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
27 #include <urcu-call-rcu.h>
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.
38 struct _cds_lfht_node
{
39 struct cds_lfht_node
*next
; /* ptr | DUMMY_FLAG | REMOVED_FLAG */
40 unsigned long reverse_hash
;
43 struct cds_lfht_node
{
44 /* cache-hot for iteration */
45 struct _cds_lfht_node p
; /* needs to be first field */
48 /* cache-cold for iteration */
56 * Ensure reader and writer threads are registered as urcu readers.
59 typedef unsigned long (*cds_lfht_hash_fct
)(void *key
, size_t length
,
61 typedef unsigned long (*cds_lfht_compare_fct
)(void *key1
, size_t key1_len
,
62 void *key2
, size_t key2_len
);
65 * cds_lfht_node_init - initialize a hash table node
68 void cds_lfht_node_init(struct cds_lfht_node
*node
, void *key
,
72 node
->key_len
= key_len
;
76 * Hash table creation flags.
79 CDS_LFHT_AUTO_RESIZE
= (1U << 0),
83 * cds_lfht_new - allocate a hash table.
85 * init_size must be power of two.
86 * Return NULL on error.
88 struct cds_lfht
*cds_lfht_new(cds_lfht_hash_fct hash_fct
,
89 cds_lfht_compare_fct compare_fct
,
90 unsigned long hash_seed
,
91 unsigned long init_size
,
93 void (*cds_lfht_call_rcu
)(struct rcu_head
*head
,
94 void (*func
)(struct rcu_head
*head
)),
95 void (*cds_lfht_synchronize_rcu
)(void));
98 * cds_lfht_destroy - destroy a hash table.
100 * Return 0 on success, negative error value on error.
102 int cds_lfht_destroy(struct cds_lfht
*ht
);
105 * cds_lfht_count_nodes - count the number of nodes in the hash table.
107 * Call with rcu_read_lock held.
109 void cds_lfht_count_nodes(struct cds_lfht
*ht
,
110 unsigned long *count
,
111 unsigned long *removed
);
114 * cds_lfht_lookup - lookup a node by key.
116 * Return NULL if not found.
117 * Call with rcu_read_lock held.
119 struct cds_lfht_node
*cds_lfht_lookup(struct cds_lfht
*ht
, void *key
, size_t key_len
);
122 * cds_lfht_next - get the next item with same key (after a lookup).
124 * Return NULL if no following node exists with same key.
125 * RCU read-side lock must be held across cds_lfht_lookup and cds_lfht_next calls, and also
126 * between cds_lfht_next calls using the node returned by a previous cds_lfht_next.
127 * Call with rcu_read_lock held.
129 struct cds_lfht_node
*cds_lfht_next(struct cds_lfht
*ht
, struct cds_lfht_node
*node
);
132 * cds_lfht_add - add a node to the hash table.
134 * Call with rcu_read_lock held.
136 void cds_lfht_add(struct cds_lfht
*ht
, struct cds_lfht_node
*node
);
139 * cds_lfht_add_unique - add a node to hash table, if key is not present.
141 * Return the node added upon success.
142 * Return the unique node already present upon failure. If cds_lfht_add_unique fails,
143 * the node passed as parameter should be freed by the caller.
144 * Call with rcu_read_lock held.
146 struct cds_lfht_node
*cds_lfht_add_unique(struct cds_lfht
*ht
, struct cds_lfht_node
*node
);
149 * cds_lfht_remove - remove node from hash table.
151 * Node can be looked up with cds_lfht_lookup. RCU read-side lock must be held between
152 * lookup and removal.
153 * Call with rcu_read_lock held.
155 int cds_lfht_remove(struct cds_lfht
*ht
, struct cds_lfht_node
*node
);
158 * cds_lfht_resize - Force a hash table resize
159 * @new_size: update to this hash table size.
161 void cds_lfht_resize(struct cds_lfht
*ht
, unsigned long new_size
);
167 #endif /* _URCU_RCULFHASH_H */