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 /*
  40  * Important !
  41  *
  42  * Each thread containing read-side critical sections must be registered
  43  * with rcu_register_thread() before calling rcu_read_lock().
  44  * rcu_unregister_thread() should be called before the thread exits.
  45  */
  46
  47 #ifdef _LGPL_SOURCE
  48
  49 #include <urcu-qsbr-static.h>
  50
  51 /*
  52  * Mappings for static use of the userspace RCU library.
  53  * Should only be used in LGPL-compatible code.
  54  */
  55
  56 /*
  57  * rcu_read_lock()
  58  * rcu_read_unlock()
  59  *
  60  * Mark the beginning and end of a read-side critical section.
  61  * DON'T FORGET TO USE RCU_REGISTER/UNREGISTER_THREAD() FOR EACH THREAD WITH
  62  * READ-SIDE CRITICAL SECTION.
  63  */
  64 #define rcu_read_lock()         _rcu_read_lock()
  65 #define rcu_read_unlock()       _rcu_read_unlock()
  66
  67 #define rcu_quiescent_state()   _rcu_quiescent_state()
  68 #define rcu_thread_offline()    _rcu_thread_offline()
  69 #define rcu_thread_online()     _rcu_thread_online()
  70
  71 #else /* !_LGPL_SOURCE */
  72
  73 /*
  74  * library wrappers to be used by non-LGPL compatible source code.
  75  */
  76
  77 /*
  78  * QSBR read lock/unlock are guaranteed to be no-ops. Therefore, we expose them
  79  * in the LGPL header for any code to use. However, the debug version is not
  80  * nops and may contain sanity checks. To activate it, applications must be
  81  * recompiled with -DURCU_DEBUG (even non-LGPL/GPL applications). This is the
  82  * best trade-off between license/performance/code triviality and
  83  * library debugging & tracing features we could come up with.
  84  */
  85
  86 #if (!defined(BUILD_QSBR_LIB) && defined(URCU_DEBUG))
  87
  88 static inline void rcu_read_lock(void)
  89 {
  90 }
  91
  92 static inline void rcu_read_lock(void)
  93 {
  94 }
  95
  96 #else /* !URCU_DEBUG */
  97
  98 extern void rcu_read_lock(void);
  99 extern void rcu_read_unlock(void);
 100
 101 #endif /* !URCU_DEBUG */
 102
 103 extern void rcu_quiescent_state(void);
 104 extern void rcu_thread_offline(void);
 105 extern void rcu_thread_online(void);
 106
 107 #endif /* !_LGPL_SOURCE */
 108
 109 extern void synchronize_rcu(void);
 110
 111 /*
 112  * Reader thread registration.
 113  */
 114 extern void rcu_register_thread(void);
 115 extern void rcu_unregister_thread(void);
 116
 117 #endif /* _URCU_QSBR_H */