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<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<!DOCTYPE html><html xmlns="http://www.w3.org/1999/xhtml">
<head>
<title xmlns:xlink="http://www.w3.org/1999/xlink">eglClientWaitSync - EGL Reference Pages</title>
<link rel="stylesheet" type="text/css" href="khronos-man.css"/>
<meta name="generator" content="DocBook XSL Stylesheets V1.79.1"/>
</head>
<body>
<header/>
<div class="refentry" id="eglClientWaitSync">
<div class="titlepage"/>
<div class="refnamediv">
<h2>Name</h2>
<p>eglClientWaitSync —
Wait in the client for a sync object to be signalled
</p>
</div>
<div class="refsynopsisdiv">
<h2>C Specification</h2>
<div class="funcsynopsis">
<table style="border: 0; cellspacing: 0; cellpadding: 0;" class="funcprototype-table">
<tr>
<td>
<code class="funcdef">EGLint <strong class="fsfunc">eglClientWaitSync</strong>(</code>
</td>
<td>(EGLDisplay <var class="pdparam">display</var>, </td>
</tr>
<tr>
<td> </td>
<td>EGLSync <var class="pdparam">sync</var>, </td>
</tr>
<tr>
<td> </td>
<td>EGLint <var class="pdparam">flags</var>, </td>
</tr>
<tr>
<td> </td>
<td>EGLTime <var class="pdparam">timeout</var><code>)</code>;</td>
</tr>
</table>
<div class="funcprototype-spacer"> </div>
</div>
</div>
<div class="refsect1" id="parameters">
<h2>Parameters</h2>
<div class="variablelist">
<dl class="variablelist">
<dt>
<span class="term">
<em class="parameter">
<code>display</code>
</em>
</span>
</dt>
<dd>
<p>
Specifies the <abbr class="acronym">EGL</abbr> display connection.
</p>
</dd>
<dt>
<span class="term">
<em class="parameter">
<code>sync</code>
</em>
</span>
</dt>
<dd>
<p>
Specifies the sync object to wait on.
</p>
</dd>
<dt>
<span class="term">
<em class="parameter">
<code>flags</code>
</em>
</span>
</dt>
<dd>
<p>
Specifies flags controlling wait behavior.
</p>
</dd>
<dt>
<span class="term">
<em class="parameter">
<code>timeout</code>
</em>
</span>
</dt>
<dd>
<p>
Specifies wait timeout interval.
</p>
</dd>
</dl>
</div>
</div>
<div class="refsect1" id="description">
<h2>Description</h2>
<p>
<code class="function">eglClientWaitSync</code> blocks the calling thread
until the specified sync object <em class="parameter"><code>sync</code></em> is
signaled, or until <em class="parameter"><code>timeout</code></em> nanoseconds
have passed.
</p>
<p>
More than one <code class="function">eglClientWaitSync</code> may be
outstanding on the same <em class="parameter"><code>sync</code></em> at any given
time. When there are multiple threads blocked on the same
<em class="parameter"><code>sync</code></em> and the sync object is signaled, all
such threads are released, but the order in which they are
released is not defined.
</p>
<p>
If the value of <em class="parameter"><code>timeout</code></em> is zero, then
<code class="function">eglClientWaitSync</code> simply tests the current
status of <em class="parameter"><code>sync</code></em>. If the value of
<em class="parameter"><code>timeout</code></em> is the special value
<code class="constant">EGL_FOREVER</code>, then
<code class="function">eglClientWaitSync</code> does not time out. For
all other values, <em class="parameter"><code>timeout</code></em> is adjusted to
the closest value allowed by the implementation-dependent
timeout accuracy, which may be substantially longer than one
nanosecond.
</p>
<p>
<code class="function">eglClientWaitSync</code> returns one of three
status values describing the reason for returning. A return
value of <code class="constant">EGL_TIMEOUT_EXPIRED</code> indicates that
the specified timeout period expired before
<em class="parameter"><code>sync</code></em> was signaled, or if
<em class="parameter"><code>timeout</code></em> is zero, indicates that
<em class="parameter"><code>sync</code></em> is not signaled. A return value of
<code class="constant">EGL_CONDITION_SATISFIED</code> indicates that
<em class="parameter"><code>sync</code></em> was signaled before the timeout
expired, which includes the case when
<em class="parameter"><code>sync</code></em> was already signaled when
<code class="function">eglClientWaitSync</code> was called. If an error
occurs then an error is generated and
<code class="constant">EGL_FALSE</code> is returned.
</p>
<p>
If the sync object being blocked upon will not be signaled in
finite time (for example, by an associated fence command issued
previously, but not yet flushed to the graphics pipeline), then
<code class="function">eglClientWaitSync</code> may wait forever. To help
prevent this behavior, if the
<code class="constant">EGL_SYNC_FLUSH_COMMANDS_BIT</code> bit is set in
<em class="parameter"><code>flags</code></em>, and <em class="parameter"><code>sync</code></em> is
unsignaled when <code class="function">eglClientWaitSync</code> is
called, then the equivalent of Flush() will be performed for the
current API context (i.e., the context returned by
<code class="function">eglGetCurrentContext</code>) before blocking on
<em class="parameter"><code>sync</code></em>. If no context is current for the
bound API, the <code class="constant">EGL_SYNC_FLUSH_COMMANDS_BIT</code>
bit is ignored.
</p>
<p>
Note: the simple Flush behavior defined by
<code class="constant">EGL_SYNC_FLUSH_COMMANDS_BIT</code> will not help
when waiting for a fence command issued in a different context's
command stream. Applications which block on a fence sync object
must take additional steps to ensure that the context from which
the associated fence command was issued has flushed that command
to the graphics pipeline.
</p>
</div>
<div class="refsect1" id="errors">
<h2>Errors</h2>
<p>
<code class="function">eglClientWaitSync</code> returns
<code class="constant">EGL_FALSE</code> on failure.
</p>
<p>
If <em class="parameter"><code>sync</code></em> is not a valid sync object for
<em class="parameter"><code>display</code></em>, an
<code class="constant">EGL_BAD_PARAMETER</code> error is generated.
</p>
<p>
If <em class="parameter"><code>display</code></em> does not match the
<span class="type">EGLDisplay</span> passed to
<code class="function">eglCreateSync</code> when
<em class="parameter"><code>sync</code></em> was created, the behaviour is
undefined.
</p>
</div>
<div class="refsect1" id="notes">
<h2>Notes</h2>
<p>
<code class="function">eglClientWaitSync</code> is available only if the
EGL version is 1.5 or greater.
</p>
</div>
<div class="refsect1" id="seealso">
<h2>See Also</h2>
<p>
<a class="citerefentry" href="eglCreateSync.xhtml"><span class="citerefentry"><span class="refentrytitle">eglCreateSync</span></span></a>,
<a class="citerefentry" href="eglGetCurrentContext.xhtml"><span class="citerefentry"><span class="refentrytitle">eglGetCurrentContext</span></span></a>,
<a class="citerefentry" href="eglWaitSync.xhtml"><span class="citerefentry"><span class="refentrytitle">eglWaitSync</span></span></a>,
<code class="function">glFinish</code>,
<code class="function">vgFinish</code>
</p>
</div>
<p>
</p>
<div class="refsect3" id="copyright">
<img src="KhronosLogo.jpg"/>
<p>
Copyright © 2003-2014 The Khronos Group Inc.
Permission is hereby granted, free of charge, to any person obtaining a
copy of this software and/or associated documentation files (the
"Materials"), to deal in the Materials without restriction, including
without limitation the rights to use, copy, modify, merge, publish,
distribute, sublicense, and/or sell copies of the Materials, and to
permit persons to whom the Materials are furnished to do so, subject to
the condition that this copyright notice and permission notice shall be included
in all copies or substantial portions of the Materials.
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