wfcqueue: add C++ compatibility API
[urcu.git] / urcu / wfcqueue.h
CommitLineData
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1#ifndef _URCU_WFCQUEUE_H
2#define _URCU_WFCQUEUE_H
3
4/*
47215721 5 * urcu/wfcqueue.h
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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
34extern "C" {
35#endif
36
37/*
38 * Concurrent queue with wait-free enqueue/blocking dequeue.
39 *
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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.
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44 */
45
0b73c819 46#define CDS_WFCQ_WOULDBLOCK ((struct cds_wfcq_node *) -1UL)
47215721 47
23773356 48enum cds_wfcq_ret {
f878b49e 49 CDS_WFCQ_RET_WOULDBLOCK = -1,
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50 CDS_WFCQ_RET_DEST_EMPTY = 0,
51 CDS_WFCQ_RET_DEST_NON_EMPTY = 1,
52 CDS_WFCQ_RET_SRC_EMPTY = 2,
53};
54
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55enum cds_wfcq_state {
56 CDS_WFCQ_STATE_LAST = (1U << 0),
57};
58
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59struct 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 */
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68struct __cds_wfcq_head {
69 struct cds_wfcq_node node;
70};
71
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72struct cds_wfcq_head {
73 struct cds_wfcq_node node;
74 pthread_mutex_t lock;
75};
76
4d0d7cbc 77#ifndef __cplusplus
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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 */
5135c0fd 83typedef union {
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84 struct __cds_wfcq_head *_h;
85 struct cds_wfcq_head *h;
5135c0fd 86} __attribute__((__transparent_union__)) cds_wfcq_head_ptr_t;
f637f191 87
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88/*
89 * This static inline is only present for compatibility with C++. It is
90 * effect-less in C.
91 */
92static 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 */
101static 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. */
108typedef 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. */
114static 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. */
120static 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
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127struct 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_empty _cds_wfcq_empty
138#define cds_wfcq_enqueue _cds_wfcq_enqueue
139
140/* Dequeue locking */
141#define cds_wfcq_dequeue_lock _cds_wfcq_dequeue_lock
142#define cds_wfcq_dequeue_unlock _cds_wfcq_dequeue_unlock
143
144/* Locking performed within cds_wfcq calls. */
145#define cds_wfcq_dequeue_blocking _cds_wfcq_dequeue_blocking
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146#define cds_wfcq_dequeue_with_state_blocking \
147 _cds_wfcq_dequeue_with_state_blocking
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148#define cds_wfcq_splice_blocking _cds_wfcq_splice_blocking
149#define cds_wfcq_first_blocking _cds_wfcq_first_blocking
150#define cds_wfcq_next_blocking _cds_wfcq_next_blocking
151
152/* Locking ensured by caller by holding cds_wfcq_dequeue_lock() */
153#define __cds_wfcq_dequeue_blocking ___cds_wfcq_dequeue_blocking
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154#define __cds_wfcq_dequeue_with_state_blocking \
155 ___cds_wfcq_dequeue_with_state_blocking
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156#define __cds_wfcq_splice_blocking ___cds_wfcq_splice_blocking
157#define __cds_wfcq_first_blocking ___cds_wfcq_first_blocking
158#define __cds_wfcq_next_blocking ___cds_wfcq_next_blocking
159
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160/*
161 * Locking ensured by caller by holding cds_wfcq_dequeue_lock().
162 * Non-blocking: deque, first, next return CDS_WFCQ_WOULDBLOCK if they
163 * need to block. splice returns nonzero if it needs to block.
164 */
165#define __cds_wfcq_dequeue_nonblocking ___cds_wfcq_dequeue_nonblocking
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166#define __cds_wfcq_dequeue_with_state_nonblocking \
167 ___cds_wfcq_dequeue_with_state_nonblocking
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168#define __cds_wfcq_splice_nonblocking ___cds_wfcq_splice_nonblocking
169#define __cds_wfcq_first_nonblocking ___cds_wfcq_first_nonblocking
170#define __cds_wfcq_next_nonblocking ___cds_wfcq_next_nonblocking
171
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172#else /* !_LGPL_SOURCE */
173
174/*
175 * Mutual exclusion of cds_wfcq_* / __cds_wfcq_* API
176 *
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177 * Synchronization table:
178 *
179 * External synchronization techniques described in the API below is
180 * required between pairs marked with "X". No external synchronization
181 * required between pairs marked with "-".
182 *
183 * Legend:
184 * [1] cds_wfcq_enqueue
185 * [2] __cds_wfcq_splice (destination queue)
186 * [3] __cds_wfcq_dequeue
187 * [4] __cds_wfcq_splice (source queue)
188 * [5] __cds_wfcq_first
189 * [6] __cds_wfcq_next
190 *
191 * [1] [2] [3] [4] [5] [6]
192 * [1] - - - - - -
193 * [2] - - - - - -
194 * [3] - - X X X X
195 * [4] - - X - X X
196 * [5] - - X X - -
197 * [6] - - X X - -
198 *
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199 * Mutual exclusion can be ensured by holding cds_wfcq_dequeue_lock().
200 *
201 * For convenience, cds_wfcq_dequeue_blocking() and
202 * cds_wfcq_splice_blocking() hold the dequeue lock.
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203 *
204 * Besides locking, mutual exclusion of dequeue, splice and iteration
205 * can be ensured by performing all of those operations from a single
206 * thread, without requiring any lock.
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207 */
208
209/*
210 * cds_wfcq_node_init: initialize wait-free queue node.
211 */
212extern void cds_wfcq_node_init(struct cds_wfcq_node *node);
213
214/*
215 * cds_wfcq_init: initialize wait-free queue.
216 */
217extern void cds_wfcq_init(struct cds_wfcq_head *head,
218 struct cds_wfcq_tail *tail);
219
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220/*
221 * __cds_wfcq_init: initialize wait-free queue.
222 */
223extern void __cds_wfcq_init(struct __cds_wfcq_head *head,
224 struct cds_wfcq_tail *tail);
225
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226/*
227 * cds_wfcq_empty: return whether wait-free queue is empty.
228 *
229 * No memory barrier is issued. No mutual exclusion is required.
230 */
f637f191 231extern bool cds_wfcq_empty(cds_wfcq_head_ptr_t head,
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232 struct cds_wfcq_tail *tail);
233
234/*
235 * cds_wfcq_dequeue_lock: take the dequeue mutual exclusion lock.
236 */
237extern void cds_wfcq_dequeue_lock(struct cds_wfcq_head *head,
238 struct cds_wfcq_tail *tail);
239
240/*
241 * cds_wfcq_dequeue_unlock: release the dequeue mutual exclusion lock.
242 */
243extern void cds_wfcq_dequeue_unlock(struct cds_wfcq_head *head,
244 struct cds_wfcq_tail *tail);
245
246/*
247 * cds_wfcq_enqueue: enqueue a node into a wait-free queue.
248 *
249 * Issues a full memory barrier before enqueue. No mutual exclusion is
250 * required.
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251 *
252 * Returns false if the queue was empty prior to adding the node.
253 * Returns true otherwise.
8ad4ce58 254 */
f637f191 255extern bool cds_wfcq_enqueue(cds_wfcq_head_ptr_t head,
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256 struct cds_wfcq_tail *tail,
257 struct cds_wfcq_node *node);
258
259/*
260 * cds_wfcq_dequeue_blocking: dequeue a node from a wait-free queue.
261 *
262 * Content written into the node before enqueue is guaranteed to be
263 * consistent, but no other memory ordering is ensured.
264 * It is valid to reuse and free a dequeued node immediately.
ffa11a18 265 * Mutual exclusion with cds_wfcq_dequeue_blocking and dequeue lock is
1fe734e1 266 * ensured.
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267 */
268extern struct cds_wfcq_node *cds_wfcq_dequeue_blocking(
269 struct cds_wfcq_head *head,
270 struct cds_wfcq_tail *tail);
271
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272/*
273 * cds_wfcq_dequeue_with_state_blocking: dequeue with state.
274 *
275 * Same as cds_wfcq_dequeue_blocking, but saves whether dequeueing the
276 * last node of the queue into state (CDS_WFCQ_STATE_LAST).
277 */
278extern struct cds_wfcq_node *cds_wfcq_dequeue_with_state_blocking(
279 struct cds_wfcq_head *head,
280 struct cds_wfcq_tail *tail,
281 int *state);
282
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283/*
284 * cds_wfcq_splice_blocking: enqueue all src_q nodes at the end of dest_q.
285 *
286 * Dequeue all nodes from src_q.
287 * dest_q must be already initialized.
288 * Content written into the node before enqueue is guaranteed to be
289 * consistent, but no other memory ordering is ensured.
ffa11a18 290 * Mutual exclusion with cds_wfcq_dequeue_blocking and dequeue lock is
1fe734e1 291 * ensured.
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292 *
293 * Returns enum cds_wfcq_ret which indicates the state of the src or
b94aaf6f 294 * dest queue.
8ad4ce58 295 */
23773356 296extern enum cds_wfcq_ret cds_wfcq_splice_blocking(
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297 struct cds_wfcq_head *dest_q_head,
298 struct cds_wfcq_tail *dest_q_tail,
299 struct cds_wfcq_head *src_q_head,
300 struct cds_wfcq_tail *src_q_tail);
301
302/*
47215721 303 * __cds_wfcq_dequeue_blocking: dequeue a node from a wait-free queue.
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304 *
305 * Content written into the node before enqueue is guaranteed to be
306 * consistent, but no other memory ordering is ensured.
307 * It is valid to reuse and free a dequeued node immediately.
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308 * Dequeue/splice/iteration mutual exclusion should be ensured by the
309 * caller.
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310 */
311extern struct cds_wfcq_node *__cds_wfcq_dequeue_blocking(
f637f191 312 cds_wfcq_head_ptr_t head,
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313 struct cds_wfcq_tail *tail);
314
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315/*
316 * __cds_wfcq_dequeue_with_state_blocking: dequeue with state.
317 *
318 * Same as __cds_wfcq_dequeue_blocking, but saves whether dequeueing the
319 * last node of the queue into state (CDS_WFCQ_STATE_LAST).
320 */
321extern struct cds_wfcq_node *__cds_wfcq_dequeue_with_state_blocking(
f637f191 322 cds_wfcq_head_ptr_t head,
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323 struct cds_wfcq_tail *tail,
324 int *state);
325
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326/*
327 * __cds_wfcq_dequeue_nonblocking: dequeue a node from a wait-free queue.
328 *
329 * Same as __cds_wfcq_dequeue_blocking, but returns CDS_WFCQ_WOULDBLOCK
330 * if it needs to block.
331 */
332extern struct cds_wfcq_node *__cds_wfcq_dequeue_nonblocking(
f637f191 333 cds_wfcq_head_ptr_t head,
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334 struct cds_wfcq_tail *tail);
335
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336/*
337 * __cds_wfcq_dequeue_with_state_blocking: dequeue with state.
338 *
339 * Same as __cds_wfcq_dequeue_nonblocking, but saves whether dequeueing
340 * the last node of the queue into state (CDS_WFCQ_STATE_LAST).
341 */
342extern struct cds_wfcq_node *__cds_wfcq_dequeue_with_state_nonblocking(
f637f191 343 cds_wfcq_head_ptr_t head,
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344 struct cds_wfcq_tail *tail,
345 int *state);
346
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347/*
348 * __cds_wfcq_splice_blocking: enqueue all src_q nodes at the end of dest_q.
349 *
350 * Dequeue all nodes from src_q.
351 * dest_q must be already initialized.
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352 * Mutual exclusion for src_q should be ensured by the caller as
353 * specified in the "Synchronisation table".
23773356 354 * Returns enum cds_wfcq_ret which indicates the state of the src or
f878b49e 355 * dest queue. Never returns CDS_WFCQ_RET_WOULDBLOCK.
8ad4ce58 356 */
23773356 357extern enum cds_wfcq_ret __cds_wfcq_splice_blocking(
f637f191 358 cds_wfcq_head_ptr_t dest_q_head,
8ad4ce58 359 struct cds_wfcq_tail *dest_q_tail,
f637f191 360 cds_wfcq_head_ptr_t src_q_head,
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361 struct cds_wfcq_tail *src_q_tail);
362
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363/*
364 * __cds_wfcq_splice_nonblocking: enqueue all src_q nodes at the end of dest_q.
365 *
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366 * Same as __cds_wfcq_splice_blocking, but returns
367 * CDS_WFCQ_RET_WOULDBLOCK if it needs to block.
47215721 368 */
23773356 369extern enum cds_wfcq_ret __cds_wfcq_splice_nonblocking(
f637f191 370 cds_wfcq_head_ptr_t dest_q_head,
47215721 371 struct cds_wfcq_tail *dest_q_tail,
f637f191 372 cds_wfcq_head_ptr_t src_q_head,
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373 struct cds_wfcq_tail *src_q_tail);
374
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375/*
376 * __cds_wfcq_first_blocking: get first node of a queue, without dequeuing.
377 *
378 * Content written into the node before enqueue is guaranteed to be
379 * consistent, but no other memory ordering is ensured.
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380 * Dequeue/splice/iteration mutual exclusion should be ensured by the
381 * caller.
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382 *
383 * Used by for-like iteration macros:
384 * __cds_wfcq_for_each_blocking()
385 * __cds_wfcq_for_each_blocking_safe()
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386 *
387 * Returns NULL if queue is empty, first node otherwise.
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388 */
389extern struct cds_wfcq_node *__cds_wfcq_first_blocking(
f637f191 390 cds_wfcq_head_ptr_t head,
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391 struct cds_wfcq_tail *tail);
392
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393/*
394 * __cds_wfcq_first_nonblocking: get first node of a queue, without dequeuing.
395 *
396 * Same as __cds_wfcq_first_blocking, but returns CDS_WFCQ_WOULDBLOCK if
397 * it needs to block.
398 */
399extern struct cds_wfcq_node *__cds_wfcq_first_nonblocking(
f637f191 400 cds_wfcq_head_ptr_t head,
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401 struct cds_wfcq_tail *tail);
402
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403/*
404 * __cds_wfcq_next_blocking: get next node of a queue, without dequeuing.
405 *
406 * Content written into the node before enqueue is guaranteed to be
407 * consistent, but no other memory ordering is ensured.
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408 * Dequeue/splice/iteration mutual exclusion should be ensured by the
409 * caller.
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410 *
411 * Used by for-like iteration macros:
412 * __cds_wfcq_for_each_blocking()
413 * __cds_wfcq_for_each_blocking_safe()
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414 *
415 * Returns NULL if reached end of queue, non-NULL next queue node
416 * otherwise.
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417 */
418extern struct cds_wfcq_node *__cds_wfcq_next_blocking(
f637f191 419 cds_wfcq_head_ptr_t head,
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420 struct cds_wfcq_tail *tail,
421 struct cds_wfcq_node *node);
422
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423/*
424 * __cds_wfcq_next_blocking: get next node of a queue, without dequeuing.
425 *
426 * Same as __cds_wfcq_next_blocking, but returns CDS_WFCQ_WOULDBLOCK if
427 * it needs to block.
428 */
429extern struct cds_wfcq_node *__cds_wfcq_next_nonblocking(
f637f191 430 cds_wfcq_head_ptr_t head,
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431 struct cds_wfcq_tail *tail,
432 struct cds_wfcq_node *node);
433
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434#endif /* !_LGPL_SOURCE */
435
436/*
437 * __cds_wfcq_for_each_blocking: Iterate over all nodes in a queue,
438 * without dequeuing them.
f637f191 439 * @head: head of the queue (struct cds_wfcq_head or __cds_wfcq_head pointer).
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440 * @tail: tail of the queue (struct cds_wfcq_tail pointer).
441 * @node: iterator on the queue (struct cds_wfcq_node pointer).
442 *
443 * Content written into each node before enqueue is guaranteed to be
444 * consistent, but no other memory ordering is ensured.
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445 * Dequeue/splice/iteration mutual exclusion should be ensured by the
446 * caller.
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447 */
448#define __cds_wfcq_for_each_blocking(head, tail, node) \
449 for (node = __cds_wfcq_first_blocking(head, tail); \
450 node != NULL; \
451 node = __cds_wfcq_next_blocking(head, tail, node))
452
453/*
454 * __cds_wfcq_for_each_blocking_safe: Iterate over all nodes in a queue,
455 * without dequeuing them. Safe against deletion.
f637f191 456 * @head: head of the queue (struct cds_wfcq_head or __cds_wfcq_head pointer).
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457 * @tail: tail of the queue (struct cds_wfcq_tail pointer).
458 * @node: iterator on the queue (struct cds_wfcq_node pointer).
459 * @n: struct cds_wfcq_node pointer holding the next pointer (used
460 * internally).
461 *
462 * Content written into each node before enqueue is guaranteed to be
463 * consistent, but no other memory ordering is ensured.
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464 * Dequeue/splice/iteration mutual exclusion should be ensured by the
465 * caller.
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466 */
467#define __cds_wfcq_for_each_blocking_safe(head, tail, node, n) \
468 for (node = __cds_wfcq_first_blocking(head, tail), \
469 n = (node ? __cds_wfcq_next_blocking(head, tail, node) : NULL); \
470 node != NULL; \
471 node = n, n = (node ? __cds_wfcq_next_blocking(head, tail, node) : NULL))
472
473#ifdef __cplusplus
474}
475#endif
476
477#endif /* _URCU_WFCQUEUE_H */
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