/
reentrant.h
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reentrant.h
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/*-
* Copyright (c) 1997,98 The NetBSD Foundation, Inc.
* All rights reserved.
*
* This code is derived from software contributed to The NetBSD Foundation
* by J.T. Conklin.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the NetBSD
* Foundation, Inc. and its contributors.
* 4. Neither the name of The NetBSD Foundation nor the names of its
* contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*
* $FreeBSD: src/lib/libc/include/reentrant.h,v 1.3 2004/02/25 21:03:45 green Exp $
*/
/*
* Requirements:
*
* 1. The thread safe mechanism should be lightweight so the library can
* be used by non-threaded applications without unreasonable overhead.
*
* 2. There should be no dependency on a thread engine for non-threaded
* applications.
*
* 3. There should be no dependency on any particular thread engine.
*
* 4. The library should be able to be compiled without support for thread
* safety.
*
*
* Rationale:
*
* One approach for thread safety is to provide discrete versions of the
* library: one thread safe, the other not. The disadvantage of this is
* that libc is rather large, and two copies of a library which are 99%+
* identical is not an efficent use of resources.
*
* Another approach is to provide a single thread safe library. However,
* it should not add significant run time or code size overhead to non-
* threaded applications.
*
* Since the NetBSD C library is used in other projects, it should be
* easy to replace the mutual exclusion primitives with ones provided by
* another system. Similarly, it should also be easy to remove all
* support for thread safety completely if the target environment does
* not support threads.
*
*
* Implementation Details:
*
* The mutex primitives used by the library (mutex_t, mutex_lock, etc.)
* are macros which expand to the cooresponding primitives provided by
* the thread engine or to nothing. The latter is used so that code is
* not unreasonably cluttered with #ifdefs when all thread safe support
* is removed.
*
* The mutex macros can be directly mapped to the mutex primitives from
* pthreads, however it should be reasonably easy to wrap another mutex
* implementation so it presents a similar interface.
*
* Stub implementations of the mutex functions are provided with *weak*
* linkage. These functions simply return success. When linked with a
* thread library (i.e. -lpthread), the functions will override the
* stubs.
*/
#include <pthread.h>
#include <pthread_np.h>
#include "libc_private.h"
#define mutex_t pthread_mutex_t
#define cond_t pthread_cond_t
#define rwlock_t pthread_rwlock_t
#define once_t pthread_once_t
#define thread_key_t pthread_key_t
#define MUTEX_INITIALIZER PTHREAD_MUTEX_INITIALIZER
#define RWLOCK_INITIALIZER PTHREAD_RWLOCK_INITIALIZER
#define ONCE_INITIALIZER PTHREAD_ONCE_INIT
#define mutex_init(m, a) _pthread_mutex_init(m, a)
#define mutex_lock(m) if (__isthreaded) \
_pthread_mutex_lock(m)
#define mutex_unlock(m) if (__isthreaded) \
_pthread_mutex_unlock(m)
#define mutex_trylock(m) (__isthreaded ? 0 : _pthread_mutex_trylock(m))
#define cond_init(c, a, p) _pthread_cond_init(c, a)
#define cond_signal(m) if (__isthreaded) \
_pthread_cond_signal(m)
#define cond_broadcast(m) if (__isthreaded) \
_pthread_cond_broadcast(m)
#define cond_wait(c, m) if (__isthreaded) \
_pthread_cond_wait(c, m)
#define rwlock_init(l, a) _pthread_rwlock_init(l, a)
#define rwlock_rdlock(l) if (__isthreaded) \
_pthread_rwlock_rdlock(l)
#define rwlock_wrlock(l) if (__isthreaded) \
_pthread_rwlock_wrlock(l)
#define rwlock_unlock(l) if (__isthreaded) \
_pthread_rwlock_unlock(l)
#define thr_keycreate(k, d) _pthread_key_create(k, d)
#define thr_setspecific(k, p) _pthread_setspecific(k, p)
#define thr_getspecific(k) _pthread_getspecific(k)
#define thr_sigsetmask(f, n, o) _pthread_sigmask(f, n, o)
#define thr_once(o, i) _pthread_once(o, i)
#define thr_self() _pthread_self()
#define thr_exit(x) _pthread_exit(x)
#define thr_main() _pthread_main_np()