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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 | ||
af67624d MD |
61 | #define CDS_WFS_WOULDBLOCK ((void *) -1UL) |
62 | ||
c8975b94 MD |
63 | enum cds_wfs_state { |
64 | CDS_WFS_STATE_LAST = (1U << 0), | |
65 | }; | |
66 | ||
edac6b69 MD |
67 | /* |
68 | * struct cds_wfs_node is returned by __cds_wfs_pop, and also used as | |
69 | * iterator on stack. It is not safe to dereference the node next | |
70 | * pointer when returned by __cds_wfs_pop_blocking. | |
71 | */ | |
16aa9ee8 DG |
72 | struct cds_wfs_node { |
73 | struct cds_wfs_node *next; | |
cb3f3d6b MD |
74 | }; |
75 | ||
edac6b69 MD |
76 | /* |
77 | * struct cds_wfs_head is returned by __cds_wfs_pop_all, and can be used | |
78 | * to begin iteration on the stack. "node" needs to be the first field of | |
79 | * cds_wfs_head, so the end-of-stack pointer value can be used for both | |
80 | * types. | |
81 | */ | |
82 | struct cds_wfs_head { | |
83 | struct cds_wfs_node node; | |
84 | }; | |
85 | ||
718eb63e EW |
86 | struct __cds_wfs_stack { |
87 | struct cds_wfs_head *head; | |
88 | }; | |
89 | ||
16aa9ee8 | 90 | struct cds_wfs_stack { |
edac6b69 | 91 | struct cds_wfs_head *head; |
cb3f3d6b MD |
92 | pthread_mutex_t lock; |
93 | }; | |
94 | ||
718eb63e EW |
95 | /* |
96 | * The transparent union allows calling functions that work on both | |
97 | * struct cds_wfs_stack and struct __cds_wfs_stack on any of those two | |
98 | * types. | |
99 | */ | |
100 | typedef union __attribute__((__transparent_union__)) { | |
101 | struct __cds_wfs_stack *_s; | |
102 | struct cds_wfs_stack *s; | |
103 | } cds_wfs_stack_ptr_t; | |
104 | ||
294d3396 | 105 | #ifdef _LGPL_SOURCE |
cb3f3d6b | 106 | |
af7c2dbe | 107 | #include <urcu/static/wfstack.h> |
cb3f3d6b | 108 | |
16aa9ee8 | 109 | #define cds_wfs_node_init _cds_wfs_node_init |
edac6b69 MD |
110 | #define cds_wfs_init _cds_wfs_init |
111 | #define cds_wfs_empty _cds_wfs_empty | |
112 | #define cds_wfs_push _cds_wfs_push | |
113 | ||
114 | /* Locking performed internally */ | |
115 | #define cds_wfs_pop_blocking _cds_wfs_pop_blocking | |
c8975b94 | 116 | #define cds_wfs_pop_with_state_blocking _cds_wfs_pop_with_state_blocking |
edac6b69 MD |
117 | #define cds_wfs_pop_all_blocking _cds_wfs_pop_all_blocking |
118 | ||
119 | /* | |
120 | * For iteration on cds_wfs_head returned by __cds_wfs_pop_all or | |
121 | * cds_wfs_pop_all_blocking. | |
122 | */ | |
c7ba06ba | 123 | #define cds_wfs_first _cds_wfs_first |
edac6b69 | 124 | #define cds_wfs_next_blocking _cds_wfs_next_blocking |
150fc1bb | 125 | #define cds_wfs_next_nonblocking _cds_wfs_next_nonblocking |
edac6b69 MD |
126 | |
127 | /* Pop locking with internal mutex */ | |
128 | #define cds_wfs_pop_lock _cds_wfs_pop_lock | |
129 | #define cds_wfs_pop_unlock _cds_wfs_pop_unlock | |
130 | ||
131 | /* Synchronization ensured by the caller. See synchronization table. */ | |
132 | #define __cds_wfs_pop_blocking ___cds_wfs_pop_blocking | |
c8975b94 MD |
133 | #define __cds_wfs_pop_with_state_blocking \ |
134 | ___cds_wfs_pop_with_state_blocking | |
150fc1bb | 135 | #define __cds_wfs_pop_nonblocking ___cds_wfs_pop_nonblocking |
c8975b94 MD |
136 | #define __cds_wfs_pop_with_state_nonblocking \ |
137 | ___cds_wfs_pop_with_state_nonblocking | |
edac6b69 | 138 | #define __cds_wfs_pop_all ___cds_wfs_pop_all |
cb3f3d6b | 139 | |
294d3396 | 140 | #else /* !_LGPL_SOURCE */ |
cb3f3d6b | 141 | |
edac6b69 MD |
142 | /* |
143 | * cds_wfs_node_init: initialize wait-free stack node. | |
144 | */ | |
16aa9ee8 | 145 | extern void cds_wfs_node_init(struct cds_wfs_node *node); |
edac6b69 MD |
146 | |
147 | /* | |
148 | * cds_wfs_init: initialize wait-free stack. | |
149 | */ | |
16aa9ee8 | 150 | extern void cds_wfs_init(struct cds_wfs_stack *s); |
edac6b69 | 151 | |
718eb63e EW |
152 | /* |
153 | * __cds_wfs_init: initialize wait-free stack. | |
154 | */ | |
155 | extern void __cds_wfs_init(struct __cds_wfs_stack *s); | |
156 | ||
edac6b69 MD |
157 | /* |
158 | * cds_wfs_empty: return whether wait-free stack is empty. | |
159 | * | |
160 | * No memory barrier is issued. No mutual exclusion is required. | |
161 | */ | |
718eb63e | 162 | extern bool cds_wfs_empty(cds_wfs_stack_ptr_t u_stack); |
edac6b69 MD |
163 | |
164 | /* | |
165 | * cds_wfs_push: push a node into the stack. | |
166 | * | |
167 | * Issues a full memory barrier before push. No mutual exclusion is | |
168 | * required. | |
169 | * | |
170 | * Returns 0 if the stack was empty prior to adding the node. | |
171 | * Returns non-zero otherwise. | |
172 | */ | |
718eb63e | 173 | extern int cds_wfs_push(cds_wfs_stack_ptr_t u_stack, struct cds_wfs_node *node); |
edac6b69 MD |
174 | |
175 | /* | |
176 | * cds_wfs_pop_blocking: pop a node from the stack. | |
177 | * | |
178 | * Calls __cds_wfs_pop_blocking with an internal pop mutex held. | |
179 | */ | |
16aa9ee8 | 180 | extern struct cds_wfs_node *cds_wfs_pop_blocking(struct cds_wfs_stack *s); |
cb3f3d6b | 181 | |
c8975b94 MD |
182 | /* |
183 | * cds_wfs_pop_with_state_blocking: pop a node from the stack, with state. | |
184 | * | |
185 | * Same as cds_wfs_pop_blocking, but stores whether the stack was | |
186 | * empty into state (CDS_WFS_STATE_LAST). | |
187 | */ | |
188 | extern struct cds_wfs_node * | |
189 | cds_wfs_pop_with_state_blocking(struct cds_wfs_stack *s, int *state); | |
190 | ||
edac6b69 MD |
191 | /* |
192 | * cds_wfs_pop_all_blocking: pop all nodes from a stack. | |
193 | * | |
194 | * Calls __cds_wfs_pop_all with an internal pop mutex held. | |
195 | */ | |
196 | extern struct cds_wfs_head *cds_wfs_pop_all_blocking(struct cds_wfs_stack *s); | |
197 | ||
198 | /* | |
c7ba06ba | 199 | * cds_wfs_first: get first node of a popped stack. |
edac6b69 MD |
200 | * |
201 | * Content written into the node before enqueue is guaranteed to be | |
202 | * consistent, but no other memory ordering is ensured. | |
203 | * | |
204 | * Used by for-like iteration macros in urcu/wfstack.h: | |
205 | * cds_wfs_for_each_blocking() | |
206 | * cds_wfs_for_each_blocking_safe() | |
8af2956c MD |
207 | * |
208 | * Returns NULL if popped stack is empty, top stack node otherwise. | |
edac6b69 | 209 | */ |
c7ba06ba | 210 | extern struct cds_wfs_node *cds_wfs_first(struct cds_wfs_head *head); |
edac6b69 MD |
211 | |
212 | /* | |
213 | * cds_wfs_next_blocking: get next node of a popped stack. | |
214 | * | |
215 | * Content written into the node before enqueue is guaranteed to be | |
216 | * consistent, but no other memory ordering is ensured. | |
217 | * | |
218 | * Used by for-like iteration macros in urcu/wfstack.h: | |
219 | * cds_wfs_for_each_blocking() | |
220 | * cds_wfs_for_each_blocking_safe() | |
8af2956c MD |
221 | * |
222 | * Returns NULL if reached end of popped stack, non-NULL next stack | |
223 | * node otherwise. | |
edac6b69 MD |
224 | */ |
225 | extern struct cds_wfs_node *cds_wfs_next_blocking(struct cds_wfs_node *node); | |
226 | ||
af67624d MD |
227 | /* |
228 | * cds_wfs_next_nonblocking: get next node of a popped stack. | |
229 | * | |
230 | * Same as cds_wfs_next_blocking, but returns CDS_WFS_WOULDBLOCK if it | |
231 | * needs to block. | |
232 | */ | |
233 | extern struct cds_wfs_node *cds_wfs_next_nonblocking(struct cds_wfs_node *node); | |
234 | ||
edac6b69 MD |
235 | /* |
236 | * cds_wfs_pop_lock: lock stack pop-protection mutex. | |
237 | */ | |
238 | extern void cds_wfs_pop_lock(struct cds_wfs_stack *s); | |
239 | ||
240 | /* | |
241 | * cds_wfs_pop_unlock: unlock stack pop-protection mutex. | |
242 | */ | |
243 | extern void cds_wfs_pop_unlock(struct cds_wfs_stack *s); | |
244 | ||
245 | /* | |
246 | * __cds_wfs_pop_blocking: pop a node from the stack. | |
247 | * | |
248 | * Returns NULL if stack is empty. | |
249 | * | |
250 | * __cds_wfs_pop_blocking needs to be synchronized using one of the | |
251 | * following techniques: | |
252 | * | |
253 | * 1) Calling __cds_wfs_pop_blocking under rcu read lock critical | |
254 | * section. The caller must wait for a grace period to pass before | |
255 | * freeing the returned node or modifying the cds_wfs_node structure. | |
256 | * 2) Using mutual exclusion (e.g. mutexes) to protect | |
257 | * __cds_wfs_pop_blocking and __cds_wfs_pop_all callers. | |
258 | * 3) Ensuring that only ONE thread can call __cds_wfs_pop_blocking() | |
259 | * and __cds_wfs_pop_all(). (multi-provider/single-consumer scheme). | |
260 | */ | |
261 | extern struct cds_wfs_node *__cds_wfs_pop_blocking(struct cds_wfs_stack *s); | |
262 | ||
c8975b94 MD |
263 | /* |
264 | * __cds_wfs_pop_with_state_blocking: pop a node from the stack, with state. | |
265 | * | |
266 | * Same as __cds_wfs_pop_blocking, but stores whether the stack was | |
267 | * empty into state (CDS_WFS_STATE_LAST). | |
268 | */ | |
269 | extern struct cds_wfs_node * | |
270 | __cds_wfs_pop_with_state_blocking(struct cds_wfs_stack *s, int *state); | |
271 | ||
af67624d MD |
272 | /* |
273 | * __cds_wfs_pop_nonblocking: pop a node from the stack. | |
274 | * | |
275 | * Same as __cds_wfs_pop_blocking, but returns CDS_WFS_WOULDBLOCK if | |
276 | * it needs to block. | |
277 | */ | |
278 | extern struct cds_wfs_node *__cds_wfs_pop_nonblocking(struct cds_wfs_stack *s); | |
279 | ||
c8975b94 MD |
280 | /* |
281 | * __cds_wfs_pop_with_state_nonblocking: pop a node from the stack, with state. | |
282 | * | |
283 | * Same as __cds_wfs_pop_nonblocking, but stores whether the stack was | |
284 | * empty into state (CDS_WFS_STATE_LAST). | |
285 | */ | |
286 | extern struct cds_wfs_node * | |
287 | __cds_wfs_pop_with_state_nonblocking(struct cds_wfs_stack *s, | |
288 | int *state); | |
289 | ||
edac6b69 MD |
290 | /* |
291 | * __cds_wfs_pop_all: pop all nodes from a stack. | |
292 | * | |
293 | * __cds_wfs_pop_all does not require any synchronization with other | |
294 | * push, nor with other __cds_wfs_pop_all, but requires synchronization | |
295 | * matching the technique used to synchronize __cds_wfs_pop_blocking: | |
296 | * | |
297 | * 1) If __cds_wfs_pop_blocking is called under rcu read lock critical | |
298 | * section, both __cds_wfs_pop_blocking and cds_wfs_pop_all callers | |
299 | * must wait for a grace period to pass before freeing the returned | |
300 | * node or modifying the cds_wfs_node structure. However, no RCU | |
301 | * read-side critical section is needed around __cds_wfs_pop_all. | |
302 | * 2) Using mutual exclusion (e.g. mutexes) to protect | |
303 | * __cds_wfs_pop_blocking and __cds_wfs_pop_all callers. | |
304 | * 3) Ensuring that only ONE thread can call __cds_wfs_pop_blocking() | |
305 | * and __cds_wfs_pop_all(). (multi-provider/single-consumer scheme). | |
306 | */ | |
307 | extern struct cds_wfs_head *__cds_wfs_pop_all(struct cds_wfs_stack *s); | |
308 | ||
294d3396 | 309 | #endif /* !_LGPL_SOURCE */ |
cb3f3d6b MD |
310 | |
311 | #ifdef __cplusplus | |
312 | } | |
313 | #endif | |
314 | ||
edac6b69 MD |
315 | /* |
316 | * cds_wfs_for_each_blocking: Iterate over all nodes returned by | |
317 | * __cds_wfs_pop_all(). | |
318 | * @head: head of the queue (struct cds_wfs_head pointer). | |
319 | * @node: iterator (struct cds_wfs_node pointer). | |
320 | * | |
321 | * Content written into each node before enqueue is guaranteed to be | |
322 | * consistent, but no other memory ordering is ensured. | |
323 | */ | |
324 | #define cds_wfs_for_each_blocking(head, node) \ | |
c7ba06ba | 325 | for (node = cds_wfs_first(head); \ |
edac6b69 MD |
326 | node != NULL; \ |
327 | node = cds_wfs_next_blocking(node)) | |
328 | ||
329 | /* | |
330 | * cds_wfs_for_each_blocking_safe: Iterate over all nodes returned by | |
331 | * __cds_wfs_pop_all(). Safe against deletion. | |
332 | * @head: head of the queue (struct cds_wfs_head pointer). | |
333 | * @node: iterator (struct cds_wfs_node pointer). | |
334 | * @n: struct cds_wfs_node pointer holding the next pointer (used | |
335 | * internally). | |
336 | * | |
337 | * Content written into each node before enqueue is guaranteed to be | |
338 | * consistent, but no other memory ordering is ensured. | |
339 | */ | |
340 | #define cds_wfs_for_each_blocking_safe(head, node, n) \ | |
c7ba06ba | 341 | for (node = cds_wfs_first(head), \ |
edac6b69 MD |
342 | n = (node ? cds_wfs_next_blocking(node) : NULL); \ |
343 | node != NULL; \ | |
344 | node = n, n = (node ? cds_wfs_next_blocking(node) : NULL)) | |
345 | ||
cb3f3d6b | 346 | #endif /* _URCU_WFSTACK_H */ |