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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 | ||
0b73c819 | 46 | #define CDS_WFCQ_WOULDBLOCK ((struct cds_wfcq_node *) -1UL) |
47215721 | 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 | ||
4d0d7cbc | 77 | #ifndef __cplusplus |
f637f191 MD |
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 | 83 | typedef union { |
f637f191 MD |
84 | struct __cds_wfcq_head *_h; |
85 | struct cds_wfcq_head *h; | |
5135c0fd | 86 | } __attribute__((__transparent_union__)) cds_wfcq_head_ptr_t; |
f637f191 | 87 | |
4d0d7cbc MD |
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 | ||
8ad4ce58 MD |
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_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 | |
eec791af MD |
146 | #define cds_wfcq_dequeue_with_state_blocking \ |
147 | _cds_wfcq_dequeue_with_state_blocking | |
8ad4ce58 MD |
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 | |
eec791af MD |
154 | #define __cds_wfcq_dequeue_with_state_blocking \ |
155 | ___cds_wfcq_dequeue_with_state_blocking | |
8ad4ce58 MD |
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 | ||
47215721 MD |
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 | |
eec791af MD |
166 | #define __cds_wfcq_dequeue_with_state_nonblocking \ |
167 | ___cds_wfcq_dequeue_with_state_nonblocking | |
47215721 MD |
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 | ||
8ad4ce58 MD |
172 | #else /* !_LGPL_SOURCE */ |
173 | ||
174 | /* | |
175 | * Mutual exclusion of cds_wfcq_* / __cds_wfcq_* API | |
176 | * | |
f878b49e MD |
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 | * | |
8ad4ce58 MD |
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. | |
1fe734e1 MD |
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. | |
8ad4ce58 MD |
207 | */ |
208 | ||
209 | /* | |
210 | * cds_wfcq_node_init: initialize wait-free queue node. | |
211 | */ | |
212 | extern void cds_wfcq_node_init(struct cds_wfcq_node *node); | |
213 | ||
214 | /* | |
215 | * cds_wfcq_init: initialize wait-free queue. | |
216 | */ | |
217 | extern void cds_wfcq_init(struct cds_wfcq_head *head, | |
218 | struct cds_wfcq_tail *tail); | |
219 | ||
f637f191 MD |
220 | /* |
221 | * __cds_wfcq_init: initialize wait-free queue. | |
222 | */ | |
223 | extern void __cds_wfcq_init(struct __cds_wfcq_head *head, | |
224 | struct cds_wfcq_tail *tail); | |
225 | ||
8ad4ce58 MD |
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 | 231 | extern bool cds_wfcq_empty(cds_wfcq_head_ptr_t head, |
8ad4ce58 MD |
232 | struct cds_wfcq_tail *tail); |
233 | ||
234 | /* | |
235 | * cds_wfcq_dequeue_lock: take the dequeue mutual exclusion lock. | |
236 | */ | |
237 | extern 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 | */ | |
243 | extern 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. | |
23773356 MD |
251 | * |
252 | * Returns false if the queue was empty prior to adding the node. | |
253 | * Returns true otherwise. | |
8ad4ce58 | 254 | */ |
f637f191 | 255 | extern bool cds_wfcq_enqueue(cds_wfcq_head_ptr_t head, |
8ad4ce58 MD |
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. |
8ad4ce58 MD |
267 | */ |
268 | extern struct cds_wfcq_node *cds_wfcq_dequeue_blocking( | |
269 | struct cds_wfcq_head *head, | |
270 | struct cds_wfcq_tail *tail); | |
271 | ||
eec791af MD |
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 | */ | |
278 | extern 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 | ||
8ad4ce58 MD |
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. |
23773356 MD |
292 | * |
293 | * Returns enum cds_wfcq_ret which indicates the state of the src or | |
b94aaf6f | 294 | * dest queue. |
8ad4ce58 | 295 | */ |
23773356 | 296 | extern enum cds_wfcq_ret cds_wfcq_splice_blocking( |
8ad4ce58 MD |
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. |
8ad4ce58 MD |
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. | |
1fe734e1 MD |
308 | * Dequeue/splice/iteration mutual exclusion should be ensured by the |
309 | * caller. | |
8ad4ce58 MD |
310 | */ |
311 | extern struct cds_wfcq_node *__cds_wfcq_dequeue_blocking( | |
f637f191 | 312 | cds_wfcq_head_ptr_t head, |
8ad4ce58 MD |
313 | struct cds_wfcq_tail *tail); |
314 | ||
eec791af MD |
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 | */ | |
321 | extern struct cds_wfcq_node *__cds_wfcq_dequeue_with_state_blocking( | |
f637f191 | 322 | cds_wfcq_head_ptr_t head, |
eec791af MD |
323 | struct cds_wfcq_tail *tail, |
324 | int *state); | |
325 | ||
47215721 MD |
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 | */ | |
332 | extern struct cds_wfcq_node *__cds_wfcq_dequeue_nonblocking( | |
f637f191 | 333 | cds_wfcq_head_ptr_t head, |
47215721 MD |
334 | struct cds_wfcq_tail *tail); |
335 | ||
eec791af MD |
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 | */ | |
342 | extern struct cds_wfcq_node *__cds_wfcq_dequeue_with_state_nonblocking( | |
f637f191 | 343 | cds_wfcq_head_ptr_t head, |
eec791af MD |
344 | struct cds_wfcq_tail *tail, |
345 | int *state); | |
346 | ||
8ad4ce58 MD |
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. | |
f878b49e MD |
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 | 357 | extern 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, |
8ad4ce58 MD |
361 | struct cds_wfcq_tail *src_q_tail); |
362 | ||
47215721 MD |
363 | /* |
364 | * __cds_wfcq_splice_nonblocking: enqueue all src_q nodes at the end of dest_q. | |
365 | * | |
23773356 MD |
366 | * Same as __cds_wfcq_splice_blocking, but returns |
367 | * CDS_WFCQ_RET_WOULDBLOCK if it needs to block. | |
47215721 | 368 | */ |
23773356 | 369 | extern 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, |
47215721 MD |
373 | struct cds_wfcq_tail *src_q_tail); |
374 | ||
8ad4ce58 MD |
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. | |
1fe734e1 MD |
380 | * Dequeue/splice/iteration mutual exclusion should be ensured by the |
381 | * caller. | |
f94061a3 MD |
382 | * |
383 | * Used by for-like iteration macros: | |
384 | * __cds_wfcq_for_each_blocking() | |
385 | * __cds_wfcq_for_each_blocking_safe() | |
131a29a6 MD |
386 | * |
387 | * Returns NULL if queue is empty, first node otherwise. | |
8ad4ce58 MD |
388 | */ |
389 | extern struct cds_wfcq_node *__cds_wfcq_first_blocking( | |
f637f191 | 390 | cds_wfcq_head_ptr_t head, |
8ad4ce58 MD |
391 | struct cds_wfcq_tail *tail); |
392 | ||
47215721 MD |
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 | */ | |
399 | extern struct cds_wfcq_node *__cds_wfcq_first_nonblocking( | |
f637f191 | 400 | cds_wfcq_head_ptr_t head, |
47215721 MD |
401 | struct cds_wfcq_tail *tail); |
402 | ||
8ad4ce58 MD |
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. | |
1fe734e1 MD |
408 | * Dequeue/splice/iteration mutual exclusion should be ensured by the |
409 | * caller. | |
f94061a3 MD |
410 | * |
411 | * Used by for-like iteration macros: | |
412 | * __cds_wfcq_for_each_blocking() | |
413 | * __cds_wfcq_for_each_blocking_safe() | |
131a29a6 MD |
414 | * |
415 | * Returns NULL if reached end of queue, non-NULL next queue node | |
416 | * otherwise. | |
8ad4ce58 MD |
417 | */ |
418 | extern struct cds_wfcq_node *__cds_wfcq_next_blocking( | |
f637f191 | 419 | cds_wfcq_head_ptr_t head, |
8ad4ce58 MD |
420 | struct cds_wfcq_tail *tail, |
421 | struct cds_wfcq_node *node); | |
422 | ||
47215721 MD |
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 | */ | |
429 | extern struct cds_wfcq_node *__cds_wfcq_next_nonblocking( | |
f637f191 | 430 | cds_wfcq_head_ptr_t head, |
47215721 MD |
431 | struct cds_wfcq_tail *tail, |
432 | struct cds_wfcq_node *node); | |
433 | ||
8ad4ce58 MD |
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). |
8ad4ce58 MD |
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. | |
1fe734e1 MD |
445 | * Dequeue/splice/iteration mutual exclusion should be ensured by the |
446 | * caller. | |
8ad4ce58 MD |
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). |
8ad4ce58 MD |
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. | |
1fe734e1 MD |
464 | * Dequeue/splice/iteration mutual exclusion should be ensured by the |
465 | * caller. | |
8ad4ce58 MD |
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 */ |