rculfstack: header implementation should be defined as static inline
[urcu.git] / urcu / rculfqueue.h
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1#ifndef _URCU_RCULFQUEUE_H
2#define _URCU_RCULFQUEUE_H
3
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4/*
5 * rculfqueue.h
6 *
7 * Userspace RCU library - Lock-Free RCU Queue
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
f9bf6d54 26#include <urcu/ref.h>
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27#include <assert.h>
28
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29#ifdef __cplusplus
30extern "C" {
31#endif
32
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33/*
34 * Lock-free RCU queue using reference counting. Enqueue and dequeue operations
35 * hold a RCU read lock to deal with cmpxchg ABA problem. This implementation
36 * keeps a dummy head node to ensure we can always update the queue locklessly.
37 * Given that this is a queue, the dummy head node must always advance as we
38 * dequeue entries. Therefore, we keep a reference count on each entry we are
39 * dequeueing, so they can be kept as dummy head node until the next dequeue, at
40 * which point their reference count will be decremented.
41 */
42
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43struct cds_lfq_queue_rcu;
44
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45struct cds_lfq_node_rcu {
46 struct cds_lfq_node_rcu *next;
453629a9 47 struct urcu_ref ref;
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48 struct cds_lfq_queue_rcu *queue;
49 struct rcu_head rcu_head;
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50};
51
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52struct cds_lfq_queue_rcu {
53 struct cds_lfq_node_rcu *head, *tail;
54 struct cds_lfq_node_rcu init; /* Dummy initialization node */
d9b52143 55 void (*release)(struct urcu_ref *ref);
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56};
57
3d02c34d 58#ifdef _LGPL_SOURCE
453629a9 59
af7c2dbe 60#include <urcu/static/rculfqueue.h>
453629a9 61
a34df756 62#define cds_lfq_node_init_rcu _cds_lfq_node_init_rcu
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63#define cds_lfq_init_rcu _cds_lfq_init_rcu
64#define cds_lfq_enqueue_rcu _cds_lfq_enqueue_rcu
65#define cds_lfq_dequeue_rcu _cds_lfq_dequeue_rcu
453629a9 66
3d02c34d 67#else /* !_LGPL_SOURCE */
453629a9 68
16aa9ee8 69extern void cds_lfq_node_init_rcu(struct cds_lfq_node_rcu *node);
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70extern void cds_lfq_init_rcu(struct cds_lfq_queue_rcu *q,
71 void (*release)(struct urcu_ref *ref));
72
73/*
74 * Should be called under rcu read lock critical section.
75 */
76extern void cds_lfq_enqueue_rcu(struct cds_lfq_queue_rcu *q,
77 struct cds_lfq_node_rcu *node);
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78
79/*
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80 * Should be called under rcu read lock critical section.
81 *
82 * The entry returned by dequeue must be taken care of by doing a
a34df756 83 * sequence of urcu_ref_put which release handler should do a call_rcu.
d9b52143 84 *
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85 * In other words, the entry lfq node returned by dequeue must not be
86 * modified/re-used/freed until the reference count reaches zero and a grace
87 * period has elapsed (after the refcount reached 0).
453629a9 88 */
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89extern
90struct cds_lfq_node_rcu *cds_lfq_dequeue_rcu(struct cds_lfq_queue_rcu *q);
453629a9 91
3d02c34d 92#endif /* !_LGPL_SOURCE */
c3f74cb2 93
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94#ifdef __cplusplus
95}
96#endif
97
c3f74cb2 98#endif /* _URCU_RCULFQUEUE_H */
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