160 lines
4.2 KiB
Groff
160 lines
4.2 KiB
Groff
.\" Copyright (c) 2004 Michael Telahun Makonnen
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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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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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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.\" $FreeBSD$
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.\"
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.Dd February 19, 2004
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.Dt PTHREAD_BARRIER 3
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.Os
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.Sh NAME
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.Nm pthread_barrier_destroy , pthread_barrier_init , pthread_barrier_wait
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.Nd "destroy, initialize or wait on a barrier object"
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.Sh LIBRARY
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.Lb libpthread
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.Lb libthr
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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_barrier_destroy "pthread_barrier_t *barrier"
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.Ft int
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.Fn pthread_barrier_init "pthread_barrier_t *barrier" "const pthread_barrierattr_t *attr" "unsigned count"
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.Ft int
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.Fn pthread_barrier_wait "pthread_barrier_t *barrier"
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.Sh DESCRIPTION
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The
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.Fn pthread_barrier_init
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function will initialize
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.Fa barrier
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with attributes specified in
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.Fa attr ,
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or if it is
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.Dv NULL ,
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with default attributes.
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The number of threads that must call
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.Fn pthread_barrier_wait
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before any of the waiting threads can be
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released is specified by
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.Fa count .
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The
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.Fn pthread_barrier_destroy
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function will destroy
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.Fa barrier
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and release any resources that may have been allocated on its behalf.
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.Pp
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The
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.Fn pthread_barrier_wait
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function will synchronize calling threads at
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.Fa barrier .
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The threads will be blocked from
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making further progress until
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a sufficient number of threads calls this function.
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The number of threads that must call it before
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any of them will be released is determined by the
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.Fa count
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argument to
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.Fn pthread_barrier_init .
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Once the threads have been released the barrier will be reset.
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.Sh IMPLEMENTATION NOTES
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In both
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.Lb libpthread
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and
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.Lb libthr
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the
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.Dv PTHREAD_BARRIER_SERIAL_THREAD
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return value will
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always be returned by the last thread to reach the barrier.
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.Sh RETURN VALUES
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If successful,
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both
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.Fn pthread_barrier_destroy
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and
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.Fn pthread_barrier_init
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will return zero.
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Otherwise, an error number will be returned to indicate the error.
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If the call to
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.Fn pthread_barrier_wait
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is successful, all but one of the threads will return zero.
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That one thread will return
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.Dv PTHREAD_BARRIER_SERIAL_THREAD .
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Otherwise, an error number will be returned to indicate the error.
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.Pp
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None of these functions will return
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.Er EINTR .
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.Sh ERRORS
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The
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.Fn pthread_barrier_destroy
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function will fail if:
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.Bl -tag -width Er
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.It Bq Er EBUSY
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An attempt was made to destroy
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.Fa barrier
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while it was in use.
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.El
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.Pp
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The
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.Fn pthread_barrier_destroy
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and
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.Fn pthread_barrier_wait
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functions 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 barrier
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is invalid.
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.El
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.Pp
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The
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.Fn pthread_barrier_init
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function will fail if:
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.Bl -tag -width Er
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.It Bq Er EAGAIN
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The system lacks resources,
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other than memory,
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to initialize
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.Fa barrier .
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.It Bq Er EINVAL
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The
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.Fa count
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argument is less than 1.
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.It Bq Er ENOMEM
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Insufficient memory to initialize
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.Fa barrier .
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.El
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.Sh SEE ALSO
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.Xr pthread_barrierattr 3
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.Sh HISTORY
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The
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.Fn pthread_barrier_destroy ,
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.Fn pthread_barrier_init
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and
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.Fn pthread_barrier_wait
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functions first appeared in
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.Lb libpthread
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in
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.Fx 5.2 ,
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and in
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.Lb libthr
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in
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.Fx 5.3 .
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