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10544ee8 | 1 | /* |
c0c0989a | 2 | * SPDX-License-Identifier: LGPL-2.1-or-later |
10544ee8 | 3 | * |
c0c0989a MJ |
4 | * Copyright 2011 Mathieu Desnoyers <mathieu.desnoyers@efficios.com> |
5 | * Copyright 2011 Lai Jiangshan <laijs@cn.fujitsu.com> | |
10544ee8 | 6 | * |
c0c0989a | 7 | * Userspace RCU library - Lock-Free RCU Hash Table |
10544ee8 MD |
8 | */ |
9 | ||
c0c0989a MJ |
10 | #ifndef _LTTNG_UST_RCULFHASH_H |
11 | #define _LTTNG_UST_RCULFHASH_H | |
12 | ||
10544ee8 MD |
13 | #include <stdint.h> |
14 | #include <pthread.h> | |
15 | #include <urcu/compiler.h> | |
864a1eda | 16 | #include "ust-helper.h" |
10544ee8 MD |
17 | |
18 | #ifdef __cplusplus | |
19 | extern "C" { | |
20 | #endif | |
21 | ||
22 | struct lttng_ust_lfht; | |
23 | ||
24 | /* | |
25 | * lttng_ust_lfht_node: Contains the next pointers and reverse-hash | |
26 | * value required for lookup and traversal of the hash table. | |
27 | * | |
28 | * struct lttng_ust_lfht_node should be aligned on 8-bytes boundaries because | |
29 | * the three lower bits are used as flags. It is worth noting that the | |
30 | * information contained within these three bits could be represented on | |
31 | * two bits by re-using the same bit for REMOVAL_OWNER_FLAG and | |
32 | * BUCKET_FLAG. This can be done if we ensure that no iterator nor | |
33 | * updater check the BUCKET_FLAG after it detects that the REMOVED_FLAG | |
34 | * is set. Given the minimum size of struct lttng_ust_lfht_node is 8 bytes on | |
35 | * 32-bit architectures, we choose to go for simplicity and reserve | |
36 | * three bits. | |
37 | * | |
38 | * struct lttng_ust_lfht_node can be embedded into a structure (as a field). | |
39 | * caa_container_of() can be used to get the structure from the struct | |
40 | * lttng_ust_lfht_node after a lookup. | |
41 | * | |
42 | * The structure which embeds it typically holds the key (or key-value | |
43 | * pair) of the object. The caller code is responsible for calculation | |
44 | * of the hash value for lttng_ust_lfht APIs. | |
45 | */ | |
46 | struct lttng_ust_lfht_node { | |
47 | struct lttng_ust_lfht_node *next; /* ptr | REMOVAL_OWNER_FLAG | BUCKET_FLAG | REMOVED_FLAG */ | |
48 | unsigned long reverse_hash; | |
49 | } __attribute__((aligned(8))); | |
50 | ||
51 | /* lttng_ust_lfht_iter: Used to track state while traversing a hash chain. */ | |
52 | struct lttng_ust_lfht_iter { | |
53 | struct lttng_ust_lfht_node *node, *next; | |
54 | }; | |
55 | ||
56 | static inline | |
57 | struct lttng_ust_lfht_node *lttng_ust_lfht_iter_get_node(struct lttng_ust_lfht_iter *iter) | |
58 | { | |
59 | return iter->node; | |
60 | } | |
61 | ||
62 | struct rcu_flavor_struct; | |
63 | ||
64 | /* | |
65 | * Caution ! | |
66 | * Ensure reader and writer threads are registered as urcu readers. | |
67 | */ | |
68 | ||
69 | typedef int (*lttng_ust_lfht_match_fct)(struct lttng_ust_lfht_node *node, const void *key); | |
70 | ||
71 | /* | |
72 | * lttng_ust_lfht_node_init - initialize a hash table node | |
73 | * @node: the node to initialize. | |
74 | * | |
75 | * This function is kept to be eventually used for debugging purposes | |
76 | * (detection of memory corruption). | |
77 | */ | |
78 | static inline | |
79 | void lttng_ust_lfht_node_init(struct lttng_ust_lfht_node *node) | |
80 | { | |
81 | } | |
82 | ||
83 | /* | |
84 | * Hash table creation flags. | |
85 | */ | |
86 | enum { | |
87 | LTTNG_UST_LFHT_AUTO_RESIZE = (1U << 0), | |
88 | LTTNG_UST_LFHT_ACCOUNTING = (1U << 1), | |
89 | }; | |
90 | ||
91 | struct lttng_ust_lfht_mm_type { | |
92 | struct lttng_ust_lfht *(*alloc_lttng_ust_lfht)(unsigned long min_nr_alloc_buckets, | |
93 | unsigned long max_nr_buckets); | |
94 | void (*alloc_bucket_table)(struct lttng_ust_lfht *ht, unsigned long order); | |
95 | void (*free_bucket_table)(struct lttng_ust_lfht *ht, unsigned long order); | |
96 | struct lttng_ust_lfht_node *(*bucket_at)(struct lttng_ust_lfht *ht, | |
97 | unsigned long index); | |
98 | }; | |
99 | ||
d2dd7baa | 100 | LTTNG_HIDDEN |
10544ee8 | 101 | extern const struct lttng_ust_lfht_mm_type lttng_ust_lfht_mm_order; |
d2dd7baa | 102 | LTTNG_HIDDEN |
10544ee8 | 103 | extern const struct lttng_ust_lfht_mm_type lttng_ust_lfht_mm_chunk; |
d2dd7baa | 104 | LTTNG_HIDDEN |
10544ee8 MD |
105 | extern const struct lttng_ust_lfht_mm_type lttng_ust_lfht_mm_mmap; |
106 | ||
107 | /* | |
108 | * lttng_ust_lfht_new - allocate a hash table. | |
109 | * @init_size: number of buckets to allocate initially. Must be power of two. | |
110 | * @min_nr_alloc_buckets: the minimum number of allocated buckets. | |
111 | * (must be power of two) | |
112 | * @max_nr_buckets: the maximum number of hash table buckets allowed. | |
113 | * (must be power of two, 0 is accepted, means | |
114 | * "infinite") | |
115 | * @flags: hash table creation flags (can be combined with bitwise or: '|'). | |
116 | * 0: no flags. | |
117 | * LTTNG_UST_LFHT_AUTO_RESIZE: automatically resize hash table. | |
118 | * LTTNG_UST_LFHT_ACCOUNTING: count the number of node addition | |
119 | * and removal in the table | |
120 | * | |
121 | * Return NULL on error. | |
122 | * Note: the RCU flavor must be already included before the hash table header. | |
123 | */ | |
d2dd7baa MJ |
124 | LTTNG_HIDDEN |
125 | extern struct lttng_ust_lfht *lttng_ust_lfht_new(unsigned long init_size, | |
10544ee8 MD |
126 | unsigned long min_nr_alloc_buckets, |
127 | unsigned long max_nr_buckets, | |
128 | int flags, | |
129 | const struct lttng_ust_lfht_mm_type *mm); | |
130 | ||
131 | /* | |
132 | * lttng_ust_lfht_destroy - destroy a hash table. | |
133 | * @ht: the hash table to destroy. | |
134 | * | |
135 | * Return 0 on success, negative error value on error. | |
136 | ||
137 | * Prior to liburcu 0.10: | |
138 | * - Threads calling this API need to be registered RCU read-side | |
139 | * threads. | |
140 | * - lttng_ust_lfht_destroy should *not* be called from a RCU read-side | |
141 | * critical section. It should *not* be called from a call_rcu thread | |
142 | * context neither. | |
143 | * | |
144 | * Starting from liburcu 0.10, rculfhash implements its own worker | |
145 | * thread to handle resize operations, which removes RCU requirements on | |
146 | * lttng_ust_lfht_destroy. | |
147 | */ | |
d2dd7baa MJ |
148 | LTTNG_HIDDEN |
149 | extern int lttng_ust_lfht_destroy(struct lttng_ust_lfht *ht); | |
10544ee8 MD |
150 | |
151 | /* | |
152 | * lttng_ust_lfht_count_nodes - count the number of nodes in the hash table. | |
153 | * @ht: the hash table. | |
154 | * @split_count_before: sample the node count split-counter before traversal. | |
155 | * @count: traverse the hash table, count the number of nodes observed. | |
156 | * @split_count_after: sample the node count split-counter after traversal. | |
157 | * | |
158 | * Call with rcu_read_lock held. | |
159 | * Threads calling this API need to be registered RCU read-side threads. | |
160 | */ | |
d2dd7baa MJ |
161 | LTTNG_HIDDEN |
162 | extern void lttng_ust_lfht_count_nodes(struct lttng_ust_lfht *ht, | |
10544ee8 MD |
163 | long *split_count_before, |
164 | unsigned long *count, | |
165 | long *split_count_after); | |
166 | ||
167 | /* | |
168 | * lttng_ust_lfht_lookup - lookup a node by key. | |
169 | * @ht: the hash table. | |
170 | * @hash: the key hash. | |
171 | * @match: the key match function. | |
172 | * @key: the current node key. | |
173 | * @iter: node, if found (output). *iter->node set to NULL if not found. | |
174 | * | |
175 | * Call with rcu_read_lock held. | |
176 | * Threads calling this API need to be registered RCU read-side threads. | |
177 | * This function acts as a rcu_dereference() to read the node pointer. | |
178 | */ | |
d2dd7baa MJ |
179 | LTTNG_HIDDEN |
180 | extern void lttng_ust_lfht_lookup(struct lttng_ust_lfht *ht, unsigned long hash, | |
10544ee8 MD |
181 | lttng_ust_lfht_match_fct match, const void *key, |
182 | struct lttng_ust_lfht_iter *iter); | |
183 | ||
184 | /* | |
185 | * lttng_ust_lfht_next_duplicate - get the next item with same key, after iterator. | |
186 | * @ht: the hash table. | |
187 | * @match: the key match function. | |
188 | * @key: the current node key. | |
189 | * @iter: input: current iterator. | |
190 | * output: node, if found. *iter->node set to NULL if not found. | |
191 | * | |
192 | * Uses an iterator initialized by a lookup or traversal. Important: the | |
193 | * iterator _needs_ to be initialized before calling | |
194 | * lttng_ust_lfht_next_duplicate. | |
195 | * Sets *iter-node to the following node with same key. | |
196 | * Sets *iter->node to NULL if no following node exists with same key. | |
197 | * RCU read-side lock must be held across lttng_ust_lfht_lookup and | |
198 | * lttng_ust_lfht_next calls, and also between lttng_ust_lfht_next calls using the | |
199 | * node returned by a previous lttng_ust_lfht_next. | |
200 | * Call with rcu_read_lock held. | |
201 | * Threads calling this API need to be registered RCU read-side threads. | |
202 | * This function acts as a rcu_dereference() to read the node pointer. | |
203 | */ | |
d2dd7baa MJ |
204 | LTTNG_HIDDEN |
205 | extern void lttng_ust_lfht_next_duplicate(struct lttng_ust_lfht *ht, | |
10544ee8 MD |
206 | lttng_ust_lfht_match_fct match, const void *key, |
207 | struct lttng_ust_lfht_iter *iter); | |
208 | ||
209 | /* | |
210 | * lttng_ust_lfht_first - get the first node in the table. | |
211 | * @ht: the hash table. | |
212 | * @iter: First node, if exists (output). *iter->node set to NULL if not found. | |
213 | * | |
214 | * Output in "*iter". *iter->node set to NULL if table is empty. | |
215 | * Call with rcu_read_lock held. | |
216 | * Threads calling this API need to be registered RCU read-side threads. | |
217 | * This function acts as a rcu_dereference() to read the node pointer. | |
218 | */ | |
d2dd7baa MJ |
219 | LTTNG_HIDDEN |
220 | extern void lttng_ust_lfht_first(struct lttng_ust_lfht *ht, struct lttng_ust_lfht_iter *iter); | |
10544ee8 MD |
221 | |
222 | /* | |
223 | * lttng_ust_lfht_next - get the next node in the table. | |
224 | * @ht: the hash table. | |
225 | * @iter: input: current iterator. | |
226 | * output: next node, if exists. *iter->node set to NULL if not found. | |
227 | * | |
228 | * Input/Output in "*iter". *iter->node set to NULL if *iter was | |
229 | * pointing to the last table node. | |
230 | * Call with rcu_read_lock held. | |
231 | * Threads calling this API need to be registered RCU read-side threads. | |
232 | * This function acts as a rcu_dereference() to read the node pointer. | |
233 | */ | |
d2dd7baa MJ |
234 | LTTNG_HIDDEN |
235 | extern void lttng_ust_lfht_next(struct lttng_ust_lfht *ht, struct lttng_ust_lfht_iter *iter); | |
10544ee8 MD |
236 | |
237 | /* | |
238 | * lttng_ust_lfht_add - add a node to the hash table. | |
239 | * @ht: the hash table. | |
240 | * @hash: the key hash. | |
241 | * @node: the node to add. | |
242 | * | |
243 | * This function supports adding redundant keys into the table. | |
244 | * Call with rcu_read_lock held. | |
245 | * Threads calling this API need to be registered RCU read-side threads. | |
246 | * This function issues a full memory barrier before and after its | |
247 | * atomic commit. | |
248 | */ | |
d2dd7baa MJ |
249 | LTTNG_HIDDEN |
250 | extern void lttng_ust_lfht_add(struct lttng_ust_lfht *ht, unsigned long hash, | |
10544ee8 MD |
251 | struct lttng_ust_lfht_node *node); |
252 | ||
253 | /* | |
254 | * lttng_ust_lfht_add_unique - add a node to hash table, if key is not present. | |
255 | * @ht: the hash table. | |
256 | * @hash: the node's hash. | |
257 | * @match: the key match function. | |
258 | * @key: the node's key. | |
259 | * @node: the node to try adding. | |
260 | * | |
261 | * Return the node added upon success. | |
262 | * Return the unique node already present upon failure. If | |
263 | * lttng_ust_lfht_add_unique fails, the node passed as parameter should be | |
264 | * freed by the caller. In this case, the caller does NOT need to wait | |
265 | * for a grace period before freeing or re-using the node. | |
266 | * Call with rcu_read_lock held. | |
267 | * Threads calling this API need to be registered RCU read-side threads. | |
268 | * | |
269 | * The semantic of this function is that if only this function is used | |
270 | * to add keys into the table, no duplicated keys should ever be | |
271 | * observable in the table. The same guarantee apply for combination of | |
272 | * add_unique and add_replace (see below). | |
273 | * | |
274 | * Upon success, this function issues a full memory barrier before and | |
275 | * after its atomic commit. Upon failure, this function acts like a | |
276 | * simple lookup operation: it acts as a rcu_dereference() to read the | |
277 | * node pointer. The failure case does not guarantee any other memory | |
278 | * barrier. | |
279 | */ | |
d2dd7baa MJ |
280 | LTTNG_HIDDEN |
281 | extern struct lttng_ust_lfht_node *lttng_ust_lfht_add_unique(struct lttng_ust_lfht *ht, | |
10544ee8 MD |
282 | unsigned long hash, |
283 | lttng_ust_lfht_match_fct match, | |
284 | const void *key, | |
285 | struct lttng_ust_lfht_node *node); | |
286 | ||
287 | /* | |
288 | * lttng_ust_lfht_add_replace - replace or add a node within hash table. | |
289 | * @ht: the hash table. | |
290 | * @hash: the node's hash. | |
291 | * @match: the key match function. | |
292 | * @key: the node's key. | |
293 | * @node: the node to add. | |
294 | * | |
295 | * Return the node replaced upon success. If no node matching the key | |
296 | * was present, return NULL, which also means the operation succeeded. | |
297 | * This replacement operation should never fail. | |
298 | * Call with rcu_read_lock held. | |
299 | * Threads calling this API need to be registered RCU read-side threads. | |
300 | * After successful replacement, a grace period must be waited for before | |
301 | * freeing or re-using the memory reserved for the returned node. | |
302 | * | |
303 | * The semantic of replacement vs lookups and traversals is the | |
304 | * following: if lookups and traversals are performed between a key | |
305 | * unique insertion and its removal, we guarantee that the lookups and | |
306 | * traversals will always find exactly one instance of the key if it is | |
307 | * replaced concurrently with the lookups. | |
308 | * | |
309 | * Providing this semantic allows us to ensure that replacement-only | |
310 | * schemes will never generate duplicated keys. It also allows us to | |
311 | * guarantee that a combination of add_replace and add_unique updates | |
312 | * will never generate duplicated keys. | |
313 | * | |
314 | * This function issues a full memory barrier before and after its | |
315 | * atomic commit. | |
316 | */ | |
d2dd7baa MJ |
317 | LTTNG_HIDDEN |
318 | extern struct lttng_ust_lfht_node *lttng_ust_lfht_add_replace(struct lttng_ust_lfht *ht, | |
10544ee8 MD |
319 | unsigned long hash, |
320 | lttng_ust_lfht_match_fct match, | |
321 | const void *key, | |
322 | struct lttng_ust_lfht_node *node); | |
323 | ||
324 | /* | |
325 | * lttng_ust_lfht_replace - replace a node pointed to by iter within hash table. | |
326 | * @ht: the hash table. | |
327 | * @old_iter: the iterator position of the node to replace. | |
328 | * @hash: the node's hash. | |
329 | * @match: the key match function. | |
330 | * @key: the node's key. | |
331 | * @new_node: the new node to use as replacement. | |
332 | * | |
333 | * Return 0 if replacement is successful, negative value otherwise. | |
334 | * Replacing a NULL old node or an already removed node will fail with | |
335 | * -ENOENT. | |
336 | * If the hash or value of the node to replace and the new node differ, | |
337 | * this function returns -EINVAL without proceeding to the replacement. | |
338 | * Old node can be looked up with lttng_ust_lfht_lookup and lttng_ust_lfht_next. | |
339 | * RCU read-side lock must be held between lookup and replacement. | |
340 | * Call with rcu_read_lock held. | |
341 | * Threads calling this API need to be registered RCU read-side threads. | |
342 | * After successful replacement, a grace period must be waited for before | |
343 | * freeing or re-using the memory reserved for the old node (which can | |
344 | * be accessed with lttng_ust_lfht_iter_get_node). | |
345 | * | |
346 | * The semantic of replacement vs lookups is the same as | |
347 | * lttng_ust_lfht_add_replace(). | |
348 | * | |
349 | * Upon success, this function issues a full memory barrier before and | |
350 | * after its atomic commit. Upon failure, this function does not issue | |
351 | * any memory barrier. | |
352 | */ | |
d2dd7baa MJ |
353 | LTTNG_HIDDEN |
354 | extern int lttng_ust_lfht_replace(struct lttng_ust_lfht *ht, | |
10544ee8 MD |
355 | struct lttng_ust_lfht_iter *old_iter, |
356 | unsigned long hash, | |
357 | lttng_ust_lfht_match_fct match, | |
358 | const void *key, | |
359 | struct lttng_ust_lfht_node *new_node); | |
360 | ||
361 | /* | |
362 | * lttng_ust_lfht_del - remove node pointed to by iterator from hash table. | |
363 | * @ht: the hash table. | |
364 | * @node: the node to delete. | |
365 | * | |
366 | * Return 0 if the node is successfully removed, negative value | |
367 | * otherwise. | |
368 | * Deleting a NULL node or an already removed node will fail with a | |
369 | * negative value. | |
370 | * Node can be looked up with lttng_ust_lfht_lookup and lttng_ust_lfht_next, | |
371 | * followed by use of lttng_ust_lfht_iter_get_node. | |
372 | * RCU read-side lock must be held between lookup and removal. | |
373 | * Call with rcu_read_lock held. | |
374 | * Threads calling this API need to be registered RCU read-side threads. | |
375 | * After successful removal, a grace period must be waited for before | |
376 | * freeing or re-using the memory reserved for old node (which can be | |
377 | * accessed with lttng_ust_lfht_iter_get_node). | |
378 | * Upon success, this function issues a full memory barrier before and | |
379 | * after its atomic commit. Upon failure, this function does not issue | |
380 | * any memory barrier. | |
381 | */ | |
d2dd7baa MJ |
382 | LTTNG_HIDDEN |
383 | extern int lttng_ust_lfht_del(struct lttng_ust_lfht *ht, struct lttng_ust_lfht_node *node); | |
10544ee8 MD |
384 | |
385 | /* | |
386 | * lttng_ust_lfht_is_node_deleted - query whether a node is removed from hash table. | |
387 | * | |
388 | * Return non-zero if the node is deleted from the hash table, 0 | |
389 | * otherwise. | |
390 | * Node can be looked up with lttng_ust_lfht_lookup and lttng_ust_lfht_next, | |
391 | * followed by use of lttng_ust_lfht_iter_get_node. | |
392 | * RCU read-side lock must be held between lookup and call to this | |
393 | * function. | |
394 | * Call with rcu_read_lock held. | |
395 | * Threads calling this API need to be registered RCU read-side threads. | |
396 | * This function does not issue any memory barrier. | |
397 | */ | |
d2dd7baa MJ |
398 | LTTNG_HIDDEN |
399 | extern int lttng_ust_lfht_is_node_deleted(const struct lttng_ust_lfht_node *node); | |
10544ee8 MD |
400 | |
401 | /* | |
402 | * lttng_ust_lfht_resize - Force a hash table resize | |
403 | * @ht: the hash table. | |
404 | * @new_size: update to this hash table size. | |
405 | * | |
406 | * Threads calling this API need to be registered RCU read-side threads. | |
407 | * This function does not (necessarily) issue memory barriers. | |
408 | * lttng_ust_lfht_resize should *not* be called from a RCU read-side critical | |
409 | * section. | |
410 | */ | |
d2dd7baa MJ |
411 | LTTNG_HIDDEN |
412 | extern void lttng_ust_lfht_resize(struct lttng_ust_lfht *ht, unsigned long new_size); | |
10544ee8 MD |
413 | |
414 | /* | |
415 | * Note: it is safe to perform element removal (del), replacement, or | |
416 | * any hash table update operation during any of the following hash | |
417 | * table traversals. | |
418 | * These functions act as rcu_dereference() to read the node pointers. | |
419 | */ | |
420 | #define lttng_ust_lfht_for_each(ht, iter, node) \ | |
421 | for (lttng_ust_lfht_first(ht, iter), \ | |
422 | node = lttng_ust_lfht_iter_get_node(iter); \ | |
423 | node != NULL; \ | |
424 | lttng_ust_lfht_next(ht, iter), \ | |
425 | node = lttng_ust_lfht_iter_get_node(iter)) | |
426 | ||
427 | #define lttng_ust_lfht_for_each_duplicate(ht, hash, match, key, iter, node) \ | |
428 | for (lttng_ust_lfht_lookup(ht, hash, match, key, iter), \ | |
429 | node = lttng_ust_lfht_iter_get_node(iter); \ | |
430 | node != NULL; \ | |
431 | lttng_ust_lfht_next_duplicate(ht, match, key, iter), \ | |
432 | node = lttng_ust_lfht_iter_get_node(iter)) | |
433 | ||
434 | #define lttng_ust_lfht_for_each_entry(ht, iter, pos, member) \ | |
435 | for (lttng_ust_lfht_first(ht, iter), \ | |
436 | pos = caa_container_of(lttng_ust_lfht_iter_get_node(iter), \ | |
437 | __typeof__(*(pos)), member); \ | |
438 | lttng_ust_lfht_iter_get_node(iter) != NULL; \ | |
439 | lttng_ust_lfht_next(ht, iter), \ | |
440 | pos = caa_container_of(lttng_ust_lfht_iter_get_node(iter), \ | |
441 | __typeof__(*(pos)), member)) | |
442 | ||
443 | #define lttng_ust_lfht_for_each_entry_duplicate(ht, hash, match, key, \ | |
444 | iter, pos, member) \ | |
445 | for (lttng_ust_lfht_lookup(ht, hash, match, key, iter), \ | |
446 | pos = caa_container_of(lttng_ust_lfht_iter_get_node(iter), \ | |
447 | __typeof__(*(pos)), member); \ | |
448 | lttng_ust_lfht_iter_get_node(iter) != NULL; \ | |
449 | lttng_ust_lfht_next_duplicate(ht, match, key, iter), \ | |
450 | pos = caa_container_of(lttng_ust_lfht_iter_get_node(iter), \ | |
451 | __typeof__(*(pos)), member)) | |
452 | ||
453 | #ifdef __cplusplus | |
454 | } | |
455 | #endif | |
456 | ||
457 | #endif /* _LTTNG_UST_RCULFHASH_H */ |