Fix: uatomic arm32: add missing release barrier before uatomic_xchg
[urcu.git] / include / urcu / wfcqueue.h
1 #ifndef _URCU_WFCQUEUE_H
2 #define _URCU_WFCQUEUE_H
3
4 /*
5 * urcu/wfcqueue.h
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 *
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.
44 */
45
46 #define CDS_WFCQ_WOULDBLOCK ((struct cds_wfcq_node *) -1UL)
47
48 enum cds_wfcq_ret {
49 CDS_WFCQ_RET_WOULDBLOCK = -1,
50 CDS_WFCQ_RET_DEST_EMPTY = 0,
51 CDS_WFCQ_RET_DEST_NON_EMPTY = 1,
52 CDS_WFCQ_RET_SRC_EMPTY = 2,
53 };
54
55 enum cds_wfcq_state {
56 CDS_WFCQ_STATE_LAST = (1U << 0),
57 };
58
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 };
71
72 struct cds_wfcq_head {
73 struct cds_wfcq_node node;
74 pthread_mutex_t lock;
75 };
76
77 #ifndef __cplusplus
78 /*
79 * The transparent union allows calling functions that work on both
80 * struct cds_wfcq_head and struct __cds_wfcq_head on any of those two
81 * types.
82 */
83 typedef union {
84 struct __cds_wfcq_head *_h;
85 struct cds_wfcq_head *h;
86 } __attribute__((__transparent_union__)) cds_wfcq_head_ptr_t;
87
88 /*
89 * This static inline is only present for compatibility with C++. It is
90 * effect-less in C.
91 */
92 static inline struct __cds_wfcq_head *__cds_wfcq_head_cast(struct __cds_wfcq_head *head)
93 {
94 return head;
95 }
96
97 /*
98 * This static inline is only present for compatibility with C++. It is
99 * effect-less in C.
100 */
101 static inline struct cds_wfcq_head *cds_wfcq_head_cast(struct cds_wfcq_head *head)
102 {
103 return head;
104 }
105 #else /* #ifndef __cplusplus */
106
107 /* C++ ignores transparent union. */
108 typedef union {
109 struct __cds_wfcq_head *_h;
110 struct cds_wfcq_head *h;
111 } cds_wfcq_head_ptr_t;
112
113 /* C++ ignores transparent union. Requires an explicit conversion. */
114 static inline cds_wfcq_head_ptr_t __cds_wfcq_head_cast(struct __cds_wfcq_head *head)
115 {
116 cds_wfcq_head_ptr_t ret = { ._h = head };
117 return ret;
118 }
119 /* C++ ignores transparent union. Requires an explicit conversion. */
120 static inline cds_wfcq_head_ptr_t cds_wfcq_head_cast(struct cds_wfcq_head *head)
121 {
122 cds_wfcq_head_ptr_t ret = { .h = head };
123 return ret;
124 }
125 #endif /* #else #ifndef __cplusplus */
126
127 struct cds_wfcq_tail {
128 struct cds_wfcq_node *p;
129 };
130
131 #ifdef _LGPL_SOURCE
132
133 #include <urcu/static/wfcqueue.h>
134
135 #define cds_wfcq_node_init _cds_wfcq_node_init
136 #define cds_wfcq_init _cds_wfcq_init
137 #define __cds_wfcq_init ___cds_wfcq_init
138 #define cds_wfcq_destroy _cds_wfcq_destroy
139 #define cds_wfcq_empty _cds_wfcq_empty
140 #define cds_wfcq_enqueue _cds_wfcq_enqueue
141
142 /* Dequeue locking */
143 #define cds_wfcq_dequeue_lock _cds_wfcq_dequeue_lock
144 #define cds_wfcq_dequeue_unlock _cds_wfcq_dequeue_unlock
145
146 /* Locking performed within cds_wfcq calls. */
147 #define cds_wfcq_dequeue_blocking _cds_wfcq_dequeue_blocking
148 #define cds_wfcq_dequeue_with_state_blocking \
149 _cds_wfcq_dequeue_with_state_blocking
150 #define cds_wfcq_splice_blocking _cds_wfcq_splice_blocking
151 #define cds_wfcq_first_blocking _cds_wfcq_first_blocking
152 #define cds_wfcq_next_blocking _cds_wfcq_next_blocking
153
154 /* Locking ensured by caller by holding cds_wfcq_dequeue_lock() */
155 #define __cds_wfcq_dequeue_blocking ___cds_wfcq_dequeue_blocking
156 #define __cds_wfcq_dequeue_with_state_blocking \
157 ___cds_wfcq_dequeue_with_state_blocking
158 #define __cds_wfcq_splice_blocking ___cds_wfcq_splice_blocking
159 #define __cds_wfcq_first_blocking ___cds_wfcq_first_blocking
160 #define __cds_wfcq_next_blocking ___cds_wfcq_next_blocking
161
162 /*
163 * Locking ensured by caller by holding cds_wfcq_dequeue_lock().
164 * Non-blocking: deque, first, next return CDS_WFCQ_WOULDBLOCK if they
165 * need to block. splice returns nonzero if it needs to block.
166 */
167 #define __cds_wfcq_dequeue_nonblocking ___cds_wfcq_dequeue_nonblocking
168 #define __cds_wfcq_dequeue_with_state_nonblocking \
169 ___cds_wfcq_dequeue_with_state_nonblocking
170 #define __cds_wfcq_splice_nonblocking ___cds_wfcq_splice_nonblocking
171 #define __cds_wfcq_first_nonblocking ___cds_wfcq_first_nonblocking
172 #define __cds_wfcq_next_nonblocking ___cds_wfcq_next_nonblocking
173
174 #else /* !_LGPL_SOURCE */
175
176 /*
177 * Mutual exclusion of cds_wfcq_* / __cds_wfcq_* API
178 *
179 * Synchronization table:
180 *
181 * External synchronization techniques described in the API below is
182 * required between pairs marked with "X". No external synchronization
183 * required between pairs marked with "-".
184 *
185 * Legend:
186 * [1] cds_wfcq_enqueue
187 * [2] __cds_wfcq_splice (destination queue)
188 * [3] __cds_wfcq_dequeue
189 * [4] __cds_wfcq_splice (source queue)
190 * [5] __cds_wfcq_first
191 * [6] __cds_wfcq_next
192 *
193 * [1] [2] [3] [4] [5] [6]
194 * [1] - - - - - -
195 * [2] - - - - - -
196 * [3] - - X X X X
197 * [4] - - X - X X
198 * [5] - - X X - -
199 * [6] - - X X - -
200 *
201 * Mutual exclusion can be ensured by holding cds_wfcq_dequeue_lock().
202 *
203 * For convenience, cds_wfcq_dequeue_blocking() and
204 * cds_wfcq_splice_blocking() hold the dequeue lock.
205 *
206 * Besides locking, mutual exclusion of dequeue, splice and iteration
207 * can be ensured by performing all of those operations from a single
208 * thread, without requiring any lock.
209 */
210
211 /*
212 * cds_wfcq_node_init: initialize wait-free queue node.
213 */
214 extern void cds_wfcq_node_init(struct cds_wfcq_node *node);
215
216 /*
217 * cds_wfcq_init: initialize wait-free queue. Pair with
218 * cds_wfcq_destroy().
219 */
220 extern void cds_wfcq_init(struct cds_wfcq_head *head,
221 struct cds_wfcq_tail *tail);
222
223 /*
224 * cds_wfcq_destroy: destroy wait-free queue. Pair with
225 * cds_wfcq_init().
226 */
227 extern void cds_wfcq_destroy(struct cds_wfcq_head *head,
228 struct cds_wfcq_tail *tail);
229
230 /*
231 * __cds_wfcq_init: initialize wait-free queue (without lock). Don't
232 * pair with any destroy function.
233 */
234 extern void __cds_wfcq_init(struct __cds_wfcq_head *head,
235 struct cds_wfcq_tail *tail);
236
237 /*
238 * cds_wfcq_empty: return whether wait-free queue is empty.
239 *
240 * No memory barrier is issued. No mutual exclusion is required.
241 */
242 extern bool cds_wfcq_empty(cds_wfcq_head_ptr_t head,
243 struct cds_wfcq_tail *tail);
244
245 /*
246 * cds_wfcq_dequeue_lock: take the dequeue mutual exclusion lock.
247 */
248 extern void cds_wfcq_dequeue_lock(struct cds_wfcq_head *head,
249 struct cds_wfcq_tail *tail);
250
251 /*
252 * cds_wfcq_dequeue_unlock: release the dequeue mutual exclusion lock.
253 */
254 extern void cds_wfcq_dequeue_unlock(struct cds_wfcq_head *head,
255 struct cds_wfcq_tail *tail);
256
257 /*
258 * cds_wfcq_enqueue: enqueue a node into a wait-free queue.
259 *
260 * Issues a full memory barrier before enqueue. No mutual exclusion is
261 * required.
262 *
263 * Returns false if the queue was empty prior to adding the node.
264 * Returns true otherwise.
265 */
266 extern bool cds_wfcq_enqueue(cds_wfcq_head_ptr_t head,
267 struct cds_wfcq_tail *tail,
268 struct cds_wfcq_node *node);
269
270 /*
271 * cds_wfcq_dequeue_blocking: dequeue a node from a wait-free queue.
272 *
273 * Content written into the node before enqueue is guaranteed to be
274 * consistent, but no other memory ordering is ensured.
275 * It is valid to reuse and free a dequeued node immediately.
276 * Mutual exclusion with cds_wfcq_dequeue_blocking and dequeue lock is
277 * ensured.
278 */
279 extern struct cds_wfcq_node *cds_wfcq_dequeue_blocking(
280 struct cds_wfcq_head *head,
281 struct cds_wfcq_tail *tail);
282
283 /*
284 * cds_wfcq_dequeue_with_state_blocking: dequeue with state.
285 *
286 * Same as cds_wfcq_dequeue_blocking, but saves whether dequeueing the
287 * last node of the queue into state (CDS_WFCQ_STATE_LAST).
288 */
289 extern struct cds_wfcq_node *cds_wfcq_dequeue_with_state_blocking(
290 struct cds_wfcq_head *head,
291 struct cds_wfcq_tail *tail,
292 int *state);
293
294 /*
295 * cds_wfcq_splice_blocking: enqueue all src_q nodes at the end of dest_q.
296 *
297 * Dequeue all nodes from src_q.
298 * dest_q must be already initialized.
299 * Content written into the node before enqueue is guaranteed to be
300 * consistent, but no other memory ordering is ensured.
301 * Mutual exclusion with cds_wfcq_dequeue_blocking and dequeue lock is
302 * ensured.
303 *
304 * Returns enum cds_wfcq_ret which indicates the state of the src or
305 * dest queue.
306 */
307 extern enum cds_wfcq_ret cds_wfcq_splice_blocking(
308 struct cds_wfcq_head *dest_q_head,
309 struct cds_wfcq_tail *dest_q_tail,
310 struct cds_wfcq_head *src_q_head,
311 struct cds_wfcq_tail *src_q_tail);
312
313 /*
314 * __cds_wfcq_dequeue_blocking: dequeue a node from a wait-free queue.
315 *
316 * Content written into the node before enqueue is guaranteed to be
317 * consistent, but no other memory ordering is ensured.
318 * It is valid to reuse and free a dequeued node immediately.
319 * Dequeue/splice/iteration mutual exclusion should be ensured by the
320 * caller.
321 */
322 extern struct cds_wfcq_node *__cds_wfcq_dequeue_blocking(
323 cds_wfcq_head_ptr_t head,
324 struct cds_wfcq_tail *tail);
325
326 /*
327 * __cds_wfcq_dequeue_with_state_blocking: dequeue with state.
328 *
329 * Same as __cds_wfcq_dequeue_blocking, but saves whether dequeueing the
330 * last node of the queue into state (CDS_WFCQ_STATE_LAST).
331 */
332 extern struct cds_wfcq_node *__cds_wfcq_dequeue_with_state_blocking(
333 cds_wfcq_head_ptr_t head,
334 struct cds_wfcq_tail *tail,
335 int *state);
336
337 /*
338 * __cds_wfcq_dequeue_nonblocking: dequeue a node from a wait-free queue.
339 *
340 * Same as __cds_wfcq_dequeue_blocking, but returns CDS_WFCQ_WOULDBLOCK
341 * if it needs to block.
342 */
343 extern struct cds_wfcq_node *__cds_wfcq_dequeue_nonblocking(
344 cds_wfcq_head_ptr_t head,
345 struct cds_wfcq_tail *tail);
346
347 /*
348 * __cds_wfcq_dequeue_with_state_blocking: dequeue with state.
349 *
350 * Same as __cds_wfcq_dequeue_nonblocking, but saves whether dequeueing
351 * the last node of the queue into state (CDS_WFCQ_STATE_LAST).
352 */
353 extern struct cds_wfcq_node *__cds_wfcq_dequeue_with_state_nonblocking(
354 cds_wfcq_head_ptr_t head,
355 struct cds_wfcq_tail *tail,
356 int *state);
357
358 /*
359 * __cds_wfcq_splice_blocking: enqueue all src_q nodes at the end of dest_q.
360 *
361 * Dequeue all nodes from src_q.
362 * dest_q must be already initialized.
363 * Mutual exclusion for src_q should be ensured by the caller as
364 * specified in the "Synchronisation table".
365 * Returns enum cds_wfcq_ret which indicates the state of the src or
366 * dest queue. Never returns CDS_WFCQ_RET_WOULDBLOCK.
367 */
368 extern enum cds_wfcq_ret __cds_wfcq_splice_blocking(
369 cds_wfcq_head_ptr_t dest_q_head,
370 struct cds_wfcq_tail *dest_q_tail,
371 cds_wfcq_head_ptr_t src_q_head,
372 struct cds_wfcq_tail *src_q_tail);
373
374 /*
375 * __cds_wfcq_splice_nonblocking: enqueue all src_q nodes at the end of dest_q.
376 *
377 * Same as __cds_wfcq_splice_blocking, but returns
378 * CDS_WFCQ_RET_WOULDBLOCK if it needs to block.
379 */
380 extern enum cds_wfcq_ret __cds_wfcq_splice_nonblocking(
381 cds_wfcq_head_ptr_t dest_q_head,
382 struct cds_wfcq_tail *dest_q_tail,
383 cds_wfcq_head_ptr_t src_q_head,
384 struct cds_wfcq_tail *src_q_tail);
385
386 /*
387 * __cds_wfcq_first_blocking: get first node of a queue, without dequeuing.
388 *
389 * Content written into the node before enqueue is guaranteed to be
390 * consistent, but no other memory ordering is ensured.
391 * Dequeue/splice/iteration mutual exclusion should be ensured by the
392 * caller.
393 *
394 * Used by for-like iteration macros:
395 * __cds_wfcq_for_each_blocking()
396 * __cds_wfcq_for_each_blocking_safe()
397 *
398 * Returns NULL if queue is empty, first node otherwise.
399 */
400 extern struct cds_wfcq_node *__cds_wfcq_first_blocking(
401 cds_wfcq_head_ptr_t head,
402 struct cds_wfcq_tail *tail);
403
404 /*
405 * __cds_wfcq_first_nonblocking: get first node of a queue, without dequeuing.
406 *
407 * Same as __cds_wfcq_first_blocking, but returns CDS_WFCQ_WOULDBLOCK if
408 * it needs to block.
409 */
410 extern struct cds_wfcq_node *__cds_wfcq_first_nonblocking(
411 cds_wfcq_head_ptr_t head,
412 struct cds_wfcq_tail *tail);
413
414 /*
415 * __cds_wfcq_next_blocking: get next node of a queue, without dequeuing.
416 *
417 * Content written into the node before enqueue is guaranteed to be
418 * consistent, but no other memory ordering is ensured.
419 * Dequeue/splice/iteration mutual exclusion should be ensured by the
420 * caller.
421 *
422 * Used by for-like iteration macros:
423 * __cds_wfcq_for_each_blocking()
424 * __cds_wfcq_for_each_blocking_safe()
425 *
426 * Returns NULL if reached end of queue, non-NULL next queue node
427 * otherwise.
428 */
429 extern struct cds_wfcq_node *__cds_wfcq_next_blocking(
430 cds_wfcq_head_ptr_t head,
431 struct cds_wfcq_tail *tail,
432 struct cds_wfcq_node *node);
433
434 /*
435 * __cds_wfcq_next_blocking: get next node of a queue, without dequeuing.
436 *
437 * Same as __cds_wfcq_next_blocking, but returns CDS_WFCQ_WOULDBLOCK if
438 * it needs to block.
439 */
440 extern struct cds_wfcq_node *__cds_wfcq_next_nonblocking(
441 cds_wfcq_head_ptr_t head,
442 struct cds_wfcq_tail *tail,
443 struct cds_wfcq_node *node);
444
445 #endif /* !_LGPL_SOURCE */
446
447 /*
448 * __cds_wfcq_for_each_blocking: Iterate over all nodes in a queue,
449 * without dequeuing them.
450 * @head: head of the queue (struct cds_wfcq_head or __cds_wfcq_head pointer).
451 * @tail: tail of the queue (struct cds_wfcq_tail pointer).
452 * @node: iterator on the queue (struct cds_wfcq_node pointer).
453 *
454 * Content written into each node before enqueue is guaranteed to be
455 * consistent, but no other memory ordering is ensured.
456 * Dequeue/splice/iteration mutual exclusion should be ensured by the
457 * caller.
458 */
459 #define __cds_wfcq_for_each_blocking(head, tail, node) \
460 for (node = __cds_wfcq_first_blocking(head, tail); \
461 node != NULL; \
462 node = __cds_wfcq_next_blocking(head, tail, node))
463
464 /*
465 * __cds_wfcq_for_each_blocking_safe: Iterate over all nodes in a queue,
466 * without dequeuing them. Safe against deletion.
467 * @head: head of the queue (struct cds_wfcq_head or __cds_wfcq_head pointer).
468 * @tail: tail of the queue (struct cds_wfcq_tail pointer).
469 * @node: iterator on the queue (struct cds_wfcq_node pointer).
470 * @n: struct cds_wfcq_node pointer holding the next pointer (used
471 * internally).
472 *
473 * Content written into each node before enqueue is guaranteed to be
474 * consistent, but no other memory ordering is ensured.
475 * Dequeue/splice/iteration mutual exclusion should be ensured by the
476 * caller.
477 */
478 #define __cds_wfcq_for_each_blocking_safe(head, tail, node, n) \
479 for (node = __cds_wfcq_first_blocking(head, tail), \
480 n = (node ? __cds_wfcq_next_blocking(head, tail, node) : NULL); \
481 node != NULL; \
482 node = n, n = (node ? __cds_wfcq_next_blocking(head, tail, node) : NULL))
483
484 #ifdef __cplusplus
485 }
486 #endif
487
488 #endif /* _URCU_WFCQUEUE_H */
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