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cb3f3d6b MD |
1 | #ifndef _URCU_WFSTACK_H |
2 | #define _URCU_WFSTACK_H | |
3 | ||
4 | /* | |
edac6b69 | 5 | * urcu/wfstack.h |
cb3f3d6b | 6 | * |
edac6b69 | 7 | * Userspace RCU library - Stack with wait-free push, blocking traversal. |
cb3f3d6b | 8 | * |
a03a0f42 | 9 | * Copyright 2010-2012 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com> |
cb3f3d6b MD |
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 <pthread.h> | |
27 | #include <assert.h> | |
edac6b69 | 28 | #include <stdbool.h> |
cb3f3d6b MD |
29 | #include <urcu/compiler.h> |
30 | ||
31 | #ifdef __cplusplus | |
32 | extern "C" { | |
33 | #endif | |
34 | ||
edac6b69 MD |
35 | /* |
36 | * Stack with wait-free push, blocking traversal. | |
37 | * | |
38 | * Stack implementing push, pop, pop_all operations, as well as iterator | |
39 | * on the stack head returned by pop_all. | |
40 | * | |
c97c6ce5 MD |
41 | * Wait-free operations: cds_wfs_push, __cds_wfs_pop_all, cds_wfs_empty, |
42 | * cds_wfs_first. | |
43 | * Blocking operations: cds_wfs_pop, cds_wfs_pop_all, cds_wfs_next, | |
44 | * iteration on stack head returned by pop_all. | |
edac6b69 MD |
45 | * |
46 | * Synchronization table: | |
47 | * | |
48 | * External synchronization techniques described in the API below is | |
49 | * required between pairs marked with "X". No external synchronization | |
50 | * required between pairs marked with "-". | |
51 | * | |
52 | * cds_wfs_push __cds_wfs_pop __cds_wfs_pop_all | |
53 | * cds_wfs_push - - - | |
54 | * __cds_wfs_pop - X X | |
55 | * __cds_wfs_pop_all - X - | |
56 | * | |
57 | * cds_wfs_pop and cds_wfs_pop_all use an internal mutex to provide | |
58 | * synchronization. | |
59 | */ | |
60 | ||
61 | /* | |
62 | * struct cds_wfs_node is returned by __cds_wfs_pop, and also used as | |
63 | * iterator on stack. It is not safe to dereference the node next | |
64 | * pointer when returned by __cds_wfs_pop_blocking. | |
65 | */ | |
16aa9ee8 DG |
66 | struct cds_wfs_node { |
67 | struct cds_wfs_node *next; | |
cb3f3d6b MD |
68 | }; |
69 | ||
edac6b69 MD |
70 | /* |
71 | * struct cds_wfs_head is returned by __cds_wfs_pop_all, and can be used | |
72 | * to begin iteration on the stack. "node" needs to be the first field of | |
73 | * cds_wfs_head, so the end-of-stack pointer value can be used for both | |
74 | * types. | |
75 | */ | |
76 | struct cds_wfs_head { | |
77 | struct cds_wfs_node node; | |
78 | }; | |
79 | ||
16aa9ee8 | 80 | struct cds_wfs_stack { |
edac6b69 | 81 | struct cds_wfs_head *head; |
cb3f3d6b MD |
82 | pthread_mutex_t lock; |
83 | }; | |
84 | ||
294d3396 | 85 | #ifdef _LGPL_SOURCE |
cb3f3d6b | 86 | |
af7c2dbe | 87 | #include <urcu/static/wfstack.h> |
cb3f3d6b | 88 | |
16aa9ee8 | 89 | #define cds_wfs_node_init _cds_wfs_node_init |
edac6b69 MD |
90 | #define cds_wfs_init _cds_wfs_init |
91 | #define cds_wfs_empty _cds_wfs_empty | |
92 | #define cds_wfs_push _cds_wfs_push | |
93 | ||
94 | /* Locking performed internally */ | |
95 | #define cds_wfs_pop_blocking _cds_wfs_pop_blocking | |
96 | #define cds_wfs_pop_all_blocking _cds_wfs_pop_all_blocking | |
97 | ||
98 | /* | |
99 | * For iteration on cds_wfs_head returned by __cds_wfs_pop_all or | |
100 | * cds_wfs_pop_all_blocking. | |
101 | */ | |
c7ba06ba | 102 | #define cds_wfs_first _cds_wfs_first |
edac6b69 MD |
103 | #define cds_wfs_next_blocking _cds_wfs_next_blocking |
104 | ||
105 | /* Pop locking with internal mutex */ | |
106 | #define cds_wfs_pop_lock _cds_wfs_pop_lock | |
107 | #define cds_wfs_pop_unlock _cds_wfs_pop_unlock | |
108 | ||
109 | /* Synchronization ensured by the caller. See synchronization table. */ | |
110 | #define __cds_wfs_pop_blocking ___cds_wfs_pop_blocking | |
111 | #define __cds_wfs_pop_all ___cds_wfs_pop_all | |
cb3f3d6b | 112 | |
294d3396 | 113 | #else /* !_LGPL_SOURCE */ |
cb3f3d6b | 114 | |
edac6b69 MD |
115 | /* |
116 | * cds_wfs_node_init: initialize wait-free stack node. | |
117 | */ | |
16aa9ee8 | 118 | extern void cds_wfs_node_init(struct cds_wfs_node *node); |
edac6b69 MD |
119 | |
120 | /* | |
121 | * cds_wfs_init: initialize wait-free stack. | |
122 | */ | |
16aa9ee8 | 123 | extern void cds_wfs_init(struct cds_wfs_stack *s); |
edac6b69 MD |
124 | |
125 | /* | |
126 | * cds_wfs_empty: return whether wait-free stack is empty. | |
127 | * | |
128 | * No memory barrier is issued. No mutual exclusion is required. | |
129 | */ | |
130 | extern bool cds_wfs_empty(struct cds_wfs_stack *s); | |
131 | ||
132 | /* | |
133 | * cds_wfs_push: push a node into the stack. | |
134 | * | |
135 | * Issues a full memory barrier before push. No mutual exclusion is | |
136 | * required. | |
137 | * | |
138 | * Returns 0 if the stack was empty prior to adding the node. | |
139 | * Returns non-zero otherwise. | |
140 | */ | |
191098fc | 141 | extern int cds_wfs_push(struct cds_wfs_stack *s, struct cds_wfs_node *node); |
edac6b69 MD |
142 | |
143 | /* | |
144 | * cds_wfs_pop_blocking: pop a node from the stack. | |
145 | * | |
146 | * Calls __cds_wfs_pop_blocking with an internal pop mutex held. | |
147 | */ | |
16aa9ee8 | 148 | extern struct cds_wfs_node *cds_wfs_pop_blocking(struct cds_wfs_stack *s); |
cb3f3d6b | 149 | |
edac6b69 MD |
150 | /* |
151 | * cds_wfs_pop_all_blocking: pop all nodes from a stack. | |
152 | * | |
153 | * Calls __cds_wfs_pop_all with an internal pop mutex held. | |
154 | */ | |
155 | extern struct cds_wfs_head *cds_wfs_pop_all_blocking(struct cds_wfs_stack *s); | |
156 | ||
157 | /* | |
c7ba06ba | 158 | * cds_wfs_first: get first node of a popped stack. |
edac6b69 MD |
159 | * |
160 | * Content written into the node before enqueue is guaranteed to be | |
161 | * consistent, but no other memory ordering is ensured. | |
162 | * | |
163 | * Used by for-like iteration macros in urcu/wfstack.h: | |
164 | * cds_wfs_for_each_blocking() | |
165 | * cds_wfs_for_each_blocking_safe() | |
8af2956c MD |
166 | * |
167 | * Returns NULL if popped stack is empty, top stack node otherwise. | |
edac6b69 | 168 | */ |
c7ba06ba | 169 | extern struct cds_wfs_node *cds_wfs_first(struct cds_wfs_head *head); |
edac6b69 MD |
170 | |
171 | /* | |
172 | * cds_wfs_next_blocking: get next node of a popped stack. | |
173 | * | |
174 | * Content written into the node before enqueue is guaranteed to be | |
175 | * consistent, but no other memory ordering is ensured. | |
176 | * | |
177 | * Used by for-like iteration macros in urcu/wfstack.h: | |
178 | * cds_wfs_for_each_blocking() | |
179 | * cds_wfs_for_each_blocking_safe() | |
8af2956c MD |
180 | * |
181 | * Returns NULL if reached end of popped stack, non-NULL next stack | |
182 | * node otherwise. | |
edac6b69 MD |
183 | */ |
184 | extern struct cds_wfs_node *cds_wfs_next_blocking(struct cds_wfs_node *node); | |
185 | ||
186 | /* | |
187 | * cds_wfs_pop_lock: lock stack pop-protection mutex. | |
188 | */ | |
189 | extern void cds_wfs_pop_lock(struct cds_wfs_stack *s); | |
190 | ||
191 | /* | |
192 | * cds_wfs_pop_unlock: unlock stack pop-protection mutex. | |
193 | */ | |
194 | extern void cds_wfs_pop_unlock(struct cds_wfs_stack *s); | |
195 | ||
196 | /* | |
197 | * __cds_wfs_pop_blocking: pop a node from the stack. | |
198 | * | |
199 | * Returns NULL if stack is empty. | |
200 | * | |
201 | * __cds_wfs_pop_blocking needs to be synchronized using one of the | |
202 | * following techniques: | |
203 | * | |
204 | * 1) Calling __cds_wfs_pop_blocking under rcu read lock critical | |
205 | * section. The caller must wait for a grace period to pass before | |
206 | * freeing the returned node or modifying the cds_wfs_node structure. | |
207 | * 2) Using mutual exclusion (e.g. mutexes) to protect | |
208 | * __cds_wfs_pop_blocking and __cds_wfs_pop_all callers. | |
209 | * 3) Ensuring that only ONE thread can call __cds_wfs_pop_blocking() | |
210 | * and __cds_wfs_pop_all(). (multi-provider/single-consumer scheme). | |
211 | */ | |
212 | extern struct cds_wfs_node *__cds_wfs_pop_blocking(struct cds_wfs_stack *s); | |
213 | ||
214 | /* | |
215 | * __cds_wfs_pop_all: pop all nodes from a stack. | |
216 | * | |
217 | * __cds_wfs_pop_all does not require any synchronization with other | |
218 | * push, nor with other __cds_wfs_pop_all, but requires synchronization | |
219 | * matching the technique used to synchronize __cds_wfs_pop_blocking: | |
220 | * | |
221 | * 1) If __cds_wfs_pop_blocking is called under rcu read lock critical | |
222 | * section, both __cds_wfs_pop_blocking and cds_wfs_pop_all callers | |
223 | * must wait for a grace period to pass before freeing the returned | |
224 | * node or modifying the cds_wfs_node structure. However, no RCU | |
225 | * read-side critical section is needed around __cds_wfs_pop_all. | |
226 | * 2) Using mutual exclusion (e.g. mutexes) to protect | |
227 | * __cds_wfs_pop_blocking and __cds_wfs_pop_all callers. | |
228 | * 3) Ensuring that only ONE thread can call __cds_wfs_pop_blocking() | |
229 | * and __cds_wfs_pop_all(). (multi-provider/single-consumer scheme). | |
230 | */ | |
231 | extern struct cds_wfs_head *__cds_wfs_pop_all(struct cds_wfs_stack *s); | |
232 | ||
294d3396 | 233 | #endif /* !_LGPL_SOURCE */ |
cb3f3d6b MD |
234 | |
235 | #ifdef __cplusplus | |
236 | } | |
237 | #endif | |
238 | ||
edac6b69 MD |
239 | /* |
240 | * cds_wfs_for_each_blocking: Iterate over all nodes returned by | |
241 | * __cds_wfs_pop_all(). | |
242 | * @head: head of the queue (struct cds_wfs_head pointer). | |
243 | * @node: iterator (struct cds_wfs_node pointer). | |
244 | * | |
245 | * Content written into each node before enqueue is guaranteed to be | |
246 | * consistent, but no other memory ordering is ensured. | |
247 | */ | |
248 | #define cds_wfs_for_each_blocking(head, node) \ | |
c7ba06ba | 249 | for (node = cds_wfs_first(head); \ |
edac6b69 MD |
250 | node != NULL; \ |
251 | node = cds_wfs_next_blocking(node)) | |
252 | ||
253 | /* | |
254 | * cds_wfs_for_each_blocking_safe: Iterate over all nodes returned by | |
255 | * __cds_wfs_pop_all(). Safe against deletion. | |
256 | * @head: head of the queue (struct cds_wfs_head pointer). | |
257 | * @node: iterator (struct cds_wfs_node pointer). | |
258 | * @n: struct cds_wfs_node pointer holding the next pointer (used | |
259 | * internally). | |
260 | * | |
261 | * Content written into each node before enqueue is guaranteed to be | |
262 | * consistent, but no other memory ordering is ensured. | |
263 | */ | |
264 | #define cds_wfs_for_each_blocking_safe(head, node, n) \ | |
c7ba06ba | 265 | for (node = cds_wfs_first(head), \ |
edac6b69 MD |
266 | n = (node ? cds_wfs_next_blocking(node) : NULL); \ |
267 | node != NULL; \ | |
268 | node = n, n = (node ? cds_wfs_next_blocking(node) : NULL)) | |
269 | ||
cb3f3d6b | 270 | #endif /* _URCU_WFSTACK_H */ |