Add extern "C" to support linking userspace RCU library with C++ applications
[urcu.git] / urcu-qsbr.h
1 #ifndef _URCU_QSBR_H
2 #define _URCU_QSBR_H
3
4 /*
5 * urcu-qsbr.h
6 *
7 * Userspace RCU QSBR header.
8 *
9 * LGPL-compatible code should include this header with :
10 *
11 * #define _LGPL_SOURCE
12 * #include <urcu.h>
13 *
14 * This library is free software; you can redistribute it and/or
15 * modify it under the terms of the GNU Lesser General Public
16 * License as published by the Free Software Foundation; either
17 * version 2.1 of the License, or (at your option) any later version.
18 *
19 * This library is distributed in the hope that it will be useful,
20 * but WITHOUT ANY WARRANTY; without even the implied warranty of
21 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
22 * Lesser General Public License for more details.
23 *
24 * You should have received a copy of the GNU Lesser General Public
25 * License along with this library; if not, write to the Free Software
26 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
27 *
28 * IBM's contributions to this file may be relicensed under LGPLv2 or later.
29 */
30
31 #include <stdlib.h>
32 #include <pthread.h>
33
34 /*
35 * See urcu-pointer.h and urcu-pointer-static.h for pointer publication headers.
36 */
37 #include <urcu-pointer.h>
38
39 #ifdef __cplusplus
40 extern "C" {
41 #endif
42
43 /*
44 * Important !
45 *
46 * Each thread containing read-side critical sections must be registered
47 * with rcu_register_thread() before calling rcu_read_lock().
48 * rcu_unregister_thread() should be called before the thread exits.
49 */
50
51 #ifdef _LGPL_SOURCE
52
53 #include <urcu-qsbr-static.h>
54
55 /*
56 * Mappings for static use of the userspace RCU library.
57 * Should only be used in LGPL-compatible code.
58 */
59
60 /*
61 * rcu_read_lock()
62 * rcu_read_unlock()
63 *
64 * Mark the beginning and end of a read-side critical section.
65 * DON'T FORGET TO USE RCU_REGISTER/UNREGISTER_THREAD() FOR EACH THREAD WITH
66 * READ-SIDE CRITICAL SECTION.
67 */
68 #define rcu_read_lock() _rcu_read_lock()
69 #define rcu_read_unlock() _rcu_read_unlock()
70
71 #define rcu_quiescent_state() _rcu_quiescent_state()
72 #define rcu_thread_offline() _rcu_thread_offline()
73 #define rcu_thread_online() _rcu_thread_online()
74
75 #else /* !_LGPL_SOURCE */
76
77 /*
78 * library wrappers to be used by non-LGPL compatible source code.
79 */
80
81 /*
82 * QSBR read lock/unlock are guaranteed to be no-ops. Therefore, we expose them
83 * in the LGPL header for any code to use. However, the debug version is not
84 * nops and may contain sanity checks. To activate it, applications must be
85 * recompiled with -DURCU_DEBUG (even non-LGPL/GPL applications). This is the
86 * best trade-off between license/performance/code triviality and
87 * library debugging & tracing features we could come up with.
88 */
89
90 #if (!defined(BUILD_QSBR_LIB) && defined(URCU_DEBUG))
91
92 static inline void rcu_read_lock(void)
93 {
94 }
95
96 static inline void rcu_read_lock(void)
97 {
98 }
99
100 #else /* !URCU_DEBUG */
101
102 extern void rcu_read_lock(void);
103 extern void rcu_read_unlock(void);
104
105 #endif /* !URCU_DEBUG */
106
107 extern void rcu_quiescent_state(void);
108 extern void rcu_thread_offline(void);
109 extern void rcu_thread_online(void);
110
111 #endif /* !_LGPL_SOURCE */
112
113 extern void synchronize_rcu(void);
114
115 /*
116 * Reader thread registration.
117 */
118 extern void rcu_register_thread(void);
119 extern void rcu_unregister_thread(void);
120
121 #ifdef __cplusplus
122 }
123 #endif
124
125 #endif /* _URCU_QSBR_H */
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