<?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" xmlns:xi="http://www.w3.org/2001/XInclude"> <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 an 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>usec</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> may be used to run a single iteration of the event loop specified in the <parameter>event</parameter> parameter. The function waits until an event to process is available, and dispatches the registered handler for it. The <parameter>usec</parameter> parameter specifies the maximum time (in microseconds) to wait for an event. Use <constant>(uint64_t) -1</constant> to specify an infinite timeout.</para> <para><function>sd_event_loop()</function> invokes <function>sd_event_run()</function> in a loop, thus implementing the actual event loop. The call returns as soon as exiting was requested using <citerefentry><refentrytitle>sd_event_exit</refentrytitle><manvolnum>3</manvolnum></citerefentry>.</para> <para>The event loop object <parameter>event</parameter> is created with <citerefentry><refentrytitle>sd_event_new</refentrytitle><manvolnum>3</manvolnum></citerefentry>. Events sources to wait for and their handlers may be registered with <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> and <citerefentry><refentrytitle>sd_event_add_exit</refentrytitle><manvolnum>3</manvolnum></citerefentry>. </para> <para>For low-level control of event loop execution, use <citerefentry><refentrytitle>sd_event_prepare</refentrytitle><manvolnum>3</manvolnum></citerefentry>, <citerefentry><refentrytitle>sd_event_wait</refentrytitle><manvolnum>3</manvolnum></citerefentry> and <citerefentry><refentrytitle>sd_event_dispatch</refentrytitle><manvolnum>3</manvolnum></citerefentry> which are wrapped by <function>sd_event_run()</function>. Along with <citerefentry><refentrytitle>sd_event_get_fd</refentrytitle><manvolnum>3</manvolnum></citerefentry>, these functions allow integration of an <citerefentry><refentrytitle>sd-event</refentrytitle><manvolnum>3</manvolnum></citerefentry> event loop into foreign event loop implementations.</para> </refsect1> <refsect1> <title>Return Value</title> <para>On failure, these functions return a negative errno-style error code. <function>sd_event_run()</function> returns a positive, non-zero integer if an event source was dispatched, and zero when the specified timeout hit before an event source has seen any event, and hence no event source was dispatched. <function>sd_event_loop()</function> returns the exit code specified when invoking <function>sd_event_exit()</function>.</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 invalid or <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> <xi:include href="libsystemd-pkgconfig.xml" /> <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_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>, <citerefentry><refentrytitle>sd_event_exit</refentrytitle><manvolnum>3</manvolnum></citerefentry>, <citerefentry><refentrytitle>sd_event_get_fd</refentrytitle><manvolnum>3</manvolnum></citerefentry>, <citerefentry><refentrytitle>sd_event_wait</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>