e1ad3d8dcd33fe91acdffd64989e3e6561eab47aChristian Maeder<?xml version='1.0'?> <!--*-nxml-*-->

e1ad3d8dcd33fe91acdffd64989e3e6561eab47aChristian Maeder<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"

dc62afbf79603699b39b2387f48298634f642e67cmaeder"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">

e1ad3d8dcd33fe91acdffd64989e3e6561eab47aChristian Maeder

<refentry id="sd_event_new" conditional="ENABLE_KDBUS">

<refentryinfo>

<title>sd_event_new</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_new</refentrytitle>

<manvolnum>3</manvolnum>

</refmeta>

<refnamediv>

<refname>sd_event_new</refname>

<refname>sd_event_default</refname>

<refname>sd_event_ref</refname>

<refname>sd_event_unref</refname>

<refpurpose>Acquire and release an event loop object</refpurpose>

</refnamediv>

<refsynopsisdiv>

<funcsynopsis>

<funcsynopsisinfo>#include &lt;systemd/sd-bus.h&gt;</funcsynopsisinfo>

<funcprototype>

<funcdef>int <function>sd_event_new</function></funcdef>

<paramdef>sd_bus **<parameter>event</parameter></paramdef>

</funcprototype>

<funcprototype>

<funcdef>int <function>sd_event_default</function></funcdef>

<paramdef>sd_bus **<parameter>event</parameter></paramdef>

</funcprototype>

<funcprototype>

<funcdef>sd_bus *<function>sd_event_ref</function></funcdef>

<paramdef>sd_bus *<parameter>event</parameter></paramdef>

</funcprototype>

<funcprototype>

<funcdef>sd_bus *<function>sd_event_unref</function></funcdef>

<paramdef>sd_bus *<parameter>event</parameter></paramdef>

</funcprototype>

</funcsynopsis>

</refsynopsisdiv>

<refsect1>

<title>Description</title>

<para><function>sd_event_new()</function> allocates a new event

loop object. The event loop object is returned in the

<parameter>event</parameter> parameter. After use, drop

the returned reference with

<function>sd_event_unref()</function>. When the last reference is

dropped, the event loop is freed.</para>

<para><function>sd_event_default()</function> acquires a reference

to the default event loop object of the calling thread, possibly

allocating a new object if no default event loop object has been

allocated yet for the thread. After use, drop the returned

reference with <function>sd_event_unref()</function>. When the

last reference is dropped, the event loop is freed. If this

function is called while the object returned from a previous call

from the same thread is still referenced, the same object is

returned again, but the reference is increased by one. It is

recommended to use this call instead of

<function>sd_event_new()</function> in order to share event loop

objects between various components that are dispatched in the same

thread. All threads either have exactly zero or one default event loop

associated, but never more.</para>

<para><function>sd_event_ref()</function> increases the reference

counter of the specified event loop object by one.</para>

<para><function>sd_event_unref()</function> decreases the

reference counter of the specified event loop object by one. If

the counter hits zero, the event loop object is freed. Note that it

is freed regardless of whether it is the default event loop object for a

thread or not. This means that allocating an event loop with

<function>sd_event_default()</function>, then releasing it, and

then acquiring a new one with

<function>sd_event_default()</function> will result in two

distinct objects. Note that, in order to free an event loop object,

all remaining event sources of the event loop also need to be

freed as they each keep a reference to it.</para>

</refsect1>

<refsect1>

<title>Return Value</title>

<para>On success, <function>sd_event_new()</function> and

<function>sd_event_default()</function> return 0 or a positive

integer. On failure, they return a negative errno-style error

code. <function>sd_event_ref()</function> always returns a pointer

to the event loop object passed

in. <function>sd_event_unref()</function> always returns

NULL.</para>

</refsect1>

<refsect1>

<title>Errors</title>

<para>Returned errors may indicate the following problems:</para>

<variablelist>

<varlistentry>

<term><varname>-ENOMEM</varname></term>

<listitem><para>Not enough memory to allocate object</para></listitem>

</varlistentry>

<varlistentry>

<term><varname>-EMFILE</varname></term>

<listitem><para>The maximum number of event loops has been allocated.</para></listitem>

</varlistentry>

</variablelist>

</refsect1>

<refsect1>

<title>Notes</title>

<para><function>sd_event_new()</function> and the other functions

described here are available as a shared library, which can be

compiled and linked to with the

<constant>libsystemd</constant> <citerefentry><refentrytitle>pkg-config</refentrytitle><manvolnum>1</manvolnum></citerefentry>

file.</para>

</refsect1>

<refsect1>

<title>See Also</title>

<para>

<citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,

<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_defer</refentrytitle><manvolnum>3</manvolnum></citerefentry>,

<citerefentry><refentrytitle>sd_event_add_post</refentrytitle><manvolnum>3</manvolnum></citerefentry>,

<citerefentry><refentrytitle>sd_event_add_exit</refentrytitle><manvolnum>3</manvolnum></citerefentry>

</para>

</refsect1>

</refentry>