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authorLennart Poettering <lennart@poettering.net>2014-04-01 19:12:59 +0200
committerLennart Poettering <lennart@poettering.net>2014-04-13 17:41:01 -0700
commitfaae655de3cdbed4be1d472b01ce0c4d81e905ed (patch)
treece17ad66a5ceb4c7ef3c65ea4d9267d4f6ae3ae7 /man/sd_event_new.xml
parent9ea28c55a2488e6cd4a44ac5786f12b71ad5bc9f (diff)
man: add man page for sd_event_new()
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+<?xml version='1.0'?> <!--*-nxml-*-->
+<!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 Lennart Poettering
+
+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_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
+ referened 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 no or one default event loops
+ 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. Not that it
+ is freed regardless if it is the default event loop object of 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>