rculfhash: Ensure future-proof memory barrier semantic consistency
[urcu.git] / urcu / wfqueue.h
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1#ifndef _URCU_WFQUEUE_H
2#define _URCU_WFQUEUE_H
3
4/*
5 * wfqueue.h
6 *
7 * Userspace RCU library - Queue with Wait-Free Enqueue/Blocking Dequeue
8 *
9 * Copyright 2010 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
10 *
11 * This library is free software; you can redistribute it and/or
12 * modify it under the terms of the GNU Lesser General Public
13 * License as published by the Free Software Foundation; either
14 * version 2.1 of the License, or (at your option) any later version.
15 *
16 * This library is distributed in the hope that it will be useful,
17 * but WITHOUT ANY WARRANTY; without even the implied warranty of
18 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
19 * Lesser General Public License for more details.
20 *
21 * You should have received a copy of the GNU Lesser General Public
22 * License along with this library; if not, write to the Free Software
23 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
24 */
25
26#include <pthread.h>
27#include <assert.h>
28#include <urcu/compiler.h>
29
30#ifdef __cplusplus
31extern "C" {
32#endif
33
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34/*
35 * Queue with wait-free enqueue/blocking dequeue.
36 * This implementation adds a dummy head node when the queue is empty to ensure
37 * we can always update the queue locklessly.
38 *
39 * Inspired from half-wait-free/half-blocking queue implementation done by
40 * Paul E. McKenney.
41 */
42
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43struct cds_wfq_node {
44 struct cds_wfq_node *next;
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45};
46
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47struct cds_wfq_queue {
48 struct cds_wfq_node *head, **tail;
49 struct cds_wfq_node dummy; /* Dummy node */
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50 pthread_mutex_t lock;
51};
52
4d001e96 53#ifdef _LGPL_SOURCE
4afee0a7 54
af7c2dbe 55#include <urcu/static/wfqueue.h>
4afee0a7 56
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57#define cds_wfq_node_init _cds_wfq_node_init
58#define cds_wfq_init _cds_wfq_init
59#define cds_wfq_enqueue _cds_wfq_enqueue
60#define __cds_wfq_dequeue_blocking ___cds_wfq_dequeue_blocking
61#define cds_wfq_dequeue_blocking _cds_wfq_dequeue_blocking
4afee0a7 62
4d001e96 63#else /* !_LGPL_SOURCE */
4afee0a7 64
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65extern void cds_wfq_node_init(struct cds_wfq_node *node);
66extern void cds_wfq_init(struct cds_wfq_queue *q);
67extern void cds_wfq_enqueue(struct cds_wfq_queue *q, struct cds_wfq_node *node);
68/* __cds_wfq_dequeue_blocking: caller ensures mutual exclusion between dequeues */
69extern struct cds_wfq_node *__cds_wfq_dequeue_blocking(struct cds_wfq_queue *q);
70extern struct cds_wfq_node *cds_wfq_dequeue_blocking(struct cds_wfq_queue *q);
4afee0a7 71
4d001e96 72#endif /* !_LGPL_SOURCE */
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73
74#ifdef __cplusplus
75}
76#endif
77
78#endif /* _URCU_WFQUEUE_H */
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