+<?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 2014 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_add_defer" xmlns:xi="http://www.w3.org/2001/XInclude">
+
+ <refentryinfo>
+ <title>sd_event_add_defer</title>
+ <productname>systemd</productname>
+
+ <authorgroup>
+ <author>
+ <contrib>More text</contrib>
+ <firstname>Zbigniew</firstname>
+ <surname>Jędrzejewski-Szmek</surname>
+ <email>zbyszek@in.waw.pl</email>
+ </author>
+ </authorgroup>
+ </refentryinfo>
+
+ <refmeta>
+ <refentrytitle>sd_event_add_defer</refentrytitle>
+ <manvolnum>3</manvolnum>
+ </refmeta>
+
+ <refnamediv>
+ <refname>sd_event_add_defer</refname>
+ <refname>sd_event_add_post</refname>
+ <refname>sd_event_add_exit</refname>
+ <refname>sd_event_handler_t</refname>
+
+ <refpurpose>Add static event sources to an event loop</refpurpose>
+ </refnamediv>
+
+ <refsynopsisdiv>
+ <funcsynopsis>
+ <funcsynopsisinfo>#include <systemd/sd-event.h></funcsynopsisinfo>
+
+ <funcsynopsisinfo><token>typedef</token> struct sd_event_source sd_event_source;</funcsynopsisinfo>
+
+ <funcprototype>
+ <funcdef>typedef int (*<function>sd_event_handler_t</function>)</funcdef>
+ <paramdef>sd_event_source *<parameter>s</parameter></paramdef>
+ <paramdef>void *<parameter>userdata</parameter></paramdef>
+ </funcprototype>
+
+ <funcprototype>
+ <funcdef>int <function>sd_event_add_defer</function></funcdef>
+ <paramdef>sd_event *<parameter>event</parameter></paramdef>
+ <paramdef>sd_event_source **<parameter>source</parameter></paramdef>
+ <paramdef>sd_event_handler_t <parameter>handler</parameter></paramdef>
+ <paramdef>void *<parameter>userdata</parameter></paramdef>
+ </funcprototype>
+
+ <funcprototype>
+ <funcdef>int <function>sd_event_add_post</function></funcdef>
+ <paramdef>sd_event *<parameter>event</parameter></paramdef>
+ <paramdef>sd_event_source **<parameter>source</parameter></paramdef>
+ <paramdef>sd_event_handler_t <parameter>handler</parameter></paramdef>
+ <paramdef>void *<parameter>userdata</parameter></paramdef>
+ </funcprototype>
+
+ <funcprototype>
+ <funcdef>int <function>sd_event_add_exit</function></funcdef>
+ <paramdef>sd_event *<parameter>event</parameter></paramdef>
+ <paramdef>sd_event_source **<parameter>source</parameter></paramdef>
+ <paramdef>sd_event_handler_t <parameter>handler</parameter></paramdef>
+ <paramdef>void *<parameter>userdata</parameter></paramdef>
+ </funcprototype>
+
+ </funcsynopsis>
+ </refsynopsisdiv>
+
+ <refsect1>
+ <title>Description</title>
+
+ <para>These three functions add new static event sources to an
+ event loop. The event loop object is specified in the
+ <parameter>event</parameter> parameter, the event source object is
+ returned in the <parameter>source</parameter> parameter. The event
+ sources are enabled statically and will "fire" when the event loop
+ is run and the conditions described below are met. The handler
+ function will be passed the <parameter>userdata</parameter>
+ pointer, which may be chosen freely by the caller.</para>
+
+ <para><function>sd_event_add_defer()</function> adds a new event
+ source that will be dispatched instantly, before the event loop
+ goes to sleep again and waits for new events. By default, the
+ handler will be called once
+ (<constant>SD_EVENT_ONESHOT</constant>). Note that if the event
+ source is set to <constant>SD_EVENT_ON</constant> the event loop
+ will never go to sleep again, but continuously call the handler,
+ possibly interleaved with other event sources.</para>
+
+ <para><function>sd_event_add_post()</function> adds a new event
+ source that is run before the event loop will sleep and wait
+ for new events, but only after at least one other non-post event
+ source was dispatched. By default, the source is enabled
+ permanently (<constant>SD_EVENT_ON</constant>). Note that this
+ event source type will still allow the event loop to go to sleep
+ again, even if set to <constant>SD_EVENT_ON</constant>, as long as
+ no other event source is ever triggered.</para>
+
+ <para><function>sd_event_add_exit()</function> adds a new event
+ source that will be dispatched when the event loop is terminated
+ with <citerefentry><refentrytitle>sd_event_exit</refentrytitle><manvolnum>3</manvolnum></citerefentry>.</para>
+
+ <para>The
+ <citerefentry><refentrytitle>sd_event_source_set_enabled</refentrytitle><manvolnum>3</manvolnum></citerefentry>
+ function may be used to enable the event source permanently
+ (<constant>SD_EVENT_ON</constant>) or to make it fire just once
+ (<constant>SD_EVENT_ONESHOT</constant>).</para>
+
+ <para>If the handler function returns a negative error code, it
+ will be disabled after the invocation, even if the
+ <constant>SD_EVENT_ON</constant> mode was requested before.</para>
+
+ <para>To destroy an event source object use
+ <citerefentry><refentrytitle>sd_event_source_unref</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
+ but note that the event source is only removed from the event loop
+ when all references to the event source are dropped. To make sure
+ an event source does not fire anymore, even when there's still a
+ reference to it kept, consider setting the event source to
+ <constant>SD_EVENT_OFF</constant> with
+ <citerefentry><refentrytitle>sd_event_source_set_enabled</refentrytitle><manvolnum>3</manvolnum></citerefentry>.</para>
+
+ <para>If the second parameter of these functions is passed as
+ NULL no reference to the event source object is returned. In this
+ case the event source is considered "floating", and will be
+ destroyed implicitly when the event loop itself is
+ destroyed.</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.</para>
+ </refsect1>
+
+ <refsect1>
+ <title>Errors</title>
+
+ <para>Returned errors may indicate the following problems:</para>
+
+ <variablelist>
+ <varlistentry>
+ <term><constant>-ENOMEM</constant></term>
+
+ <listitem><para>Not enough memory to allocate an object.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><constant>-EINVAL</constant></term>
+
+ <listitem><para>An invalid argument has been passed.</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>
+ </refsect1>
+
+ <xi:include href="libelogind-pkgconfig.xml" />
+
+ <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_new</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
+ <citerefentry><refentrytitle>sd_event_now</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_source_set_enabled</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
+ <citerefentry><refentrytitle>sd_event_source_set_priority</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
+ <citerefentry><refentrytitle>sd_event_source_set_userdata</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
+ <citerefentry><refentrytitle>sd_event_source_set_description</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
+ <citerefentry><refentrytitle>sd_event_exit</refentrytitle><manvolnum>3</manvolnum></citerefentry>
+ </para>
+ </refsect1>
+
+</refentry>
~ianmdlvl / elogind.git / blobdiff