-<?xml version='1.0'?> <!--*-nxml-*-->
+<?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.
+ This file is part of elogind.
-Copyright 2014 Lennart Poettering
+ 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.
+ elogind 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.
+ elogind 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/>.
+ You should have received a copy of the GNU Lesser General Public License
+ along with elogind; If not, see <http://www.gnu.org/licenses/>.
-->
-<refentry id="sd_event_new" conditional="ENABLE_KDBUS">
+<refentry id="sd_event_new" xmlns:xi="http://www.w3.org/2001/XInclude">
<refentryinfo>
<title>sd_event_new</title>
- <productname>systemd</productname>
+ <productname>elogind</productname>
<authorgroup>
<author>
<refname>sd_event_default</refname>
<refname>sd_event_ref</refname>
<refname>sd_event_unref</refname>
+ <refname>sd_event_unrefp</refname>
+ <refname>sd_event_get_tid</refname>
+ <refname>sd_event</refname>
<refpurpose>Acquire and release an event loop object</refpurpose>
</refnamediv>
<refsynopsisdiv>
<funcsynopsis>
- <funcsynopsisinfo>#include <systemd/sd-bus.h></funcsynopsisinfo>
+ <funcsynopsisinfo>#include <elogind/sd-event.h></funcsynopsisinfo>
+
+ <funcsynopsisinfo><token>typedef</token> struct sd_event sd_event;</funcsynopsisinfo>
<funcprototype>
<funcdef>int <function>sd_event_new</function></funcdef>
- <paramdef>sd_
bus **<parameter>event</parameter></paramdef>
+ <paramdef>sd_
event **<parameter>event</parameter></paramdef>
</funcprototype>
<funcprototype>
<funcdef>int <function>sd_event_default</function></funcdef>
- <paramdef>sd_bus **<parameter>event</parameter></paramdef>
+ <paramdef>sd_event **<parameter>event</parameter></paramdef>
+ </funcprototype>
+
+ <funcprototype>
+ <funcdef>sd_event *<function>sd_event_ref</function></funcdef>
+ <paramdef>sd_event *<parameter>event</parameter></paramdef>
</funcprototype>
<funcprototype>
- <funcdef>sd_bus *<function>sd_event_ref</function></funcdef>
- <paramdef>sd_
bus *<parameter>event</parameter></paramdef>
+ <funcdef>sd_event *<function>sd_event_unref</function></funcdef>
+ <paramdef>sd_
event *<parameter>event</parameter></paramdef>
</funcprototype>
<funcprototype>
- <funcdef>sd_bus *<function>sd_event_unref</function></funcdef>
- <paramdef>sd_bus *<parameter>event</parameter></paramdef>
+ <funcdef>void <function>sd_event_unrefp</function></funcdef>
+ <paramdef>sd_event **<parameter>event</parameter></paramdef>
+ </funcprototype>
+
+ <funcprototype>
+ <funcdef>int <function>sd_event_get_tid</function></funcdef>
+ <paramdef>sd_event *<parameter>event</parameter></paramdef>
+ <paramdef>pid_t *<parameter>tid</parameter></paramdef>
</funcprototype>
</funcsynopsis>
<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
+ <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>
+ dropped, the object 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
+ 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
+ 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>
+ thread. All threads have exactly either zero or one default event loop
+ objects associated, but never more.</para>
+
+ <para>After allocating an event loop object, add event sources to
+ it 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>
+ or
+ <citerefentry><refentrytitle>sd_event_add_defer</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
+ and then execute the event loop using
+ <citerefentry><refentrytitle>sd_event_run</refentrytitle><manvolnum>3</manvolnum></citerefentry>.</para>
<para><function>sd_event_ref()</function> increases the reference
- counter of the specified event loop object by one.</para>
+ count 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
+ reference count of the specified event loop object by one. If
+ the count hits zero, the 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
+ <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
+ 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>
+ freed as each keeps a reference to it.</para>
+
+ <para><function>sd_event_unrefp()</function> is similar to
+ <function>sd_event_unref()</function> but takes a pointer to a
+ pointer to an <type>sd_event</type> object. This call is useful in
+ conjunction with GCC's and LLVM's <ulink
+ url="https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html">Clean-up
+ Variable Attribute</ulink>. Note that this function is defined as
+ inline function. Use a declaration like the following,
+ in order to allocate an event loop object that is freed
+ automatically as the code block is left:</para>
+
+ <programlisting>{
+ __attribute__((cleanup(sd_event_unrefp)) sd_event *event = NULL;
+ int r;
+ …
+ r = sd_event_default(&event);
+ if (r < 0)
+ fprintf(stderr, "Failed to allocate event loop: %s\n", strerror(-r));
+ …
+}</programlisting>
+
+ <para><function>sd_event_ref()</function>,
+ <function>sd_event_unref()</function> and
+ <function>sd_event_unrefp()</function> execute no operation if the
+ passed in event loop object is <constant>NULL</constant>.</para>
+
+ <para><function>sd_event_get_tid()</function> retrieves the thread
+ identifier ("TID") of the thread the specified event loop object
+ is associated with. This call is only supported for event loops
+ allocated with <function>sd_event_default()</function>, and
+ returns the identifier for the thread the event loop is the
+ default event loop of. See <citerefentry
+ project='man-pages'><refentrytitle>gettid</refentrytitle><manvolnum>2</manvolnum></citerefentry>
+ for more information on thread identifiers.</para>
</refsect1>
<refsect1>
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>
+ <constant>NULL</constant>.</para>
</refsect1>
<refsect1>
<variablelist>
<varlistentry>
- <term><varname>-ENOMEM</varname></term>
+ <term><constant>-ENOMEM</constant></term>
- <listitem><para>Not enough memory to allocate object</para></listitem>
+ <listitem><para>Not enough memory to allocate the object.</para></listitem>
</varlistentry>
<varlistentry>
- <term><varname>-EMFILE</varname></term>
+ <term><constant>-EMFILE</constant></term>
<listitem><para>The maximum number of event loops has been allocated.</para></listitem>
</varlistentry>
- </variablelist>
- </refsect1>
- <refsect1>
- <title>Notes</title>
+ <varlistentry>
+ <term><constant>-ENXIO</constant></term>
- <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>
+ <listitem><para><function>sd_event_get_tid()</function> was
+ invoked on an event loop object that was not allocated with
+ <function>sd_event_default()</function>.</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>elogind</refentrytitle><manvolnum>8</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_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>
+ <citerefentry><refentrytitle>sd_event_add_exit</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
+ <citerefentry><refentrytitle>sd_event_run</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
+ <citerefentry project='man-pages'><refentrytitle>gettid</refentrytitle><manvolnum>2</manvolnum></citerefentry>
</para>
</refsect1>
~ianmdlvl / elogind.git / blobdiff