<?xml version='1.0'?> <!--*- Mode: nxml; nxml-child-indent: 2; indent-tabs-mode: nil -*--> <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN" "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd"> <!-- This file is part of systemd. Copyright 2015 Lennart Poettering systemd is free software; you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation; either version 2.1 of the License, or (at your option) any later version. systemd is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details. You should have received a copy of the GNU Lesser General Public License along with systemd; If not, see <http://www.gnu.org/licenses/>. --> <refentry id="sd_event_source_unref" xmlns:xi="http://www.w3.org/2001/XInclude"> <refentryinfo> <title>sd_event_source_unref</title> <productname>systemd</productname> <authorgroup> <author> <contrib>Developer</contrib> <firstname>Lennart</firstname> <surname>Poettering</surname> <email>lennart@poettering.net</email> </author> </authorgroup> </refentryinfo> <refmeta> <refentrytitle>sd_event_source_unref</refentrytitle> <manvolnum>3</manvolnum> </refmeta> <refnamediv> <refname>sd_event_source_unref</refname> <refname>sd_event_source_unrefp</refname> <refname>sd_event_source_ref</refname> <refpurpose>Increase or decrease event source reference counters</refpurpose> </refnamediv> <refsynopsisdiv> <funcsynopsis> <funcsynopsisinfo>#include <systemd/sd-event.h></funcsynopsisinfo> <funcprototype> <funcdef>sd_event_source* <function>sd_event_source_unref</function></funcdef> <paramdef>sd_event_source *<parameter>source</parameter></paramdef> </funcprototype> <funcprototype> <funcdef>void <function>sd_event_source_unrefp</function></funcdef> <paramdef>sd_event_source **<parameter>source</parameter></paramdef> </funcprototype> <funcprototype> <funcdef>sd_event_source* <function>sd_event_source_ref</function></funcdef> <paramdef>sd_event_source *<parameter>source</parameter></paramdef> </funcprototype> </funcsynopsis> </refsynopsisdiv> <refsect1> <title>Description</title> <para><function>sd_event_source_unref()</function> may be used to decrement by one the reference counter of the event source object specified as <parameter>source</parameter>. The reference counter is initially set to one, when the event source is created with calls such as <citerefentry><refentrytitle>sd_event_add_io</refentrytitle><manvolnum>3</manvolnum></citerefentry> or <citerefentry><refentrytitle>sd_event_add_time</refentrytitle><manvolnum>3</manvolnum></citerefentry>. When the reference counter reaches zero it is removed from its event loop object and destroyed.</para> <para><function>sd_event_source_unrefp()</function> is similar to <function>sd_event_source_unref()</function> but takes a pointer to a pointer to an <type>sd_event_source</type> object. This call is useful in conjunction with GCC's and LLVM's <ulink url="https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html">Clean-up Variable Attribute</ulink>. Note that this function is defined as inline function.</para> <para><function>sd_event_source_ref()</function> may be used to increase by one the reference counter of the event source object specified as <parameter>source</parameter>.</para> <para><function>sd_event_source_unref()</function>, <function>sd_bus_creds_unrefp()</function> and <function>sd_bus_creds_ref()</function> execute no operation if the passed event source object is <constant>NULL</constant>.</para> <para>Note that event source objects stay alive and may be dispatched as long as they have a reference counter greater than zero. In order to drop a reference of an event source and make sure the associated event source handler function is not called anymore it is recommended to combine a call of <function>sd_event_source_unref()</function> with a prior call to <function>sd_event_source_set_enabled()</function> with <constant>SD_EVENT_OFF</constant>.</para> </refsect1> <refsect1> <title>Return Value</title> <para><function>sd_event_source_unref()</function> always returns <constant>NULL</constant>. <function>sd_event_source_ref()</function> always returns the event source object passed in.</para> </refsect1> <xi:include href="libsystemd-pkgconfig.xml" /> <refsect1> <title>See Also</title> <para> <citerefentry><refentrytitle>sd-event</refentrytitle><manvolnum>3</manvolnum></citerefentry>, <citerefentry><refentrytitle>sd_event_add_io</refentrytitle><manvolnum>3</manvolnum></citerefentry>, <citerefentry><refentrytitle>sd_event_add_time</refentrytitle><manvolnum>3</manvolnum></citerefentry>, <citerefentry><refentrytitle>sd_event_add_child</refentrytitle><manvolnum>3</manvolnum></citerefentry>, <citerefentry><refentrytitle>sd_event_add_signal</refentrytitle><manvolnum>3</manvolnum></citerefentry>, <citerefentry><refentrytitle>sd_event_add_defer</refentrytitle><manvolnum>3</manvolnum></citerefentry>, <citerefentry><refentrytitle>sd_event_source_set_enabled</refentrytitle><manvolnum>3</manvolnum></citerefentry> </para> </refsect1> </refentry>