69608794a7628c8f409199c63153d8bf0052edf7
[urcu.git] / include / 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 <pthread.h>
31 #include <urcu/compiler.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, 0 is accepted, means
137 * "infinite")
138 * @flags: hash table creation flags (can be combined with bitwise or: '|').
139 * 0: no flags.
140 * CDS_LFHT_AUTO_RESIZE: automatically resize hash table.
141 * CDS_LFHT_ACCOUNTING: count the number of node addition
142 * and removal in the table
143 * @attr: optional resize worker thread attributes. NULL for default.
144 *
145 * Return NULL on error.
146 * Note: the RCU flavor must be already included before the hash table header.
147 *
148 * The programmer is responsible for ensuring that resize operation has a
149 * priority equal to hash table updater threads. It should be performed by
150 * specifying the appropriate priority in the pthread "attr" argument, and,
151 * for CDS_LFHT_AUTO_RESIZE, by ensuring that call_rcu worker threads also have
152 * this priority level. Having lower priority for call_rcu and resize threads
153 * does not pose any correctness issue, but the resize operations could be
154 * starved by updates, thus leading to long hash table bucket chains.
155 * Threads calling cds_lfht_new are NOT required to be registered RCU
156 * read-side threads. It can be called very early. (e.g. before RCU is
157 * initialized)
158 */
159 static inline
160 struct cds_lfht *cds_lfht_new(unsigned long init_size,
161 unsigned long min_nr_alloc_buckets,
162 unsigned long max_nr_buckets,
163 int flags,
164 pthread_attr_t *attr)
165 {
166 return _cds_lfht_new(init_size, min_nr_alloc_buckets, max_nr_buckets,
167 flags, NULL, &rcu_flavor, attr);
168 }
169
170 /*
171 * cds_lfht_destroy - destroy a hash table.
172 * @ht: the hash table to destroy.
173 * @attr: (output) resize worker thread attributes, as received by cds_lfht_new.
174 * The caller will typically want to free this pointer if dynamically
175 * allocated. The attr point can be NULL if the caller does not
176 * need to be informed of the value passed to cds_lfht_new().
177 *
178 * Return 0 on success, negative error value on error.
179
180 * Prior to liburcu 0.10:
181 * - Threads calling this API need to be registered RCU read-side
182 * threads.
183 * - cds_lfht_destroy should *not* be called from a RCU read-side
184 * critical section. It should *not* be called from a call_rcu thread
185 * context neither.
186 *
187 * Starting from liburcu 0.10, rculfhash implements its own worker
188 * thread to handle resize operations, which removes RCU requirements on
189 * cds_lfht_destroy.
190 */
191 extern
192 int cds_lfht_destroy(struct cds_lfht *ht, pthread_attr_t **attr);
193
194 /*
195 * cds_lfht_count_nodes - count the number of nodes in the hash table.
196 * @ht: the hash table.
197 * @split_count_before: sample the node count split-counter before traversal.
198 * @count: traverse the hash table, count the number of nodes observed.
199 * @split_count_after: sample the node count split-counter after traversal.
200 *
201 * Call with rcu_read_lock held.
202 * Threads calling this API need to be registered RCU read-side threads.
203 */
204 extern
205 void cds_lfht_count_nodes(struct cds_lfht *ht,
206 long *split_count_before,
207 unsigned long *count,
208 long *split_count_after);
209
210 /*
211 * cds_lfht_lookup - lookup a node by key.
212 * @ht: the hash table.
213 * @hash: the key hash.
214 * @match: the key match function.
215 * @key: the current node key.
216 * @iter: node, if found (output). *iter->node set to NULL if not found.
217 *
218 * Call with rcu_read_lock held.
219 * Threads calling this API need to be registered RCU read-side threads.
220 * This function acts as a rcu_dereference() to read the node pointer.
221 */
222 extern
223 void cds_lfht_lookup(struct cds_lfht *ht, unsigned long hash,
224 cds_lfht_match_fct match, const void *key,
225 struct cds_lfht_iter *iter);
226
227 /*
228 * cds_lfht_next_duplicate - get the next item with same key, after iterator.
229 * @ht: the hash table.
230 * @match: the key match function.
231 * @key: the current node key.
232 * @iter: input: current iterator.
233 * output: node, if found. *iter->node set to NULL if not found.
234 *
235 * Uses an iterator initialized by a lookup or traversal. Important: the
236 * iterator _needs_ to be initialized before calling
237 * cds_lfht_next_duplicate.
238 * Sets *iter-node to the following node with same key.
239 * Sets *iter->node to NULL if no following node exists with same key.
240 * RCU read-side lock must be held across cds_lfht_lookup and
241 * cds_lfht_next calls, and also between cds_lfht_next calls using the
242 * node returned by a previous cds_lfht_next.
243 * Call with rcu_read_lock held.
244 * Threads calling this API need to be registered RCU read-side threads.
245 * This function acts as a rcu_dereference() to read the node pointer.
246 */
247 extern
248 void cds_lfht_next_duplicate(struct cds_lfht *ht,
249 cds_lfht_match_fct match, const void *key,
250 struct cds_lfht_iter *iter);
251
252 /*
253 * cds_lfht_first - get the first node in the table.
254 * @ht: the hash table.
255 * @iter: First node, if exists (output). *iter->node set to NULL if not found.
256 *
257 * Output in "*iter". *iter->node set to NULL if table is empty.
258 * Call with rcu_read_lock held.
259 * Threads calling this API need to be registered RCU read-side threads.
260 * This function acts as a rcu_dereference() to read the node pointer.
261 */
262 extern
263 void cds_lfht_first(struct cds_lfht *ht, struct cds_lfht_iter *iter);
264
265 /*
266 * cds_lfht_next - get the next node in the table.
267 * @ht: the hash table.
268 * @iter: input: current iterator.
269 * output: next node, if exists. *iter->node set to NULL if not found.
270 *
271 * Input/Output in "*iter". *iter->node set to NULL if *iter was
272 * pointing to the last table node.
273 * Call with rcu_read_lock held.
274 * Threads calling this API need to be registered RCU read-side threads.
275 * This function acts as a rcu_dereference() to read the node pointer.
276 */
277 extern
278 void cds_lfht_next(struct cds_lfht *ht, struct cds_lfht_iter *iter);
279
280 /*
281 * cds_lfht_add - add a node to the hash table.
282 * @ht: the hash table.
283 * @hash: the key hash.
284 * @node: the node to add.
285 *
286 * This function supports adding redundant keys into the table.
287 * Call with rcu_read_lock held.
288 * Threads calling this API need to be registered RCU read-side threads.
289 * This function issues a full memory barrier before and after its
290 * atomic commit.
291 */
292 extern
293 void cds_lfht_add(struct cds_lfht *ht, unsigned long hash,
294 struct cds_lfht_node *node);
295
296 /*
297 * cds_lfht_add_unique - add a node to hash table, if key is not present.
298 * @ht: the hash table.
299 * @hash: the node's hash.
300 * @match: the key match function.
301 * @key: the node's key.
302 * @node: the node to try adding.
303 *
304 * Return the node added upon success.
305 * Return the unique node already present upon failure. If
306 * cds_lfht_add_unique fails, the node passed as parameter should be
307 * freed by the caller. In this case, the caller does NOT need to wait
308 * for a grace period before freeing or re-using the node.
309 * Call with rcu_read_lock held.
310 * Threads calling this API need to be registered RCU read-side threads.
311 *
312 * The semantic of this function is that if only this function is used
313 * to add keys into the table, no duplicated keys should ever be
314 * observable in the table. The same guarantee apply for combination of
315 * add_unique and add_replace (see below).
316 *
317 * Upon success, this function issues a full memory barrier before and
318 * after its atomic commit. Upon failure, this function acts like a
319 * simple lookup operation: it acts as a rcu_dereference() to read the
320 * node pointer. The failure case does not guarantee any other memory
321 * barrier.
322 */
323 extern
324 struct cds_lfht_node *cds_lfht_add_unique(struct cds_lfht *ht,
325 unsigned long hash,
326 cds_lfht_match_fct match,
327 const void *key,
328 struct cds_lfht_node *node);
329
330 /*
331 * cds_lfht_add_replace - replace or add a node within hash table.
332 * @ht: the hash table.
333 * @hash: the node's hash.
334 * @match: the key match function.
335 * @key: the node's key.
336 * @node: the node to add.
337 *
338 * Return the node replaced upon success. If no node matching the key
339 * was present, return NULL, which also means the operation succeeded.
340 * This replacement operation should never fail.
341 * Call with rcu_read_lock held.
342 * Threads calling this API need to be registered RCU read-side threads.
343 * After successful replacement, a grace period must be waited for before
344 * freeing or re-using the memory reserved for the returned node.
345 *
346 * The semantic of replacement vs lookups and traversals is the
347 * following: if lookups and traversals are performed between a key
348 * unique insertion and its removal, we guarantee that the lookups and
349 * traversals will always find exactly one instance of the key if it is
350 * replaced concurrently with the lookups.
351 *
352 * Providing this semantic allows us to ensure that replacement-only
353 * schemes will never generate duplicated keys. It also allows us to
354 * guarantee that a combination of add_replace and add_unique updates
355 * will never generate duplicated keys.
356 *
357 * This function issues a full memory barrier before and after its
358 * atomic commit.
359 */
360 extern
361 struct cds_lfht_node *cds_lfht_add_replace(struct cds_lfht *ht,
362 unsigned long hash,
363 cds_lfht_match_fct match,
364 const void *key,
365 struct cds_lfht_node *node);
366
367 /*
368 * cds_lfht_replace - replace a node pointed to by iter within hash table.
369 * @ht: the hash table.
370 * @old_iter: the iterator position of the node to replace.
371 * @hash: the node's hash.
372 * @match: the key match function.
373 * @key: the node's key.
374 * @new_node: the new node to use as replacement.
375 *
376 * Return 0 if replacement is successful, negative value otherwise.
377 * Replacing a NULL old node or an already removed node will fail with
378 * -ENOENT.
379 * If the hash or value of the node to replace and the new node differ,
380 * this function returns -EINVAL without proceeding to the replacement.
381 * Old node can be looked up with cds_lfht_lookup and cds_lfht_next.
382 * RCU read-side lock must be held between lookup and replacement.
383 * Call with rcu_read_lock held.
384 * Threads calling this API need to be registered RCU read-side threads.
385 * After successful replacement, a grace period must be waited for before
386 * freeing or re-using the memory reserved for the old node (which can
387 * be accessed with cds_lfht_iter_get_node).
388 *
389 * The semantic of replacement vs lookups is the same as
390 * cds_lfht_add_replace().
391 *
392 * Upon success, this function issues a full memory barrier before and
393 * after its atomic commit. Upon failure, this function does not issue
394 * any memory barrier.
395 */
396 extern
397 int cds_lfht_replace(struct cds_lfht *ht,
398 struct cds_lfht_iter *old_iter,
399 unsigned long hash,
400 cds_lfht_match_fct match,
401 const void *key,
402 struct cds_lfht_node *new_node);
403
404 /*
405 * cds_lfht_del - remove node pointed to by iterator from hash table.
406 * @ht: the hash table.
407 * @node: the node to delete.
408 *
409 * Return 0 if the node is successfully removed, negative value
410 * otherwise.
411 * Deleting a NULL node or an already removed node will fail with a
412 * negative value.
413 * Node can be looked up with cds_lfht_lookup and cds_lfht_next,
414 * followed by use of cds_lfht_iter_get_node.
415 * RCU read-side lock must be held between lookup and removal.
416 * Call with rcu_read_lock held.
417 * Threads calling this API need to be registered RCU read-side threads.
418 * After successful removal, a grace period must be waited for before
419 * freeing or re-using the memory reserved for old node (which can be
420 * accessed with cds_lfht_iter_get_node).
421 * Upon success, this function issues a full memory barrier before and
422 * after its atomic commit. Upon failure, this function does not issue
423 * any memory barrier.
424 */
425 extern
426 int cds_lfht_del(struct cds_lfht *ht, struct cds_lfht_node *node);
427
428 /*
429 * cds_lfht_is_node_deleted - query whether a node is removed from hash table.
430 *
431 * Return non-zero if the node is deleted from the hash table, 0
432 * otherwise.
433 * Node can be looked up with cds_lfht_lookup and cds_lfht_next,
434 * followed by use of cds_lfht_iter_get_node.
435 * RCU read-side lock must be held between lookup and call to this
436 * function.
437 * Call with rcu_read_lock held.
438 * Threads calling this API need to be registered RCU read-side threads.
439 * This function does not issue any memory barrier.
440 */
441 extern
442 int cds_lfht_is_node_deleted(struct cds_lfht_node *node);
443
444 /*
445 * cds_lfht_resize - Force a hash table resize
446 * @ht: the hash table.
447 * @new_size: update to this hash table size.
448 *
449 * Threads calling this API need to be registered RCU read-side threads.
450 * This function does not (necessarily) issue memory barriers.
451 * cds_lfht_resize should *not* be called from a RCU read-side critical
452 * section.
453 */
454 extern
455 void cds_lfht_resize(struct cds_lfht *ht, unsigned long new_size);
456
457 /*
458 * Note: it is safe to perform element removal (del), replacement, or
459 * any hash table update operation during any of the following hash
460 * table traversals.
461 * These functions act as rcu_dereference() to read the node pointers.
462 */
463 #define cds_lfht_for_each(ht, iter, node) \
464 for (cds_lfht_first(ht, iter), \
465 node = cds_lfht_iter_get_node(iter); \
466 node != NULL; \
467 cds_lfht_next(ht, iter), \
468 node = cds_lfht_iter_get_node(iter))
469
470 #define cds_lfht_for_each_duplicate(ht, hash, match, key, iter, node) \
471 for (cds_lfht_lookup(ht, hash, match, key, iter), \
472 node = cds_lfht_iter_get_node(iter); \
473 node != NULL; \
474 cds_lfht_next_duplicate(ht, match, key, iter), \
475 node = cds_lfht_iter_get_node(iter))
476
477 #define cds_lfht_for_each_entry(ht, iter, pos, member) \
478 for (cds_lfht_first(ht, iter), \
479 pos = caa_container_of(cds_lfht_iter_get_node(iter), \
480 __typeof__(*(pos)), member); \
481 cds_lfht_iter_get_node(iter) != NULL; \
482 cds_lfht_next(ht, iter), \
483 pos = caa_container_of(cds_lfht_iter_get_node(iter), \
484 __typeof__(*(pos)), member))
485
486 #define cds_lfht_for_each_entry_duplicate(ht, hash, match, key, \
487 iter, pos, member) \
488 for (cds_lfht_lookup(ht, hash, match, key, iter), \
489 pos = caa_container_of(cds_lfht_iter_get_node(iter), \
490 __typeof__(*(pos)), member); \
491 cds_lfht_iter_get_node(iter) != NULL; \
492 cds_lfht_next_duplicate(ht, match, key, iter), \
493 pos = caa_container_of(cds_lfht_iter_get_node(iter), \
494 __typeof__(*(pos)), member))
495
496 #ifdef __cplusplus
497 }
498 #endif
499
500 #endif /* _URCU_RCULFHASH_H */
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