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.Dd August 17, 2018 26.Dt PTHREAD_BARRIER 3 27.Os 28.Sh NAME 29.Nm pthread_barrier_destroy , pthread_barrier_init , pthread_barrier_wait 30.Nd "destroy, initialize or wait on a barrier object" 31.Sh LIBRARY 32.Lb libpthread 33.Sh SYNOPSIS 34.In pthread.h 35.Ft int 36.Fn pthread_barrier_destroy "pthread_barrier_t *barrier" 37.Ft int 38.Fn pthread_barrier_init "pthread_barrier_t *restrict barrier" "const pthread_barrierattr_t *attr" "unsigned count" 39.Ft int 40.Fn pthread_barrier_wait "pthread_barrier_t *barrier" 41.Sh DESCRIPTION 42The 43.Fn pthread_barrier_init 44function will initialize 45.Fa barrier 46with attributes specified in 47.Fa attr , 48or if it is 49.Dv NULL , 50with default attributes. 51The number of threads that must call 52.Fn pthread_barrier_wait 53before any of the waiting threads can be 54released is specified by 55.Fa count . 56The 57.Fn pthread_barrier_destroy 58function will destroy 59.Fa barrier 60and release any resources that may have been allocated on its behalf. 61.Pp 62The 63.Fn pthread_barrier_wait 64function will synchronize calling threads at 65.Fa barrier . 66The threads will be blocked from 67making further progress until 68a sufficient number of threads calls this function. 69The number of threads that must call it before 70any of them will be released is determined by the 71.Fa count 72argument to 73.Fn pthread_barrier_init . 74Once the threads have been released the barrier will be reset. 75.Sh IMPLEMENTATION NOTES 76In 77.Lb libthr 78the 79.Dv PTHREAD_BARRIER_SERIAL_THREAD 80return value will 81always be returned by the last thread to reach the barrier. 82.Sh RETURN VALUES 83If successful, 84both 85.Fn pthread_barrier_destroy 86and 87.Fn pthread_barrier_init 88will return zero. 89Otherwise, an error number will be returned to indicate the error. 90If the call to 91.Fn pthread_barrier_wait 92is successful, all but one of the threads will return zero. 93That one thread will return 94.Dv PTHREAD_BARRIER_SERIAL_THREAD . 95Otherwise, an error number will be returned to indicate the error. 96.Pp 97None of these functions will return 98.Er EINTR . 99.Sh ERRORS 100The 101.Fn pthread_barrier_destroy 102function will fail if: 103.Bl -tag -width Er 104.It Bq Er EBUSY 105An attempt was made to destroy 106.Fa barrier 107while it was in use. 108.El 109.Pp 110The 111.Fn pthread_barrier_destroy 112and 113.Fn pthread_barrier_wait 114functions may fail if: 115.Bl -tag -width Er 116.It Bq Er EINVAL 117The value specified by 118.Fa barrier 119is invalid. 120.El 121.Pp 122The 123.Fn pthread_barrier_init 124function will fail if: 125.Bl -tag -width Er 126.It Bq Er EAGAIN 127The system lacks resources, 128other than memory, 129to initialize 130.Fa barrier . 131.It Bq Er EINVAL 132The 133.Fa count 134argument is less than 1. 135.It Bq Er ENOMEM 136Insufficient memory to initialize 137.Fa barrier . 138.El 139.Sh SEE ALSO 140.Xr pthread_barrierattr 3 141.Sh HISTORY 142The 143.Fn pthread_barrier_destroy , 144.Fn pthread_barrier_init 145and 146.Fn pthread_barrier_wait 147functions first appeared in 148.Lb libkse 149in 150.Fx 5.2 , 151and in 152.Lb libthr 153in 154.Fx 5.3 . 155