121 lines
4.9 KiB
Groff
121 lines
4.9 KiB
Groff
.\" $NetBSD: pthread_cond_init.3,v 1.7 2005/06/17 18:26:53 wiz Exp $
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.\"
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.\" Copyright (c) 2002 The NetBSD Foundation, Inc.
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.\" All rights reserved.
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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. 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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.\" 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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.\" Copyright (c) 1997 Brian Cully <shmit@kublai.com>
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.\" All rights reserved.
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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. Neither the name of the author nor the names of any co-contributors
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.\" may be used to endorse or promote products derived from this software
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.\" without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY JOHN BIRRELL AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" $FreeBSD: src/lib/libpthread/man/pthread_cond_init.3,v 1.13 2002/09/16 19:29:28 mini Exp $
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.\"
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.Dd January 30, 2003
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.Dt PTHREAD_COND_INIT 3
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.Os
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.Sh NAME
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.Nm pthread_cond_init
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.Nd create a condition variable
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.Sh LIBRARY
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.Lb libpthread
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.Sh SYNOPSIS
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.In pthread.h
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.Ft int
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.Fn pthread_cond_init "pthread_cond_t * restrict cond" "const pthread_condattr_t * restrict attr"
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.Sh DESCRIPTION
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The
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.Fn pthread_cond_init
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function creates a new condition variable, with attributes specified with
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.Fa attr .
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If
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.Fa attr
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is NULL the default attributes are used.
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.Pp
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Condition variables are intended to be used to communicate changes in
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the state of data shared between threads.
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Condition variables are always associated with a mutex to provide
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synchronized access to the shared data.
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A single predicate should always be associated with a
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condition variable.
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The predicate should identify a state of the
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shared data that must be true before the thread proceeds.
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.Sh RETURN VALUES
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If successful, the
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.Fn pthread_cond_init
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function will return zero and put the new condition variable id into
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.Fa cond ,
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otherwise an error number will be returned to indicate the error.
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.Sh ERRORS
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.Fn pthread_cond_init
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shall fail if:
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.Bl -tag -width Er
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.It Bq Er ENOMEM
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The process cannot allocate enough memory to initialize another condition
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variable.
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.It Bq Er EAGAIN
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The system lacks the resources to initialize another condition variable.
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.El
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.Pp
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.Fn pthread_cond_init
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may fail if:
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.Bl -tag -width Er
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.It Bq Er EINVAL
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The value specified by
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.Fa attr
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is invalid.
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.El
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.Sh SEE ALSO
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.Xr pthread_cond_broadcast 3 ,
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.Xr pthread_cond_destroy 3 ,
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.Xr pthread_cond_signal 3 ,
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.Xr pthread_cond_timedwait 3 ,
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.Xr pthread_cond_wait 3
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.Sh STANDARDS
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.Fn pthread_cond_init
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conforms to
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.St -p1003.1-96 .
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