liblttng-ust/rculfhash.h

   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 #include "helper.h"
  31
  32 #ifdef __cplusplus
  33 extern "C" {
  34 #endif
  35
  36 struct lttng_ust_lfht;
  37
  38 /*
  39  * lttng_ust_lfht_node: Contains the next pointers and reverse-hash
  40  * value required for lookup and traversal of the hash table.
  41  *
  42  * struct lttng_ust_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 lttng_ust_lfht_node is 8 bytes on
  49  * 32-bit architectures, we choose to go for simplicity and reserve
  50  * three bits.
  51  *
  52  * struct lttng_ust_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  * lttng_ust_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 lttng_ust_lfht APIs.
  59  */
  60 struct lttng_ust_lfht_node {
  61         struct lttng_ust_lfht_node *next;       /* ptr | REMOVAL_OWNER_FLAG | BUCKET_FLAG | REMOVED_FLAG */
  62         unsigned long reverse_hash;
  63 } __attribute__((aligned(8)));
  64
  65 /* lttng_ust_lfht_iter: Used to track state while traversing a hash chain. */
  66 struct lttng_ust_lfht_iter {
  67         struct lttng_ust_lfht_node *node, *next;
  68 };
  69
  70 static inline
  71 struct lttng_ust_lfht_node *lttng_ust_lfht_iter_get_node(struct lttng_ust_lfht_iter *iter)
  72 {
  73         return iter->node;
  74 }
  75
  76 struct rcu_flavor_struct;
  77
  78 /*
  79  * Caution !
  80  * Ensure reader and writer threads are registered as urcu readers.
  81  */
  82
  83 typedef int (*lttng_ust_lfht_match_fct)(struct lttng_ust_lfht_node *node, const void *key);
  84
  85 /*
  86  * lttng_ust_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 lttng_ust_lfht_node_init(struct lttng_ust_lfht_node *node)
  94 {
  95 }
  96
  97 /*
  98  * Hash table creation flags.
  99  */
 100 enum {
 101         LTTNG_UST_LFHT_AUTO_RESIZE = (1U << 0),
 102         LTTNG_UST_LFHT_ACCOUNTING = (1U << 1),
 103 };
 104
 105 struct lttng_ust_lfht_mm_type {
 106         struct lttng_ust_lfht *(*alloc_lttng_ust_lfht)(unsigned long min_nr_alloc_buckets,
 107                         unsigned long max_nr_buckets);
 108         void (*alloc_bucket_table)(struct lttng_ust_lfht *ht, unsigned long order);
 109         void (*free_bucket_table)(struct lttng_ust_lfht *ht, unsigned long order);
 110         struct lttng_ust_lfht_node *(*bucket_at)(struct lttng_ust_lfht *ht,
 111                         unsigned long index);
 112 };
 113
 114 LTTNG_HIDDEN
 115 extern const struct lttng_ust_lfht_mm_type lttng_ust_lfht_mm_order;
 116 LTTNG_HIDDEN
 117 extern const struct lttng_ust_lfht_mm_type lttng_ust_lfht_mm_chunk;
 118 LTTNG_HIDDEN
 119 extern const struct lttng_ust_lfht_mm_type lttng_ust_lfht_mm_mmap;
 120
 121 /*
 122  * lttng_ust_lfht_new - allocate a hash table.
 123  * @init_size: number of buckets to allocate initially. Must be power of two.
 124  * @min_nr_alloc_buckets: the minimum number of allocated buckets.
 125  *                        (must be power of two)
 126  * @max_nr_buckets: the maximum number of hash table buckets allowed.
 127  *                  (must be power of two, 0 is accepted, means
 128  *                  "infinite")
 129  * @flags: hash table creation flags (can be combined with bitwise or: '|').
 130  *           0: no flags.
 131  *           LTTNG_UST_LFHT_AUTO_RESIZE: automatically resize hash table.
 132  *           LTTNG_UST_LFHT_ACCOUNTING: count the number of node addition
 133  *                                and removal in the table
 134  *
 135  * Return NULL on error.
 136  * Note: the RCU flavor must be already included before the hash table header.
 137  */
 138 LTTNG_HIDDEN
 139 extern struct lttng_ust_lfht *lttng_ust_lfht_new(unsigned long init_size,
 140                         unsigned long min_nr_alloc_buckets,
 141                         unsigned long max_nr_buckets,
 142                         int flags,
 143                         const struct lttng_ust_lfht_mm_type *mm);
 144
 145 /*
 146  * lttng_ust_lfht_destroy - destroy a hash table.
 147  * @ht: the hash table to destroy.
 148  *
 149  * Return 0 on success, negative error value on error.
 150
 151  * Prior to liburcu 0.10:
 152  * - Threads calling this API need to be registered RCU read-side
 153  *   threads.
 154  * - lttng_ust_lfht_destroy should *not* be called from a RCU read-side
 155  *   critical section. It should *not* be called from a call_rcu thread
 156  *   context neither.
 157  *
 158  * Starting from liburcu 0.10, rculfhash implements its own worker
 159  * thread to handle resize operations, which removes RCU requirements on
 160  * lttng_ust_lfht_destroy.
 161  */
 162 LTTNG_HIDDEN
 163 extern int lttng_ust_lfht_destroy(struct lttng_ust_lfht *ht);
 164
 165 /*
 166  * lttng_ust_lfht_count_nodes - count the number of nodes in the hash table.
 167  * @ht: the hash table.
 168  * @split_count_before: sample the node count split-counter before traversal.
 169  * @count: traverse the hash table, count the number of nodes observed.
 170  * @split_count_after: sample the node count split-counter after traversal.
 171  *
 172  * Call with rcu_read_lock held.
 173  * Threads calling this API need to be registered RCU read-side threads.
 174  */
 175 LTTNG_HIDDEN
 176 extern void lttng_ust_lfht_count_nodes(struct lttng_ust_lfht *ht,
 177                 long *split_count_before,
 178                 unsigned long *count,
 179                 long *split_count_after);
 180
 181 /*
 182  * lttng_ust_lfht_lookup - lookup a node by key.
 183  * @ht: the hash table.
 184  * @hash: the key hash.
 185  * @match: the key match function.
 186  * @key: the current node key.
 187  * @iter: node, if found (output). *iter->node set to NULL if not found.
 188  *
 189  * Call with rcu_read_lock held.
 190  * Threads calling this API need to be registered RCU read-side threads.
 191  * This function acts as a rcu_dereference() to read the node pointer.
 192  */
 193 LTTNG_HIDDEN
 194 extern void lttng_ust_lfht_lookup(struct lttng_ust_lfht *ht, unsigned long hash,
 195                 lttng_ust_lfht_match_fct match, const void *key,
 196                 struct lttng_ust_lfht_iter *iter);
 197
 198 /*
 199  * lttng_ust_lfht_next_duplicate - get the next item with same key, after iterator.
 200  * @ht: the hash table.
 201  * @match: the key match function.
 202  * @key: the current node key.
 203  * @iter: input: current iterator.
 204  *        output: node, if found. *iter->node set to NULL if not found.
 205  *
 206  * Uses an iterator initialized by a lookup or traversal. Important: the
 207  * iterator _needs_ to be initialized before calling
 208  * lttng_ust_lfht_next_duplicate.
 209  * Sets *iter-node to the following node with same key.
 210  * Sets *iter->node to NULL if no following node exists with same key.
 211  * RCU read-side lock must be held across lttng_ust_lfht_lookup and
 212  * lttng_ust_lfht_next calls, and also between lttng_ust_lfht_next calls using the
 213  * node returned by a previous lttng_ust_lfht_next.
 214  * Call with rcu_read_lock held.
 215  * Threads calling this API need to be registered RCU read-side threads.
 216  * This function acts as a rcu_dereference() to read the node pointer.
 217  */
 218 LTTNG_HIDDEN
 219 extern void lttng_ust_lfht_next_duplicate(struct lttng_ust_lfht *ht,
 220                 lttng_ust_lfht_match_fct match, const void *key,
 221                 struct lttng_ust_lfht_iter *iter);
 222
 223 /*
 224  * lttng_ust_lfht_first - get the first node in the table.
 225  * @ht: the hash table.
 226  * @iter: First node, if exists (output). *iter->node set to NULL if not found.
 227  *
 228  * Output in "*iter". *iter->node set to NULL if table is empty.
 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 LTTNG_HIDDEN
 234 extern void lttng_ust_lfht_first(struct lttng_ust_lfht *ht, struct lttng_ust_lfht_iter *iter);
 235
 236 /*
 237  * lttng_ust_lfht_next - get the next node in the table.
 238  * @ht: the hash table.
 239  * @iter: input: current iterator.
 240  *        output: next node, if exists. *iter->node set to NULL if not found.
 241  *
 242  * Input/Output in "*iter". *iter->node set to NULL if *iter was
 243  * pointing to the last table node.
 244  * Call with rcu_read_lock held.
 245  * Threads calling this API need to be registered RCU read-side threads.
 246  * This function acts as a rcu_dereference() to read the node pointer.
 247  */
 248 LTTNG_HIDDEN
 249 extern void lttng_ust_lfht_next(struct lttng_ust_lfht *ht, struct lttng_ust_lfht_iter *iter);
 250
 251 /*
 252  * lttng_ust_lfht_add - add a node to the hash table.
 253  * @ht: the hash table.
 254  * @hash: the key hash.
 255  * @node: the node to add.
 256  *
 257  * This function supports adding redundant keys into the table.
 258  * Call with rcu_read_lock held.
 259  * Threads calling this API need to be registered RCU read-side threads.
 260  * This function issues a full memory barrier before and after its
 261  * atomic commit.
 262  */
 263 LTTNG_HIDDEN
 264 extern void lttng_ust_lfht_add(struct lttng_ust_lfht *ht, unsigned long hash,
 265                 struct lttng_ust_lfht_node *node);
 266
 267 /*
 268  * lttng_ust_lfht_add_unique - add a node to hash table, if key is not present.
 269  * @ht: the hash table.
 270  * @hash: the node's hash.
 271  * @match: the key match function.
 272  * @key: the node's key.
 273  * @node: the node to try adding.
 274  *
 275  * Return the node added upon success.
 276  * Return the unique node already present upon failure. If
 277  * lttng_ust_lfht_add_unique fails, the node passed as parameter should be
 278  * freed by the caller. In this case, the caller does NOT need to wait
 279  * for a grace period before freeing or re-using the node.
 280  * Call with rcu_read_lock held.
 281  * Threads calling this API need to be registered RCU read-side threads.
 282  *
 283  * The semantic of this function is that if only this function is used
 284  * to add keys into the table, no duplicated keys should ever be
 285  * observable in the table. The same guarantee apply for combination of
 286  * add_unique and add_replace (see below).
 287  *
 288  * Upon success, this function issues a full memory barrier before and
 289  * after its atomic commit. Upon failure, this function acts like a
 290  * simple lookup operation: it acts as a rcu_dereference() to read the
 291  * node pointer. The failure case does not guarantee any other memory
 292  * barrier.
 293  */
 294 LTTNG_HIDDEN
 295 extern struct lttng_ust_lfht_node *lttng_ust_lfht_add_unique(struct lttng_ust_lfht *ht,
 296                 unsigned long hash,
 297                 lttng_ust_lfht_match_fct match,
 298                 const void *key,
 299                 struct lttng_ust_lfht_node *node);
 300
 301 /*
 302  * lttng_ust_lfht_add_replace - replace or add a node within hash table.
 303  * @ht: the hash table.
 304  * @hash: the node's hash.
 305  * @match: the key match function.
 306  * @key: the node's key.
 307  * @node: the node to add.
 308  *
 309  * Return the node replaced upon success. If no node matching the key
 310  * was present, return NULL, which also means the operation succeeded.
 311  * This replacement operation should never fail.
 312  * Call with rcu_read_lock held.
 313  * Threads calling this API need to be registered RCU read-side threads.
 314  * After successful replacement, a grace period must be waited for before
 315  * freeing or re-using the memory reserved for the returned node.
 316  *
 317  * The semantic of replacement vs lookups and traversals is the
 318  * following: if lookups and traversals are performed between a key
 319  * unique insertion and its removal, we guarantee that the lookups and
 320  * traversals will always find exactly one instance of the key if it is
 321  * replaced concurrently with the lookups.
 322  *
 323  * Providing this semantic allows us to ensure that replacement-only
 324  * schemes will never generate duplicated keys. It also allows us to
 325  * guarantee that a combination of add_replace and add_unique updates
 326  * will never generate duplicated keys.
 327  *
 328  * This function issues a full memory barrier before and after its
 329  * atomic commit.
 330  */
 331 LTTNG_HIDDEN
 332 extern struct lttng_ust_lfht_node *lttng_ust_lfht_add_replace(struct lttng_ust_lfht *ht,
 333                 unsigned long hash,
 334                 lttng_ust_lfht_match_fct match,
 335                 const void *key,
 336                 struct lttng_ust_lfht_node *node);
 337
 338 /*
 339  * lttng_ust_lfht_replace - replace a node pointed to by iter within hash table.
 340  * @ht: the hash table.
 341  * @old_iter: the iterator position of the node to replace.
 342  * @hash: the node's hash.
 343  * @match: the key match function.
 344  * @key: the node's key.
 345  * @new_node: the new node to use as replacement.
 346  *
 347  * Return 0 if replacement is successful, negative value otherwise.
 348  * Replacing a NULL old node or an already removed node will fail with
 349  * -ENOENT.
 350  * If the hash or value of the node to replace and the new node differ,
 351  * this function returns -EINVAL without proceeding to the replacement.
 352  * Old node can be looked up with lttng_ust_lfht_lookup and lttng_ust_lfht_next.
 353  * RCU read-side lock must be held between lookup and replacement.
 354  * Call with rcu_read_lock held.
 355  * Threads calling this API need to be registered RCU read-side threads.
 356  * After successful replacement, a grace period must be waited for before
 357  * freeing or re-using the memory reserved for the old node (which can
 358  * be accessed with lttng_ust_lfht_iter_get_node).
 359  *
 360  * The semantic of replacement vs lookups is the same as
 361  * lttng_ust_lfht_add_replace().
 362  *
 363  * Upon success, this function issues a full memory barrier before and
 364  * after its atomic commit. Upon failure, this function does not issue
 365  * any memory barrier.
 366  */
 367 LTTNG_HIDDEN
 368 extern int lttng_ust_lfht_replace(struct lttng_ust_lfht *ht,
 369                 struct lttng_ust_lfht_iter *old_iter,
 370                 unsigned long hash,
 371                 lttng_ust_lfht_match_fct match,
 372                 const void *key,
 373                 struct lttng_ust_lfht_node *new_node);
 374
 375 /*
 376  * lttng_ust_lfht_del - remove node pointed to by iterator from hash table.
 377  * @ht: the hash table.
 378  * @node: the node to delete.
 379  *
 380  * Return 0 if the node is successfully removed, negative value
 381  * otherwise.
 382  * Deleting a NULL node or an already removed node will fail with a
 383  * negative value.
 384  * Node can be looked up with lttng_ust_lfht_lookup and lttng_ust_lfht_next,
 385  * followed by use of lttng_ust_lfht_iter_get_node.
 386  * RCU read-side lock must be held between lookup and removal.
 387  * Call with rcu_read_lock held.
 388  * Threads calling this API need to be registered RCU read-side threads.
 389  * After successful removal, a grace period must be waited for before
 390  * freeing or re-using the memory reserved for old node (which can be
 391  * accessed with lttng_ust_lfht_iter_get_node).
 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 LTTNG_HIDDEN
 397 extern int lttng_ust_lfht_del(struct lttng_ust_lfht *ht, struct lttng_ust_lfht_node *node);
 398
 399 /*
 400  * lttng_ust_lfht_is_node_deleted - query whether a node is removed from hash table.
 401  *
 402  * Return non-zero if the node is deleted from the hash table, 0
 403  * otherwise.
 404  * Node can be looked up with lttng_ust_lfht_lookup and lttng_ust_lfht_next,
 405  * followed by use of lttng_ust_lfht_iter_get_node.
 406  * RCU read-side lock must be held between lookup and call to this
 407  * function.
 408  * Call with rcu_read_lock held.
 409  * Threads calling this API need to be registered RCU read-side threads.
 410  * This function does not issue any memory barrier.
 411  */
 412 LTTNG_HIDDEN
 413 extern int lttng_ust_lfht_is_node_deleted(const struct lttng_ust_lfht_node *node);
 414
 415 /*
 416  * lttng_ust_lfht_resize - Force a hash table resize
 417  * @ht: the hash table.
 418  * @new_size: update to this hash table size.
 419  *
 420  * Threads calling this API need to be registered RCU read-side threads.
 421  * This function does not (necessarily) issue memory barriers.
 422  * lttng_ust_lfht_resize should *not* be called from a RCU read-side critical
 423  * section.
 424  */
 425 LTTNG_HIDDEN
 426 extern void lttng_ust_lfht_resize(struct lttng_ust_lfht *ht, unsigned long new_size);
 427
 428 /*
 429  * Note: it is safe to perform element removal (del), replacement, or
 430  * any hash table update operation during any of the following hash
 431  * table traversals.
 432  * These functions act as rcu_dereference() to read the node pointers.
 433  */
 434 #define lttng_ust_lfht_for_each(ht, iter, node)                         \
 435         for (lttng_ust_lfht_first(ht, iter),                                    \
 436                         node = lttng_ust_lfht_iter_get_node(iter);              \
 437                 node != NULL;                                           \
 438                 lttng_ust_lfht_next(ht, iter),                          \
 439                         node = lttng_ust_lfht_iter_get_node(iter))
 440
 441 #define lttng_ust_lfht_for_each_duplicate(ht, hash, match, key, iter, node)     \
 442         for (lttng_ust_lfht_lookup(ht, hash, match, key, iter),         \
 443                         node = lttng_ust_lfht_iter_get_node(iter);              \
 444                 node != NULL;                                           \
 445                 lttng_ust_lfht_next_duplicate(ht, match, key, iter),            \
 446                         node = lttng_ust_lfht_iter_get_node(iter))
 447
 448 #define lttng_ust_lfht_for_each_entry(ht, iter, pos, member)                    \
 449         for (lttng_ust_lfht_first(ht, iter),                                    \
 450                         pos = caa_container_of(lttng_ust_lfht_iter_get_node(iter), \
 451                                         __typeof__(*(pos)), member);    \
 452                 lttng_ust_lfht_iter_get_node(iter) != NULL;                     \
 453                 lttng_ust_lfht_next(ht, iter),                          \
 454                         pos = caa_container_of(lttng_ust_lfht_iter_get_node(iter), \
 455                                         __typeof__(*(pos)), member))
 456
 457 #define lttng_ust_lfht_for_each_entry_duplicate(ht, hash, match, key,           \
 458                                 iter, pos, member)                      \
 459         for (lttng_ust_lfht_lookup(ht, hash, match, key, iter),         \
 460                         pos = caa_container_of(lttng_ust_lfht_iter_get_node(iter), \
 461                                         __typeof__(*(pos)), member);    \
 462                 lttng_ust_lfht_iter_get_node(iter) != NULL;                     \
 463                 lttng_ust_lfht_next_duplicate(ht, match, key, iter),            \
 464                         pos = caa_container_of(lttng_ust_lfht_iter_get_node(iter), \
 465                                         __typeof__(*(pos)), member))
 466
 467 #ifdef __cplusplus
 468 }
 469 #endif
 470
 471 #endif /* _LTTNG_UST_RCULFHASH_H */