158 lines
5.7 KiB
C
158 lines
5.7 KiB
C
/* $NetBSD: reentrant.h,v 1.6 2000/06/02 23:11:06 fvdl Exp $ */
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/*-
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* Copyright (c) 1997,98 The NetBSD Foundation, Inc.
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* All rights reserved.
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*
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* This code is derived from software contributed to The NetBSD Foundation
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* by J.T. Conklin.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by the NetBSD
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* Foundation, Inc. and its contributors.
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* 4. Neither the name of The NetBSD Foundation nor the names of its
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* contributors may be used to endorse or promote products derived
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* from this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
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* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
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* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
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* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*/
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/*
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* Requirements:
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*
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* 1. The thread safe mechanism should be lightweight so the library can
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* be used by non-threaded applications without unreasonable overhead.
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*
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* 2. There should be no dependency on a thread engine for non-threaded
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* applications.
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*
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* 3. There should be no dependency on any particular thread engine.
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*
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* 4. The library should be able to be compiled without support for thread
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* safety.
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*
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*
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* Rationale:
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*
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* One approach for thread safety is to provide discrete versions of the
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* library: one thread safe, the other not. The disadvantage of this is
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* that libc is rather large, and two copies of a library which are 99%+
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* identical is not an efficent use of resources.
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*
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* Another approach is to provide a single thread safe library. However,
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* it should not add significant run time or code size overhead to non-
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* threaded applications.
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*
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* Since the NetBSD C library is used in other projects, it should be
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* easy to replace the mutual exclusion primitives with ones provided by
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* another system. Similarly, it should also be easy to remove all
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* support for thread safety completely if the target environment does
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* not support threads.
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*
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*
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* Implementation Details:
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*
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* The mutex primitives used by the library (mutex_t, mutex_lock, etc.)
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* are macros which expand to the cooresponding primitives provided by
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* the thread engine or to nothing. The latter is used so that code is
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* not unreasonably cluttered with #ifdefs when all thread safe support
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* is removed.
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*
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* The mutex macros can be directly mapped to the mutex primitives from
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* pthreads, however it should be reasonably easy to wrap another mutex
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* implementation so it presents a similar interface.
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*
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* Stub implementations of the mutex functions are provided with *weak*
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* linkage. These functions simply return success. When linked with a
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* thread library (i.e. -lpthread), the functions will override the
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* stubs.
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*/
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/* FIXME: Using _REENT during integration testing. It should be changed
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to _REENTRANT once pthread engine is available */
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#ifdef _REENT
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#include <pthread.h>
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#define mutex_t pthread_mutex_t
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#define MUTEX_INITIALIZER PTHREAD_MUTEX_INITIALIZER
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#define mutex_init(m, a) pthread_mutex_init(m, a)
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#define mutex_lock(m) pthread_mutex_lock(m)
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#define mutex_trylock(m) pthread_mutex_trylock(m)
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#define mutex_unlock(m) pthread_mutex_unlock(m)
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#define cond_t pthread_cond_t
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#define cond_signal(m) pthread_cond_signal(m)
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#define cond_wait(c, m) pthread_cond_wait(c, m)
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#define cond_init(c, a, p) pthread_cond_init(c, a)
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#define rwlock_t pthread_rwlock_t
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#define RWLOCK_INITIALIZER PTHREAD_RWLOCK_INITIALIZER
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#define rwlock_init(l, a) pthread_rwlock_init(l, a)
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#define rwlock_rdlock(l) pthread_rwlock_rdlock(l)
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#define rwlock_wrlock(l) pthread_rwlock_wrlock(l)
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#define rwlock_unlock(l) pthread_rwlock_unlock(l)
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#define thread_key_t pthread_key_t
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#define thr_keycreate(k, d) pthread_key_create(k, d)
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#define thr_setspecific(k, p) pthread_setspecific(k, p)
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#define thr_getspecific(k) pthread_getspecific(k)
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#define thr_sigsetmask(f, n, o) pthread_sigmask(f, n, o)
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#define thr_self() pthread_self()
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#define thr_exit(x) pthread_exit(x)
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#define FLOCKFILE(fp) flockfile(fp)
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#define FUNLOCKFILE(fp) funlockfile(fp)
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#else
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#define mutex_init(m, a)
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#define mutex_lock(m)
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#define mutex_trylock(m)
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#define mutex_unlock(m)
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#define cond_signal(m)
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#define cond_wait(c, m)
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#define cond_init(c, a, p)
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#define rwlock_init(l, a)
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#define rwlock_rdlock(l)
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#define rwlock_wrlock(l)
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#define rwlock_unlock(l)
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#define thr_keycreate(k, d)
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#define thr_setspecific(k, p)
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#define thr_getspecific(k)
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#define thr_sigsetmask(f, n, o)
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#define thr_self()
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#define thr_exit()
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#define FLOCKFILE(fp)
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#define FUNLOCKFILE(fp)
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#endif
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