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<?xml version='1.0'?>
<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
<!-- SPDX-License-Identifier: LGPL-2.1-or-later -->
<refentry id="sd_event_source_unref" xmlns:xi="http://www.w3.org/2001/XInclude">
<refentryinfo>
<title>sd_event_source_unref</title>
<productname>systemd</productname>
</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>
<refname>sd_event_source_disable_unref</refname>
<refname>sd_event_source_disable_unrefp</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>
<funcprototype>
<funcdef>sd_event_source* <function>sd_event_source_disable_unref</function></funcdef>
<paramdef>sd_event_source *<parameter>source</parameter></paramdef>
</funcprototype>
<funcprototype>
<funcdef>void <function>sd_event_source_disable_unrefp</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 internal 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, the object is detached from the 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 internal 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> or call
<function>sd_event_source_disable_unref()</function>, see below.</para>
<para><function>sd_event_source_disable_unref()</function> combines a call to
<function>sd_event_source_set_enabled()</function> with <constant>SD_EVENT_OFF</constant> with
<function>sd_event_source_unref()</function>. This ensures that the source is disabled before the local
reference to it is lost. The <parameter>source</parameter> parameter is allowed to be
<constant>NULL</constant>.</para>
<para><function>sd_event_source_disable_unrefp()</function> is similar to
<function>sd_event_source_unrefp()</function>, but in addition disables the source first. 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>
</refsect1>
<refsect1>
<title>Return Value</title>
<para><function>sd_event_source_unref()</function> and
<function>sd_event_source_disable_unref()</function> always return <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_signal</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
<citerefentry><refentrytitle>sd_event_add_child</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
<citerefentry><refentrytitle>sd_event_add_inotify</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>
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