afd0c3eafb34aff325843ea476b4714d90e86fe5
[urcu.git] / urcu / rculfhash.h
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 * Copyright 2011 - Lai Jiangshan <laijs@cn.fujitsu.com>
11 *
12 * This library is free software; you can redistribute it and/or
13 * modify it under the terms of the GNU Lesser General Public
14 * License as published by the Free Software Foundation; either
15 * version 2.1 of the License, or (at your option) any later version.
16 *
17 * This library is distributed in the hope that it will be useful,
18 * but WITHOUT ANY WARRANTY; without even the implied warranty of
19 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
20 * Lesser General Public License for more details.
21 *
22 * You should have received a copy of the GNU Lesser General Public
23 * License along with this library; if not, write to the Free Software
24 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
25 *
26 * Include this file _after_ including your URCU flavor.
27 */
28
29 #include <stdint.h>
30 #include <urcu/compiler.h>
31 #include <urcu-call-rcu.h>
32 #include <urcu-flavor.h>
33
34 #ifdef __cplusplus
35 extern "C" {
36 #endif
37
38 /*
39 * cds_lfht_node: Contains the next pointers and reverse-hash
40 * value required for lookup and traversal of the hash table.
41 *
42 * struct cds_lfht_node should be aligned on 8-bytes boundaries because
43 * the three lower bits are used as flags. It is worth noting that the
44 * information contained within these three bits could be represented on
45 * two bits by re-using the same bit for REMOVAL_OWNER_FLAG and
46 * BUCKET_FLAG. This can be done if we ensure that no iterator nor
47 * updater check the BUCKET_FLAG after it detects that the REMOVED_FLAG
48 * is set. Given the minimum size of struct cds_lfht_node is 8 bytes on
49 * 32-bit architectures, we choose to go for simplicity and reserve
50 * three bits.
51 *
52 * struct cds_lfht_node can be embedded into a structure (as a field).
53 * caa_container_of() can be used to get the structure from the struct
54 * cds_lfht_node after a lookup.
55 *
56 * The structure which embeds it typically holds the key (or key-value
57 * pair) of the object. The caller code is responsible for calculation
58 * of the hash value for cds_lfht APIs.
59 */
60 struct cds_lfht_node {
61 struct cds_lfht_node *next; /* ptr | REMOVAL_OWNER_FLAG | BUCKET_FLAG | REMOVED_FLAG */
62 unsigned long reverse_hash;
63 } __attribute__((aligned(8)));
64
65 /* cds_lfht_iter: Used to track state while traversing a hash chain. */
66 struct cds_lfht_iter {
67 struct cds_lfht_node *node, *next;
68 };
69
70 static inline
71 struct cds_lfht_node *cds_lfht_iter_get_node(struct cds_lfht_iter *iter)
72 {
73 return iter->node;
74 }
75
76 struct cds_lfht;
77
78 /*
79 * Caution !
80 * Ensure reader and writer threads are registered as urcu readers.
81 */
82
83 typedef int (*cds_lfht_match_fct)(struct cds_lfht_node *node, const void *key);
84
85 /*
86 * cds_lfht_node_init - initialize a hash table node
87 * @node: the node to initialize.
88 *
89 * This function is kept to be eventually used for debugging purposes
90 * (detection of memory corruption).
91 */
92 static inline
93 void cds_lfht_node_init(struct cds_lfht_node *node)
94 {
95 }
96
97 /*
98 * Hash table creation flags.
99 */
100 enum {
101 CDS_LFHT_AUTO_RESIZE = (1U << 0),
102 CDS_LFHT_ACCOUNTING = (1U << 1),
103 };
104
105 struct cds_lfht_mm_type {
106 struct cds_lfht *(*alloc_cds_lfht)(unsigned long min_nr_alloc_buckets,
107 unsigned long max_nr_buckets);
108 void (*alloc_bucket_table)(struct cds_lfht *ht, unsigned long order);
109 void (*free_bucket_table)(struct cds_lfht *ht, unsigned long order);
110 struct cds_lfht_node *(*bucket_at)(struct cds_lfht *ht,
111 unsigned long index);
112 };
113
114 extern const struct cds_lfht_mm_type cds_lfht_mm_order;
115 extern const struct cds_lfht_mm_type cds_lfht_mm_chunk;
116 extern const struct cds_lfht_mm_type cds_lfht_mm_mmap;
117
118 /*
119 * _cds_lfht_new - API used by cds_lfht_new wrapper. Do not use directly.
120 */
121 extern
122 struct cds_lfht *_cds_lfht_new(unsigned long init_size,
123 unsigned long min_nr_alloc_buckets,
124 unsigned long max_nr_buckets,
125 int flags,
126 const struct cds_lfht_mm_type *mm,
127 const struct rcu_flavor_struct *flavor,
128 pthread_attr_t *attr);
129
130 /*
131 * cds_lfht_new - allocate a hash table.
132 * @init_size: number of buckets to allocate initially. Must be power of two.
133 * @min_nr_alloc_buckets: the minimum number of allocated buckets.
134 * (must be power of two)
135 * @max_nr_buckets: the maximum number of hash table buckets allowed.
136 * (must be power of two)
137 * @flags: hash table creation flags (can be combined with bitwise or: '|').
138 * 0: no flags.
139 * CDS_LFHT_AUTO_RESIZE: automatically resize hash table.
140 * CDS_LFHT_ACCOUNTING: count the number of node addition
141 * and removal in the table
142 * @attr: optional resize worker thread attributes. NULL for default.
143 *
144 * Return NULL on error.
145 * Note: the RCU flavor must be already included before the hash table header.
146 *
147 * The programmer is responsible for ensuring that resize operation has a
148 * priority equal to hash table updater threads. It should be performed by
149 * specifying the appropriate priority in the pthread "attr" argument, and,
150 * for CDS_LFHT_AUTO_RESIZE, by ensuring that call_rcu worker threads also have
151 * this priority level. Having lower priority for call_rcu and resize threads
152 * does not pose any correctness issue, but the resize operations could be
153 * starved by updates, thus leading to long hash table bucket chains.
154 * Threads calling cds_lfht_new are NOT required to be registered RCU
155 * read-side threads. It can be called very early. (e.g. before RCU is
156 * initialized)
157 */
158 static inline
159 struct cds_lfht *cds_lfht_new(unsigned long init_size,
160 unsigned long min_nr_alloc_buckets,
161 unsigned long max_nr_buckets,
162 int flags,
163 pthread_attr_t *attr)
164 {
165 return _cds_lfht_new(init_size, min_nr_alloc_buckets, max_nr_buckets,
166 flags, NULL, &rcu_flavor, attr);
167 }
168
169 /*
170 * cds_lfht_destroy - destroy a hash table.
171 * @ht: the hash table to destroy.
172 * @attr: (output) resize worker thread attributes, as received by cds_lfht_new.
173 * The caller will typically want to free this pointer if dynamically
174 * allocated. The attr point can be NULL if the caller does not
175 * need to be informed of the value passed to cds_lfht_new().
176 *
177 * Return 0 on success, negative error value on error.
178 * Threads calling this API need to be registered RCU read-side threads.
179 * cds_lfht_destroy should *not* be called from a RCU read-side critical
180 * section. It should *not* be called from a call_rcu thread context
181 * neither.
182 */
183 extern
184 int cds_lfht_destroy(struct cds_lfht *ht, pthread_attr_t **attr);
185
186 /*
187 * cds_lfht_count_nodes - count the number of nodes in the hash table.
188 * @ht: the hash table.
189 * @split_count_before: sample the node count split-counter before traversal.
190 * @count: traverse the hash table, count the number of nodes observed.
191 * @split_count_after: sample the node count split-counter after traversal.
192 *
193 * Call with rcu_read_lock held.
194 * Threads calling this API need to be registered RCU read-side threads.
195 */
196 extern
197 void cds_lfht_count_nodes(struct cds_lfht *ht,
198 long *split_count_before,
199 unsigned long *count,
200 long *split_count_after);
201
202 /*
203 * cds_lfht_lookup - lookup a node by key.
204 * @ht: the hash table.
205 * @hash: the key hash.
206 * @match: the key match function.
207 * @key: the current node key.
208 * @iter: node, if found (output). *iter->node set to NULL if not found.
209 *
210 * Call with rcu_read_lock held.
211 * Threads calling this API need to be registered RCU read-side threads.
212 * This function acts as a rcu_dereference() to read the node pointer.
213 */
214 extern
215 void cds_lfht_lookup(struct cds_lfht *ht, unsigned long hash,
216 cds_lfht_match_fct match, const void *key,
217 struct cds_lfht_iter *iter);
218
219 /*
220 * cds_lfht_next_duplicate - get the next item with same key, after iterator.
221 * @ht: the hash table.
222 * @match: the key match function.
223 * @key: the current node key.
224 * @iter: input: current iterator.
225 * output: node, if found. *iter->node set to NULL if not found.
226 *
227 * Uses an iterator initialized by a lookup or traversal. Important: the
228 * iterator _needs_ to be initialized before calling
229 * cds_lfht_next_duplicate.
230 * Sets *iter-node to the following node with same key.
231 * Sets *iter->node to NULL if no following node exists with same key.
232 * RCU read-side lock must be held across cds_lfht_lookup and
233 * cds_lfht_next calls, and also between cds_lfht_next calls using the
234 * node returned by a previous cds_lfht_next.
235 * Call with rcu_read_lock held.
236 * Threads calling this API need to be registered RCU read-side threads.
237 * This function acts as a rcu_dereference() to read the node pointer.
238 */
239 extern
240 void cds_lfht_next_duplicate(struct cds_lfht *ht,
241 cds_lfht_match_fct match, const void *key,
242 struct cds_lfht_iter *iter);
243
244 /*
245 * cds_lfht_first - get the first node in the table.
246 * @ht: the hash table.
247 * @iter: First node, if exists (output). *iter->node set to NULL if not found.
248 *
249 * Output in "*iter". *iter->node set to NULL if table is empty.
250 * Call with rcu_read_lock held.
251 * Threads calling this API need to be registered RCU read-side threads.
252 * This function acts as a rcu_dereference() to read the node pointer.
253 */
254 extern
255 void cds_lfht_first(struct cds_lfht *ht, struct cds_lfht_iter *iter);
256
257 /*
258 * cds_lfht_next - get the next node in the table.
259 * @ht: the hash table.
260 * @iter: input: current iterator.
261 * output: next node, if exists. *iter->node set to NULL if not found.
262 *
263 * Input/Output in "*iter". *iter->node set to NULL if *iter was
264 * pointing to the last table node.
265 * Call with rcu_read_lock held.
266 * Threads calling this API need to be registered RCU read-side threads.
267 * This function acts as a rcu_dereference() to read the node pointer.
268 */
269 extern
270 void cds_lfht_next(struct cds_lfht *ht, struct cds_lfht_iter *iter);
271
272 /*
273 * cds_lfht_add - add a node to the hash table.
274 * @ht: the hash table.
275 * @hash: the key hash.
276 * @node: the node to add.
277 *
278 * This function supports adding redundant keys into the table.
279 * Call with rcu_read_lock held.
280 * Threads calling this API need to be registered RCU read-side threads.
281 * This function issues a full memory barrier before and after its
282 * atomic commit.
283 */
284 extern
285 void cds_lfht_add(struct cds_lfht *ht, unsigned long hash,
286 struct cds_lfht_node *node);
287
288 /*
289 * cds_lfht_add_unique - add a node to hash table, if key is not present.
290 * @ht: the hash table.
291 * @hash: the node's hash.
292 * @match: the key match function.
293 * @key: the node's key.
294 * @node: the node to try adding.
295 *
296 * Return the node added upon success.
297 * Return the unique node already present upon failure. If
298 * cds_lfht_add_unique fails, the node passed as parameter should be
299 * freed by the caller. In this case, the caller does NOT need to wait
300 * for a grace period before freeing the node.
301 * Call with rcu_read_lock held.
302 * Threads calling this API need to be registered RCU read-side threads.
303 *
304 * The semantic of this function is that if only this function is used
305 * to add keys into the table, no duplicated keys should ever be
306 * observable in the table. The same guarantee apply for combination of
307 * add_unique and add_replace (see below).
308 *
309 * Upon success, this function issues a full memory barrier before and
310 * after its atomic commit. Upon failure, this function acts like a
311 * simple lookup operation: it acts as a rcu_dereference() to read the
312 * node pointer. The failure case does not guarantee any other memory
313 * barrier.
314 */
315 extern
316 struct cds_lfht_node *cds_lfht_add_unique(struct cds_lfht *ht,
317 unsigned long hash,
318 cds_lfht_match_fct match,
319 const void *key,
320 struct cds_lfht_node *node);
321
322 /*
323 * cds_lfht_add_replace - replace or add a node within hash table.
324 * @ht: the hash table.
325 * @hash: the node's hash.
326 * @match: the key match function.
327 * @key: the node's key.
328 * @node: the node to add.
329 *
330 * Return the node replaced upon success. If no node matching the key
331 * was present, return NULL, which also means the operation succeeded.
332 * This replacement operation should never fail.
333 * Call with rcu_read_lock held.
334 * Threads calling this API need to be registered RCU read-side threads.
335 * After successful replacement, a grace period must be waited for before
336 * freeing the memory reserved for the returned node.
337 *
338 * The semantic of replacement vs lookups and traversals is the
339 * following: if lookups and traversals are performed between a key
340 * unique insertion and its removal, we guarantee that the lookups and
341 * traversals will always find exactly one instance of the key if it is
342 * replaced concurrently with the lookups.
343 *
344 * Providing this semantic allows us to ensure that replacement-only
345 * schemes will never generate duplicated keys. It also allows us to
346 * guarantee that a combination of add_replace and add_unique updates
347 * will never generate duplicated keys.
348 *
349 * This function issues a full memory barrier before and after its
350 * atomic commit.
351 */
352 extern
353 struct cds_lfht_node *cds_lfht_add_replace(struct cds_lfht *ht,
354 unsigned long hash,
355 cds_lfht_match_fct match,
356 const void *key,
357 struct cds_lfht_node *node);
358
359 /*
360 * cds_lfht_replace - replace a node pointed to by iter within hash table.
361 * @ht: the hash table.
362 * @old_iter: the iterator position of the node to replace.
363 * @hash: the node's hash.
364 * @match: the key match function.
365 * @key: the node's key.
366 * @new_node: the new node to use as replacement.
367 *
368 * Return 0 if replacement is successful, negative value otherwise.
369 * Replacing a NULL old node or an already removed node will fail with
370 * -ENOENT.
371 * If the hash or value of the node to replace and the new node differ,
372 * this function returns -EINVAL without proceeding to the replacement.
373 * Old node can be looked up with cds_lfht_lookup and cds_lfht_next.
374 * RCU read-side lock must be held between lookup and replacement.
375 * Call with rcu_read_lock held.
376 * Threads calling this API need to be registered RCU read-side threads.
377 * After successful replacement, a grace period must be waited for before
378 * freeing the memory reserved for the old node (which can be accessed
379 * with cds_lfht_iter_get_node).
380 *
381 * The semantic of replacement vs lookups is the same as
382 * cds_lfht_add_replace().
383 *
384 * Upon success, this function issues a full memory barrier before and
385 * after its atomic commit. Upon failure, this function does not issue
386 * any memory barrier.
387 */
388 extern
389 int cds_lfht_replace(struct cds_lfht *ht,
390 struct cds_lfht_iter *old_iter,
391 unsigned long hash,
392 cds_lfht_match_fct match,
393 const void *key,
394 struct cds_lfht_node *new_node);
395
396 /*
397 * cds_lfht_del - remove node pointed to by iterator from hash table.
398 * @ht: the hash table.
399 * @node: the node to delete.
400 *
401 * Return 0 if the node is successfully removed, negative value
402 * otherwise.
403 * Deleting a NULL node or an already removed node will fail with a
404 * negative value.
405 * Node can be looked up with cds_lfht_lookup and cds_lfht_next,
406 * followed by use of cds_lfht_iter_get_node.
407 * RCU read-side lock must be held between lookup and removal.
408 * Call with rcu_read_lock held.
409 * Threads calling this API need to be registered RCU read-side threads.
410 * After successful removal, a grace period must be waited for before
411 * freeing the memory reserved for old node (which can be accessed with
412 * cds_lfht_iter_get_node).
413 * Upon success, this function issues a full memory barrier before and
414 * after its atomic commit. Upon failure, this function does not issue
415 * any memory barrier.
416 */
417 extern
418 int cds_lfht_del(struct cds_lfht *ht, struct cds_lfht_node *node);
419
420 /*
421 * cds_lfht_is_node_deleted - query whether a node is removed from hash table.
422 *
423 * Return non-zero if the node is deleted from the hash table, 0
424 * otherwise.
425 * Node can be looked up with cds_lfht_lookup and cds_lfht_next,
426 * followed by use of cds_lfht_iter_get_node.
427 * RCU read-side lock must be held between lookup and call to this
428 * function.
429 * Call with rcu_read_lock held.
430 * Threads calling this API need to be registered RCU read-side threads.
431 * This function does not issue any memory barrier.
432 */
433 extern
434 int cds_lfht_is_node_deleted(struct cds_lfht_node *node);
435
436 /*
437 * cds_lfht_resize - Force a hash table resize
438 * @ht: the hash table.
439 * @new_size: update to this hash table size.
440 *
441 * Threads calling this API need to be registered RCU read-side threads.
442 * This function does not (necessarily) issue memory barriers.
443 * cds_lfht_resize should *not* be called from a RCU read-side critical
444 * section.
445 */
446 extern
447 void cds_lfht_resize(struct cds_lfht *ht, unsigned long new_size);
448
449 /*
450 * Note: it is safe to perform element removal (del), replacement, or
451 * any hash table update operation during any of the following hash
452 * table traversals.
453 * These functions act as rcu_dereference() to read the node pointers.
454 */
455 #define cds_lfht_for_each(ht, iter, node) \
456 for (cds_lfht_first(ht, iter), \
457 node = cds_lfht_iter_get_node(iter); \
458 node != NULL; \
459 cds_lfht_next(ht, iter), \
460 node = cds_lfht_iter_get_node(iter))
461
462 #define cds_lfht_for_each_duplicate(ht, hash, match, key, iter, node) \
463 for (cds_lfht_lookup(ht, hash, match, key, iter), \
464 node = cds_lfht_iter_get_node(iter); \
465 node != NULL; \
466 cds_lfht_next_duplicate(ht, match, key, iter), \
467 node = cds_lfht_iter_get_node(iter))
468
469 #define cds_lfht_for_each_entry(ht, iter, pos, member) \
470 for (cds_lfht_first(ht, iter), \
471 pos = caa_container_of(cds_lfht_iter_get_node(iter), \
472 __typeof__(*(pos)), member); \
473 &(pos)->member != NULL; \
474 cds_lfht_next(ht, iter), \
475 pos = caa_container_of(cds_lfht_iter_get_node(iter), \
476 __typeof__(*(pos)), member))
477
478 #define cds_lfht_for_each_entry_duplicate(ht, hash, match, key, \
479 iter, pos, member) \
480 for (cds_lfht_lookup(ht, hash, match, key, iter), \
481 pos = caa_container_of(cds_lfht_iter_get_node(iter), \
482 __typeof__(*(pos)), member); \
483 &(pos)->member != NULL; \
484 cds_lfht_next_duplicate(ht, match, key, iter), \
485 pos = caa_container_of(cds_lfht_iter_get_node(iter), \
486 __typeof__(*(pos)), member))
487
488 #ifdef __cplusplus
489 }
490 #endif
491
492 #endif /* _URCU_RCULFHASH_H */
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