liblttng-ust/rculfhash.h

   1 /*
   2  * SPDX-License-Identifier: LGPL-2.1-or-later
   3  *
   4  * Copyright 2011 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   5  * Copyright 2011 Lai Jiangshan <laijs@cn.fujitsu.com>
   6  *
   7  * Userspace RCU library - Lock-Free RCU Hash Table
   8  */
   9
  10 #ifndef _LTTNG_UST_RCULFHASH_H
  11 #define _LTTNG_UST_RCULFHASH_H
  12
  13 #include <stdint.h>
  14 #include <pthread.h>
  15 #include <urcu/compiler.h>
  16 #include "helper.h"
  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
 100 LTTNG_HIDDEN
 101 extern const struct lttng_ust_lfht_mm_type lttng_ust_lfht_mm_order;
 102 LTTNG_HIDDEN
 103 extern const struct lttng_ust_lfht_mm_type lttng_ust_lfht_mm_chunk;
 104 LTTNG_HIDDEN
 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  */
 124 LTTNG_HIDDEN
 125 extern struct lttng_ust_lfht *lttng_ust_lfht_new(unsigned long init_size,
 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  */
 148 LTTNG_HIDDEN
 149 extern int lttng_ust_lfht_destroy(struct lttng_ust_lfht *ht);
 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  */
 161 LTTNG_HIDDEN
 162 extern void lttng_ust_lfht_count_nodes(struct lttng_ust_lfht *ht,
 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  */
 179 LTTNG_HIDDEN
 180 extern void lttng_ust_lfht_lookup(struct lttng_ust_lfht *ht, unsigned long hash,
 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  */
 204 LTTNG_HIDDEN
 205 extern void lttng_ust_lfht_next_duplicate(struct lttng_ust_lfht *ht,
 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  */
 219 LTTNG_HIDDEN
 220 extern void lttng_ust_lfht_first(struct lttng_ust_lfht *ht, struct lttng_ust_lfht_iter *iter);
 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  */
 234 LTTNG_HIDDEN
 235 extern void lttng_ust_lfht_next(struct lttng_ust_lfht *ht, struct lttng_ust_lfht_iter *iter);
 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  */
 249 LTTNG_HIDDEN
 250 extern void lttng_ust_lfht_add(struct lttng_ust_lfht *ht, unsigned long hash,
 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  */
 280 LTTNG_HIDDEN
 281 extern struct lttng_ust_lfht_node *lttng_ust_lfht_add_unique(struct lttng_ust_lfht *ht,
 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  */
 317 LTTNG_HIDDEN
 318 extern struct lttng_ust_lfht_node *lttng_ust_lfht_add_replace(struct lttng_ust_lfht *ht,
 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  */
 353 LTTNG_HIDDEN
 354 extern int lttng_ust_lfht_replace(struct lttng_ust_lfht *ht,
 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  */
 382 LTTNG_HIDDEN
 383 extern int lttng_ust_lfht_del(struct lttng_ust_lfht *ht, struct lttng_ust_lfht_node *node);
 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  */
 398 LTTNG_HIDDEN
 399 extern int lttng_ust_lfht_is_node_deleted(const struct lttng_ust_lfht_node *node);
 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  */
 411 LTTNG_HIDDEN
 412 extern void lttng_ust_lfht_resize(struct lttng_ust_lfht *ht, unsigned long new_size);
 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 */