sdk/2.1/docs/man/clReleaseEvent.xml

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<refentry>
    <refentryinfo>
        <keywordset>
            <keyword>clReleaseEvent</keyword>
        </keywordset>
    </refentryinfo>

    <refmeta>
        <refentrytitle>
            clReleaseEvent
        </refentrytitle>

        <refmiscinfo>
            <copyright>
                <year>2007-2013</year>
                <holder>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.</holder>
            </copyright>
        </refmiscinfo>
        <manvolnum>3</manvolnum>
    </refmeta>

<!-- ================================ SYNOPSIS -->

    <refnamediv id="clReleaseEvent">
        <refname>
            clReleaseEvent
        </refname>

        <refpurpose>
            Decrements the <varname>event</varname> reference count.
        </refpurpose>
    </refnamediv>

    <refsynopsisdiv xmlns:xlink="http://www.w3.org/1999/xlink"><title></title>
        <funcsynopsis>
            <funcprototype>
                <funcdef>
                    <link xlink:href="scalarDataTypes.html">cl_int</link>
 <function>clReleaseEvent</function>
                </funcdef>
                <paramdef><link xlink:href="abstractDataTypes.html">cl_event</link><parameter>event</parameter></paramdef>
            </funcprototype>
        </funcsynopsis>
    </refsynopsisdiv>

<!-- ================================ PARAMETERS -->

    <refsect1 id="parameters">
        <title>Parameters</title>
        <variablelist>

            <varlistentry>
                <term><varname>event</varname></term>

                <listitem>
                    <para>Event object being released.</para>
               </listitem>
           </varlistentry>
        </variablelist>
    </refsect1>

<!-- ================================ NOTES  -->

    <refsect1 id="notes"><title>Notes</title>
        <para>
            Decrements the <varname>event</varname> reference count.
        </para>

        <para>
          The event object is deleted once the reference count becomes zero, the specific command
          identified by this event has completed (or terminated) and there are no commands in
          the command-queues of a context that require a wait for this event to complete.
          Using this function
          to release a reference that was not obtained by creating the object or by calling 
          <citerefentry><refentrytitle>clRetainEvent</refentrytitle></citerefentry>
          causes undefined behavior.
        </para>

        <para>
          Developers should be careful when releasing their last reference count on events
          created by <citerefentry><refentrytitle>clCreateUserEvent</refentrytitle></citerefentry>
          that have not yet been set to status of <constant>CL_COMPLETE</constant> or an error.
          If the user event was used in the <varname>event_wait_list</varname> argument passed to
          a <function>clEnqueue***</function> API or another application host thread is waiting
          for it in <citerefentry><refentrytitle>clWaitForEvents</refentrytitle></citerefentry>,
          those commands and host threads will continue to wait for the event status to reach
          <constant>CL_COMPLETE</constant> or error, even after the user has released the object.
          Since in this scenario the developer has released his last reference count to the
          user event, it would be in principle no longer valid for him to change the status
          of the event to unblock all the other machinery.  As a result the waiting tasks will
          wait forever, and associated events, <type>cl_mem</type> objects, command queues and
          contexts are likely to leak.  In-order command queues caught up in this deadlock may
          cease to do any work.
        </para>
    </refsect1>

<!-- ================================ ERRORS  -->

     <refsect1 id="errors"><title>Errors</title>
        <para>
          Returns <errorname>CL_SUCCESS</errorname> if the function executed
          successfully. Otherwise, it returns one of the following errors:
        </para>

        <itemizedlist mark="disc">
            <listitem>
              <errorname>CL_INVALID_EVENT</errorname> if <varname>event</varname> is not a
              valid event object.
            </listitem>

            <listitem>
              <errorname>CL_OUT_OF_RESOURCES</errorname> if there is a failure to allocate
              resources required by the OpenCL implementation on the device.
            </listitem>

            <listitem>
              <errorname>CL_OUT_OF_HOST_MEMORY</errorname> if there is a failure to allocate
              resources required by the OpenCL implementation on the host.
            </listitem>
        </itemizedlist>
    </refsect1>

<!-- ================================ EXAMPLE  -->
<!-- DO NOT DELETE IN CASE AN EXAMPLE IS ADDED IN THE FUTURE -->
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    <refsect2 id="example1">
        <title>
            Example
        </title>

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            <tgroup cols="1" align="left" colsep="0" rowsep="0">
                <colspec colname="col1" colnum="1" />
                <tbody>
                    <row>
                        <entry>
                            Example goes here - it will be set in "code" type with white space preserved.
                        </entry>
                    </row>
                </tbody>
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        </informaltable>
    </refsect2>
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<!-- ================================ SPECIFICATION  -->
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    <refsect1 id="specification"><title>Specification</title>
        <para>
            <imageobject>
                <imagedata fileref="pdficon_small1.gif" format="gif" />
            </imageobject>

            <olink uri="clReleaseEvent">OpenCL Specification</olink>
        </para>
    </refsect1>

<!-- ================================ ALSO SEE  -->

    <refsect1 id="seealso"><title>Also see</title>
        <para>
            <citerefentry><refentrytitle>clGetEventInfo</refentrytitle></citerefentry>,
            <citerefentry><refentrytitle>clRetainEvent</refentrytitle></citerefentry>,
            <citerefentry><refentrytitle>clWaitForEvents</refentrytitle></citerefentry>
        </para>
    </refsect1>

<!-- ================================ COPYRIGHT  -->
<!-- Content included from copyright.inc.xsl -->

    <refsect3 id="Copyright"><title></title>
        <imageobject>
                <imagedata fileref="KhronosLogo.jpg" format="jpg" />
        </imageobject>
        <para />
    </refsect3>

 <!-- 27-Oct-2015, API rev. 19 -->
</refentry>