lib/libc/include/reentrant.h

   1 /*-
   2  * Copyright (c) 1997,98 The NetBSD Foundation, Inc.
   3  * All rights reserved.
   4  *
   5  * This code is derived from software contributed to The NetBSD Foundation
   6  * by J.T. Conklin.
   7  *
   8  * Redistribution and use in source and binary forms, with or without
   9  * modification, are permitted provided that the following conditions
  10  * are met:
  11  * 1. Redistributions of source code must retain the above copyright
  12  *    notice, this list of conditions and the following disclaimer.
  13  * 2. Redistributions in binary form must reproduce the above copyright
  14  *    notice, this list of conditions and the following disclaimer in the
  15  *    documentation and/or other materials provided with the distribution.
  16  * 3. All advertising materials mentioning features or use of this software
  17  *    must display the following acknowledgement:
  18  *        This product includes software developed by the NetBSD
  19  *        Foundation, Inc. and its contributors.
  20  * 4. Neither the name of The NetBSD Foundation nor the names of its
  21  *    contributors may be used to endorse or promote products derived
  22  *    from this software without specific prior written permission.
  23  *
  24  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
  25  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
  26  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  27  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
  28  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
  29  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
  30  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  31  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
  32  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  33  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  34  * POSSIBILITY OF SUCH DAMAGE.
  35  *
  36  * $FreeBSD: src/lib/libc/include/reentrant.h,v 1.3 2004/02/25 21:03:45 green Exp $
  37  * $DragonFly$
  38  */
  39
  40 /*
  41  * Requirements:
  42  *
  43  * 1. The thread safe mechanism should be lightweight so the library can
  44  *    be used by non-threaded applications without unreasonable overhead.
  45  *
  46  * 2. There should be no dependency on a thread engine for non-threaded
  47  *    applications.
  48  *
  49  * 3. There should be no dependency on any particular thread engine.
  50  *
  51  * 4. The library should be able to be compiled without support for thread
  52  *    safety.
  53  *
  54  *
  55  * Rationale:
  56  *
  57  * One approach for thread safety is to provide discrete versions of the
  58  * library: one thread safe, the other not.  The disadvantage of this is
  59  * that libc is rather large, and two copies of a library which are 99%+
  60  * identical is not an efficent use of resources.
  61  *
  62  * Another approach is to provide a single thread safe library.  However,
  63  * it should not add significant run time or code size overhead to non-
  64  * threaded applications.
  65  *
  66  * Since the NetBSD C library is used in other projects, it should be
  67  * easy to replace the mutual exclusion primitives with ones provided by
  68  * another system.  Similarly, it should also be easy to remove all
  69  * support for thread safety completely if the target environment does
  70  * not support threads.
  71  *
  72  *
  73  * Implementation Details:
  74  *
  75  * The mutex primitives used by the library (mutex_t, mutex_lock, etc.)
  76  * are macros which expand to the cooresponding primitives provided by
  77  * the thread engine or to nothing.  The latter is used so that code is
  78  * not unreasonably cluttered with #ifdefs when all thread safe support
  79  * is removed.
  80  *
  81  * The mutex macros can be directly mapped to the mutex primitives from
  82  * pthreads, however it should be reasonably easy to wrap another mutex
  83  * implementation so it presents a similar interface.
  84  *
  85  * Stub implementations of the mutex functions are provided with *weak*
  86  * linkage.  These functions simply return success.  When linked with a
  87  * thread library (i.e. -lpthread), the functions will override the
  88  * stubs.
  89  */
  90
  91 #include <pthread.h>
  92 #include <pthread_np.h>
  93 #include "libc_private.h"
  94
  95 #define mutex_t                 pthread_mutex_t
  96 #define cond_t                  pthread_cond_t
  97 #define rwlock_t                pthread_rwlock_t
  98 #define once_t                  pthread_once_t
  99
 100 #define thread_key_t            pthread_key_t
 101 #define MUTEX_INITIALIZER       PTHREAD_MUTEX_INITIALIZER
 102 #define RWLOCK_INITIALIZER      PTHREAD_RWLOCK_INITIALIZER
 103 #define ONCE_INITIALIZER        PTHREAD_ONCE_INIT
 104
 105 #define mutex_init(m, a)        _pthread_mutex_init(m, a)
 106 #define mutex_lock(m)           if (__isthreaded) \
 107                                 _pthread_mutex_lock(m)
 108 #define mutex_unlock(m)         if (__isthreaded) \
 109                                 _pthread_mutex_unlock(m)
 110 #define mutex_trylock(m)        (__isthreaded ? 0 : _pthread_mutex_trylock(m))
 111
 112 #define cond_init(c, a, p)      _pthread_cond_init(c, a)
 113 #define cond_signal(m)          if (__isthreaded) \
 114                                 _pthread_cond_signal(m)
 115 #define cond_broadcast(m)       if (__isthreaded) \
 116                                 _pthread_cond_broadcast(m)
 117 #define cond_wait(c, m)         if (__isthreaded) \
 118                                 _pthread_cond_wait(c, m)
 119
 120 #define rwlock_init(l, a)       _pthread_rwlock_init(l, a)
 121 #define rwlock_rdlock(l)        if (__isthreaded) \
 122                                 _pthread_rwlock_rdlock(l)
 123 #define rwlock_wrlock(l)        if (__isthreaded) \
 124                                 _pthread_rwlock_wrlock(l)
 125 #define rwlock_unlock(l)        if (__isthreaded) \
 126                                 _pthread_rwlock_unlock(l)
 127
 128 #define thr_keycreate(k, d)     _pthread_key_create(k, d)
 129 #define thr_setspecific(k, p)   _pthread_setspecific(k, p)
 130 #define thr_getspecific(k)      _pthread_getspecific(k)
 131 #define thr_sigsetmask(f, n, o) _pthread_sigmask(f, n, o)
 132
 133 #define thr_once(o, i)          _pthread_once(o, i)
 134 #define thr_self()              _pthread_self()
 135 #define thr_exit(x)             _pthread_exit(x)
 136 #define thr_main()              _pthread_main_np()