_add_unique fails, the node passed as parameter should be | |
231 | * freed by the caller. | |
232 | * Call with rcu_read_lock held. | |
233 | * | |
234 | * The semantic of this function is that if only this function is used | |
235 | * to add keys into the table, no duplicated keys should ever be | |
236 | * observable in the table. The same guarantee apply for combination of | |
237 | * add_unique and add_replace (see below). | |
238 | */ | |
239 | struct cds_lfht_node *cds_lfht_add_unique(struct cds_lfht *ht, | |
240 | struct cds_lfht_node *node); | |
241 | ||
242 | /* | |
243 | * cds_lfht_add_replace - replace or add a node within hash table. | |
244 | * | |
245 | * Return the node replaced upon success. If no node matching the key | |
246 | * was present, return NULL, which also means the operation succeeded. | |
247 | * This replacement operation should never fail. | |
248 | * Call with rcu_read_lock held. | |
249 | * After successful replacement, a grace period must be waited for before | |
250 | * freeing the memory reserved for the returned node. | |
251 | * | |
252 | * The semantic of replacement vs lookups is the following: if lookups | |
253 | * are performed between a key unique insertion and its removal, we | |
254 | * guarantee that the lookups and get next will always find exactly one | |
255 | * instance of the key if it is replaced concurrently with the lookups. | |
256 | * | |
257 | * Providing this semantic allows us to ensure that replacement-only | |
258 | * schemes will never generate duplicated keys. It also allows us to | |
259 | * guarantee that a combination of add_replace and add_unique updates | |
260 | * will never generate duplicated keys. | |
261 | */ | |
262 | struct cds_lfht_node *cds_lfht_add_replace(struct cds_lfht *ht, | |
263 | struct cds_lfht_node *node); | |
264 | ||
265 | /* | |
266 | * cds_lfht_replace - replace a node pointer to by iter within hash table. | |
267 | * | |
268 | * Return 0 if replacement is successful, negative value otherwise. | |
269 | * Replacing a NULL old node or an already removed node will fail with a | |
270 | * negative value. | |
271 | * Old node can be looked up with cds_lfht_lookup and cds_lfht_next. | |
272 | * RCU read-side lock must be held between lookup and replacement. | |
273 | * Call with rcu_read_lock held. | |
274 | * After successful replacement, a grace period must be waited for before | |
275 | * freeing the memory reserved for the old node (which can be accessed | |
276 | * with cds_lfht_iter_get_node). | |
277 | * | |
278 | * The semantic of replacement vs lookups is the following: if lookups | |
279 | * are performed between a key unique insertion and its removal, we | |
280 | * guarantee that the lookups and get next will always find exactly one | |
281 | * instance of the key if it is replaced concurrently with the lookups. | |
282 | * | |
283 | * Providing this semantic allows us to ensure that replacement-only | |
284 | * schemes will never generate duplicated keys. It also allows us to | |
285 | * guarantee that a combination of add_replace and add_unique updates | |
286 | * will never generate duplicated keys. | |
287 | */ | |
288 | int cds_lfht_replace(struct cds_lfht *ht, struct cds_lfht_iter *old_iter, | |
289 | struct cds_lfht_node *new_node); | |
290 | ||
291 | /* | |
292 | * cds_lfht_del - remove node pointed to by iterator from hash table. | |
293 | * | |
294 | * Return 0 if the node is successfully removed, negative value | |
295 | * otherwise. | |
296 | * Replacing a NULL node or an already removed node will fail with a | |
297 | * negative value. | |
298 | * Node can be looked up with cds_lfht_lookup and cds_lfht_next. | |
299 | * cds_lfht_iter_get_node. | |
300 | * RCU read-side lock must be held between lookup and removal. | |
301 | * Call with rcu_read_lock held. | |
302 | * After successful removal, a grace period must be waited for before | |
303 | * freeing the memory reserved for old node (which can be accessed with | |
304 | * cds_lfht_iter_get_node). | |
305 | */ | |
306 | int cds_lfht_del(struct cds_lfht *ht, struct cds_lfht_iter *iter); | |
307 | ||
308 | /* | |
309 | * cds_lfht_resize - Force a hash table resize | |
310 | * @new_size: update to this hash table size. | |
311 | */ | |
312 | void cds_lfht_resize(struct cds_lfht *ht, unsigned long new_size); | |
313 | ||
314 | #ifdef __cplusplus | |
315 | } | |
316 | #endif | |
317 | ||
318 | #endif /* _URCU_RCULFHASH_H */ |