rculfhash: put thread offline before taking mutex (fix G.P. deadlock)
[userspace-rcu.git] / 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 - allocate a hash table.
84 *
85 * init_size must be power of two.
86 * Return NULL on error.
87 */
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,
92 int flags,
93 void (*cds_lfht_call_rcu)(struct rcu_head *head,
94 void (*func)(struct rcu_head *head)),
95 void (*cds_lfht_synchronize_rcu)(void),
96 void (*cds_lfht_rcu_read_lock)(void),
97 void (*cds_lfht_rcu_read_unlock)(void),
98 void (*cds_lfht_rcu_thread_offline)(void),
99 void (*cds_lfht_rcu_thread_online)(void));
100
101 /*
102 * cds_lfht_destroy - destroy a hash table.
103 *
104 * Return 0 on success, negative error value on error.
105 */
106 int cds_lfht_destroy(struct cds_lfht *ht);
107
108 /*
109 * cds_lfht_count_nodes - count the number of nodes in the hash table.
110 *
111 * Call with rcu_read_lock held.
112 */
113 void cds_lfht_count_nodes(struct cds_lfht *ht,
114 unsigned long *count,
115 unsigned long *removed);
116
117 /*
118 * cds_lfht_lookup - lookup a node by key.
119 *
120 * Return NULL if not found.
121 * Call with rcu_read_lock held.
122 */
123 struct cds_lfht_node *cds_lfht_lookup(struct cds_lfht *ht, void *key, size_t key_len);
124
125 /*
126 * cds_lfht_next - get the next item with same key (after a lookup).
127 *
128 * Return NULL if no following node exists with same key.
129 * RCU read-side lock must be held across cds_lfht_lookup and cds_lfht_next calls, and also
130 * between cds_lfht_next calls using the node returned by a previous cds_lfht_next.
131 * Call with rcu_read_lock held.
132 */
133 struct cds_lfht_node *cds_lfht_next(struct cds_lfht *ht, struct cds_lfht_node *node);
134
135 /*
136 * cds_lfht_add - add a node to the hash table.
137 *
138 * Call with rcu_read_lock held.
139 */
140 void cds_lfht_add(struct cds_lfht *ht, struct cds_lfht_node *node);
141
142 /*
143 * cds_lfht_add_unique - add a node to hash table, if key is not present.
144 *
145 * Return the node added upon success.
146 * Return the unique node already present upon failure. If cds_lfht_add_unique fails,
147 * the node passed as parameter should be freed by the caller.
148 * Call with rcu_read_lock held.
149 */
150 struct cds_lfht_node *cds_lfht_add_unique(struct cds_lfht *ht, struct cds_lfht_node *node);
151
152 /*
153 * cds_lfht_remove - remove node from hash table.
154 *
155 * Node can be looked up with cds_lfht_lookup. RCU read-side lock must be held between
156 * lookup and removal.
157 * Call with rcu_read_lock held.
158 */
159 int cds_lfht_remove(struct cds_lfht *ht, struct cds_lfht_node *node);
160
161 /*
162 * cds_lfht_resize - Force a hash table resize
163 * @new_size: update to this hash table size.
164 */
165 void cds_lfht_resize(struct cds_lfht *ht, unsigned long new_size);
166
167 #ifdef __cplusplus
168 }
169 #endif
170
171 #endif /* _URCU_RCULFHASH_H */
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