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c3f74cb2 MD |
1 | #ifndef _URCU_RCULFQUEUE_H |
2 | #define _URCU_RCULFQUEUE_H | |
3 | ||
453629a9 MD |
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 | ||
26 | #include <urcu/urcu_ref.h> | |
27 | #include <assert.h> | |
28 | ||
0e2e9380 MD |
29 | #ifdef __cplusplus |
30 | extern "C" { | |
31 | #endif | |
32 | ||
453629a9 MD |
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 | ||
16aa9ee8 DG |
43 | struct cds_lfq_node_rcu { |
44 | struct cds_lfq_node_rcu *next; | |
453629a9 MD |
45 | struct urcu_ref ref; |
46 | }; | |
47 | ||
16aa9ee8 DG |
48 | struct cds_lfq_queue_rcu { |
49 | struct cds_lfq_node_rcu *head, *tail; | |
50 | struct cds_lfq_node_rcu init; /* Dummy initialization node */ | |
453629a9 MD |
51 | }; |
52 | ||
3d02c34d | 53 | #ifdef _LGPL_SOURCE |
453629a9 | 54 | |
3d02c34d | 55 | #include <urcu/rculfqueue-static.h> |
453629a9 | 56 | |
16aa9ee8 DG |
57 | #define cds_lfq_node_init_rcu _cds_lfq_node_init_rcu |
58 | #define cds_lfq_init_rcu _cds_lfq_init_rcu | |
59 | #define cds_lfq_enqueue_rcu _cds_lfq_enqueue_rcu | |
60 | #define cds_lfq_dequeue_rcu _cds_lfq_dequeue_rcu | |
453629a9 | 61 | |
3d02c34d | 62 | #else /* !_LGPL_SOURCE */ |
453629a9 | 63 | |
16aa9ee8 DG |
64 | extern void cds_lfq_node_init_rcu(struct cds_lfq_node_rcu *node); |
65 | extern void cds_lfq_init_rcu(struct cds_lfq_queue_rcu *q); | |
66 | extern void cds_lfq_enqueue_rcu(struct cds_lfq_queue_rcu *q, struct cds_lfq_node_rcu *node); | |
453629a9 MD |
67 | |
68 | /* | |
69 | * The entry returned by dequeue must be taken care of by doing a urcu_ref_put, | |
70 | * which calls the release primitive when the reference count drops to zero. A | |
c97740a3 | 71 | * grace period must be waited after execution of the release callback before |
16aa9ee8 | 72 | * performing the actual memory reclamation or modifying the cds_lfq_node_rcu |
c97740a3 MD |
73 | * structure. |
74 | * In other words, the entry lfq node returned by dequeue must not be | |
75 | * modified/re-used/freed until the reference count reaches zero and a grace | |
76 | * period has elapsed (after the refcount reached 0). | |
453629a9 | 77 | */ |
16aa9ee8 DG |
78 | extern struct cds_lfq_node_rcu * |
79 | cds_lfq_dequeue_rcu(struct cds_lfq_queue_rcu *q, void (*release)(struct urcu_ref *)); | |
453629a9 | 80 | |
3d02c34d | 81 | #endif /* !_LGPL_SOURCE */ |
c3f74cb2 | 82 | |
0e2e9380 MD |
83 | #ifdef __cplusplus |
84 | } | |
85 | #endif | |
86 | ||
c3f74cb2 | 87 | #endif /* _URCU_RCULFQUEUE_H */ |