rculfhash: remove duplicated code
[urcu.git] / urcu / lfstack.h
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1#ifndef _URCU_LFSTACK_H
2#define _URCU_LFSTACK_H
3
4/*
5 * lfstack.h
6 *
7 * Userspace RCU library - Lock-Free Stack
8 *
9 * Copyright 2010-2012 - 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#ifdef __cplusplus
27extern "C" {
28#endif
29
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30#include <stdbool.h>
31#include <pthread.h>
32
33/*
34 * Lock-free stack.
35 *
36 * Stack implementing push, pop, pop_all operations, as well as iterator
37 * on the stack head returned by pop_all.
38 *
39 * Synchronization table:
40 *
41 * External synchronization techniques described in the API below is
42 * required between pairs marked with "X". No external synchronization
43 * required between pairs marked with "-".
44 *
45 * cds_lfs_push __cds_lfs_pop __cds_lfs_pop_all
46 * cds_lfs_push - - -
47 * __cds_lfs_pop - X X
48 * __cds_lfs_pop_all - X -
49 *
50 * cds_lfs_pop_blocking and cds_lfs_pop_all_blocking use an internal
51 * mutex to provide synchronization.
52 */
53
54/*
55 * struct cds_lfs_node is returned by cds_lfs_pop, and also used as
56 * iterator on stack. It is not safe to dereference the node next
57 * pointer when returned by cds_lfs_pop.
58 */
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59struct cds_lfs_node {
60 struct cds_lfs_node *next;
61};
62
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63/*
64 * struct cds_lfs_head is returned by __cds_lfs_pop_all, and can be used
65 * to begin iteration on the stack. "node" needs to be the first field
66 * of cds_lfs_head, so the end-of-stack pointer value can be used for
67 * both types.
68 */
69struct cds_lfs_head {
70 struct cds_lfs_node node;
71};
72
d3bfcb24 73struct cds_lfs_stack {
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74 struct cds_lfs_head *head;
75 pthread_mutex_t lock;
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76};
77
78#ifdef _LGPL_SOURCE
79
80#include <urcu/static/lfstack.h>
81
82#define cds_lfs_node_init _cds_lfs_node_init
83#define cds_lfs_init _cds_lfs_init
7294103b 84#define cds_lfs_empty _cds_lfs_empty
d3bfcb24 85#define cds_lfs_push _cds_lfs_push
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86
87/* Locking performed internally */
88#define cds_lfs_pop_blocking _cds_lfs_pop_blocking
89#define cds_lfs_pop_all_blocking _cds_lfs_pop_all_blocking
90
91/* Synchronize pop with internal mutex */
92#define cds_lfs_pop_lock _cds_lfs_pop_lock
93#define cds_lfs_pop_unlock _cds_lfs_pop_unlock
94
95/* Synchronization ensured by the caller. See synchronization table. */
96#define __cds_lfs_pop ___cds_lfs_pop
97#define __cds_lfs_pop_all ___cds_lfs_pop_all
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98
99#else /* !_LGPL_SOURCE */
100
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101/*
102 * cds_lfs_node_init: initialize lock-free stack node.
103 */
d3bfcb24 104extern void cds_lfs_node_init(struct cds_lfs_node *node);
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105
106/*
107 * cds_lfs_init: initialize lock-free stack.
108 */
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109extern void cds_lfs_init(struct cds_lfs_stack *s);
110
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111/*
112 * cds_lfs_empty: return whether lock-free stack is empty.
113 *
114 * No memory barrier is issued. No mutual exclusion is required.
115 */
116extern bool cds_lfs_empty(struct cds_lfs_stack *s);
117
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118/*
119 * cds_lfs_push: push a node into the stack.
120 *
121 * Does not require any synchronization with other push nor pop.
122 *
123 * Returns 0 if the stack was empty prior to adding the node.
124 * Returns non-zero otherwise.
125 */
7294103b 126extern bool cds_lfs_push(struct cds_lfs_stack *s,
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127 struct cds_lfs_node *node);
128
129/*
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130 * cds_lfs_pop_blocking: pop a node from the stack.
131 *
132 * Calls __cds_lfs_pop with an internal pop mutex held.
133 */
134extern struct cds_lfs_node *cds_lfs_pop_blocking(struct cds_lfs_stack *s);
135
136/*
137 * cds_lfs_pop_all_blocking: pop all nodes from a stack.
138 *
139 * Calls __cds_lfs_pop_all with an internal pop mutex held.
140 */
141extern struct cds_lfs_head *cds_lfs_pop_all_blocking(struct cds_lfs_stack *s);
142
143/*
144 * cds_lfs_pop_lock: lock stack pop-protection mutex.
145 */
146extern void cds_lfs_pop_lock(struct cds_lfs_stack *s);
147
148/*
149 * cds_lfs_pop_unlock: unlock stack pop-protection mutex.
150 */
151extern void cds_lfs_pop_unlock(struct cds_lfs_stack *s);
152
153/*
154 * __cds_lfs_pop: pop a node from the stack.
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155 *
156 * Returns NULL if stack is empty.
157 *
7294103b 158 * __cds_lfs_pop needs to be synchronized using one of the following
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159 * techniques:
160 *
7294103b 161 * 1) Calling __cds_lfs_pop under rcu read lock critical section. The
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162 * caller must wait for a grace period to pass before freeing the
163 * returned node or modifying the cds_lfs_node structure.
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164 * 2) Using mutual exclusion (e.g. mutexes) to protect __cds_lfs_pop
165 * and __cds_lfs_pop_all callers.
166 * 3) Ensuring that only ONE thread can call __cds_lfs_pop() and
167 * __cds_lfs_pop_all(). (multi-provider/single-consumer scheme).
d3bfcb24 168 */
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169extern struct cds_lfs_node *__cds_lfs_pop(struct cds_lfs_stack *s);
170
171/*
172 * __cds_lfs_pop_all: pop all nodes from a stack.
173 *
174 * __cds_lfs_pop_all does not require any synchronization with other
175 * push, nor with other __cds_lfs_pop_all, but requires synchronization
176 * matching the technique used to synchronize __cds_lfs_pop:
177 *
178 * 1) If __cds_lfs_pop is called under rcu read lock critical section,
179 * both __cds_lfs_pop and cds_lfs_pop_all callers must wait for a
180 * grace period to pass before freeing the returned node or modifying
181 * the cds_lfs_node structure. However, no RCU read-side critical
182 * section is needed around __cds_lfs_pop_all.
183 * 2) Using mutual exclusion (e.g. mutexes) to protect __cds_lfs_pop and
184 * __cds_lfs_pop_all callers.
185 * 3) Ensuring that only ONE thread can call __cds_lfs_pop() and
186 * __cds_lfs_pop_all(). (multi-provider/single-consumer scheme).
187 */
188extern struct cds_lfs_head *__cds_lfs_pop_all(struct cds_lfs_stack *s);
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189
190#endif /* !_LGPL_SOURCE */
191
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192/*
193 * cds_lfs_for_each: Iterate over all nodes returned by
194 * __cds_lfs_pop_all.
195 * @__head: node returned by __cds_lfs_pop_all (struct cds_lfs_head pointer).
196 * @__node: node to use as iterator (struct cds_lfs_node pointer).
197 *
198 * Content written into each node before push is guaranteed to be
199 * consistent, but no other memory ordering is ensured.
200 */
201#define cds_lfs_for_each(__head, __node) \
202 for (__node = &__head->node; \
203 __node != NULL; \
204 __node = __node->next)
205
206/*
207 * cds_lfs_for_each_safe: Iterate over all nodes returned by
208 * __cds_lfs_pop_all, safe against node deletion.
209 * @__head: node returned by __cds_lfs_pop_all (struct cds_lfs_head pointer).
210 * @__node: node to use as iterator (struct cds_lfs_node pointer).
211 * @__n: struct cds_lfs_node pointer holding the next pointer (used
212 * internally).
213 *
214 * Content written into each node before push is guaranteed to be
215 * consistent, but no other memory ordering is ensured.
216 */
217#define cds_lfs_for_each_safe(__head, __node, __n) \
218 for (__node = &__head->node, __n = (__node ? __node->next : NULL); \
219 __node != NULL; \
220 __node = __n, __n = (__node ? __node->next : NULL))
221
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222#ifdef __cplusplus
223}
224#endif
225
226#endif /* _URCU_LFSTACK_H */
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