'\" et
.TH PTHREAD_BARRIER_DESTROY "3P" 2017 "IEEE/The Open Group" "POSIX Programmer's Manual"
.\"
.SH PROLOG
This manual page is part of the POSIX Programmer's Manual.
The Linux implementation of this interface may differ (consult
the corresponding Linux manual page for details of Linux behavior),
or the interface may not be implemented on Linux.
.\"
.SH NAME
pthread_barrier_destroy,
pthread_barrier_init
\(em destroy and initialize a barrier object
.SH SYNOPSIS
.LP
.nf
#include <pthread.h>
.P
int pthread_barrier_destroy(pthread_barrier_t *\fIbarrier\fP);
int pthread_barrier_init(pthread_barrier_t *restrict \fIbarrier\fP,
    const pthread_barrierattr_t *restrict \fIattr\fP, unsigned \fIcount\fP);
.fi
.SH DESCRIPTION
The
\fIpthread_barrier_destroy\fR()
function shall destroy the barrier referenced by
.IR barrier
and release any resources used by the barrier. The effect of
subsequent use of the barrier is undefined until the barrier is
reinitialized by another call to
\fIpthread_barrier_init\fR().
An implementation may use this function to set
.IR barrier
to an invalid value. The results are undefined if
\fIpthread_barrier_destroy\fR()
is called when any thread is blocked on the barrier, or if this
function is called with an uninitialized barrier.
.P
The
\fIpthread_barrier_init\fR()
function shall allocate any resources required to use the barrier
referenced by
.IR barrier
and shall initialize the barrier with attributes referenced by
.IR attr .
If
.IR attr
is NULL, the default barrier attributes shall be used; the effect is
the same as passing the address of a default barrier attributes
object. The results are undefined if
\fIpthread_barrier_init\fR()
is called when any thread is blocked on the barrier (that is, has not
returned from the
\fIpthread_barrier_wait\fR()
call). The results are undefined if a barrier is used without first
being initialized. The results are undefined if
\fIpthread_barrier_init\fR()
is called specifying an already initialized barrier.
.P
The
.IR count
argument specifies the number of threads that must call
\fIpthread_barrier_wait\fR()
before any of them successfully return from the call. The value
specified by
.IR count
must be greater than zero.
.P
If the
\fIpthread_barrier_init\fR()
function fails, the barrier shall not be initialized and the contents
of
.IR barrier
are undefined.
.P
See
.IR "Section 2.9.9" ", " "Synchronization Object Copies and Alternative Mappings"
for further requirements.
.SH "RETURN VALUE"
Upon successful completion, these functions shall return zero;
otherwise, an error number shall be returned to indicate the error.
.SH ERRORS
The
\fIpthread_barrier_init\fR()
function shall fail if:
.TP
.BR EAGAIN
The system lacks the necessary resources to initialize another barrier.
.TP
.BR EINVAL
The value specified by
.IR count
is equal to zero.
.TP
.BR ENOMEM
Insufficient memory exists to initialize the barrier.
.P
These functions shall not return an error code of
.BR [EINTR] .
.LP
.IR "The following sections are informative."
.SH EXAMPLES
None.
.SH "APPLICATION USAGE"
None.
.SH RATIONALE
If an implementation detects that the value specified by the
.IR barrier
argument to
\fIpthread_barrier_destroy\fR()
does not refer to an initialized barrier object, it is recommended that
the function should fail and report an
.BR [EINVAL] 
error.
.P
If an implementation detects that the value specified by the
.IR attr
argument to
\fIpthread_barrier_init\fR()
does not refer to an initialized barrier attributes object, it is
recommended that the function should fail and report an
.BR [EINVAL] 
error.
.P
If an implementation detects that the value specified by the
.IR barrier
argument to
\fIpthread_barrier_destroy\fR()
or
\fIpthread_barrier_init\fR()
refers to a barrier that is in use (for example, in a
\fIpthread_barrier_wait\fR()
call) by another thread, or detects that the value specified by the
.IR barrier
argument to
\fIpthread_barrier_init\fR()
refers to an already initialized barrier object, it is recommended
that the function should fail and report an
.BR [EBUSY] 
error.
.SH "FUTURE DIRECTIONS"
None.
.SH "SEE ALSO"
.IR "\fIpthread_barrier_wait\fR\^(\|)"
.P
The Base Definitions volume of POSIX.1\(hy2017,
.IR "\fB<pthread.h>\fP"
.\"
.SH COPYRIGHT
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1-2017, Standard for Information Technology
-- Portable Operating System Interface (POSIX), The Open Group Base
Specifications Issue 7, 2018 Edition,
Copyright (C) 2018 by the Institute of
Electrical and Electronics Engineers, Inc and The Open Group.
In the event of any discrepancy between this version and the original IEEE and
The Open Group Standard, the original IEEE and The Open Group Standard
is the referee document. The original Standard can be obtained online at
http://www.opengroup.org/unix/online.html .
.PP
Any typographical or formatting errors that appear
in this page are most likely
to have been introduced during the conversion of the source files to
man page format. To report such errors, see
https://www.kernel.org/doc/man-pages/reporting_bugs.html .