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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 | |
27 | extern "C" { | |
28 | #endif | |
29 | ||
7294103b MD |
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 | */ | |
d3bfcb24 MD |
59 | struct cds_lfs_node { |
60 | struct cds_lfs_node *next; | |
61 | }; | |
62 | ||
7294103b MD |
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 | */ | |
69 | struct cds_lfs_head { | |
70 | struct cds_lfs_node node; | |
71 | }; | |
72 | ||
d3bfcb24 | 73 | struct cds_lfs_stack { |
7294103b MD |
74 | struct cds_lfs_head *head; |
75 | pthread_mutex_t lock; | |
d3bfcb24 MD |
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 |
7294103b MD |
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 | |
d3bfcb24 MD |
98 | |
99 | #else /* !_LGPL_SOURCE */ | |
100 | ||
7294103b MD |
101 | /* |
102 | * cds_lfs_node_init: initialize lock-free stack node. | |
103 | */ | |
d3bfcb24 | 104 | extern void cds_lfs_node_init(struct cds_lfs_node *node); |
7294103b MD |
105 | |
106 | /* | |
107 | * cds_lfs_init: initialize lock-free stack. | |
108 | */ | |
d3bfcb24 MD |
109 | extern void cds_lfs_init(struct cds_lfs_stack *s); |
110 | ||
7294103b MD |
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 | */ | |
116 | extern bool cds_lfs_empty(struct cds_lfs_stack *s); | |
117 | ||
d3bfcb24 MD |
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 | 126 | extern bool cds_lfs_push(struct cds_lfs_stack *s, |
d3bfcb24 MD |
127 | struct cds_lfs_node *node); |
128 | ||
129 | /* | |
7294103b MD |
130 | * cds_lfs_pop_blocking: pop a node from the stack. |
131 | * | |
132 | * Calls __cds_lfs_pop with an internal pop mutex held. | |
133 | */ | |
134 | extern 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 | */ | |
141 | extern 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 | */ | |
146 | extern void cds_lfs_pop_lock(struct cds_lfs_stack *s); | |
147 | ||
148 | /* | |
149 | * cds_lfs_pop_unlock: unlock stack pop-protection mutex. | |
150 | */ | |
151 | extern void cds_lfs_pop_unlock(struct cds_lfs_stack *s); | |
152 | ||
153 | /* | |
154 | * __cds_lfs_pop: pop a node from the stack. | |
d3bfcb24 MD |
155 | * |
156 | * Returns NULL if stack is empty. | |
157 | * | |
7294103b | 158 | * __cds_lfs_pop needs to be synchronized using one of the following |
d3bfcb24 MD |
159 | * techniques: |
160 | * | |
7294103b | 161 | * 1) Calling __cds_lfs_pop under rcu read lock critical section. The |
d3bfcb24 MD |
162 | * caller must wait for a grace period to pass before freeing the |
163 | * returned node or modifying the cds_lfs_node structure. | |
7294103b MD |
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 | */ |
7294103b MD |
169 | extern 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 | */ | |
188 | extern struct cds_lfs_head *__cds_lfs_pop_all(struct cds_lfs_stack *s); | |
d3bfcb24 MD |
189 | |
190 | #endif /* !_LGPL_SOURCE */ | |
191 | ||
7294103b MD |
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 | ||
d3bfcb24 MD |
222 | #ifdef __cplusplus |
223 | } | |
224 | #endif | |
225 | ||
226 | #endif /* _URCU_LFSTACK_H */ |