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  *
  11  * This library is free software; you can redistribute it and/or
  12  * modify it under the terms of the GNU Lesser General Public
  13  * License as published by the Free Software Foundation; either
  14  * version 2.1 of the License, or (at your option) any later version.
  15  *
  16  * This library is distributed in the hope that it will be useful,
  17  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  18  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  19  * Lesser General Public License for more details.
  20  *
  21  * You should have received a copy of the GNU Lesser General Public
  22  * License along with this library; if not, write to the Free Software
  23  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  24  */
  25
  26 #include <stdint.h>
  27 #include <urcu-call-rcu.h>
  28
  29 #ifdef __cplusplus
  30 extern "C" {
  31 #endif
  32
  33 /*
  34  * struct cds_lfht_node and struct _cds_lfht_node should be aligned on
  35  * 4-bytes boundaries because the two lower bits are used as flags.
  36  */
  37
  38 struct _cds_lfht_node {
  39         struct cds_lfht_node *next;     /* ptr | DUMMY_FLAG | REMOVED_FLAG */
  40         unsigned long reverse_hash;
  41 };
  42
  43 struct cds_lfht_node {
  44         /* cache-hot for iteration */
  45         struct _cds_lfht_node p;          /* needs to be first field */
  46         void *key;
  47         unsigned int key_len;
  48         /* cache-cold for iteration */
  49         struct rcu_head head;
  50 };
  51
  52 struct cds_lfht;
  53
  54 /*
  55  * Caution !
  56  * Ensure reader and writer threads are registered as urcu readers.
  57  */
  58
  59 typedef unsigned long (*cds_lfht_hash_fct)(void *key, size_t length,
  60                                         unsigned long seed);
  61 typedef unsigned long (*cds_lfht_compare_fct)(void *key1, size_t key1_len,
  62                                         void *key2, size_t key2_len);
  63
  64 /*
  65  * cds_lfht_node_init - initialize a hash table node
  66  */
  67 static inline
  68 void cds_lfht_node_init(struct cds_lfht_node *node, void *key,
  69                         size_t key_len)
  70 {
  71         node->key = key;
  72         node->key_len = key_len;
  73 }
  74
  75 /*
  76  * Hash table creation flags.
  77  */
  78 enum {
  79         CDS_LFHT_AUTO_RESIZE = (1U << 0),
  80 };
  81
  82 /*
  83  * _cds_lfht_new - API used by cds_lfht_new wrapper. Do not use directly.
  84  */
  85 struct cds_lfht *_cds_lfht_new(cds_lfht_hash_fct hash_fct,
  86                         cds_lfht_compare_fct compare_fct,
  87                         unsigned long hash_seed,
  88                         unsigned long init_size,
  89                         int flags,
  90                         void (*cds_lfht_call_rcu)(struct rcu_head *head,
  91                                 void (*func)(struct rcu_head *head)),
  92                         void (*cds_lfht_synchronize_rcu)(void),
  93                         void (*cds_lfht_rcu_read_lock)(void),
  94                         void (*cds_lfht_rcu_read_unlock)(void),
  95                         void (*cds_lfht_rcu_thread_offline)(void),
  96                         void (*cds_lfht_rcu_thread_online)(void));
  97
  98 /*
  99  * cds_lfht_new - allocate a hash table.
 100  *
 101  * init_size must be power of two.
 102  * Return NULL on error.
 103  * Note: the RCU flavor must be already included before the hash table header.
 104  */
 105 static inline
 106 struct cds_lfht *cds_lfht_new(cds_lfht_hash_fct hash_fct,
 107                         cds_lfht_compare_fct compare_fct,
 108                         unsigned long hash_seed,
 109                         unsigned long init_size,
 110                         int flags)
 111 {
 112         return _cds_lfht_new(hash_fct, compare_fct, hash_seed,
 113                         init_size, flags,
 114                         call_rcu, synchronize_rcu, rcu_read_lock,
 115                         rcu_read_unlock, rcu_thread_offline,
 116                         rcu_thread_online);
 117 }
 118
 119 /*
 120  * cds_lfht_destroy - destroy a hash table.
 121  *
 122  * Return 0 on success, negative error value on error.
 123  */
 124 int cds_lfht_destroy(struct cds_lfht *ht);
 125
 126 /*
 127  * cds_lfht_count_nodes - count the number of nodes in the hash table.
 128  *
 129  * Call with rcu_read_lock held.
 130  */
 131 void cds_lfht_count_nodes(struct cds_lfht *ht,
 132                         unsigned long *count,
 133                         unsigned long *removed);
 134
 135 /*
 136  * cds_lfht_lookup - lookup a node by key.
 137  *
 138  * Return NULL if not found.
 139  * Call with rcu_read_lock held.
 140  */
 141 struct cds_lfht_node *cds_lfht_lookup(struct cds_lfht *ht, void *key, size_t key_len);
 142
 143 /*
 144  * cds_lfht_next - get the next item with same key (after a lookup).
 145  *
 146  * Return NULL if no following node exists with same key.
 147  * RCU read-side lock must be held across cds_lfht_lookup and cds_lfht_next calls, and also
 148  * between cds_lfht_next calls using the node returned by a previous cds_lfht_next.
 149  * Call with rcu_read_lock held.
 150  */
 151 struct cds_lfht_node *cds_lfht_next(struct cds_lfht *ht, struct cds_lfht_node *node);
 152
 153 /*
 154  * cds_lfht_add - add a node to the hash table.
 155  *
 156  * Call with rcu_read_lock held.
 157  */
 158 void cds_lfht_add(struct cds_lfht *ht, struct cds_lfht_node *node);
 159
 160 /*
 161  * cds_lfht_add_unique - add a node to hash table, if key is not present.
 162  *
 163  * Return the node added upon success.
 164  * Return the unique node already present upon failure. If cds_lfht_add_unique fails,
 165  * the node passed as parameter should be freed by the caller.
 166  * Call with rcu_read_lock held.
 167  */
 168 struct cds_lfht_node *cds_lfht_add_unique(struct cds_lfht *ht, struct cds_lfht_node *node);
 169
 170 /*
 171  * cds_lfht_remove - remove node from hash table.
 172  *
 173  * Node can be looked up with cds_lfht_lookup. RCU read-side lock must be held between
 174  * lookup and removal.
 175  * Call with rcu_read_lock held.
 176  */
 177 int cds_lfht_remove(struct cds_lfht *ht, struct cds_lfht_node *node);
 178
 179 /*
 180  * cds_lfht_resize - Force a hash table resize
 181  * @new_size: update to this hash table size.
 182  */
 183 void cds_lfht_resize(struct cds_lfht *ht, unsigned long new_size);
 184
 185 #ifdef __cplusplus
 186 }
 187 #endif
 188
 189 #endif /* _URCU_RCULFHASH_H */