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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 | */ | |
f637f191 MD |
68 | struct __cds_wfcq_head { |
69 | struct cds_wfcq_node node; | |
70 | }; | |
71 | ||
8ad4ce58 MD |
72 | struct cds_wfcq_head { |
73 | struct cds_wfcq_node node; | |
74 | pthread_mutex_t lock; | |
75 | }; | |
76 | ||
f637f191 MD |
77 | /* |
78 | * The transparent union allows calling functions that work on both | |
79 | * struct cds_wfcq_head and struct __cds_wfcq_head on any of those two | |
80 | * types. | |
81 | */ | |
5135c0fd | 82 | typedef union { |
f637f191 MD |
83 | struct __cds_wfcq_head *_h; |
84 | struct cds_wfcq_head *h; | |
5135c0fd | 85 | } __attribute__((__transparent_union__)) cds_wfcq_head_ptr_t; |
f637f191 | 86 | |
8ad4ce58 MD |
87 | struct cds_wfcq_tail { |
88 | struct cds_wfcq_node *p; | |
89 | }; | |
90 | ||
91 | #ifdef _LGPL_SOURCE | |
92 | ||
93 | #include <urcu/static/wfcqueue.h> | |
94 | ||
95 | #define cds_wfcq_node_init _cds_wfcq_node_init | |
96 | #define cds_wfcq_init _cds_wfcq_init | |
97 | #define cds_wfcq_empty _cds_wfcq_empty | |
98 | #define cds_wfcq_enqueue _cds_wfcq_enqueue | |
99 | ||
100 | /* Dequeue locking */ | |
101 | #define cds_wfcq_dequeue_lock _cds_wfcq_dequeue_lock | |
102 | #define cds_wfcq_dequeue_unlock _cds_wfcq_dequeue_unlock | |
103 | ||
104 | /* Locking performed within cds_wfcq calls. */ | |
105 | #define cds_wfcq_dequeue_blocking _cds_wfcq_dequeue_blocking | |
eec791af MD |
106 | #define cds_wfcq_dequeue_with_state_blocking \ |
107 | _cds_wfcq_dequeue_with_state_blocking | |
8ad4ce58 MD |
108 | #define cds_wfcq_splice_blocking _cds_wfcq_splice_blocking |
109 | #define cds_wfcq_first_blocking _cds_wfcq_first_blocking | |
110 | #define cds_wfcq_next_blocking _cds_wfcq_next_blocking | |
111 | ||
112 | /* Locking ensured by caller by holding cds_wfcq_dequeue_lock() */ | |
113 | #define __cds_wfcq_dequeue_blocking ___cds_wfcq_dequeue_blocking | |
eec791af MD |
114 | #define __cds_wfcq_dequeue_with_state_blocking \ |
115 | ___cds_wfcq_dequeue_with_state_blocking | |
8ad4ce58 MD |
116 | #define __cds_wfcq_splice_blocking ___cds_wfcq_splice_blocking |
117 | #define __cds_wfcq_first_blocking ___cds_wfcq_first_blocking | |
118 | #define __cds_wfcq_next_blocking ___cds_wfcq_next_blocking | |
119 | ||
47215721 MD |
120 | /* |
121 | * Locking ensured by caller by holding cds_wfcq_dequeue_lock(). | |
122 | * Non-blocking: deque, first, next return CDS_WFCQ_WOULDBLOCK if they | |
123 | * need to block. splice returns nonzero if it needs to block. | |
124 | */ | |
125 | #define __cds_wfcq_dequeue_nonblocking ___cds_wfcq_dequeue_nonblocking | |
eec791af MD |
126 | #define __cds_wfcq_dequeue_with_state_nonblocking \ |
127 | ___cds_wfcq_dequeue_with_state_nonblocking | |
47215721 MD |
128 | #define __cds_wfcq_splice_nonblocking ___cds_wfcq_splice_nonblocking |
129 | #define __cds_wfcq_first_nonblocking ___cds_wfcq_first_nonblocking | |
130 | #define __cds_wfcq_next_nonblocking ___cds_wfcq_next_nonblocking | |
131 | ||
8ad4ce58 MD |
132 | #else /* !_LGPL_SOURCE */ |
133 | ||
134 | /* | |
135 | * Mutual exclusion of cds_wfcq_* / __cds_wfcq_* API | |
136 | * | |
f878b49e MD |
137 | * Synchronization table: |
138 | * | |
139 | * External synchronization techniques described in the API below is | |
140 | * required between pairs marked with "X". No external synchronization | |
141 | * required between pairs marked with "-". | |
142 | * | |
143 | * Legend: | |
144 | * [1] cds_wfcq_enqueue | |
145 | * [2] __cds_wfcq_splice (destination queue) | |
146 | * [3] __cds_wfcq_dequeue | |
147 | * [4] __cds_wfcq_splice (source queue) | |
148 | * [5] __cds_wfcq_first | |
149 | * [6] __cds_wfcq_next | |
150 | * | |
151 | * [1] [2] [3] [4] [5] [6] | |
152 | * [1] - - - - - - | |
153 | * [2] - - - - - - | |
154 | * [3] - - X X X X | |
155 | * [4] - - X - X X | |
156 | * [5] - - X X - - | |
157 | * [6] - - X X - - | |
158 | * | |
8ad4ce58 MD |
159 | * Mutual exclusion can be ensured by holding cds_wfcq_dequeue_lock(). |
160 | * | |
161 | * For convenience, cds_wfcq_dequeue_blocking() and | |
162 | * cds_wfcq_splice_blocking() hold the dequeue lock. | |
1fe734e1 MD |
163 | * |
164 | * Besides locking, mutual exclusion of dequeue, splice and iteration | |
165 | * can be ensured by performing all of those operations from a single | |
166 | * thread, without requiring any lock. | |
8ad4ce58 MD |
167 | */ |
168 | ||
169 | /* | |
170 | * cds_wfcq_node_init: initialize wait-free queue node. | |
171 | */ | |
172 | extern void cds_wfcq_node_init(struct cds_wfcq_node *node); | |
173 | ||
174 | /* | |
175 | * cds_wfcq_init: initialize wait-free queue. | |
176 | */ | |
177 | extern void cds_wfcq_init(struct cds_wfcq_head *head, | |
178 | struct cds_wfcq_tail *tail); | |
179 | ||
f637f191 MD |
180 | /* |
181 | * __cds_wfcq_init: initialize wait-free queue. | |
182 | */ | |
183 | extern void __cds_wfcq_init(struct __cds_wfcq_head *head, | |
184 | struct cds_wfcq_tail *tail); | |
185 | ||
8ad4ce58 MD |
186 | /* |
187 | * cds_wfcq_empty: return whether wait-free queue is empty. | |
188 | * | |
189 | * No memory barrier is issued. No mutual exclusion is required. | |
190 | */ | |
f637f191 | 191 | extern bool cds_wfcq_empty(cds_wfcq_head_ptr_t head, |
8ad4ce58 MD |
192 | struct cds_wfcq_tail *tail); |
193 | ||
194 | /* | |
195 | * cds_wfcq_dequeue_lock: take the dequeue mutual exclusion lock. | |
196 | */ | |
197 | extern void cds_wfcq_dequeue_lock(struct cds_wfcq_head *head, | |
198 | struct cds_wfcq_tail *tail); | |
199 | ||
200 | /* | |
201 | * cds_wfcq_dequeue_unlock: release the dequeue mutual exclusion lock. | |
202 | */ | |
203 | extern void cds_wfcq_dequeue_unlock(struct cds_wfcq_head *head, | |
204 | struct cds_wfcq_tail *tail); | |
205 | ||
206 | /* | |
207 | * cds_wfcq_enqueue: enqueue a node into a wait-free queue. | |
208 | * | |
209 | * Issues a full memory barrier before enqueue. No mutual exclusion is | |
210 | * required. | |
23773356 MD |
211 | * |
212 | * Returns false if the queue was empty prior to adding the node. | |
213 | * Returns true otherwise. | |
8ad4ce58 | 214 | */ |
f637f191 | 215 | extern bool cds_wfcq_enqueue(cds_wfcq_head_ptr_t head, |
8ad4ce58 MD |
216 | struct cds_wfcq_tail *tail, |
217 | struct cds_wfcq_node *node); | |
218 | ||
219 | /* | |
220 | * cds_wfcq_dequeue_blocking: dequeue a node from a wait-free queue. | |
221 | * | |
222 | * Content written into the node before enqueue is guaranteed to be | |
223 | * consistent, but no other memory ordering is ensured. | |
224 | * It is valid to reuse and free a dequeued node immediately. | |
ffa11a18 | 225 | * Mutual exclusion with cds_wfcq_dequeue_blocking and dequeue lock is |
1fe734e1 | 226 | * ensured. |
8ad4ce58 MD |
227 | */ |
228 | extern struct cds_wfcq_node *cds_wfcq_dequeue_blocking( | |
229 | struct cds_wfcq_head *head, | |
230 | struct cds_wfcq_tail *tail); | |
231 | ||
eec791af MD |
232 | /* |
233 | * cds_wfcq_dequeue_with_state_blocking: dequeue with state. | |
234 | * | |
235 | * Same as cds_wfcq_dequeue_blocking, but saves whether dequeueing the | |
236 | * last node of the queue into state (CDS_WFCQ_STATE_LAST). | |
237 | */ | |
238 | extern struct cds_wfcq_node *cds_wfcq_dequeue_with_state_blocking( | |
239 | struct cds_wfcq_head *head, | |
240 | struct cds_wfcq_tail *tail, | |
241 | int *state); | |
242 | ||
8ad4ce58 MD |
243 | /* |
244 | * cds_wfcq_splice_blocking: enqueue all src_q nodes at the end of dest_q. | |
245 | * | |
246 | * Dequeue all nodes from src_q. | |
247 | * dest_q must be already initialized. | |
248 | * Content written into the node before enqueue is guaranteed to be | |
249 | * consistent, but no other memory ordering is ensured. | |
ffa11a18 | 250 | * Mutual exclusion with cds_wfcq_dequeue_blocking and dequeue lock is |
1fe734e1 | 251 | * ensured. |
23773356 MD |
252 | * |
253 | * Returns enum cds_wfcq_ret which indicates the state of the src or | |
b94aaf6f | 254 | * dest queue. |
8ad4ce58 | 255 | */ |
23773356 | 256 | extern enum cds_wfcq_ret cds_wfcq_splice_blocking( |
8ad4ce58 MD |
257 | struct cds_wfcq_head *dest_q_head, |
258 | struct cds_wfcq_tail *dest_q_tail, | |
259 | struct cds_wfcq_head *src_q_head, | |
260 | struct cds_wfcq_tail *src_q_tail); | |
261 | ||
262 | /* | |
47215721 | 263 | * __cds_wfcq_dequeue_blocking: dequeue a node from a wait-free queue. |
8ad4ce58 MD |
264 | * |
265 | * Content written into the node before enqueue is guaranteed to be | |
266 | * consistent, but no other memory ordering is ensured. | |
267 | * It is valid to reuse and free a dequeued node immediately. | |
1fe734e1 MD |
268 | * Dequeue/splice/iteration mutual exclusion should be ensured by the |
269 | * caller. | |
8ad4ce58 MD |
270 | */ |
271 | extern struct cds_wfcq_node *__cds_wfcq_dequeue_blocking( | |
f637f191 | 272 | cds_wfcq_head_ptr_t head, |
8ad4ce58 MD |
273 | struct cds_wfcq_tail *tail); |
274 | ||
eec791af MD |
275 | /* |
276 | * __cds_wfcq_dequeue_with_state_blocking: dequeue with state. | |
277 | * | |
278 | * Same as __cds_wfcq_dequeue_blocking, but saves whether dequeueing the | |
279 | * last node of the queue into state (CDS_WFCQ_STATE_LAST). | |
280 | */ | |
281 | extern struct cds_wfcq_node *__cds_wfcq_dequeue_with_state_blocking( | |
f637f191 | 282 | cds_wfcq_head_ptr_t head, |
eec791af MD |
283 | struct cds_wfcq_tail *tail, |
284 | int *state); | |
285 | ||
47215721 MD |
286 | /* |
287 | * __cds_wfcq_dequeue_nonblocking: dequeue a node from a wait-free queue. | |
288 | * | |
289 | * Same as __cds_wfcq_dequeue_blocking, but returns CDS_WFCQ_WOULDBLOCK | |
290 | * if it needs to block. | |
291 | */ | |
292 | extern struct cds_wfcq_node *__cds_wfcq_dequeue_nonblocking( | |
f637f191 | 293 | cds_wfcq_head_ptr_t head, |
47215721 MD |
294 | struct cds_wfcq_tail *tail); |
295 | ||
eec791af MD |
296 | /* |
297 | * __cds_wfcq_dequeue_with_state_blocking: dequeue with state. | |
298 | * | |
299 | * Same as __cds_wfcq_dequeue_nonblocking, but saves whether dequeueing | |
300 | * the last node of the queue into state (CDS_WFCQ_STATE_LAST). | |
301 | */ | |
302 | extern struct cds_wfcq_node *__cds_wfcq_dequeue_with_state_nonblocking( | |
f637f191 | 303 | cds_wfcq_head_ptr_t head, |
eec791af MD |
304 | struct cds_wfcq_tail *tail, |
305 | int *state); | |
306 | ||
8ad4ce58 MD |
307 | /* |
308 | * __cds_wfcq_splice_blocking: enqueue all src_q nodes at the end of dest_q. | |
309 | * | |
310 | * Dequeue all nodes from src_q. | |
311 | * dest_q must be already initialized. | |
f878b49e MD |
312 | * Mutual exclusion for src_q should be ensured by the caller as |
313 | * specified in the "Synchronisation table". | |
23773356 | 314 | * Returns enum cds_wfcq_ret which indicates the state of the src or |
f878b49e | 315 | * dest queue. Never returns CDS_WFCQ_RET_WOULDBLOCK. |
8ad4ce58 | 316 | */ |
23773356 | 317 | extern enum cds_wfcq_ret __cds_wfcq_splice_blocking( |
f637f191 | 318 | cds_wfcq_head_ptr_t dest_q_head, |
8ad4ce58 | 319 | struct cds_wfcq_tail *dest_q_tail, |
f637f191 | 320 | cds_wfcq_head_ptr_t src_q_head, |
8ad4ce58 MD |
321 | struct cds_wfcq_tail *src_q_tail); |
322 | ||
47215721 MD |
323 | /* |
324 | * __cds_wfcq_splice_nonblocking: enqueue all src_q nodes at the end of dest_q. | |
325 | * | |
23773356 MD |
326 | * Same as __cds_wfcq_splice_blocking, but returns |
327 | * CDS_WFCQ_RET_WOULDBLOCK if it needs to block. | |
47215721 | 328 | */ |
23773356 | 329 | extern enum cds_wfcq_ret __cds_wfcq_splice_nonblocking( |
f637f191 | 330 | cds_wfcq_head_ptr_t dest_q_head, |
47215721 | 331 | struct cds_wfcq_tail *dest_q_tail, |
f637f191 | 332 | cds_wfcq_head_ptr_t src_q_head, |
47215721 MD |
333 | struct cds_wfcq_tail *src_q_tail); |
334 | ||
8ad4ce58 MD |
335 | /* |
336 | * __cds_wfcq_first_blocking: get first node of a queue, without dequeuing. | |
337 | * | |
338 | * Content written into the node before enqueue is guaranteed to be | |
339 | * consistent, but no other memory ordering is ensured. | |
1fe734e1 MD |
340 | * Dequeue/splice/iteration mutual exclusion should be ensured by the |
341 | * caller. | |
f94061a3 MD |
342 | * |
343 | * Used by for-like iteration macros: | |
344 | * __cds_wfcq_for_each_blocking() | |
345 | * __cds_wfcq_for_each_blocking_safe() | |
131a29a6 MD |
346 | * |
347 | * Returns NULL if queue is empty, first node otherwise. | |
8ad4ce58 MD |
348 | */ |
349 | extern struct cds_wfcq_node *__cds_wfcq_first_blocking( | |
f637f191 | 350 | cds_wfcq_head_ptr_t head, |
8ad4ce58 MD |
351 | struct cds_wfcq_tail *tail); |
352 | ||
47215721 MD |
353 | /* |
354 | * __cds_wfcq_first_nonblocking: get first node of a queue, without dequeuing. | |
355 | * | |
356 | * Same as __cds_wfcq_first_blocking, but returns CDS_WFCQ_WOULDBLOCK if | |
357 | * it needs to block. | |
358 | */ | |
359 | extern struct cds_wfcq_node *__cds_wfcq_first_nonblocking( | |
f637f191 | 360 | cds_wfcq_head_ptr_t head, |
47215721 MD |
361 | struct cds_wfcq_tail *tail); |
362 | ||
8ad4ce58 MD |
363 | /* |
364 | * __cds_wfcq_next_blocking: get next node of a queue, without dequeuing. | |
365 | * | |
366 | * Content written into the node before enqueue is guaranteed to be | |
367 | * consistent, but no other memory ordering is ensured. | |
1fe734e1 MD |
368 | * Dequeue/splice/iteration mutual exclusion should be ensured by the |
369 | * caller. | |
f94061a3 MD |
370 | * |
371 | * Used by for-like iteration macros: | |
372 | * __cds_wfcq_for_each_blocking() | |
373 | * __cds_wfcq_for_each_blocking_safe() | |
131a29a6 MD |
374 | * |
375 | * Returns NULL if reached end of queue, non-NULL next queue node | |
376 | * otherwise. | |
8ad4ce58 MD |
377 | */ |
378 | extern struct cds_wfcq_node *__cds_wfcq_next_blocking( | |
f637f191 | 379 | cds_wfcq_head_ptr_t head, |
8ad4ce58 MD |
380 | struct cds_wfcq_tail *tail, |
381 | struct cds_wfcq_node *node); | |
382 | ||
47215721 MD |
383 | /* |
384 | * __cds_wfcq_next_blocking: get next node of a queue, without dequeuing. | |
385 | * | |
386 | * Same as __cds_wfcq_next_blocking, but returns CDS_WFCQ_WOULDBLOCK if | |
387 | * it needs to block. | |
388 | */ | |
389 | extern struct cds_wfcq_node *__cds_wfcq_next_nonblocking( | |
f637f191 | 390 | cds_wfcq_head_ptr_t head, |
47215721 MD |
391 | struct cds_wfcq_tail *tail, |
392 | struct cds_wfcq_node *node); | |
393 | ||
8ad4ce58 MD |
394 | #endif /* !_LGPL_SOURCE */ |
395 | ||
396 | /* | |
397 | * __cds_wfcq_for_each_blocking: Iterate over all nodes in a queue, | |
398 | * without dequeuing them. | |
f637f191 | 399 | * @head: head of the queue (struct cds_wfcq_head or __cds_wfcq_head pointer). |
8ad4ce58 MD |
400 | * @tail: tail of the queue (struct cds_wfcq_tail pointer). |
401 | * @node: iterator on the queue (struct cds_wfcq_node pointer). | |
402 | * | |
403 | * Content written into each node before enqueue is guaranteed to be | |
404 | * consistent, but no other memory ordering is ensured. | |
1fe734e1 MD |
405 | * Dequeue/splice/iteration mutual exclusion should be ensured by the |
406 | * caller. | |
8ad4ce58 MD |
407 | */ |
408 | #define __cds_wfcq_for_each_blocking(head, tail, node) \ | |
409 | for (node = __cds_wfcq_first_blocking(head, tail); \ | |
410 | node != NULL; \ | |
411 | node = __cds_wfcq_next_blocking(head, tail, node)) | |
412 | ||
413 | /* | |
414 | * __cds_wfcq_for_each_blocking_safe: Iterate over all nodes in a queue, | |
415 | * without dequeuing them. Safe against deletion. | |
f637f191 | 416 | * @head: head of the queue (struct cds_wfcq_head or __cds_wfcq_head pointer). |
8ad4ce58 MD |
417 | * @tail: tail of the queue (struct cds_wfcq_tail pointer). |
418 | * @node: iterator on the queue (struct cds_wfcq_node pointer). | |
419 | * @n: struct cds_wfcq_node pointer holding the next pointer (used | |
420 | * internally). | |
421 | * | |
422 | * Content written into each node before enqueue is guaranteed to be | |
423 | * consistent, but no other memory ordering is ensured. | |
1fe734e1 MD |
424 | * Dequeue/splice/iteration mutual exclusion should be ensured by the |
425 | * caller. | |
8ad4ce58 MD |
426 | */ |
427 | #define __cds_wfcq_for_each_blocking_safe(head, tail, node, n) \ | |
428 | for (node = __cds_wfcq_first_blocking(head, tail), \ | |
429 | n = (node ? __cds_wfcq_next_blocking(head, tail, node) : NULL); \ | |
430 | node != NULL; \ | |
431 | node = n, n = (node ? __cds_wfcq_next_blocking(head, tail, node) : NULL)) | |
432 | ||
433 | #ifdef __cplusplus | |
434 | } | |
435 | #endif | |
436 | ||
437 | #endif /* _URCU_WFCQUEUE_H */ |