2 * Copyright (c) 1997,98 The NetBSD Foundation, Inc.
5 * This code is derived from software contributed to The NetBSD Foundation
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
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.
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.
42 * 1. The thread safe mechanism should be lightweight so the library can
43 * be used by non-threaded applications without unreasonable overhead.
45 * 2. There should be no dependency on a thread engine for non-threaded
48 * 3. There should be no dependency on any particular thread engine.
50 * 4. The library should be able to be compiled without support for thread
56 * One approach for thread safety is to provide discrete versions of the
57 * library: one thread safe, the other not. The disadvantage of this is
58 * that libc is rather large, and two copies of a library which are 99%+
59 * identical is not an efficent use of resources.
61 * Another approach is to provide a single thread safe library. However,
62 * it should not add significant run time or code size overhead to non-
63 * threaded applications.
65 * Since the NetBSD C library is used in other projects, it should be
66 * easy to replace the mutual exclusion primitives with ones provided by
67 * another system. Similarly, it should also be easy to remove all
68 * support for thread safety completely if the target environment does
69 * not support threads.
72 * Implementation Details:
74 * The mutex primitives used by the library (mutex_t, mutex_lock, etc.)
75 * are macros which expand to the cooresponding primitives provided by
76 * the thread engine or to nothing. The latter is used so that code is
77 * not unreasonably cluttered with #ifdefs when all thread safe support
80 * The mutex macros can be directly mapped to the mutex primitives from
81 * pthreads, however it should be reasonably easy to wrap another mutex
82 * implementation so it presents a similar interface.
84 * Stub implementations of the mutex functions are provided with *weak*
85 * linkage. These functions simply return success. When linked with a
86 * thread library (i.e. -lpthread), the functions will override the
91 #include <pthread_np.h>
92 #include "libc_private.h"
94 #define mutex_t pthread_mutex_t
95 #define cond_t pthread_cond_t
96 #define rwlock_t pthread_rwlock_t
98 #define thread_key_t pthread_key_t
99 #define MUTEX_INITIALIZER PTHREAD_MUTEX_INITIALIZER
100 #define RWLOCK_INITIALIZER PTHREAD_RWLOCK_INITIALIZER
102 #define mutex_init(m, a) _pthread_mutex_init(m, a)
103 #define mutex_lock(m) if (__isthreaded) \
104 _pthread_mutex_lock(m)
105 #define mutex_unlock(m) if (__isthreaded) \
106 _pthread_mutex_unlock(m)
107 #define mutex_trylock(m) (__isthreaded ? 0 : _pthread_mutex_trylock(m))
109 #define cond_init(c, a, p) _pthread_cond_init(c, a)
110 #define cond_signal(m) if (__isthreaded) \
111 _pthread_cond_signal(m)
112 #define cond_wait(c, m) if (__isthreaded) \
113 _pthread_cond_wait(c, m)
115 #define rwlock_init(l, a) _pthread_rwlock_init(l, a)
116 #define rwlock_rdlock(l) if (__isthreaded) \
117 _pthread_rwlock_rdlock(l)
118 #define rwlock_wrlock(l) if (__isthreaded) \
119 _pthread_rwlock_wrlock(l)
120 #define rwlock_unlock(l) if (__isthreaded) \
121 _pthread_rwlock_unlock(l)
123 #define thr_keycreate(k, d) _pthread_key_create(k, d)
124 #define thr_setspecific(k, p) _pthread_setspecific(k, p)
125 #define thr_getspecific(k) _pthread_getspecific(k)
126 #define thr_sigsetmask(f, n, o) _pthread_sigmask(f, n, o)
128 #define thr_self() _pthread_self()
129 #define thr_exit(x) _pthread_exit(x)
130 #define thr_main() _pthread_main_np()