1.\" Copyright (c) 2004 Michael Telahun Makonnen 2.\" All rights reserved. 3.\" 4.\" Redistribution and use in source and binary forms, with or without 5.\" modification, are permitted provided that the following conditions 6.\" are met: 7.\" 1. Redistributions of source code must retain the above copyright 8.\" notice, this list of conditions and the following disclaimer. 9.\" 2. Redistributions in binary form must reproduce the above copyright 10.\" notice, this list of conditions and the following disclaimer in the 11.\" documentation and/or other materials provided with the distribution. 12.\" 13.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 14.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 15.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 16.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 17.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 18.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 19.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 20.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 21.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 22.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 23.\" SUCH DAMAGE. 24.\" 25.\" $FreeBSD$ 26.\" 27.Dd February 19, 2004 28.Dt PTHREAD_BARRIER 3 29.Os 30.Sh NAME 31.Nm pthread_barrier_destroy , pthread_barrier_init , pthread_barrier_wait 32.Nd "destroy, initialize or wait on a barrier object" 33.Sh LIBRARY 34.Lb libpthread 35.Sh SYNOPSIS 36.In pthread.h 37.Ft int 38.Fn pthread_barrier_destroy "pthread_barrier_t *barrier" 39.Ft int 40.Fn pthread_barrier_init "pthread_barrier_t *barrier" "const pthread_barrierattr_t *attr" "unsigned count" 41.Ft int 42.Fn pthread_barrier_wait "pthread_barrier_t *barrier" 43.Sh DESCRIPTION 44The 45.Fn pthread_barrier_init 46function will initialize 47.Fa barrier 48with attributes specified in 49.Fa attr , 50or if it is 51.Dv NULL , 52with default attributes. 53The number of threads that must call 54.Fn pthread_barrier_wait 55before any of the waiting threads can be 56released is specified by 57.Fa count . 58The 59.Fn pthread_barrier_destroy 60function will destroy 61.Fa barrier 62and release any resources that may have been allocated on its behalf. 63.Pp 64The 65.Fn pthread_barrier_wait 66function will synchronize calling threads at 67.Fa barrier . 68The threads will be blocked from 69making further progress until 70a sufficient number of threads calls this function. 71The number of threads that must call it before 72any of them will be released is determined by the 73.Fa count 74argument to 75.Fn pthread_barrier_init . 76Once the threads have been released the barrier will be reset. 77.Sh IMPLEMENTATION NOTES 78In 79.Lb libthr 80the 81.Dv PTHREAD_BARRIER_SERIAL_THREAD 82return value will 83always be returned by the last thread to reach the barrier. 84.Sh RETURN VALUES 85If successful, 86both 87.Fn pthread_barrier_destroy 88and 89.Fn pthread_barrier_init 90will return zero. 91Otherwise, an error number will be returned to indicate the error. 92If the call to 93.Fn pthread_barrier_wait 94is successful, all but one of the threads will return zero. 95That one thread will return 96.Dv PTHREAD_BARRIER_SERIAL_THREAD . 97Otherwise, an error number will be returned to indicate the error. 98.Pp 99None of these functions will return 100.Er EINTR . 101.Sh ERRORS 102The 103.Fn pthread_barrier_destroy 104function will fail if: 105.Bl -tag -width Er 106.It Bq Er EBUSY 107An attempt was made to destroy 108.Fa barrier 109while it was in use. 110.El 111.Pp 112The 113.Fn pthread_barrier_destroy 114and 115.Fn pthread_barrier_wait 116functions may fail if: 117.Bl -tag -width Er 118.It Bq Er EINVAL 119The value specified by 120.Fa barrier 121is invalid. 122.El 123.Pp 124The 125.Fn pthread_barrier_init 126function will fail if: 127.Bl -tag -width Er 128.It Bq Er EAGAIN 129The system lacks resources, 130other than memory, 131to initialize 132.Fa barrier . 133.It Bq Er EINVAL 134The 135.Fa count 136argument is less than 1. 137.It Bq Er ENOMEM 138Insufficient memory to initialize 139.Fa barrier . 140.El 141.Sh SEE ALSO 142.Xr pthread_barrierattr 3 143.Sh HISTORY 144The 145.Fn pthread_barrier_destroy , 146.Fn pthread_barrier_init 147and 148.Fn pthread_barrier_wait 149functions first appeared in 150.Lb libkse 151in 152.Fx 5.2 , 153and in 154.Lb libthr 155in 156.Fx 5.3 . 157