1 #ifndef _URCU_RCULFHASH_H
2 #define _URCU_RCULFHASH_H
7 * Userspace RCU library - Lock-Free RCU Hash Table
9 * Copyright 2011 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
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.
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.
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
25 * Include this file _after_ including your URCU flavor.
29 #include <urcu-call-rcu.h>
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.
40 struct _cds_lfht_node
{
41 struct cds_lfht_node
*next
; /* ptr | DUMMY_FLAG | REMOVED_FLAG */
42 unsigned long reverse_hash
;
45 struct cds_lfht_node
{
46 /* cache-hot for iteration */
47 struct _cds_lfht_node p
; /* needs to be first field */
50 /* cache-cold for iteration */
58 * Ensure reader and writer threads are registered as urcu readers.
61 typedef unsigned long (*cds_lfht_hash_fct
)(void *key
, size_t length
,
63 typedef unsigned long (*cds_lfht_compare_fct
)(void *key1
, size_t key1_len
,
64 void *key2
, size_t key2_len
);
67 * cds_lfht_node_init - initialize a hash table node
70 void cds_lfht_node_init(struct cds_lfht_node
*node
, void *key
,
74 node
->key_len
= key_len
;
78 * Hash table creation flags.
81 CDS_LFHT_AUTO_RESIZE
= (1U << 0),
85 * _cds_lfht_new - API used by cds_lfht_new wrapper. Do not use directly.
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
,
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));
101 * cds_lfht_new - allocate a hash table.
102 * @hash_fct: the hashing function.
103 * @compare_fct: the key comparison function.
104 * @hash_seed: the seed for hash function.
105 * @init_size: number of nodes to allocate initially. Must be power of two.
106 * @flags: hash table creation flags (can be combined with bitwise or: '|').
108 * CDS_LFHT_AUTO_RESIZE: automatically resize hash table.
110 * Return NULL on error.
111 * Note: the RCU flavor must be already included before the hash table header.
114 struct cds_lfht
*cds_lfht_new(cds_lfht_hash_fct hash_fct
,
115 cds_lfht_compare_fct compare_fct
,
116 unsigned long hash_seed
,
117 unsigned long init_size
,
120 return _cds_lfht_new(hash_fct
, compare_fct
, hash_seed
,
122 call_rcu
, synchronize_rcu
, rcu_read_lock
,
123 rcu_read_unlock
, rcu_thread_offline
,
128 * cds_lfht_destroy - destroy a hash table.
130 * Return 0 on success, negative error value on error.
132 int cds_lfht_destroy(struct cds_lfht
*ht
);
135 * cds_lfht_count_nodes - count the number of nodes in the hash table.
137 * Call with rcu_read_lock held.
139 void cds_lfht_count_nodes(struct cds_lfht
*ht
,
140 unsigned long *count
,
141 unsigned long *removed
);
144 * cds_lfht_lookup - lookup a node by key.
146 * Return NULL if not found.
147 * Call with rcu_read_lock held.
149 struct cds_lfht_node
*cds_lfht_lookup(struct cds_lfht
*ht
, void *key
, size_t key_len
);
152 * cds_lfht_next - get the next item with same key (after a lookup).
154 * Return NULL if no following node exists with same key.
155 * RCU read-side lock must be held across cds_lfht_lookup and cds_lfht_next calls, and also
156 * between cds_lfht_next calls using the node returned by a previous cds_lfht_next.
157 * Call with rcu_read_lock held.
159 struct cds_lfht_node
*cds_lfht_next(struct cds_lfht
*ht
, struct cds_lfht_node
*node
);
162 * cds_lfht_add - add a node to the hash table.
164 * Call with rcu_read_lock held.
166 void cds_lfht_add(struct cds_lfht
*ht
, struct cds_lfht_node
*node
);
169 * cds_lfht_add_unique - add a node to hash table, if key is not present.
171 * Return the node added upon success.
172 * Return the unique node already present upon failure. If cds_lfht_add_unique fails,
173 * the node passed as parameter should be freed by the caller.
174 * Call with rcu_read_lock held.
176 struct cds_lfht_node
*cds_lfht_add_unique(struct cds_lfht
*ht
, struct cds_lfht_node
*node
);
179 * cds_lfht_remove - remove node from hash table.
181 * Node can be looked up with cds_lfht_lookup. RCU read-side lock must be held between
182 * lookup and removal.
183 * Call with rcu_read_lock held.
185 int cds_lfht_remove(struct cds_lfht
*ht
, struct cds_lfht_node
*node
);
188 * cds_lfht_resize - Force a hash table resize
189 * @new_size: update to this hash table size.
191 void cds_lfht_resize(struct cds_lfht
*ht
, unsigned long new_size
);
197 #endif /* _URCU_RCULFHASH_H */