| 1 | #ifndef _LTTNG_UST_RCULFHASH_H |
| 2 | #define _LTTNG_UST_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 | |
| 27 | #include <stdint.h> |
| 28 | #include <pthread.h> |
| 29 | #include <urcu/compiler.h> |
| 30 | |
| 31 | #ifdef __cplusplus |
| 32 | extern "C" { |
| 33 | #endif |
| 34 | |
| 35 | struct lttng_ust_lfht; |
| 36 | |
| 37 | /* |
| 38 | * lttng_ust_lfht_node: Contains the next pointers and reverse-hash |
| 39 | * value required for lookup and traversal of the hash table. |
| 40 | * |
| 41 | * struct lttng_ust_lfht_node should be aligned on 8-bytes boundaries because |
| 42 | * the three lower bits are used as flags. It is worth noting that the |
| 43 | * information contained within these three bits could be represented on |
| 44 | * two bits by re-using the same bit for REMOVAL_OWNER_FLAG and |
| 45 | * BUCKET_FLAG. This can be done if we ensure that no iterator nor |
| 46 | * updater check the BUCKET_FLAG after it detects that the REMOVED_FLAG |
| 47 | * is set. Given the minimum size of struct lttng_ust_lfht_node is 8 bytes on |
| 48 | * 32-bit architectures, we choose to go for simplicity and reserve |
| 49 | * three bits. |
| 50 | * |
| 51 | * struct lttng_ust_lfht_node can be embedded into a structure (as a field). |
| 52 | * caa_container_of() can be used to get the structure from the struct |
| 53 | * lttng_ust_lfht_node after a lookup. |
| 54 | * |
| 55 | * The structure which embeds it typically holds the key (or key-value |
| 56 | * pair) of the object. The caller code is responsible for calculation |
| 57 | * of the hash value for lttng_ust_lfht APIs. |
| 58 | */ |
| 59 | struct lttng_ust_lfht_node { |
| 60 | struct lttng_ust_lfht_node *next; /* ptr | REMOVAL_OWNER_FLAG | BUCKET_FLAG | REMOVED_FLAG */ |
| 61 | unsigned long reverse_hash; |
| 62 | } __attribute__((aligned(8))); |
| 63 | |
| 64 | /* lttng_ust_lfht_iter: Used to track state while traversing a hash chain. */ |
| 65 | struct lttng_ust_lfht_iter { |
| 66 | struct lttng_ust_lfht_node *node, *next; |
| 67 | }; |
| 68 | |
| 69 | static inline |
| 70 | struct lttng_ust_lfht_node *lttng_ust_lfht_iter_get_node(struct lttng_ust_lfht_iter *iter) |
| 71 | { |
| 72 | return iter->node; |
| 73 | } |
| 74 | |
| 75 | struct rcu_flavor_struct; |
| 76 | |
| 77 | /* |
| 78 | * Caution ! |
| 79 | * Ensure reader and writer threads are registered as urcu readers. |
| 80 | */ |
| 81 | |
| 82 | typedef int (*lttng_ust_lfht_match_fct)(struct lttng_ust_lfht_node *node, const void *key); |
| 83 | |
| 84 | /* |
| 85 | * lttng_ust_lfht_node_init - initialize a hash table node |
| 86 | * @node: the node to initialize. |
| 87 | * |
| 88 | * This function is kept to be eventually used for debugging purposes |
| 89 | * (detection of memory corruption). |
| 90 | */ |
| 91 | static inline |
| 92 | void lttng_ust_lfht_node_init(struct lttng_ust_lfht_node *node) |
| 93 | { |
| 94 | } |
| 95 | |
| 96 | /* |
| 97 | * Hash table creation flags. |
| 98 | */ |
| 99 | enum { |
| 100 | LTTNG_UST_LFHT_AUTO_RESIZE = (1U << 0), |
| 101 | LTTNG_UST_LFHT_ACCOUNTING = (1U << 1), |
| 102 | }; |
| 103 | |
| 104 | struct lttng_ust_lfht_mm_type { |
| 105 | struct lttng_ust_lfht *(*alloc_lttng_ust_lfht)(unsigned long min_nr_alloc_buckets, |
| 106 | unsigned long max_nr_buckets); |
| 107 | void (*alloc_bucket_table)(struct lttng_ust_lfht *ht, unsigned long order); |
| 108 | void (*free_bucket_table)(struct lttng_ust_lfht *ht, unsigned long order); |
| 109 | struct lttng_ust_lfht_node *(*bucket_at)(struct lttng_ust_lfht *ht, |
| 110 | unsigned long index); |
| 111 | }; |
| 112 | |
| 113 | extern const struct lttng_ust_lfht_mm_type lttng_ust_lfht_mm_order; |
| 114 | extern const struct lttng_ust_lfht_mm_type lttng_ust_lfht_mm_chunk; |
| 115 | extern const struct lttng_ust_lfht_mm_type lttng_ust_lfht_mm_mmap; |
| 116 | |
| 117 | /* |
| 118 | * lttng_ust_lfht_new - allocate a hash table. |
| 119 | * @init_size: number of buckets to allocate initially. Must be power of two. |
| 120 | * @min_nr_alloc_buckets: the minimum number of allocated buckets. |
| 121 | * (must be power of two) |
| 122 | * @max_nr_buckets: the maximum number of hash table buckets allowed. |
| 123 | * (must be power of two, 0 is accepted, means |
| 124 | * "infinite") |
| 125 | * @flags: hash table creation flags (can be combined with bitwise or: '|'). |
| 126 | * 0: no flags. |
| 127 | * LTTNG_UST_LFHT_AUTO_RESIZE: automatically resize hash table. |
| 128 | * LTTNG_UST_LFHT_ACCOUNTING: count the number of node addition |
| 129 | * and removal in the table |
| 130 | * |
| 131 | * Return NULL on error. |
| 132 | * Note: the RCU flavor must be already included before the hash table header. |
| 133 | */ |
| 134 | extern |
| 135 | struct lttng_ust_lfht *lttng_ust_lfht_new(unsigned long init_size, |
| 136 | unsigned long min_nr_alloc_buckets, |
| 137 | unsigned long max_nr_buckets, |
| 138 | int flags, |
| 139 | const struct lttng_ust_lfht_mm_type *mm); |
| 140 | |
| 141 | /* |
| 142 | * lttng_ust_lfht_destroy - destroy a hash table. |
| 143 | * @ht: the hash table to destroy. |
| 144 | * |
| 145 | * Return 0 on success, negative error value on error. |
| 146 | |
| 147 | * Prior to liburcu 0.10: |
| 148 | * - Threads calling this API need to be registered RCU read-side |
| 149 | * threads. |
| 150 | * - lttng_ust_lfht_destroy should *not* be called from a RCU read-side |
| 151 | * critical section. It should *not* be called from a call_rcu thread |
| 152 | * context neither. |
| 153 | * |
| 154 | * Starting from liburcu 0.10, rculfhash implements its own worker |
| 155 | * thread to handle resize operations, which removes RCU requirements on |
| 156 | * lttng_ust_lfht_destroy. |
| 157 | */ |
| 158 | extern |
| 159 | int lttng_ust_lfht_destroy(struct lttng_ust_lfht *ht); |
| 160 | |
| 161 | /* |
| 162 | * lttng_ust_lfht_count_nodes - count the number of nodes in the hash table. |
| 163 | * @ht: the hash table. |
| 164 | * @split_count_before: sample the node count split-counter before traversal. |
| 165 | * @count: traverse the hash table, count the number of nodes observed. |
| 166 | * @split_count_after: sample the node count split-counter after traversal. |
| 167 | * |
| 168 | * Call with rcu_read_lock held. |
| 169 | * Threads calling this API need to be registered RCU read-side threads. |
| 170 | */ |
| 171 | extern |
| 172 | void lttng_ust_lfht_count_nodes(struct lttng_ust_lfht *ht, |
| 173 | long *split_count_before, |
| 174 | unsigned long *count, |
| 175 | long *split_count_after); |
| 176 | |
| 177 | /* |
| 178 | * lttng_ust_lfht_lookup - lookup a node by key. |
| 179 | * @ht: the hash table. |
| 180 | * @hash: the key hash. |
| 181 | * @match: the key match function. |
| 182 | * @key: the current node key. |
| 183 | * @iter: node, if found (output). *iter->node set to NULL if not found. |
| 184 | * |
| 185 | * Call with rcu_read_lock held. |
| 186 | * Threads calling this API need to be registered RCU read-side threads. |
| 187 | * This function acts as a rcu_dereference() to read the node pointer. |
| 188 | */ |
| 189 | extern |
| 190 | void lttng_ust_lfht_lookup(struct lttng_ust_lfht *ht, unsigned long hash, |
| 191 | lttng_ust_lfht_match_fct match, const void *key, |
| 192 | struct lttng_ust_lfht_iter *iter); |
| 193 | |
| 194 | /* |
| 195 | * lttng_ust_lfht_next_duplicate - get the next item with same key, after iterator. |
| 196 | * @ht: the hash table. |
| 197 | * @match: the key match function. |
| 198 | * @key: the current node key. |
| 199 | * @iter: input: current iterator. |
| 200 | * output: node, if found. *iter->node set to NULL if not found. |
| 201 | * |
| 202 | * Uses an iterator initialized by a lookup or traversal. Important: the |
| 203 | * iterator _needs_ to be initialized before calling |
| 204 | * lttng_ust_lfht_next_duplicate. |
| 205 | * Sets *iter-node to the following node with same key. |
| 206 | * Sets *iter->node to NULL if no following node exists with same key. |
| 207 | * RCU read-side lock must be held across lttng_ust_lfht_lookup and |
| 208 | * lttng_ust_lfht_next calls, and also between lttng_ust_lfht_next calls using the |
| 209 | * node returned by a previous lttng_ust_lfht_next. |
| 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 lttng_ust_lfht_next_duplicate(struct lttng_ust_lfht *ht, |
| 216 | lttng_ust_lfht_match_fct match, const void *key, |
| 217 | struct lttng_ust_lfht_iter *iter); |
| 218 | |
| 219 | /* |
| 220 | * lttng_ust_lfht_first - get the first node in the table. |
| 221 | * @ht: the hash table. |
| 222 | * @iter: First node, if exists (output). *iter->node set to NULL if not found. |
| 223 | * |
| 224 | * Output in "*iter". *iter->node set to NULL if table is empty. |
| 225 | * Call with rcu_read_lock held. |
| 226 | * Threads calling this API need to be registered RCU read-side threads. |
| 227 | * This function acts as a rcu_dereference() to read the node pointer. |
| 228 | */ |
| 229 | extern |
| 230 | void lttng_ust_lfht_first(struct lttng_ust_lfht *ht, struct lttng_ust_lfht_iter *iter); |
| 231 | |
| 232 | /* |
| 233 | * lttng_ust_lfht_next - get the next node in the table. |
| 234 | * @ht: the hash table. |
| 235 | * @iter: input: current iterator. |
| 236 | * output: next node, if exists. *iter->node set to NULL if not found. |
| 237 | * |
| 238 | * Input/Output in "*iter". *iter->node set to NULL if *iter was |
| 239 | * pointing to the last table node. |
| 240 | * Call with rcu_read_lock held. |
| 241 | * Threads calling this API need to be registered RCU read-side threads. |
| 242 | * This function acts as a rcu_dereference() to read the node pointer. |
| 243 | */ |
| 244 | extern |
| 245 | void lttng_ust_lfht_next(struct lttng_ust_lfht *ht, struct lttng_ust_lfht_iter *iter); |
| 246 | |
| 247 | /* |
| 248 | * lttng_ust_lfht_add - add a node to the hash table. |
| 249 | * @ht: the hash table. |
| 250 | * @hash: the key hash. |
| 251 | * @node: the node to add. |
| 252 | * |
| 253 | * This function supports adding redundant keys into the table. |
| 254 | * Call with rcu_read_lock held. |
| 255 | * Threads calling this API need to be registered RCU read-side threads. |
| 256 | * This function issues a full memory barrier before and after its |
| 257 | * atomic commit. |
| 258 | */ |
| 259 | extern |
| 260 | void lttng_ust_lfht_add(struct lttng_ust_lfht *ht, unsigned long hash, |
| 261 | struct lttng_ust_lfht_node *node); |
| 262 | |
| 263 | /* |
| 264 | * lttng_ust_lfht_add_unique - add a node to hash table, if key is not present. |
| 265 | * @ht: the hash table. |
| 266 | * @hash: the node's hash. |
| 267 | * @match: the key match function. |
| 268 | * @key: the node's key. |
| 269 | * @node: the node to try adding. |
| 270 | * |
| 271 | * Return the node added upon success. |
| 272 | * Return the unique node already present upon failure. If |
| 273 | * lttng_ust_lfht_add_unique fails, the node passed as parameter should be |
| 274 | * freed by the caller. In this case, the caller does NOT need to wait |
| 275 | * for a grace period before freeing or re-using the node. |
| 276 | * Call with rcu_read_lock held. |
| 277 | * Threads calling this API need to be registered RCU read-side threads. |
| 278 | * |
| 279 | * The semantic of this function is that if only this function is used |
| 280 | * to add keys into the table, no duplicated keys should ever be |
| 281 | * observable in the table. The same guarantee apply for combination of |
| 282 | * add_unique and add_replace (see below). |
| 283 | * |
| 284 | * Upon success, this function issues a full memory barrier before and |
| 285 | * after its atomic commit. Upon failure, this function acts like a |
| 286 | * simple lookup operation: it acts as a rcu_dereference() to read the |
| 287 | * node pointer. The failure case does not guarantee any other memory |
| 288 | * barrier. |
| 289 | */ |
| 290 | extern |
| 291 | struct lttng_ust_lfht_node *lttng_ust_lfht_add_unique(struct lttng_ust_lfht *ht, |
| 292 | unsigned long hash, |
| 293 | lttng_ust_lfht_match_fct match, |
| 294 | const void *key, |
| 295 | struct lttng_ust_lfht_node *node); |
| 296 | |
| 297 | /* |
| 298 | * lttng_ust_lfht_add_replace - replace or add a node within hash table. |
| 299 | * @ht: the hash table. |
| 300 | * @hash: the node's hash. |
| 301 | * @match: the key match function. |
| 302 | * @key: the node's key. |
| 303 | * @node: the node to add. |
| 304 | * |
| 305 | * Return the node replaced upon success. If no node matching the key |
| 306 | * was present, return NULL, which also means the operation succeeded. |
| 307 | * This replacement operation should never fail. |
| 308 | * Call with rcu_read_lock held. |
| 309 | * Threads calling this API need to be registered RCU read-side threads. |
| 310 | * After successful replacement, a grace period must be waited for before |
| 311 | * freeing or re-using the memory reserved for the returned node. |
| 312 | * |
| 313 | * The semantic of replacement vs lookups and traversals is the |
| 314 | * following: if lookups and traversals are performed between a key |
| 315 | * unique insertion and its removal, we guarantee that the lookups and |
| 316 | * traversals will always find exactly one instance of the key if it is |
| 317 | * replaced concurrently with the lookups. |
| 318 | * |
| 319 | * Providing this semantic allows us to ensure that replacement-only |
| 320 | * schemes will never generate duplicated keys. It also allows us to |
| 321 | * guarantee that a combination of add_replace and add_unique updates |
| 322 | * will never generate duplicated keys. |
| 323 | * |
| 324 | * This function issues a full memory barrier before and after its |
| 325 | * atomic commit. |
| 326 | */ |
| 327 | extern |
| 328 | struct lttng_ust_lfht_node *lttng_ust_lfht_add_replace(struct lttng_ust_lfht *ht, |
| 329 | unsigned long hash, |
| 330 | lttng_ust_lfht_match_fct match, |
| 331 | const void *key, |
| 332 | struct lttng_ust_lfht_node *node); |
| 333 | |
| 334 | /* |
| 335 | * lttng_ust_lfht_replace - replace a node pointed to by iter within hash table. |
| 336 | * @ht: the hash table. |
| 337 | * @old_iter: the iterator position of the node to replace. |
| 338 | * @hash: the node's hash. |
| 339 | * @match: the key match function. |
| 340 | * @key: the node's key. |
| 341 | * @new_node: the new node to use as replacement. |
| 342 | * |
| 343 | * Return 0 if replacement is successful, negative value otherwise. |
| 344 | * Replacing a NULL old node or an already removed node will fail with |
| 345 | * -ENOENT. |
| 346 | * If the hash or value of the node to replace and the new node differ, |
| 347 | * this function returns -EINVAL without proceeding to the replacement. |
| 348 | * Old node can be looked up with lttng_ust_lfht_lookup and lttng_ust_lfht_next. |
| 349 | * RCU read-side lock must be held between lookup and replacement. |
| 350 | * Call with rcu_read_lock held. |
| 351 | * Threads calling this API need to be registered RCU read-side threads. |
| 352 | * After successful replacement, a grace period must be waited for before |
| 353 | * freeing or re-using the memory reserved for the old node (which can |
| 354 | * be accessed with lttng_ust_lfht_iter_get_node). |
| 355 | * |
| 356 | * The semantic of replacement vs lookups is the same as |
| 357 | * lttng_ust_lfht_add_replace(). |
| 358 | * |
| 359 | * Upon success, this function issues a full memory barrier before and |
| 360 | * after its atomic commit. Upon failure, this function does not issue |
| 361 | * any memory barrier. |
| 362 | */ |
| 363 | extern |
| 364 | int lttng_ust_lfht_replace(struct lttng_ust_lfht *ht, |
| 365 | struct lttng_ust_lfht_iter *old_iter, |
| 366 | unsigned long hash, |
| 367 | lttng_ust_lfht_match_fct match, |
| 368 | const void *key, |
| 369 | struct lttng_ust_lfht_node *new_node); |
| 370 | |
| 371 | /* |
| 372 | * lttng_ust_lfht_del - remove node pointed to by iterator from hash table. |
| 373 | * @ht: the hash table. |
| 374 | * @node: the node to delete. |
| 375 | * |
| 376 | * Return 0 if the node is successfully removed, negative value |
| 377 | * otherwise. |
| 378 | * Deleting a NULL node or an already removed node will fail with a |
| 379 | * negative value. |
| 380 | * Node can be looked up with lttng_ust_lfht_lookup and lttng_ust_lfht_next, |
| 381 | * followed by use of lttng_ust_lfht_iter_get_node. |
| 382 | * RCU read-side lock must be held between lookup and removal. |
| 383 | * Call with rcu_read_lock held. |
| 384 | * Threads calling this API need to be registered RCU read-side threads. |
| 385 | * After successful removal, a grace period must be waited for before |
| 386 | * freeing or re-using the memory reserved for old node (which can be |
| 387 | * accessed with lttng_ust_lfht_iter_get_node). |
| 388 | * Upon success, this function issues a full memory barrier before and |
| 389 | * after its atomic commit. Upon failure, this function does not issue |
| 390 | * any memory barrier. |
| 391 | */ |
| 392 | extern |
| 393 | int lttng_ust_lfht_del(struct lttng_ust_lfht *ht, struct lttng_ust_lfht_node *node); |
| 394 | |
| 395 | /* |
| 396 | * lttng_ust_lfht_is_node_deleted - query whether a node is removed from hash table. |
| 397 | * |
| 398 | * Return non-zero if the node is deleted from the hash table, 0 |
| 399 | * otherwise. |
| 400 | * Node can be looked up with lttng_ust_lfht_lookup and lttng_ust_lfht_next, |
| 401 | * followed by use of lttng_ust_lfht_iter_get_node. |
| 402 | * RCU read-side lock must be held between lookup and call to this |
| 403 | * function. |
| 404 | * Call with rcu_read_lock held. |
| 405 | * Threads calling this API need to be registered RCU read-side threads. |
| 406 | * This function does not issue any memory barrier. |
| 407 | */ |
| 408 | extern |
| 409 | int lttng_ust_lfht_is_node_deleted(const struct lttng_ust_lfht_node *node); |
| 410 | |
| 411 | /* |
| 412 | * lttng_ust_lfht_resize - Force a hash table resize |
| 413 | * @ht: the hash table. |
| 414 | * @new_size: update to this hash table size. |
| 415 | * |
| 416 | * Threads calling this API need to be registered RCU read-side threads. |
| 417 | * This function does not (necessarily) issue memory barriers. |
| 418 | * lttng_ust_lfht_resize should *not* be called from a RCU read-side critical |
| 419 | * section. |
| 420 | */ |
| 421 | extern |
| 422 | void lttng_ust_lfht_resize(struct lttng_ust_lfht *ht, unsigned long new_size); |
| 423 | |
| 424 | /* |
| 425 | * Note: it is safe to perform element removal (del), replacement, or |
| 426 | * any hash table update operation during any of the following hash |
| 427 | * table traversals. |
| 428 | * These functions act as rcu_dereference() to read the node pointers. |
| 429 | */ |
| 430 | #define lttng_ust_lfht_for_each(ht, iter, node) \ |
| 431 | for (lttng_ust_lfht_first(ht, iter), \ |
| 432 | node = lttng_ust_lfht_iter_get_node(iter); \ |
| 433 | node != NULL; \ |
| 434 | lttng_ust_lfht_next(ht, iter), \ |
| 435 | node = lttng_ust_lfht_iter_get_node(iter)) |
| 436 | |
| 437 | #define lttng_ust_lfht_for_each_duplicate(ht, hash, match, key, iter, node) \ |
| 438 | for (lttng_ust_lfht_lookup(ht, hash, match, key, iter), \ |
| 439 | node = lttng_ust_lfht_iter_get_node(iter); \ |
| 440 | node != NULL; \ |
| 441 | lttng_ust_lfht_next_duplicate(ht, match, key, iter), \ |
| 442 | node = lttng_ust_lfht_iter_get_node(iter)) |
| 443 | |
| 444 | #define lttng_ust_lfht_for_each_entry(ht, iter, pos, member) \ |
| 445 | for (lttng_ust_lfht_first(ht, 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(ht, iter), \ |
| 450 | pos = caa_container_of(lttng_ust_lfht_iter_get_node(iter), \ |
| 451 | __typeof__(*(pos)), member)) |
| 452 | |
| 453 | #define lttng_ust_lfht_for_each_entry_duplicate(ht, hash, match, key, \ |
| 454 | iter, pos, member) \ |
| 455 | for (lttng_ust_lfht_lookup(ht, hash, match, key, iter), \ |
| 456 | pos = caa_container_of(lttng_ust_lfht_iter_get_node(iter), \ |
| 457 | __typeof__(*(pos)), member); \ |
| 458 | lttng_ust_lfht_iter_get_node(iter) != NULL; \ |
| 459 | lttng_ust_lfht_next_duplicate(ht, match, key, iter), \ |
| 460 | pos = caa_container_of(lttng_ust_lfht_iter_get_node(iter), \ |
| 461 | __typeof__(*(pos)), member)) |
| 462 | |
| 463 | #ifdef __cplusplus |
| 464 | } |
| 465 | #endif |
| 466 | |
| 467 | #endif /* _LTTNG_UST_RCULFHASH_H */ |