182 lines
6.8 KiB
XML
182 lines
6.8 KiB
XML
<?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 <systemd/sd-bus.h></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>
|