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  * 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 #include <urcu-flavor.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 4-bytes boundaries because
  43  * the two lower bits are used as flags.
  44  *
  45  * struct cds_lfht_node can be embedded into a structure (as a field).
  46  * caa_container_of() can be used to get the structure from the struct
  47  * cds_lfht_node after a lookup.
  48  *
  49  * The structure which embeds it typically holds the key (or key-value
  50  * pair) of the object. The caller code is responsible for calculation
  51  * of the hash value for cds_lfht APIs.
  52  */
  53 struct cds_lfht_node {
  54         struct cds_lfht_node *next;     /* ptr | BUCKET_FLAG | REMOVED_FLAG */
  55         unsigned long reverse_hash;
  56 } __attribute__((aligned(4)));
  57
  58 /* cds_lfht_iter: Used to track state while traversing a hash chain. */
  59 struct cds_lfht_iter {
  60         struct cds_lfht_node *node, *next;
  61 };
  62
  63 static inline
  64 struct cds_lfht_node *cds_lfht_iter_get_node(struct cds_lfht_iter *iter)
  65 {
  66         return iter->node;
  67 }
  68
  69 struct cds_lfht;
  70
  71 /*
  72  * Caution !
  73  * Ensure reader and writer threads are registered as urcu readers.
  74  */
  75
  76 typedef int (*cds_lfht_match_fct)(struct cds_lfht_node *node, const void *key);
  77
  78 /*
  79  * cds_lfht_node_init - initialize a hash table node
  80  * @node: the node to initialize.
  81  *
  82  * This function is kept to be eventually used for debugging purposes
  83  * (detection of memory corruption).
  84  */
  85 static inline
  86 void cds_lfht_node_init(struct cds_lfht_node *node)
  87 {
  88 }
  89
  90 /*
  91  * Hash table creation flags.
  92  */
  93 enum {
  94         CDS_LFHT_AUTO_RESIZE = (1U << 0),
  95         CDS_LFHT_ACCOUNTING = (1U << 1),
  96 };
  97
  98 struct cds_lfht_mm_type {
  99         struct cds_lfht *(*alloc_cds_lfht)(unsigned long min_nr_alloc_buckets,
 100                         unsigned long max_nr_buckets);
 101         void (*alloc_bucket_table)(struct cds_lfht *ht, unsigned long order);
 102         void (*free_bucket_table)(struct cds_lfht *ht, unsigned long order);
 103         struct cds_lfht_node *(*bucket_at)(struct cds_lfht *ht,
 104                         unsigned long index);
 105 };
 106
 107 extern const struct cds_lfht_mm_type cds_lfht_mm_order;
 108
 109 /*
 110  * _cds_lfht_new - API used by cds_lfht_new wrapper. Do not use directly.
 111  */
 112 struct cds_lfht *_cds_lfht_new(unsigned long init_size,
 113                         unsigned long min_nr_alloc_buckets,
 114                         unsigned long max_nr_buckets,
 115                         int flags,
 116                         const struct cds_lfht_mm_type *mm,
 117                         const struct rcu_flavor_struct *flavor,
 118                         pthread_attr_t *attr);
 119
 120 /*
 121  * cds_lfht_new - allocate a hash table.
 122  * @init_size: number of buckets to allocate initially. Must be power of two.
 123  * @min_nr_alloc_buckets: the minimum number of allocated buckets.
 124  *                        (must be power of two)
 125  * @max_nr_buckets: the maximum number of hash table buckets allowed.
 126  *                  (must be power of two)
 127  * @flags: hash table creation flags (can be combined with bitwise or: '|').
 128  *           0: no flags.
 129  *           CDS_LFHT_AUTO_RESIZE: automatically resize hash table.
 130  *           CDS_LFHT_ACCOUNTING: count the number of node addition
 131  *                                and removal in the table
 132  * @attr: optional resize worker thread attributes. NULL for default.
 133  *
 134  * Return NULL on error.
 135  * Note: the RCU flavor must be already included before the hash table header.
 136  *
 137  * The programmer is responsible for ensuring that resize operation has a
 138  * priority equal to hash table updater threads. It should be performed by
 139  * specifying the appropriate priority in the pthread "attr" argument, and,
 140  * for CDS_LFHT_AUTO_RESIZE, by ensuring that call_rcu worker threads also have
 141  * this priority level. Having lower priority for call_rcu and resize threads
 142  * does not pose any correctness issue, but the resize operations could be
 143  * starved by updates, thus leading to long hash table bucket chains.
 144  * Threads calling this API are NOT required to be registered RCU read-side
 145  * threads. It can be called very early.(before rcu is initialized ...etc.)
 146  */
 147 static inline
 148 struct cds_lfht *cds_lfht_new(unsigned long init_size,
 149                         unsigned long min_nr_alloc_buckets,
 150                         unsigned long max_nr_buckets,
 151                         int flags,
 152                         pthread_attr_t *attr)
 153 {
 154         return _cds_lfht_new(init_size, min_nr_alloc_buckets, max_nr_buckets,
 155                         flags, &cds_lfht_mm_order, &rcu_flavor, attr);
 156 }
 157
 158 /*
 159  * cds_lfht_destroy - destroy a hash table.
 160  * @ht: the hash table to destroy.
 161  * @attr: (output) resize worker thread attributes, as received by cds_lfht_new.
 162  *        The caller will typically want to free this pointer if dynamically
 163  *        allocated. The attr point can be NULL if the caller does not
 164  *        need to be informed of the value passed to cds_lfht_new().
 165  *
 166  * Return 0 on success, negative error value on error.
 167  * Threads calling this API need to be registered RCU read-side threads.
 168  */
 169 int cds_lfht_destroy(struct cds_lfht *ht, pthread_attr_t **attr);
 170
 171 /*
 172  * cds_lfht_count_nodes - count the number of nodes in the hash table.
 173  * @ht: the hash table.
 174  * @split_count_before: Sample the node count split-counter before traversal.
 175  * @count: Traverse the hash table, count the number of nodes observed.
 176  * @removed: Number of logically removed nodes observed during traversal.
 177  * @split_count_after: Sample the node count split-counter after traversal.
 178  *
 179  * Call with rcu_read_lock held.
 180  * Threads calling this API need to be registered RCU read-side threads.
 181  */
 182 void cds_lfht_count_nodes(struct cds_lfht *ht,
 183                 long *split_count_before,
 184                 unsigned long *count,
 185                 unsigned long *removed,
 186                 long *split_count_after);
 187
 188 /*
 189  * cds_lfht_lookup - lookup a node by key.
 190  * @ht: the hash table.
 191  * @hash: the key hash.
 192  * @match: the key match function.
 193  * @key: the current node key.
 194  * @iter: Node, if found (output). *iter->node set to NULL if not found.
 195  *
 196  * Call with rcu_read_lock held.
 197  * Threads calling this API need to be registered RCU read-side threads.
 198  */
 199 void cds_lfht_lookup(struct cds_lfht *ht, unsigned long hash,
 200                 cds_lfht_match_fct match, const void *key,
 201                 struct cds_lfht_iter *iter);
 202
 203 /*
 204  * cds_lfht_next_duplicate - get the next item with same key (after a lookup).
 205  * @ht: the hash table.
 206  * @match: the key match function.
 207  * @key: the current node key.
 208  * @iter: Node, if found (output). *iter->node set to NULL if not found.
 209  *
 210  * Uses an iterator initialized by a lookup.
 211  * Sets *iter-node to the following node with same key.
 212  * Sets *iter->node to NULL if no following node exists with same key.
 213  * RCU read-side lock must be held across cds_lfht_lookup and
 214  * cds_lfht_next calls, and also between cds_lfht_next calls using the
 215  * node returned by a previous cds_lfht_next.
 216  * Call with rcu_read_lock held.
 217  * Threads calling this API need to be registered RCU read-side threads.
 218  */
 219 void cds_lfht_next_duplicate(struct cds_lfht *ht,
 220                 cds_lfht_match_fct match, const void *key,
 221                 struct cds_lfht_iter *iter);
 222
 223 /*
 224  * cds_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  */
 232 void cds_lfht_first(struct cds_lfht *ht, struct cds_lfht_iter *iter);
 233
 234 /*
 235  * cds_lfht_next - get the next node in the table.
 236  * @ht: the hash table.
 237  * @iter: Next node, if exists (output). *iter->node set to NULL if not found.
 238  *
 239  * Input/Output in "*iter". *iter->node set to NULL if *iter was
 240  * pointing to the last table node.
 241  * Call with rcu_read_lock held.
 242  * Threads calling this API need to be registered RCU read-side threads.
 243  */
 244 void cds_lfht_next(struct cds_lfht *ht, struct cds_lfht_iter *iter);
 245
 246 /*
 247  * cds_lfht_add - add a node to the hash table.
 248  * @ht: the hash table.
 249  * @hash: the key hash.
 250  * @node: the node to add.
 251  *
 252  * This function supports adding redundant keys into the table.
 253  * Call with rcu_read_lock held.
 254  * Threads calling this API need to be registered RCU read-side threads.
 255  */
 256 void cds_lfht_add(struct cds_lfht *ht, unsigned long hash,
 257                 struct cds_lfht_node *node);
 258
 259 /*
 260  * cds_lfht_add_unique - add a node to hash table, if key is not present.
 261  * @ht: the hash table.
 262  * @hash: the node's hash.
 263  * @match: the key match function.
 264  * @key: the node's key.
 265  * @node: the node to try adding.
 266  *
 267  * Return the node added upon success.
 268  * Return the unique node already present upon failure. If
 269  * cds_lfht_add_unique fails, the node passed as parameter should be
 270  * freed by the caller.
 271  * Call with rcu_read_lock held.
 272  * Threads calling this API need to be registered RCU read-side threads.
 273  *
 274  * The semantic of this function is that if only this function is used
 275  * to add keys into the table, no duplicated keys should ever be
 276  * observable in the table. The same guarantee apply for combination of
 277  * add_unique and add_replace (see below).
 278  */
 279 struct cds_lfht_node *cds_lfht_add_unique(struct cds_lfht *ht,
 280                 unsigned long hash,
 281                 cds_lfht_match_fct match,
 282                 const void *key,
 283                 struct cds_lfht_node *node);
 284
 285 /*
 286  * cds_lfht_add_replace - replace or add a node within hash table.
 287  * @ht: the hash table.
 288  * @hash: the node's hash.
 289  * @match: the key match function.
 290  * @key: the node's key.
 291  * @node: the node to add.
 292  *
 293  * Return the node replaced upon success. If no node matching the key
 294  * was present, return NULL, which also means the operation succeeded.
 295  * This replacement operation should never fail.
 296  * Call with rcu_read_lock held.
 297  * Threads calling this API need to be registered RCU read-side threads.
 298  * After successful replacement, a grace period must be waited for before
 299  * freeing the memory reserved for the returned node.
 300  *
 301  * The semantic of replacement vs lookups is the following: if lookups
 302  * are performed between a key unique insertion and its removal, we
 303  * guarantee that the lookups and get next will always find exactly one
 304  * instance of the key if it is replaced concurrently with the lookups.
 305  *
 306  * Providing this semantic allows us to ensure that replacement-only
 307  * schemes will never generate duplicated keys. It also allows us to
 308  * guarantee that a combination of add_replace and add_unique updates
 309  * will never generate duplicated keys.
 310  */
 311 struct cds_lfht_node *cds_lfht_add_replace(struct cds_lfht *ht,
 312                 unsigned long hash,
 313                 cds_lfht_match_fct match,
 314                 const void *key,
 315                 struct cds_lfht_node *node);
 316
 317 /*
 318  * cds_lfht_replace - replace a node pointer to by iter within hash table.
 319  * @ht: the hash table.
 320  * @old_iter: the iterator position of the node to replace.
 321  * @now_node: the new node to try using for replacement.
 322  *
 323  * Return 0 if replacement is successful, negative value otherwise.
 324  * Replacing a NULL old node or an already removed node will fail with a
 325  * negative value.
 326  * Old node can be looked up with cds_lfht_lookup and cds_lfht_next.
 327  * RCU read-side lock must be held between lookup and replacement.
 328  * Call with rcu_read_lock held.
 329  * Threads calling this API need to be registered RCU read-side threads.
 330  * After successful replacement, a grace period must be waited for before
 331  * freeing the memory reserved for the old node (which can be accessed
 332  * with cds_lfht_iter_get_node).
 333  *
 334  * The semantic of replacement vs lookups is the following: if lookups
 335  * are performed between a key unique insertion and its removal, we
 336  * guarantee that the lookups and get next will always find exactly one
 337  * instance of the key if it is replaced concurrently with the lookups.
 338  *
 339  * Providing this semantic allows us to ensure that replacement-only
 340  * schemes will never generate duplicated keys. It also allows us to
 341  * guarantee that a combination of add_replace and add_unique updates
 342  * will never generate duplicated keys.
 343  */
 344 int cds_lfht_replace(struct cds_lfht *ht, struct cds_lfht_iter *old_iter,
 345                 struct cds_lfht_node *new_node);
 346
 347 /*
 348  * cds_lfht_del - remove node pointed to by iterator from hash table.
 349  * @ht: the hash table.
 350  * @iter: the iterator position of the node to delete.
 351  *
 352  * Return 0 if the node is successfully removed, negative value
 353  * otherwise.
 354  * Replacing a NULL node or an already removed node will fail with a
 355  * negative value.
 356  * Node can be looked up with cds_lfht_lookup and cds_lfht_next.
 357  * cds_lfht_iter_get_node.
 358  * RCU read-side lock must be held between lookup and removal.
 359  * Call with rcu_read_lock held.
 360  * Threads calling this API need to be registered RCU read-side threads.
 361  * After successful removal, a grace period must be waited for before
 362  * freeing the memory reserved for old node (which can be accessed with
 363  * cds_lfht_iter_get_node).
 364  */
 365 int cds_lfht_del(struct cds_lfht *ht, struct cds_lfht_iter *iter);
 366
 367 /*
 368  * cds_lfht_resize - Force a hash table resize
 369  * @ht: the hash table.
 370  * @new_size: update to this hash table size.
 371  *
 372  * Threads calling this API need to be registered RCU read-side threads.
 373  */
 374 void cds_lfht_resize(struct cds_lfht *ht, unsigned long new_size);
 375
 376 /*
 377  * Note: cds_lfht_for_each are safe for element removal during
 378  * iteration.
 379  */
 380 #define cds_lfht_for_each(ht, iter, node)                               \
 381         for (cds_lfht_first(ht, iter),                                  \
 382                         node = cds_lfht_iter_get_node(iter);            \
 383                 node != NULL;                                           \
 384                 cds_lfht_next(ht, iter),                                \
 385                         node = cds_lfht_iter_get_node(iter))
 386
 387 #define cds_lfht_for_each_duplicate(ht, hash, match, key, iter, node)   \
 388         for (cds_lfht_lookup(ht, hash, match, key, iter),               \
 389                         node = cds_lfht_iter_get_node(iter);            \
 390                 node != NULL;                                           \
 391                 cds_lfht_next_duplicate(ht, match, key, iter),          \
 392                         node = cds_lfht_iter_get_node(iter))
 393
 394 #define cds_lfht_for_each_entry(ht, iter, pos, member)                  \
 395         for (cds_lfht_first(ht, iter),                                  \
 396                         pos = caa_container_of(cds_lfht_iter_get_node(iter), \
 397                                         typeof(*(pos)), member);        \
 398                 &(pos)->member != NULL;                                 \
 399                 cds_lfht_next(ht, iter),                                \
 400                         pos = caa_container_of(cds_lfht_iter_get_node(iter), \
 401                                         typeof(*(pos)), member))
 402
 403 #define cds_lfht_for_each_entry_duplicate(ht, hash, match, key,         \
 404                                 iter, pos, member)                      \
 405         for (cds_lfht_lookup(ht, hash, match, key, iter),               \
 406                         pos = caa_container_of(cds_lfht_iter_get_node(iter), \
 407                                         typeof(*(pos)), member);        \
 408                 &(pos)->member != NULL;                                 \
 409                 cds_lfht_next_duplicate(ht, match, key, iter),          \
 410                         pos = caa_container_of(cds_lfht_iter_get_node(iter), \
 411                                         typeof(*(pos)), member))
 412
 413 #ifdef __cplusplus
 414 }
 415 #endif
 416
 417 #endif /* _URCU_RCULFHASH_H */