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  * Include this file _after_ including your URCU flavor.
  26  */
  27
  28 #include <stdint.h>
  29 #include <urcu-call-rcu.h>
  30
  31 #ifdef __cplusplus
  32 extern "C" {
  33 #endif
  34
  35 /*
  36  * struct cds_lfht_node and struct _cds_lfht_node should be aligned on
  37  * 4-bytes boundaries because the two lower bits are used as flags.
  38  */
  39
  40 struct _cds_lfht_node {
  41         struct cds_lfht_node *next;     /* ptr | DUMMY_FLAG | REMOVED_FLAG */
  42         unsigned long reverse_hash;
  43 };
  44
  45 struct cds_lfht_node {
  46         /* cache-hot for iteration */
  47         struct _cds_lfht_node p;          /* needs to be first field */
  48         void *key;
  49         unsigned int key_len;
  50         /* cache-cold for iteration */
  51         struct rcu_head head;
  52 };
  53
  54 struct cds_lfht;
  55
  56 /*
  57  * Caution !
  58  * Ensure reader and writer threads are registered as urcu readers.
  59  */
  60
  61 typedef unsigned long (*cds_lfht_hash_fct)(void *key, size_t length,
  62                                         unsigned long seed);
  63 typedef unsigned long (*cds_lfht_compare_fct)(void *key1, size_t key1_len,
  64                                         void *key2, size_t key2_len);
  65
  66 /*
  67  * cds_lfht_node_init - initialize a hash table node
  68  */
  69 static inline
  70 void cds_lfht_node_init(struct cds_lfht_node *node, void *key,
  71                         size_t key_len)
  72 {
  73         node->key = key;
  74         node->key_len = key_len;
  75 }
  76
  77 /*
  78  * Hash table creation flags.
  79  */
  80 enum {
  81         CDS_LFHT_AUTO_RESIZE = (1U << 0),
  82 };
  83
  84 /*
  85  * _cds_lfht_new - API used by cds_lfht_new wrapper. Do not use directly.
  86  */
  87 struct cds_lfht *_cds_lfht_new(cds_lfht_hash_fct hash_fct,
  88                         cds_lfht_compare_fct compare_fct,
  89                         unsigned long hash_seed,
  90                         unsigned long init_size,
  91                         int flags,
  92                         void (*cds_lfht_call_rcu)(struct rcu_head *head,
  93                                 void (*func)(struct rcu_head *head)),
  94                         void (*cds_lfht_synchronize_rcu)(void),
  95                         void (*cds_lfht_rcu_read_lock)(void),
  96                         void (*cds_lfht_rcu_read_unlock)(void),
  97                         void (*cds_lfht_rcu_thread_offline)(void),
  98                         void (*cds_lfht_rcu_thread_online)(void));
  99
 100 /*
 101  * cds_lfht_new - allocate a hash table.
 102  *
 103  * init_size must be power of two.
 104  * Return NULL on error.
 105  * Note: the RCU flavor must be already included before the hash table header.
 106  */
 107 static inline
 108 struct cds_lfht *cds_lfht_new(cds_lfht_hash_fct hash_fct,
 109                         cds_lfht_compare_fct compare_fct,
 110                         unsigned long hash_seed,
 111                         unsigned long init_size,
 112                         int flags)
 113 {
 114         return _cds_lfht_new(hash_fct, compare_fct, hash_seed,
 115                         init_size, flags,
 116                         call_rcu, synchronize_rcu, rcu_read_lock,
 117                         rcu_read_unlock, rcu_thread_offline,
 118                         rcu_thread_online);
 119 }
 120
 121 /*
 122  * cds_lfht_destroy - destroy a hash table.
 123  *
 124  * Return 0 on success, negative error value on error.
 125  */
 126 int cds_lfht_destroy(struct cds_lfht *ht);
 127
 128 /*
 129  * cds_lfht_count_nodes - count the number of nodes in the hash table.
 130  *
 131  * Call with rcu_read_lock held.
 132  */
 133 void cds_lfht_count_nodes(struct cds_lfht *ht,
 134                         unsigned long *count,
 135                         unsigned long *removed);
 136
 137 /*
 138  * cds_lfht_lookup - lookup a node by key.
 139  *
 140  * Return NULL if not found.
 141  * Call with rcu_read_lock held.
 142  */
 143 struct cds_lfht_node *cds_lfht_lookup(struct cds_lfht *ht, void *key, size_t key_len);
 144
 145 /*
 146  * cds_lfht_next - get the next item with same key (after a lookup).
 147  *
 148  * Return NULL if no following node exists with same key.
 149  * RCU read-side lock must be held across cds_lfht_lookup and cds_lfht_next calls, and also
 150  * between cds_lfht_next calls using the node returned by a previous cds_lfht_next.
 151  * Call with rcu_read_lock held.
 152  */
 153 struct cds_lfht_node *cds_lfht_next(struct cds_lfht *ht, struct cds_lfht_node *node);
 154
 155 /*
 156  * cds_lfht_add - add a node to the hash table.
 157  *
 158  * Call with rcu_read_lock held.
 159  */
 160 void cds_lfht_add(struct cds_lfht *ht, struct cds_lfht_node *node);
 161
 162 /*
 163  * cds_lfht_add_unique - add a node to hash table, if key is not present.
 164  *
 165  * Return the node added upon success.
 166  * Return the unique node already present upon failure. If cds_lfht_add_unique fails,
 167  * the node passed as parameter should be freed by the caller.
 168  * Call with rcu_read_lock held.
 169  */
 170 struct cds_lfht_node *cds_lfht_add_unique(struct cds_lfht *ht, struct cds_lfht_node *node);
 171
 172 /*
 173  * cds_lfht_remove - remove node from hash table.
 174  *
 175  * Node can be looked up with cds_lfht_lookup. RCU read-side lock must be held between
 176  * lookup and removal.
 177  * Call with rcu_read_lock held.
 178  */
 179 int cds_lfht_remove(struct cds_lfht *ht, struct cds_lfht_node *node);
 180
 181 /*
 182  * cds_lfht_resize - Force a hash table resize
 183  * @new_size: update to this hash table size.
 184  */
 185 void cds_lfht_resize(struct cds_lfht *ht, unsigned long new_size);
 186
 187 #ifdef __cplusplus
 188 }
 189 #endif
 190
 191 #endif /* _URCU_RCULFHASH_H */