Commit | Line | Data |
---|---|---|
8ad4ce58 MD |
1 | #ifndef _URCU_WFCQUEUE_H |
2 | #define _URCU_WFCQUEUE_H | |
3 | ||
4 | /* | |
47215721 | 5 | * urcu/wfcqueue.h |
8ad4ce58 MD |
6 | * |
7 | * Userspace RCU library - Concurrent Queue with Wait-Free Enqueue/Blocking Dequeue | |
8 | * | |
9 | * Copyright 2010-2012 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com> | |
10 | * Copyright 2011-2012 - Lai Jiangshan <laijs@cn.fujitsu.com> | |
11 | * | |
12 | * This library is free software; you can redistribute it and/or | |
13 | * modify it under the terms of the GNU Lesser General Public | |
14 | * License as published by the Free Software Foundation; either | |
15 | * version 2.1 of the License, or (at your option) any later version. | |
16 | * | |
17 | * This library is distributed in the hope that it will be useful, | |
18 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
19 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
20 | * Lesser General Public License for more details. | |
21 | * | |
22 | * You should have received a copy of the GNU Lesser General Public | |
23 | * License along with this library; if not, write to the Free Software | |
24 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA | |
25 | */ | |
26 | ||
27 | #include <pthread.h> | |
28 | #include <assert.h> | |
29 | #include <stdbool.h> | |
30 | #include <urcu/compiler.h> | |
31 | #include <urcu/arch.h> | |
32 | ||
33 | #ifdef __cplusplus | |
34 | extern "C" { | |
35 | #endif | |
36 | ||
37 | /* | |
38 | * Concurrent queue with wait-free enqueue/blocking dequeue. | |
39 | * | |
ebfd2673 MD |
40 | * This queue has been designed and implemented collaboratively by |
41 | * Mathieu Desnoyers and Lai Jiangshan. Inspired from | |
42 | * half-wait-free/half-blocking queue implementation done by Paul E. | |
43 | * McKenney. | |
8ad4ce58 MD |
44 | */ |
45 | ||
47215721 MD |
46 | #define CDS_WFCQ_WOULDBLOCK ((void *) -1UL) |
47 | ||
23773356 | 48 | enum cds_wfcq_ret { |
f878b49e | 49 | CDS_WFCQ_RET_WOULDBLOCK = -1, |
23773356 MD |
50 | CDS_WFCQ_RET_DEST_EMPTY = 0, |
51 | CDS_WFCQ_RET_DEST_NON_EMPTY = 1, | |
52 | CDS_WFCQ_RET_SRC_EMPTY = 2, | |
53 | }; | |
54 | ||
eec791af MD |
55 | enum cds_wfcq_state { |
56 | CDS_WFCQ_STATE_LAST = (1U << 0), | |
57 | }; | |
58 | ||
8ad4ce58 MD |
59 | struct cds_wfcq_node { |
60 | struct cds_wfcq_node *next; | |
61 | }; | |
62 | ||
63 | /* | |
64 | * Do not put head and tail on the same cache-line if concurrent | |
65 | * enqueue/dequeue are expected from many CPUs. This eliminates | |
66 | * false-sharing between enqueue and dequeue. | |
67 | */ | |
68 | struct cds_wfcq_head { | |
69 | struct cds_wfcq_node node; | |
70 | pthread_mutex_t lock; | |
71 | }; | |
72 | ||
73 | struct cds_wfcq_tail { | |
74 | struct cds_wfcq_node *p; | |
75 | }; | |
76 | ||
77 | #ifdef _LGPL_SOURCE | |
78 | ||
79 | #include <urcu/static/wfcqueue.h> | |
80 | ||
81 | #define cds_wfcq_node_init _cds_wfcq_node_init | |
82 | #define cds_wfcq_init _cds_wfcq_init | |
93aee570 | 83 | #define cds_wfcq_destroy _cds_wfcq_destroy |
8ad4ce58 MD |
84 | #define cds_wfcq_empty _cds_wfcq_empty |
85 | #define cds_wfcq_enqueue _cds_wfcq_enqueue | |
86 | ||
87 | /* Dequeue locking */ | |
88 | #define cds_wfcq_dequeue_lock _cds_wfcq_dequeue_lock | |
89 | #define cds_wfcq_dequeue_unlock _cds_wfcq_dequeue_unlock | |
90 | ||
91 | /* Locking performed within cds_wfcq calls. */ | |
92 | #define cds_wfcq_dequeue_blocking _cds_wfcq_dequeue_blocking | |
eec791af MD |
93 | #define cds_wfcq_dequeue_with_state_blocking \ |
94 | _cds_wfcq_dequeue_with_state_blocking | |
8ad4ce58 MD |
95 | #define cds_wfcq_splice_blocking _cds_wfcq_splice_blocking |
96 | #define cds_wfcq_first_blocking _cds_wfcq_first_blocking | |
97 | #define cds_wfcq_next_blocking _cds_wfcq_next_blocking | |
98 | ||
99 | /* Locking ensured by caller by holding cds_wfcq_dequeue_lock() */ | |
100 | #define __cds_wfcq_dequeue_blocking ___cds_wfcq_dequeue_blocking | |
eec791af MD |
101 | #define __cds_wfcq_dequeue_with_state_blocking \ |
102 | ___cds_wfcq_dequeue_with_state_blocking | |
8ad4ce58 MD |
103 | #define __cds_wfcq_splice_blocking ___cds_wfcq_splice_blocking |
104 | #define __cds_wfcq_first_blocking ___cds_wfcq_first_blocking | |
105 | #define __cds_wfcq_next_blocking ___cds_wfcq_next_blocking | |
106 | ||
47215721 MD |
107 | /* |
108 | * Locking ensured by caller by holding cds_wfcq_dequeue_lock(). | |
109 | * Non-blocking: deque, first, next return CDS_WFCQ_WOULDBLOCK if they | |
110 | * need to block. splice returns nonzero if it needs to block. | |
111 | */ | |
112 | #define __cds_wfcq_dequeue_nonblocking ___cds_wfcq_dequeue_nonblocking | |
eec791af MD |
113 | #define __cds_wfcq_dequeue_with_state_nonblocking \ |
114 | ___cds_wfcq_dequeue_with_state_nonblocking | |
47215721 MD |
115 | #define __cds_wfcq_splice_nonblocking ___cds_wfcq_splice_nonblocking |
116 | #define __cds_wfcq_first_nonblocking ___cds_wfcq_first_nonblocking | |
117 | #define __cds_wfcq_next_nonblocking ___cds_wfcq_next_nonblocking | |
118 | ||
8ad4ce58 MD |
119 | #else /* !_LGPL_SOURCE */ |
120 | ||
121 | /* | |
122 | * Mutual exclusion of cds_wfcq_* / __cds_wfcq_* API | |
123 | * | |
f878b49e MD |
124 | * Synchronization table: |
125 | * | |
126 | * External synchronization techniques described in the API below is | |
127 | * required between pairs marked with "X". No external synchronization | |
128 | * required between pairs marked with "-". | |
129 | * | |
130 | * Legend: | |
131 | * [1] cds_wfcq_enqueue | |
132 | * [2] __cds_wfcq_splice (destination queue) | |
133 | * [3] __cds_wfcq_dequeue | |
134 | * [4] __cds_wfcq_splice (source queue) | |
135 | * [5] __cds_wfcq_first | |
136 | * [6] __cds_wfcq_next | |
137 | * | |
138 | * [1] [2] [3] [4] [5] [6] | |
139 | * [1] - - - - - - | |
140 | * [2] - - - - - - | |
141 | * [3] - - X X X X | |
142 | * [4] - - X - X X | |
143 | * [5] - - X X - - | |
144 | * [6] - - X X - - | |
145 | * | |
8ad4ce58 MD |
146 | * Mutual exclusion can be ensured by holding cds_wfcq_dequeue_lock(). |
147 | * | |
148 | * For convenience, cds_wfcq_dequeue_blocking() and | |
149 | * cds_wfcq_splice_blocking() hold the dequeue lock. | |
1fe734e1 MD |
150 | * |
151 | * Besides locking, mutual exclusion of dequeue, splice and iteration | |
152 | * can be ensured by performing all of those operations from a single | |
153 | * thread, without requiring any lock. | |
8ad4ce58 MD |
154 | */ |
155 | ||
156 | /* | |
157 | * cds_wfcq_node_init: initialize wait-free queue node. | |
158 | */ | |
159 | extern void cds_wfcq_node_init(struct cds_wfcq_node *node); | |
160 | ||
161 | /* | |
93aee570 MD |
162 | * cds_wfcq_init: initialize wait-free queue. Pair with |
163 | * cds_wfcq_destroy(). | |
8ad4ce58 MD |
164 | */ |
165 | extern void cds_wfcq_init(struct cds_wfcq_head *head, | |
166 | struct cds_wfcq_tail *tail); | |
167 | ||
93aee570 MD |
168 | /* |
169 | * cds_wfcq_destroy: destroy wait-free queue. Pair with | |
170 | * cds_wfcq_init(). | |
171 | */ | |
172 | extern void cds_wfcq_destroy(struct cds_wfcq_head *head, | |
173 | struct cds_wfcq_tail *tail); | |
174 | ||
8ad4ce58 MD |
175 | /* |
176 | * cds_wfcq_empty: return whether wait-free queue is empty. | |
177 | * | |
178 | * No memory barrier is issued. No mutual exclusion is required. | |
179 | */ | |
180 | extern bool cds_wfcq_empty(struct cds_wfcq_head *head, | |
181 | struct cds_wfcq_tail *tail); | |
182 | ||
183 | /* | |
184 | * cds_wfcq_dequeue_lock: take the dequeue mutual exclusion lock. | |
185 | */ | |
186 | extern void cds_wfcq_dequeue_lock(struct cds_wfcq_head *head, | |
187 | struct cds_wfcq_tail *tail); | |
188 | ||
189 | /* | |
190 | * cds_wfcq_dequeue_unlock: release the dequeue mutual exclusion lock. | |
191 | */ | |
192 | extern void cds_wfcq_dequeue_unlock(struct cds_wfcq_head *head, | |
193 | struct cds_wfcq_tail *tail); | |
194 | ||
195 | /* | |
196 | * cds_wfcq_enqueue: enqueue a node into a wait-free queue. | |
197 | * | |
198 | * Issues a full memory barrier before enqueue. No mutual exclusion is | |
199 | * required. | |
23773356 MD |
200 | * |
201 | * Returns false if the queue was empty prior to adding the node. | |
202 | * Returns true otherwise. | |
8ad4ce58 | 203 | */ |
23773356 | 204 | extern bool cds_wfcq_enqueue(struct cds_wfcq_head *head, |
8ad4ce58 MD |
205 | struct cds_wfcq_tail *tail, |
206 | struct cds_wfcq_node *node); | |
207 | ||
208 | /* | |
209 | * cds_wfcq_dequeue_blocking: dequeue a node from a wait-free queue. | |
210 | * | |
211 | * Content written into the node before enqueue is guaranteed to be | |
212 | * consistent, but no other memory ordering is ensured. | |
213 | * It is valid to reuse and free a dequeued node immediately. | |
ffa11a18 | 214 | * Mutual exclusion with cds_wfcq_dequeue_blocking and dequeue lock is |
1fe734e1 | 215 | * ensured. |
8ad4ce58 MD |
216 | */ |
217 | extern struct cds_wfcq_node *cds_wfcq_dequeue_blocking( | |
218 | struct cds_wfcq_head *head, | |
219 | struct cds_wfcq_tail *tail); | |
220 | ||
eec791af MD |
221 | /* |
222 | * cds_wfcq_dequeue_with_state_blocking: dequeue with state. | |
223 | * | |
224 | * Same as cds_wfcq_dequeue_blocking, but saves whether dequeueing the | |
225 | * last node of the queue into state (CDS_WFCQ_STATE_LAST). | |
226 | */ | |
227 | extern struct cds_wfcq_node *cds_wfcq_dequeue_with_state_blocking( | |
228 | struct cds_wfcq_head *head, | |
229 | struct cds_wfcq_tail *tail, | |
230 | int *state); | |
231 | ||
8ad4ce58 MD |
232 | /* |
233 | * cds_wfcq_splice_blocking: enqueue all src_q nodes at the end of dest_q. | |
234 | * | |
235 | * Dequeue all nodes from src_q. | |
236 | * dest_q must be already initialized. | |
237 | * Content written into the node before enqueue is guaranteed to be | |
238 | * consistent, but no other memory ordering is ensured. | |
ffa11a18 | 239 | * Mutual exclusion with cds_wfcq_dequeue_blocking and dequeue lock is |
1fe734e1 | 240 | * ensured. |
23773356 MD |
241 | * |
242 | * Returns enum cds_wfcq_ret which indicates the state of the src or | |
243 | * dest queue. Cannot block. | |
8ad4ce58 | 244 | */ |
23773356 | 245 | extern enum cds_wfcq_ret cds_wfcq_splice_blocking( |
8ad4ce58 MD |
246 | struct cds_wfcq_head *dest_q_head, |
247 | struct cds_wfcq_tail *dest_q_tail, | |
248 | struct cds_wfcq_head *src_q_head, | |
249 | struct cds_wfcq_tail *src_q_tail); | |
250 | ||
251 | /* | |
47215721 | 252 | * __cds_wfcq_dequeue_blocking: dequeue a node from a wait-free queue. |
8ad4ce58 MD |
253 | * |
254 | * Content written into the node before enqueue is guaranteed to be | |
255 | * consistent, but no other memory ordering is ensured. | |
256 | * It is valid to reuse and free a dequeued node immediately. | |
1fe734e1 MD |
257 | * Dequeue/splice/iteration mutual exclusion should be ensured by the |
258 | * caller. | |
8ad4ce58 MD |
259 | */ |
260 | extern struct cds_wfcq_node *__cds_wfcq_dequeue_blocking( | |
261 | struct cds_wfcq_head *head, | |
262 | struct cds_wfcq_tail *tail); | |
263 | ||
eec791af MD |
264 | /* |
265 | * __cds_wfcq_dequeue_with_state_blocking: dequeue with state. | |
266 | * | |
267 | * Same as __cds_wfcq_dequeue_blocking, but saves whether dequeueing the | |
268 | * last node of the queue into state (CDS_WFCQ_STATE_LAST). | |
269 | */ | |
270 | extern struct cds_wfcq_node *__cds_wfcq_dequeue_with_state_blocking( | |
271 | struct cds_wfcq_head *head, | |
272 | struct cds_wfcq_tail *tail, | |
273 | int *state); | |
274 | ||
47215721 MD |
275 | /* |
276 | * __cds_wfcq_dequeue_nonblocking: dequeue a node from a wait-free queue. | |
277 | * | |
278 | * Same as __cds_wfcq_dequeue_blocking, but returns CDS_WFCQ_WOULDBLOCK | |
279 | * if it needs to block. | |
280 | */ | |
281 | extern struct cds_wfcq_node *__cds_wfcq_dequeue_nonblocking( | |
282 | struct cds_wfcq_head *head, | |
283 | struct cds_wfcq_tail *tail); | |
284 | ||
eec791af MD |
285 | /* |
286 | * __cds_wfcq_dequeue_with_state_blocking: dequeue with state. | |
287 | * | |
288 | * Same as __cds_wfcq_dequeue_nonblocking, but saves whether dequeueing | |
289 | * the last node of the queue into state (CDS_WFCQ_STATE_LAST). | |
290 | */ | |
291 | extern struct cds_wfcq_node *__cds_wfcq_dequeue_with_state_nonblocking( | |
292 | struct cds_wfcq_head *head, | |
293 | struct cds_wfcq_tail *tail, | |
294 | int *state); | |
295 | ||
8ad4ce58 MD |
296 | /* |
297 | * __cds_wfcq_splice_blocking: enqueue all src_q nodes at the end of dest_q. | |
298 | * | |
299 | * Dequeue all nodes from src_q. | |
300 | * dest_q must be already initialized. | |
f878b49e MD |
301 | * Mutual exclusion for src_q should be ensured by the caller as |
302 | * specified in the "Synchronisation table". | |
23773356 | 303 | * Returns enum cds_wfcq_ret which indicates the state of the src or |
f878b49e | 304 | * dest queue. Never returns CDS_WFCQ_RET_WOULDBLOCK. |
8ad4ce58 | 305 | */ |
23773356 | 306 | extern enum cds_wfcq_ret __cds_wfcq_splice_blocking( |
8ad4ce58 MD |
307 | struct cds_wfcq_head *dest_q_head, |
308 | struct cds_wfcq_tail *dest_q_tail, | |
309 | struct cds_wfcq_head *src_q_head, | |
310 | struct cds_wfcq_tail *src_q_tail); | |
311 | ||
47215721 MD |
312 | /* |
313 | * __cds_wfcq_splice_nonblocking: enqueue all src_q nodes at the end of dest_q. | |
314 | * | |
23773356 MD |
315 | * Same as __cds_wfcq_splice_blocking, but returns |
316 | * CDS_WFCQ_RET_WOULDBLOCK if it needs to block. | |
47215721 | 317 | */ |
23773356 | 318 | extern enum cds_wfcq_ret __cds_wfcq_splice_nonblocking( |
47215721 MD |
319 | struct cds_wfcq_head *dest_q_head, |
320 | struct cds_wfcq_tail *dest_q_tail, | |
321 | struct cds_wfcq_head *src_q_head, | |
322 | struct cds_wfcq_tail *src_q_tail); | |
323 | ||
8ad4ce58 MD |
324 | /* |
325 | * __cds_wfcq_first_blocking: get first node of a queue, without dequeuing. | |
326 | * | |
327 | * Content written into the node before enqueue is guaranteed to be | |
328 | * consistent, but no other memory ordering is ensured. | |
1fe734e1 MD |
329 | * Dequeue/splice/iteration mutual exclusion should be ensured by the |
330 | * caller. | |
f94061a3 MD |
331 | * |
332 | * Used by for-like iteration macros: | |
333 | * __cds_wfcq_for_each_blocking() | |
334 | * __cds_wfcq_for_each_blocking_safe() | |
131a29a6 MD |
335 | * |
336 | * Returns NULL if queue is empty, first node otherwise. | |
8ad4ce58 MD |
337 | */ |
338 | extern struct cds_wfcq_node *__cds_wfcq_first_blocking( | |
339 | struct cds_wfcq_head *head, | |
340 | struct cds_wfcq_tail *tail); | |
341 | ||
47215721 MD |
342 | /* |
343 | * __cds_wfcq_first_nonblocking: get first node of a queue, without dequeuing. | |
344 | * | |
345 | * Same as __cds_wfcq_first_blocking, but returns CDS_WFCQ_WOULDBLOCK if | |
346 | * it needs to block. | |
347 | */ | |
348 | extern struct cds_wfcq_node *__cds_wfcq_first_nonblocking( | |
349 | struct cds_wfcq_head *head, | |
350 | struct cds_wfcq_tail *tail); | |
351 | ||
8ad4ce58 MD |
352 | /* |
353 | * __cds_wfcq_next_blocking: get next node of a queue, without dequeuing. | |
354 | * | |
355 | * Content written into the node before enqueue is guaranteed to be | |
356 | * consistent, but no other memory ordering is ensured. | |
1fe734e1 MD |
357 | * Dequeue/splice/iteration mutual exclusion should be ensured by the |
358 | * caller. | |
f94061a3 MD |
359 | * |
360 | * Used by for-like iteration macros: | |
361 | * __cds_wfcq_for_each_blocking() | |
362 | * __cds_wfcq_for_each_blocking_safe() | |
131a29a6 MD |
363 | * |
364 | * Returns NULL if reached end of queue, non-NULL next queue node | |
365 | * otherwise. | |
8ad4ce58 MD |
366 | */ |
367 | extern struct cds_wfcq_node *__cds_wfcq_next_blocking( | |
368 | struct cds_wfcq_head *head, | |
369 | struct cds_wfcq_tail *tail, | |
370 | struct cds_wfcq_node *node); | |
371 | ||
47215721 MD |
372 | /* |
373 | * __cds_wfcq_next_blocking: get next node of a queue, without dequeuing. | |
374 | * | |
375 | * Same as __cds_wfcq_next_blocking, but returns CDS_WFCQ_WOULDBLOCK if | |
376 | * it needs to block. | |
377 | */ | |
378 | extern struct cds_wfcq_node *__cds_wfcq_next_nonblocking( | |
379 | struct cds_wfcq_head *head, | |
380 | struct cds_wfcq_tail *tail, | |
381 | struct cds_wfcq_node *node); | |
382 | ||
8ad4ce58 MD |
383 | #endif /* !_LGPL_SOURCE */ |
384 | ||
385 | /* | |
386 | * __cds_wfcq_for_each_blocking: Iterate over all nodes in a queue, | |
387 | * without dequeuing them. | |
388 | * @head: head of the queue (struct cds_wfcq_head pointer). | |
389 | * @tail: tail of the queue (struct cds_wfcq_tail pointer). | |
390 | * @node: iterator on the queue (struct cds_wfcq_node pointer). | |
391 | * | |
392 | * Content written into each node before enqueue is guaranteed to be | |
393 | * consistent, but no other memory ordering is ensured. | |
1fe734e1 MD |
394 | * Dequeue/splice/iteration mutual exclusion should be ensured by the |
395 | * caller. | |
8ad4ce58 MD |
396 | */ |
397 | #define __cds_wfcq_for_each_blocking(head, tail, node) \ | |
398 | for (node = __cds_wfcq_first_blocking(head, tail); \ | |
399 | node != NULL; \ | |
400 | node = __cds_wfcq_next_blocking(head, tail, node)) | |
401 | ||
402 | /* | |
403 | * __cds_wfcq_for_each_blocking_safe: Iterate over all nodes in a queue, | |
404 | * without dequeuing them. Safe against deletion. | |
405 | * @head: head of the queue (struct cds_wfcq_head pointer). | |
406 | * @tail: tail of the queue (struct cds_wfcq_tail pointer). | |
407 | * @node: iterator on the queue (struct cds_wfcq_node pointer). | |
408 | * @n: struct cds_wfcq_node pointer holding the next pointer (used | |
409 | * internally). | |
410 | * | |
411 | * Content written into each node before enqueue is guaranteed to be | |
412 | * consistent, but no other memory ordering is ensured. | |
1fe734e1 MD |
413 | * Dequeue/splice/iteration mutual exclusion should be ensured by the |
414 | * caller. | |
8ad4ce58 MD |
415 | */ |
416 | #define __cds_wfcq_for_each_blocking_safe(head, tail, node, n) \ | |
417 | for (node = __cds_wfcq_first_blocking(head, tail), \ | |
418 | n = (node ? __cds_wfcq_next_blocking(head, tail, node) : NULL); \ | |
419 | node != NULL; \ | |
420 | node = n, n = (node ? __cds_wfcq_next_blocking(head, tail, node) : NULL)) | |
421 | ||
422 | #ifdef __cplusplus | |
423 | } | |
424 | #endif | |
425 | ||
426 | #endif /* _URCU_WFCQUEUE_H */ |