man: add man page for sd_event_new()

1 files changed, 181 insertions, 0 deletions

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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>