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