Fix: provide errno as argument to urcu_die()
[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 * For use with URCU_API_MAP (API mapping of liburcu), include this file
27 * _after_ including your URCU flavor.
28 */
29
30 #include <urcu/config.h>
31 #include <stdint.h>
32 #include <pthread.h>
33 #include <urcu/compiler.h>
34
35 #ifdef __cplusplus
36 extern "C" {
37 #endif
38
39 struct cds_lfht;
40
41 /*
42 * cds_lfht_node: Contains the next pointers and reverse-hash
43 * value required for lookup and traversal of the hash table.
44 *
45 * struct cds_lfht_node should be aligned on 8-bytes boundaries because
46 * the three lower bits are used as flags. It is worth noting that the
47 * information contained within these three bits could be represented on
48 * two bits by re-using the same bit for REMOVAL_OWNER_FLAG and
49 * BUCKET_FLAG. This can be done if we ensure that no iterator nor
50 * updater check the BUCKET_FLAG after it detects that the REMOVED_FLAG
51 * is set. Given the minimum size of struct cds_lfht_node is 8 bytes on
52 * 32-bit architectures, we choose to go for simplicity and reserve
53 * three bits.
54 *
55 * struct cds_lfht_node can be embedded into a structure (as a field).
56 * caa_container_of() can be used to get the structure from the struct
57 * cds_lfht_node after a lookup.
58 *
59 * The structure which embeds it typically holds the key (or key-value
60 * pair) of the object. The caller code is responsible for calculation
61 * of the hash value for cds_lfht APIs.
62 */
63 struct cds_lfht_node {
64 struct cds_lfht_node *next; /* ptr | REMOVAL_OWNER_FLAG | BUCKET_FLAG | REMOVED_FLAG */
65 unsigned long reverse_hash;
66 } __attribute__((aligned(8)));
67
68 /* cds_lfht_iter: Used to track state while traversing a hash chain. */
69 struct cds_lfht_iter {
70 struct cds_lfht_node *node, *next;
71 /*
72 * For debugging purposes, build both API users and rculfhash
73 * library with CDS_LFHT_ITER_DEBUG defined. This enables extra
74 * consistency checks for calls to a cds_lfht_next() or
75 * cds_lfht_next_duplicate() after the iterator has been
76 * re-purposed to iterate on a different hash table. This is a
77 * common programming mistake when performing hash table lookup
78 * nested in a hash table traversal.
79 */
80 #ifdef CONFIG_CDS_LFHT_ITER_DEBUG
81 struct cds_lfht *lfht;
82 #endif
83 };
84
85 static inline
86 struct cds_lfht_node *cds_lfht_iter_get_node(struct cds_lfht_iter *iter)
87 {
88 return iter->node;
89 }
90
91 struct rcu_flavor_struct;
92
93 /*
94 * Caution !
95 * Ensure reader and writer threads are registered as urcu readers.
96 */
97
98 typedef int (*cds_lfht_match_fct)(struct cds_lfht_node *node, const void *key);
99
100 /*
101 * cds_lfht_node_init - initialize a hash table node
102 * @node: the node to initialize.
103 *
104 * This function is kept to be eventually used for debugging purposes
105 * (detection of memory corruption).
106 */
107 static inline
108 void cds_lfht_node_init(struct cds_lfht_node *node)
109 {
110 }
111
112 /*
113 * Hash table creation flags.
114 */
115 enum {
116 CDS_LFHT_AUTO_RESIZE = (1U << 0),
117 CDS_LFHT_ACCOUNTING = (1U << 1),
118 };
119
120 struct cds_lfht_mm_type {
121 struct cds_lfht *(*alloc_cds_lfht)(unsigned long min_nr_alloc_buckets,
122 unsigned long max_nr_buckets);
123 void (*alloc_bucket_table)(struct cds_lfht *ht, unsigned long order);
124 void (*free_bucket_table)(struct cds_lfht *ht, unsigned long order);
125 struct cds_lfht_node *(*bucket_at)(struct cds_lfht *ht,
126 unsigned long index);
127 };
128
129 extern const struct cds_lfht_mm_type cds_lfht_mm_order;
130 extern const struct cds_lfht_mm_type cds_lfht_mm_chunk;
131 extern const struct cds_lfht_mm_type cds_lfht_mm_mmap;
132
133 /*
134 * _cds_lfht_new - API used by cds_lfht_new wrapper. Do not use directly.
135 */
136 extern
137 struct cds_lfht *_cds_lfht_new(unsigned long init_size,
138 unsigned long min_nr_alloc_buckets,
139 unsigned long max_nr_buckets,
140 int flags,
141 const struct cds_lfht_mm_type *mm,
142 const struct rcu_flavor_struct *flavor,
143 pthread_attr_t *attr);
144
145 /*
146 * cds_lfht_new_flavor - allocate a hash table tied to a RCU flavor.
147 * @init_size: number of buckets to allocate initially. Must be power of two.
148 * @min_nr_alloc_buckets: the minimum number of allocated buckets.
149 * (must be power of two)
150 * @max_nr_buckets: the maximum number of hash table buckets allowed.
151 * (must be power of two, 0 is accepted, means
152 * "infinite")
153 * @flavor: flavor of liburcu to use to synchronize the hash table
154 * @flags: hash table creation flags (can be combined with bitwise or: '|').
155 * 0: no flags.
156 * CDS_LFHT_AUTO_RESIZE: automatically resize hash table.
157 * CDS_LFHT_ACCOUNTING: count the number of node addition
158 * and removal in the table
159 * @attr: optional resize worker thread attributes. NULL for default.
160 *
161 * Return NULL on error.
162 * Note: the RCU flavor must be already included before the hash table header.
163 *
164 * The programmer is responsible for ensuring that resize operation has a
165 * priority equal to hash table updater threads. It should be performed by
166 * specifying the appropriate priority in the pthread "attr" argument, and,
167 * for CDS_LFHT_AUTO_RESIZE, by ensuring that call_rcu worker threads also have
168 * this priority level. Having lower priority for call_rcu and resize threads
169 * does not pose any correctness issue, but the resize operations could be
170 * starved by updates, thus leading to long hash table bucket chains.
171 * Threads calling cds_lfht_new are NOT required to be registered RCU
172 * read-side threads. It can be called very early. (e.g. before RCU is
173 * initialized)
174 */
175 static inline
176 struct cds_lfht *cds_lfht_new_flavor(unsigned long init_size,
177 unsigned long min_nr_alloc_buckets,
178 unsigned long max_nr_buckets,
179 int flags,
180 const struct rcu_flavor_struct *flavor,
181 pthread_attr_t *attr)
182 {
183 return _cds_lfht_new(init_size, min_nr_alloc_buckets, max_nr_buckets,
184 flags, NULL, flavor, attr);
185 }
186
187
188 #ifdef URCU_API_MAP
189 /*
190 * cds_lfht_new - allocate a hash table.
191 * @init_size: number of buckets to allocate initially. Must be power of two.
192 * @min_nr_alloc_buckets: the minimum number of allocated buckets.
193 * (must be power of two)
194 * @max_nr_buckets: the maximum number of hash table buckets allowed.
195 * (must be power of two, 0 is accepted, means
196 * "infinite")
197 * @flags: hash table creation flags (can be combined with bitwise or: '|').
198 * 0: no flags.
199 * CDS_LFHT_AUTO_RESIZE: automatically resize hash table.
200 * CDS_LFHT_ACCOUNTING: count the number of node addition
201 * and removal in the table
202 * @attr: optional resize worker thread attributes. NULL for default.
203 *
204 * Return NULL on error.
205 * Note: the RCU flavor must be already included before the hash table header.
206 *
207 * The programmer is responsible for ensuring that resize operation has a
208 * priority equal to hash table updater threads. It should be performed by
209 * specifying the appropriate priority in the pthread "attr" argument, and,
210 * for CDS_LFHT_AUTO_RESIZE, by ensuring that call_rcu worker threads also have
211 * this priority level. Having lower priority for call_rcu and resize threads
212 * does not pose any correctness issue, but the resize operations could be
213 * starved by updates, thus leading to long hash table bucket chains.
214 * Threads calling cds_lfht_new are NOT required to be registered RCU
215 * read-side threads. It can be called very early. (e.g. before RCU is
216 * initialized)
217 */
218 static inline
219 struct cds_lfht *cds_lfht_new(unsigned long init_size,
220 unsigned long min_nr_alloc_buckets,
221 unsigned long max_nr_buckets,
222 int flags,
223 pthread_attr_t *attr)
224 {
225 return _cds_lfht_new(init_size, min_nr_alloc_buckets, max_nr_buckets,
226 flags, NULL, &rcu_flavor, attr);
227 }
228 #endif /* URCU_API_MAP */
229
230 /*
231 * cds_lfht_destroy - destroy a hash table.
232 * @ht: the hash table to destroy.
233 * @attr: (output) resize worker thread attributes, as received by cds_lfht_new.
234 * The caller will typically want to free this pointer if dynamically
235 * allocated. The attr point can be NULL if the caller does not
236 * need to be informed of the value passed to cds_lfht_new().
237 *
238 * Return 0 on success, negative error value on error.
239
240 * Prior to liburcu 0.10:
241 * - Threads calling this API need to be registered RCU read-side
242 * threads.
243 * - cds_lfht_destroy should *not* be called from a RCU read-side
244 * critical section. It should *not* be called from a call_rcu thread
245 * context neither.
246 *
247 * Starting from liburcu 0.10, rculfhash implements its own worker
248 * thread to handle resize operations, which removes RCU requirements on
249 * cds_lfht_destroy.
250 */
251 extern
252 int cds_lfht_destroy(struct cds_lfht *ht, pthread_attr_t **attr);
253
254 /*
255 * cds_lfht_count_nodes - count the number of nodes in the hash table.
256 * @ht: the hash table.
257 * @split_count_before: sample the node count split-counter before traversal.
258 * @count: traverse the hash table, count the number of nodes observed.
259 * @split_count_after: sample the node count split-counter after traversal.
260 *
261 * Call with rcu_read_lock held.
262 * Threads calling this API need to be registered RCU read-side threads.
263 */
264 extern
265 void cds_lfht_count_nodes(struct cds_lfht *ht,
266 long *split_count_before,
267 unsigned long *count,
268 long *split_count_after);
269
270 /*
271 * cds_lfht_lookup - lookup a node by key.
272 * @ht: the hash table.
273 * @hash: the key hash.
274 * @match: the key match function.
275 * @key: the current node key.
276 * @iter: node, if found (output). *iter->node set to NULL if not found.
277 *
278 * Call with rcu_read_lock held.
279 * Threads calling this API need to be registered RCU read-side threads.
280 * This function acts as a rcu_dereference() to read the node pointer.
281 */
282 extern
283 void cds_lfht_lookup(struct cds_lfht *ht, unsigned long hash,
284 cds_lfht_match_fct match, const void *key,
285 struct cds_lfht_iter *iter);
286
287 /*
288 * cds_lfht_next_duplicate - get the next item with same key, after iterator.
289 * @ht: the hash table.
290 * @match: the key match function.
291 * @key: the current node key.
292 * @iter: input: current iterator.
293 * output: node, if found. *iter->node set to NULL if not found.
294 *
295 * Uses an iterator initialized by a lookup or traversal. Important: the
296 * iterator _needs_ to be initialized before calling
297 * cds_lfht_next_duplicate.
298 * Sets *iter-node to the following node with same key.
299 * Sets *iter->node to NULL if no following node exists with same key.
300 * RCU read-side lock must be held across cds_lfht_lookup and
301 * cds_lfht_next calls, and also between cds_lfht_next calls using the
302 * node returned by a previous cds_lfht_next.
303 * Call with rcu_read_lock held.
304 * Threads calling this API need to be registered RCU read-side threads.
305 * This function acts as a rcu_dereference() to read the node pointer.
306 */
307 extern
308 void cds_lfht_next_duplicate(struct cds_lfht *ht,
309 cds_lfht_match_fct match, const void *key,
310 struct cds_lfht_iter *iter);
311
312 /*
313 * cds_lfht_first - get the first node in the table.
314 * @ht: the hash table.
315 * @iter: First node, if exists (output). *iter->node set to NULL if not found.
316 *
317 * Output in "*iter". *iter->node set to NULL if table is empty.
318 * Call with rcu_read_lock held.
319 * Threads calling this API need to be registered RCU read-side threads.
320 * This function acts as a rcu_dereference() to read the node pointer.
321 */
322 extern
323 void cds_lfht_first(struct cds_lfht *ht, struct cds_lfht_iter *iter);
324
325 /*
326 * cds_lfht_next - get the next node in the table.
327 * @ht: the hash table.
328 * @iter: input: current iterator.
329 * output: next node, if exists. *iter->node set to NULL if not found.
330 *
331 * Input/Output in "*iter". *iter->node set to NULL if *iter was
332 * pointing to the last table node.
333 * Call with rcu_read_lock held.
334 * Threads calling this API need to be registered RCU read-side threads.
335 * This function acts as a rcu_dereference() to read the node pointer.
336 */
337 extern
338 void cds_lfht_next(struct cds_lfht *ht, struct cds_lfht_iter *iter);
339
340 /*
341 * cds_lfht_add - add a node to the hash table.
342 * @ht: the hash table.
343 * @hash: the key hash.
344 * @node: the node to add.
345 *
346 * This function supports adding redundant keys into the table.
347 * Call with rcu_read_lock held.
348 * Threads calling this API need to be registered RCU read-side threads.
349 * This function issues a full memory barrier before and after its
350 * atomic commit.
351 */
352 extern
353 void cds_lfht_add(struct cds_lfht *ht, unsigned long hash,
354 struct cds_lfht_node *node);
355
356 /*
357 * cds_lfht_add_unique - add a node to hash table, if key is not present.
358 * @ht: the hash table.
359 * @hash: the node's hash.
360 * @match: the key match function.
361 * @key: the node's key.
362 * @node: the node to try adding.
363 *
364 * Return the node added upon success.
365 * Return the unique node already present upon failure. If
366 * cds_lfht_add_unique fails, the node passed as parameter should be
367 * freed by the caller. In this case, the caller does NOT need to wait
368 * for a grace period before freeing or re-using the node.
369 * Call with rcu_read_lock held.
370 * Threads calling this API need to be registered RCU read-side threads.
371 *
372 * The semantic of this function is that if only this function is used
373 * to add keys into the table, no duplicated keys should ever be
374 * observable in the table. The same guarantee apply for combination of
375 * add_unique and add_replace (see below).
376 *
377 * Upon success, this function issues a full memory barrier before and
378 * after its atomic commit. Upon failure, this function acts like a
379 * simple lookup operation: it acts as a rcu_dereference() to read the
380 * node pointer. The failure case does not guarantee any other memory
381 * barrier.
382 */
383 extern
384 struct cds_lfht_node *cds_lfht_add_unique(struct cds_lfht *ht,
385 unsigned long hash,
386 cds_lfht_match_fct match,
387 const void *key,
388 struct cds_lfht_node *node);
389
390 /*
391 * cds_lfht_add_replace - replace or add a node within hash table.
392 * @ht: the hash table.
393 * @hash: the node's hash.
394 * @match: the key match function.
395 * @key: the node's key.
396 * @node: the node to add.
397 *
398 * Return the node replaced upon success. If no node matching the key
399 * was present, return NULL, which also means the operation succeeded.
400 * This replacement operation should never fail.
401 * Call with rcu_read_lock held.
402 * Threads calling this API need to be registered RCU read-side threads.
403 * After successful replacement, a grace period must be waited for before
404 * freeing or re-using the memory reserved for the returned node.
405 *
406 * The semantic of replacement vs lookups and traversals is the
407 * following: if lookups and traversals are performed between a key
408 * unique insertion and its removal, we guarantee that the lookups and
409 * traversals will always find exactly one instance of the key if it is
410 * replaced concurrently with the lookups.
411 *
412 * Providing this semantic allows us to ensure that replacement-only
413 * schemes will never generate duplicated keys. It also allows us to
414 * guarantee that a combination of add_replace and add_unique updates
415 * will never generate duplicated keys.
416 *
417 * This function issues a full memory barrier before and after its
418 * atomic commit.
419 */
420 extern
421 struct cds_lfht_node *cds_lfht_add_replace(struct cds_lfht *ht,
422 unsigned long hash,
423 cds_lfht_match_fct match,
424 const void *key,
425 struct cds_lfht_node *node);
426
427 /*
428 * cds_lfht_replace - replace a node pointed to by iter within hash table.
429 * @ht: the hash table.
430 * @old_iter: the iterator position of the node to replace.
431 * @hash: the node's hash.
432 * @match: the key match function.
433 * @key: the node's key.
434 * @new_node: the new node to use as replacement.
435 *
436 * Return 0 if replacement is successful, negative value otherwise.
437 * Replacing a NULL old node or an already removed node will fail with
438 * -ENOENT.
439 * If the hash or value of the node to replace and the new node differ,
440 * this function returns -EINVAL without proceeding to the replacement.
441 * Old node can be looked up with cds_lfht_lookup and cds_lfht_next.
442 * RCU read-side lock must be held between lookup and replacement.
443 * Call with rcu_read_lock held.
444 * Threads calling this API need to be registered RCU read-side threads.
445 * After successful replacement, a grace period must be waited for before
446 * freeing or re-using the memory reserved for the old node (which can
447 * be accessed with cds_lfht_iter_get_node).
448 *
449 * The semantic of replacement vs lookups is the same as
450 * cds_lfht_add_replace().
451 *
452 * Upon success, this function issues a full memory barrier before and
453 * after its atomic commit. Upon failure, this function does not issue
454 * any memory barrier.
455 */
456 extern
457 int cds_lfht_replace(struct cds_lfht *ht,
458 struct cds_lfht_iter *old_iter,
459 unsigned long hash,
460 cds_lfht_match_fct match,
461 const void *key,
462 struct cds_lfht_node *new_node);
463
464 /*
465 * cds_lfht_del - remove node pointed to by iterator from hash table.
466 * @ht: the hash table.
467 * @node: the node to delete.
468 *
469 * Return 0 if the node is successfully removed, negative value
470 * otherwise.
471 * Deleting a NULL node or an already removed node will fail with a
472 * negative value.
473 * Node can be looked up with cds_lfht_lookup and cds_lfht_next,
474 * followed by use of cds_lfht_iter_get_node.
475 * RCU read-side lock must be held between lookup and removal.
476 * Call with rcu_read_lock held.
477 * Threads calling this API need to be registered RCU read-side threads.
478 * After successful removal, a grace period must be waited for before
479 * freeing or re-using the memory reserved for old node (which can be
480 * accessed with cds_lfht_iter_get_node).
481 * Upon success, this function issues a full memory barrier before and
482 * after its atomic commit. Upon failure, this function does not issue
483 * any memory barrier.
484 */
485 extern
486 int cds_lfht_del(struct cds_lfht *ht, struct cds_lfht_node *node);
487
488 /*
489 * cds_lfht_is_node_deleted - query whether a node is removed from hash table.
490 *
491 * Return non-zero if the node is deleted from the hash table, 0
492 * otherwise.
493 * Node can be looked up with cds_lfht_lookup and cds_lfht_next,
494 * followed by use of cds_lfht_iter_get_node.
495 * RCU read-side lock must be held between lookup and call to this
496 * function.
497 * Call with rcu_read_lock held.
498 * Threads calling this API need to be registered RCU read-side threads.
499 * This function does not issue any memory barrier.
500 */
501 extern
502 int cds_lfht_is_node_deleted(struct cds_lfht_node *node);
503
504 /*
505 * cds_lfht_resize - Force a hash table resize
506 * @ht: the hash table.
507 * @new_size: update to this hash table size.
508 *
509 * Threads calling this API need to be registered RCU read-side threads.
510 * This function does not (necessarily) issue memory barriers.
511 * cds_lfht_resize should *not* be called from a RCU read-side critical
512 * section.
513 */
514 extern
515 void cds_lfht_resize(struct cds_lfht *ht, unsigned long new_size);
516
517 /*
518 * Note: it is safe to perform element removal (del), replacement, or
519 * any hash table update operation during any of the following hash
520 * table traversals.
521 * These functions act as rcu_dereference() to read the node pointers.
522 */
523 #define cds_lfht_for_each(ht, iter, node) \
524 for (cds_lfht_first(ht, iter), \
525 node = cds_lfht_iter_get_node(iter); \
526 node != NULL; \
527 cds_lfht_next(ht, iter), \
528 node = cds_lfht_iter_get_node(iter))
529
530 #define cds_lfht_for_each_duplicate(ht, hash, match, key, iter, node) \
531 for (cds_lfht_lookup(ht, hash, match, key, iter), \
532 node = cds_lfht_iter_get_node(iter); \
533 node != NULL; \
534 cds_lfht_next_duplicate(ht, match, key, iter), \
535 node = cds_lfht_iter_get_node(iter))
536
537 #define cds_lfht_for_each_entry(ht, iter, pos, member) \
538 for (cds_lfht_first(ht, iter), \
539 pos = caa_container_of(cds_lfht_iter_get_node(iter), \
540 __typeof__(*(pos)), member); \
541 cds_lfht_iter_get_node(iter) != NULL; \
542 cds_lfht_next(ht, iter), \
543 pos = caa_container_of(cds_lfht_iter_get_node(iter), \
544 __typeof__(*(pos)), member))
545
546 #define cds_lfht_for_each_entry_duplicate(ht, hash, match, key, \
547 iter, pos, member) \
548 for (cds_lfht_lookup(ht, hash, match, key, iter), \
549 pos = caa_container_of(cds_lfht_iter_get_node(iter), \
550 __typeof__(*(pos)), member); \
551 cds_lfht_iter_get_node(iter) != NULL; \
552 cds_lfht_next_duplicate(ht, match, key, iter), \
553 pos = caa_container_of(cds_lfht_iter_get_node(iter), \
554 __typeof__(*(pos)), member))
555
556 #ifdef __cplusplus
557 }
558 #endif
559
560 #endif /* _URCU_RCULFHASH_H */
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