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<?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 Zbigniew Jędrzejewski-Szmek
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_run">
<refentryinfo>
<title>sd_event_run</title>
<productname>systemd</productname>
<authorgroup>
<author>
<contrib>Developer</contrib>
<firstname>Tom</firstname>
<surname>Gundersen</surname>
<email>teg@jklm.no</email>
</author>
</authorgroup>
</refentryinfo>
<refmeta>
<refentrytitle>sd_event_run</refentrytitle>
<manvolnum>3</manvolnum>
</refmeta>
<refnamediv>
<refname>sd_event_run</refname>
<refname>sd_event_loop</refname>
<refpurpose>Run the libsystemd event loop</refpurpose>
</refnamediv>
<refsynopsisdiv>
<funcsynopsis>
<funcsynopsisinfo>#include <systemd/sd-event.h></funcsynopsisinfo>
<funcprototype>
<funcdef>int <function>sd_event_run</function></funcdef>
<paramdef>sd_event *<parameter>event</parameter></paramdef>
<paramdef>uint64_t <parameter>timeout</parameter></paramdef>
</funcprototype>
<funcprototype>
<funcdef>int <function>sd_event_loop</function></funcdef>
<paramdef>sd_event *<parameter>event</parameter></paramdef>
</funcprototype>
</funcsynopsis>
</refsynopsisdiv>
<refsect1>
<title>Description</title>
<para><function>sd_event_run()</function> can be used to run one
iteration of the event loop of libsystemd. This function waits
until an event to process is available, and dispatches a handler
for it. The <parameter>timeout</parameter> parameter specifices the
maximum time (in microseconds) to wait. <constant>(uint64_t)
-1</constant> may be used to specify an infinite timeout.</para>
<para><function>sd_event_loop</function> runs
<function>sd_event_wait</function> in a loop with a timeout of
infinity. This makes it suitable for the main event loop of a
program.</para>
<para>The event loop object <parameter>event</parameter> is
created with
<function>sd_event_new</function>.
Events to wait for and their handlers can be registered with
<function>sd_event_add_time</function>,
<function>sd_event_add_child</function>,
<function>sd_event_add_signal</function>,
<function>sd_event_add_defer</function>,
<function>sd_event_add_exit</function>,
and
<function>sd_event_add_post</function>.
</para>
<para>For more fine-grained control,
<function>sd_event_prepare</function>,
<function>sd_event_wait</function>, and
<function>sd_event_dispatch</function> may be used. Along with
<function>sd_event_get_fd</function>, those functions make it
possible to integrate the libsystemd loop inside of another event
loop.</para>
</refsect1>
<refsect1>
<title>Return Value</title>
<para>On success, these functions return 0 or a positive integer.
On failure, they return a negative errno-style error code.
<function>sd_event_run</function> returns 0 if the event loop is
finished, and a positive value if it can be continued.</para>
</refsect1>
<refsect1>
<title>Errors</title>
<para>Returned errors may indicate the following problems:</para>
<variablelist>
<varlistentry>
<term><constant>-EINVAL</constant></term>
<listitem><para>The <parameter>event</parameter> parameter is
<constant>NULL</constant>.</para></listitem>
</varlistentry>
<varlistentry>
<term><constant>-EBUSY</constant></term>
<listitem><para>The event loop object is not in the right
state (see
<citerefentry><refentrytitle>sd_event_prepare</refentrytitle><manvolnum>3</manvolnum></citerefentry>
for an explanation of possible states).</para></listitem>
</varlistentry>
<varlistentry>
<term><constant>-ESTALE</constant></term>
<listitem><para>The event loop is already terminated.</para></listitem>
</varlistentry>
<varlistentry>
<term><constant>-ECHILD</constant></term>
<listitem><para>The event loop has been created in a different process.</para></listitem>
</varlistentry>
</variablelist>
<para>Other errors are possible, too.</para>
</refsect1>
<refsect1>
<title>Notes</title>
<para><function>sd_event_run()</function> and
<function>sd_event_loop()</function> are available
as a shared library, which can be compiled and linked to with the
<constant>libsystemd</constant> <citerefentry project='die-net'><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_new</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
<citerefentry><refentrytitle>sd_event_wait</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_defer</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
<citerefentry><refentrytitle>sd_event_add_exit</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
<citerefentry><refentrytitle>sd_event_add_post</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
<ulink url="https://developer.gnome.org/glib/unstable/glib-The-Main-Event-Loop.html">GLib Main Event Loop</ulink>.
</para>
</refsect1>
</refentry>
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