d6cb34ab445630cdc20174b7f346deab57ddf69c
[lttng-tools.git] / src / common / hashtable / 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
33 #include "urcu-flavor.h"
34
35 #ifdef __cplusplus
36 extern "C" {
37 #endif
38
39 /*
40 * cds_lfht_node: Contains the next pointers and reverse-hash
41 * value required for lookup and traversal of the hash table.
42 *
43 * struct cds_lfht_node should be aligned on 8-bytes boundaries because
44 * the three lower bits are used as flags. It is worth noting that the
45 * information contained within these three bits could be represented on
46 * two bits by re-using the same bit for REMOVAL_OWNER_FLAG and
47 * BUCKET_FLAG. This can be done if we ensure that no iterator nor
48 * updater check the BUCKET_FLAG after it detects that the REMOVED_FLAG
49 * is set. Given the minimum size of struct cds_lfht_node is 8 bytes on
50 * 32-bit architectures, we choose to go for simplicity and reserve
51 * three bits.
52 *
53 * struct cds_lfht_node can be embedded into a structure (as a field).
54 * caa_container_of() can be used to get the structure from the struct
55 * cds_lfht_node after a lookup.
56 *
57 * The structure which embeds it typically holds the key (or key-value
58 * pair) of the object. The caller code is responsible for calculation
59 * of the hash value for cds_lfht APIs.
60 */
61 struct cds_lfht_node {
62 struct cds_lfht_node *next; /* ptr | REMOVAL_OWNER_FLAG | BUCKET_FLAG | REMOVED_FLAG */
63 unsigned long reverse_hash;
64 } __attribute__((aligned(8)));
65
66 /* cds_lfht_iter: Used to track state while traversing a hash chain. */
67 struct cds_lfht_iter {
68 struct cds_lfht_node *node, *next;
69 };
70
71 static inline
72 struct cds_lfht_node *cds_lfht_iter_get_node(struct cds_lfht_iter *iter)
73 {
74 return iter->node;
75 }
76
77 struct cds_lfht;
78
79 /*
80 * Caution !
81 * Ensure reader and writer threads are registered as urcu readers.
82 */
83
84 typedef int (*cds_lfht_match_fct)(struct cds_lfht_node *node, const void *key);
85
86 /*
87 * cds_lfht_node_init - initialize a hash table node
88 * @node: the node to initialize.
89 *
90 * This function is kept to be eventually used for debugging purposes
91 * (detection of memory corruption).
92 */
93 static inline
94 void cds_lfht_node_init(struct cds_lfht_node *node)
95 {
96 }
97
98 /*
99 * Hash table creation flags.
100 */
101 enum {
102 CDS_LFHT_AUTO_RESIZE = (1U << 0),
103 CDS_LFHT_ACCOUNTING = (1U << 1),
104 };
105
106 struct cds_lfht_mm_type {
107 struct cds_lfht *(*alloc_cds_lfht)(unsigned long min_nr_alloc_buckets,
108 unsigned long max_nr_buckets);
109 void (*alloc_bucket_table)(struct cds_lfht *ht, unsigned long order);
110 void (*free_bucket_table)(struct cds_lfht *ht, unsigned long order);
111 struct cds_lfht_node *(*bucket_at)(struct cds_lfht *ht,
112 unsigned long index);
113 };
114
115 extern const struct cds_lfht_mm_type cds_lfht_mm_order;
116 extern const struct cds_lfht_mm_type cds_lfht_mm_chunk;
117 extern const struct cds_lfht_mm_type cds_lfht_mm_mmap;
118
119 /*
120 * _cds_lfht_new - API used by cds_lfht_new wrapper. Do not use directly.
121 */
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 */
180 int cds_lfht_destroy(struct cds_lfht *ht, pthread_attr_t **attr);
181
182 /*
183 * cds_lfht_count_nodes - count the number of nodes in the hash table.
184 * @ht: the hash table.
185 * @split_count_before: sample the node count split-counter before traversal.
186 * @count: traverse the hash table, count the number of nodes observed.
187 * @split_count_after: sample the node count split-counter after traversal.
188 *
189 * Call with rcu_read_lock held.
190 * Threads calling this API need to be registered RCU read-side threads.
191 */
192 void cds_lfht_count_nodes(struct cds_lfht *ht,
193 long *split_count_before,
194 unsigned long *count,
195 long *split_count_after);
196
197 /*
198 * cds_lfht_lookup - lookup a node by key.
199 * @ht: the hash table.
200 * @hash: the key hash.
201 * @match: the key match function.
202 * @key: the current node key.
203 * @iter: node, if found (output). *iter->node set to NULL if not found.
204 *
205 * Call with rcu_read_lock held.
206 * Threads calling this API need to be registered RCU read-side threads.
207 * This function acts as a rcu_dereference() to read the node pointer.
208 */
209 void cds_lfht_lookup(struct cds_lfht *ht, unsigned long hash,
210 cds_lfht_match_fct match, const void *key,
211 struct cds_lfht_iter *iter);
212
213 /*
214 * cds_lfht_next_duplicate - get the next item with same key, after iterator.
215 * @ht: the hash table.
216 * @match: the key match function.
217 * @key: the current node key.
218 * @iter: input: current iterator.
219 * output: node, if found. *iter->node set to NULL if not found.
220 *
221 * Uses an iterator initialized by a lookup or traversal. Important: the
222 * iterator _needs_ to be initialized before calling
223 * cds_lfht_next_duplicate.
224 * Sets *iter-node to the following node with same key.
225 * Sets *iter->node to NULL if no following node exists with same key.
226 * RCU read-side lock must be held across cds_lfht_lookup and
227 * cds_lfht_next calls, and also between cds_lfht_next calls using the
228 * node returned by a previous cds_lfht_next.
229 * Call with rcu_read_lock held.
230 * Threads calling this API need to be registered RCU read-side threads.
231 * This function acts as a rcu_dereference() to read the node pointer.
232 */
233 void cds_lfht_next_duplicate(struct cds_lfht *ht,
234 cds_lfht_match_fct match, const void *key,
235 struct cds_lfht_iter *iter);
236
237 /*
238 * cds_lfht_first - get the first node in the table.
239 * @ht: the hash table.
240 * @iter: First node, if exists (output). *iter->node set to NULL if not found.
241 *
242 * Output in "*iter". *iter->node set to NULL if table is empty.
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 void cds_lfht_first(struct cds_lfht *ht, struct cds_lfht_iter *iter);
248
249 /*
250 * cds_lfht_next - get the next node in the table.
251 * @ht: the hash table.
252 * @iter: input: current iterator.
253 * output: next node, if exists. *iter->node set to NULL if not found.
254 *
255 * Input/Output in "*iter". *iter->node set to NULL if *iter was
256 * pointing to the last table node.
257 * Call with rcu_read_lock held.
258 * Threads calling this API need to be registered RCU read-side threads.
259 * This function acts as a rcu_dereference() to read the node pointer.
260 */
261 void cds_lfht_next(struct cds_lfht *ht, struct cds_lfht_iter *iter);
262
263 /*
264 * cds_lfht_add - add a node to the hash table.
265 * @ht: the hash table.
266 * @hash: the key hash.
267 * @node: the node to add.
268 *
269 * This function supports adding redundant keys into the table.
270 * Call with rcu_read_lock held.
271 * Threads calling this API need to be registered RCU read-side threads.
272 * This function issues a full memory barrier before and after its
273 * atomic commit.
274 */
275 void cds_lfht_add(struct cds_lfht *ht, unsigned long hash,
276 struct cds_lfht_node *node);
277
278 /*
279 * cds_lfht_add_unique - add a node to hash table, if key is not present.
280 * @ht: the hash table.
281 * @hash: the node's hash.
282 * @match: the key match function.
283 * @key: the node's key.
284 * @node: the node to try adding.
285 *
286 * Return the node added upon success.
287 * Return the unique node already present upon failure. If
288 * cds_lfht_add_unique fails, the node passed as parameter should be
289 * freed by the caller. In this case, the caller does NOT need to wait
290 * for a grace period before freeing the node.
291 * Call with rcu_read_lock held.
292 * Threads calling this API need to be registered RCU read-side threads.
293 *
294 * The semantic of this function is that if only this function is used
295 * to add keys into the table, no duplicated keys should ever be
296 * observable in the table. The same guarantee apply for combination of
297 * add_unique and add_replace (see below).
298 *
299 * Upon success, this function issues a full memory barrier before and
300 * after its atomic commit. Upon failure, this function acts like a
301 * simple lookup operation: it acts as a rcu_dereference() to read the
302 * node pointer. The failure case does not guarantee any other memory
303 * barrier.
304 */
305 struct cds_lfht_node *cds_lfht_add_unique(struct cds_lfht *ht,
306 unsigned long hash,
307 cds_lfht_match_fct match,
308 const void *key,
309 struct cds_lfht_node *node);
310
311 /*
312 * cds_lfht_add_replace - replace or add a node within hash table.
313 * @ht: the hash table.
314 * @hash: the node's hash.
315 * @match: the key match function.
316 * @key: the node's key.
317 * @node: the node to add.
318 *
319 * Return the node replaced upon success. If no node matching the key
320 * was present, return NULL, which also means the operation succeeded.
321 * This replacement operation should never fail.
322 * Call with rcu_read_lock held.
323 * Threads calling this API need to be registered RCU read-side threads.
324 * After successful replacement, a grace period must be waited for before
325 * freeing the memory reserved for the returned node.
326 *
327 * The semantic of replacement vs lookups and traversals is the
328 * following: if lookups and traversals are performed between a key
329 * unique insertion and its removal, we guarantee that the lookups and
330 * traversals will always find exactly one instance of the key if it is
331 * replaced concurrently with the lookups.
332 *
333 * Providing this semantic allows us to ensure that replacement-only
334 * schemes will never generate duplicated keys. It also allows us to
335 * guarantee that a combination of add_replace and add_unique updates
336 * will never generate duplicated keys.
337 *
338 * This function issues a full memory barrier before and after its
339 * atomic commit.
340 */
341 struct cds_lfht_node *cds_lfht_add_replace(struct cds_lfht *ht,
342 unsigned long hash,
343 cds_lfht_match_fct match,
344 const void *key,
345 struct cds_lfht_node *node);
346
347 /*
348 * cds_lfht_replace - replace a node pointed to by iter within hash table.
349 * @ht: the hash table.
350 * @old_iter: the iterator position of the node to replace.
351 * @hash: the node's hash.
352 * @match: the key match function.
353 * @key: the node's key.
354 * @new_node: the new node to use as replacement.
355 *
356 * Return 0 if replacement is successful, negative value otherwise.
357 * Replacing a NULL old node or an already removed node will fail with
358 * -ENOENT.
359 * If the hash or value of the node to replace and the new node differ,
360 * this function returns -EINVAL without proceeding to the replacement.
361 * Old node can be looked up with cds_lfht_lookup and cds_lfht_next.
362 * RCU read-side lock must be held between lookup and replacement.
363 * Call with rcu_read_lock held.
364 * Threads calling this API need to be registered RCU read-side threads.
365 * After successful replacement, a grace period must be waited for before
366 * freeing the memory reserved for the old node (which can be accessed
367 * with cds_lfht_iter_get_node).
368 *
369 * The semantic of replacement vs lookups is the same as
370 * cds_lfht_add_replace().
371 *
372 * Upon success, this function issues a full memory barrier before and
373 * after its atomic commit. Upon failure, this function does not issue
374 * any memory barrier.
375 */
376 int cds_lfht_replace(struct cds_lfht *ht,
377 struct cds_lfht_iter *old_iter,
378 unsigned long hash,
379 cds_lfht_match_fct match,
380 const void *key,
381 struct cds_lfht_node *new_node);
382
383 /*
384 * cds_lfht_del - remove node pointed to by iterator from hash table.
385 * @ht: the hash table.
386 * @node: the node to delete.
387 *
388 * Return 0 if the node is successfully removed, negative value
389 * otherwise.
390 * Deleting a NULL node or an already removed node will fail with a
391 * negative value.
392 * Node can be looked up with cds_lfht_lookup and cds_lfht_next,
393 * followed by use of cds_lfht_iter_get_node.
394 * RCU read-side lock must be held between lookup and removal.
395 * Call with rcu_read_lock held.
396 * Threads calling this API need to be registered RCU read-side threads.
397 * After successful removal, a grace period must be waited for before
398 * freeing the memory reserved for old node (which can be accessed with
399 * cds_lfht_iter_get_node).
400 * Upon success, this function issues a full memory barrier before and
401 * after its atomic commit. Upon failure, this function does not issue
402 * any memory barrier.
403 */
404 int cds_lfht_del(struct cds_lfht *ht, struct cds_lfht_node *node);
405
406 /*
407 * cds_lfht_is_node_deleted - query whether a node is removed from hash table.
408 *
409 * Return non-zero if the node is deleted from the hash table, 0
410 * otherwise.
411 * Node can be looked up with cds_lfht_lookup and cds_lfht_next,
412 * followed by use of cds_lfht_iter_get_node.
413 * RCU read-side lock must be held between lookup and call to this
414 * function.
415 * Call with rcu_read_lock held.
416 * Threads calling this API need to be registered RCU read-side threads.
417 * This function does not issue any memory barrier.
418 */
419 int cds_lfht_is_node_deleted(struct cds_lfht_node *node);
420
421 /*
422 * cds_lfht_resize - Force a hash table resize
423 * @ht: the hash table.
424 * @new_size: update to this hash table size.
425 *
426 * Threads calling this API need to be registered RCU read-side threads.
427 * This function does not (necessarily) issue memory barriers.
428 */
429 void cds_lfht_resize(struct cds_lfht *ht, unsigned long new_size);
430
431 /*
432 * Note: it is safe to perform element removal (del), replacement, or
433 * any hash table update operation during any of the following hash
434 * table traversals.
435 * These functions act as rcu_dereference() to read the node pointers.
436 */
437 #define cds_lfht_for_each(ht, iter, node) \
438 for (cds_lfht_first(ht, iter), \
439 node = cds_lfht_iter_get_node(iter); \
440 node != NULL; \
441 cds_lfht_next(ht, iter), \
442 node = cds_lfht_iter_get_node(iter))
443
444 #define cds_lfht_for_each_duplicate(ht, hash, match, key, iter, node) \
445 for (cds_lfht_lookup(ht, hash, match, key, iter), \
446 node = cds_lfht_iter_get_node(iter); \
447 node != NULL; \
448 cds_lfht_next_duplicate(ht, match, key, iter), \
449 node = cds_lfht_iter_get_node(iter))
450
451 #define cds_lfht_for_each_entry(ht, iter, pos, member) \
452 for (cds_lfht_first(ht, iter), \
453 pos = caa_container_of(cds_lfht_iter_get_node(iter), \
454 __typeof__(*(pos)), member); \
455 &(pos)->member != NULL; \
456 cds_lfht_next(ht, iter), \
457 pos = caa_container_of(cds_lfht_iter_get_node(iter), \
458 __typeof__(*(pos)), member))
459
460 #define cds_lfht_for_each_entry_duplicate(ht, hash, match, key, \
461 iter, pos, member) \
462 for (cds_lfht_lookup(ht, hash, match, key, iter), \
463 pos = caa_container_of(cds_lfht_iter_get_node(iter), \
464 __typeof__(*(pos)), member); \
465 &(pos)->member != NULL; \
466 cds_lfht_next_duplicate(ht, match, key, iter), \
467 pos = caa_container_of(cds_lfht_iter_get_node(iter), \
468 __typeof__(*(pos)), member))
469
470 #ifdef __cplusplus
471 }
472 #endif
473
474 #endif /* _URCU_RCULFHASH_H */
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