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<table class="head">
<tr>
<td class="head-ltitle">PTHREAD_BARRIER(3)</td>
<td class="head-vol">Library Functions Manual</td>
<td class="head-rtitle">PTHREAD_BARRIER(3)</td>
</tr>
</table>
<div class="manual-text">
<section class="Sh">
<h1 class="Sh" id="NAME"><a class="permalink" href="#NAME">NAME</a></h1>
<p class="Pp"><code class="Nm">pthread_barrier_destroy</code>,
<code class="Nm">pthread_barrier_init</code>,
<code class="Nm">pthread_barrier_wait</code> —
<span class="Nd">destroy, initialize or wait on a barrier object</span></p>
</section>
<section class="Sh">
<h1 class="Sh" id="LIBRARY"><a class="permalink" href="#LIBRARY">LIBRARY</a></h1>
<p class="Pp"><span class="Lb">POSIX Threads Library (libpthread,
-lpthread)</span></p>
</section>
<section class="Sh">
<h1 class="Sh" id="SYNOPSIS"><a class="permalink" href="#SYNOPSIS">SYNOPSIS</a></h1>
<p class="Pp"><code class="In">#include
<<a class="In">pthread.h</a>></code></p>
<p class="Pp"><var class="Ft">int</var>
<br/>
<code class="Fn">pthread_barrier_destroy</code>(<var class="Fa" style="white-space: nowrap;">pthread_barrier_t
*barrier</var>);</p>
<p class="Pp"><var class="Ft">int</var>
<br/>
<code class="Fn">pthread_barrier_init</code>(<var class="Fa" style="white-space: nowrap;">pthread_barrier_t
*restrict barrier</var>, <var class="Fa" style="white-space: nowrap;">const
pthread_barrierattr_t *attr</var>,
<var class="Fa" style="white-space: nowrap;">unsigned count</var>);</p>
<p class="Pp"><var class="Ft">int</var>
<br/>
<code class="Fn">pthread_barrier_wait</code>(<var class="Fa" style="white-space: nowrap;">pthread_barrier_t
*barrier</var>);</p>
</section>
<section class="Sh">
<h1 class="Sh" id="DESCRIPTION"><a class="permalink" href="#DESCRIPTION">DESCRIPTION</a></h1>
<p class="Pp">The
<a class="permalink" href="#pthread_barrier_init"><code class="Fn" id="pthread_barrier_init">pthread_barrier_init</code></a>()
function will initialize <var class="Fa">barrier</var> with attributes
specified in <var class="Fa">attr</var>, or if it is
<code class="Dv">NULL</code>, with default attributes. The number of threads
that must call <code class="Fn">pthread_barrier_wait</code>() before any of
the waiting threads can be released is specified by
<var class="Fa">count</var>. The
<a class="permalink" href="#pthread_barrier_destroy"><code class="Fn" id="pthread_barrier_destroy">pthread_barrier_destroy</code></a>()
function will destroy <var class="Fa">barrier</var> and release any
resources that may have been allocated on its behalf.</p>
<p class="Pp" id="pthread_barrier_wait">The
<a class="permalink" href="#pthread_barrier_wait"><code class="Fn">pthread_barrier_wait</code></a>()
function will synchronize calling threads at <var class="Fa">barrier</var>.
The threads will be blocked from making further progress until a sufficient
number of threads calls this function. The number of threads that must call
it before any of them will be released is determined by the
<var class="Fa">count</var> argument to
<code class="Fn">pthread_barrier_init</code>(). Once the threads have been
released the barrier will be reset.</p>
</section>
<section class="Sh">
<h1 class="Sh" id="IMPLEMENTATION_NOTES"><a class="permalink" href="#IMPLEMENTATION_NOTES">IMPLEMENTATION
NOTES</a></h1>
<p class="Pp">In <span class="Lb">1:1 Threading Library (libthr, -lthr)</span>
the <code class="Dv">PTHREAD_BARRIER_SERIAL_THREAD</code> return value will
always be returned by the last thread to reach the barrier.</p>
</section>
<section class="Sh">
<h1 class="Sh" id="RETURN_VALUES"><a class="permalink" href="#RETURN_VALUES">RETURN
VALUES</a></h1>
<p class="Pp">If successful, both
<code class="Fn">pthread_barrier_destroy</code>() and
<code class="Fn">pthread_barrier_init</code>() will return zero. Otherwise,
an error number will be returned to indicate the error. If the call to
<code class="Fn">pthread_barrier_wait</code>() is successful, all but one of
the threads will return zero. That one thread will return
<code class="Dv">PTHREAD_BARRIER_SERIAL_THREAD</code>. Otherwise, an error
number will be returned to indicate the error.</p>
<p class="Pp">None of these functions will return
<code class="Er">EINTR</code>.</p>
</section>
<section class="Sh">
<h1 class="Sh" id="ERRORS"><a class="permalink" href="#ERRORS">ERRORS</a></h1>
<p class="Pp">The <code class="Fn">pthread_barrier_destroy</code>() function
will fail if:</p>
<dl class="Bl-tag">
<dt id="EBUSY">[<a class="permalink" href="#EBUSY"><code class="Er">EBUSY</code></a>]</dt>
<dd>An attempt was made to destroy <var class="Fa">barrier</var> while it was
in use.</dd>
</dl>
<p class="Pp">The <code class="Fn">pthread_barrier_destroy</code>() and
<code class="Fn">pthread_barrier_wait</code>() functions may fail if:</p>
<dl class="Bl-tag">
<dt id="EINVAL">[<a class="permalink" href="#EINVAL"><code class="Er">EINVAL</code></a>]</dt>
<dd>The value specified by <var class="Fa">barrier</var> is invalid.</dd>
</dl>
<p class="Pp">The <code class="Fn">pthread_barrier_init</code>() function will
fail if:</p>
<dl class="Bl-tag">
<dt id="EAGAIN">[<a class="permalink" href="#EAGAIN"><code class="Er">EAGAIN</code></a>]</dt>
<dd>The system lacks resources, other than memory, to initialize
<var class="Fa">barrier</var>.</dd>
<dt id="EINVAL~2">[<a class="permalink" href="#EINVAL~2"><code class="Er">EINVAL</code></a>]</dt>
<dd>The <var class="Fa">count</var> argument is less than 1.</dd>
<dt id="ENOMEM">[<a class="permalink" href="#ENOMEM"><code class="Er">ENOMEM</code></a>]</dt>
<dd>Insufficient memory to initialize <var class="Fa">barrier</var>.</dd>
</dl>
</section>
<section class="Sh">
<h1 class="Sh" id="SEE_ALSO"><a class="permalink" href="#SEE_ALSO">SEE
ALSO</a></h1>
<p class="Pp"><a class="Xr">pthread_barrierattr(3)</a></p>
</section>
<section class="Sh">
<h1 class="Sh" id="HISTORY"><a class="permalink" href="#HISTORY">HISTORY</a></h1>
<p class="Pp">The <code class="Fn">pthread_barrier_destroy</code>(),
<code class="Fn">pthread_barrier_init</code>() and
<code class="Fn">pthread_barrier_wait</code>() functions first appeared in
<span class="Lb">N:M Threading Library (libkse, -lkse)</span> in
<span class="Ux">FreeBSD 5.2</span>, and in <span class="Lb">1:1 Threading
Library (libthr, -lthr)</span> in <span class="Ux">FreeBSD 5.3</span>.</p>
</section>
</div>
<table class="foot">
<tr>
<td class="foot-date">August 17, 2018</td>
<td class="foot-os">FreeBSD 15.0</td>
</tr>
</table>
|
