man: fully document sd-event interfaces

[thirdparty/systemd.git] / man / sd_event_source_unref.xml

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+<?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 2015 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_source_unref" xmlns:xi="http://www.w3.org/2001/XInclude">
+
+  <refentryinfo>
+    <title>sd_event_source_unref</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_source_unref</refentrytitle>
+    <manvolnum>3</manvolnum>
+  </refmeta>
+
+  <refnamediv>
+    <refname>sd_event_source_unref</refname>
+    <refname>sd_event_source_ref</refname>
+
+    <refpurpose>Increase or decrease event source reference counters</refpurpose>
+  </refnamediv>
+
+  <refsynopsisdiv>
+    <funcsynopsis>
+      <funcsynopsisinfo>#include &lt;systemd/sd-event.h&gt;</funcsynopsisinfo>
+
+      <funcprototype>
+        <funcdef>sd_event_source* <function>sd_event_source_unref</function></funcdef>
+        <paramdef>sd_event_source *<parameter>source</parameter></paramdef>
+      </funcprototype>
+
+      <funcprototype>
+        <funcdef>sd_event_source* <function>sd_event_source_ref</function></funcdef>
+        <paramdef>sd_event_source *<parameter>source</parameter></paramdef>
+      </funcprototype>
+
+    </funcsynopsis>
+  </refsynopsisdiv>
+
+  <refsect1>
+    <title>Description</title>
+
+    <para><function>sd_event_source_unref()</function> may be used to
+    decrement by one the reference counter of the event source object
+    specified as <parameter>source</parameter>. The reference counter
+    is initially set to one, when the event source is created with calls
+    such as
+    <citerefentry><refentrytitle>sd_event_add_io</refentrytitle><manvolnum>3</manvolnum></citerefentry>
+    or
+    <citerefentry><refentrytitle>sd_event_add_time</refentrytitle><manvolnum>3</manvolnum></citerefentry>. When
+    the reference counter reaches zero it is removed from its event loop
+    object and destroyed.</para>
+
+    <para><function>sd_event_source_ref()</function> may be used
+    to increase by one the reference counter of the event source object
+    specified as <parameter>source</parameter>.</para>
+
+    <para>Both functions execute no operation if the passed event
+    source object is <constant>NULL</constant>.</para>
+
+    <para>Note that event source objects stay alive and may be
+    dispatched as long as they have a reference counter greater than
+    zero. In order to drop a reference of an event source and make
+    sure the associated event source handler function is not called
+    anymore it is recommended to combine a call of
+    <function>sd_event_source_unref()</function> with a prior call to
+    <function>sd_event_source_set_enabled()</function> with
+    <constant>SD_EVENT_OFF</constant>.</para>
+  </refsect1>
+
+  <refsect1>
+    <title>Return Value</title>
+
+    <para><function>sd_event_source_unref()</function> always returns
+    <constant>NULL</constant>.
+    <function>sd_event_source_ref()</function> always returns the
+    event source object passed in.</para>
+  </refsect1>
+
+  <xi:include href="libsystemd-pkgconfig.xml" />
+
+  <refsect1>
+    <title>See Also</title>
+
+    <para>
+      <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_signal</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
+      <citerefentry><refentrytitle>sd_event_add_defer</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
+      <citerefentry><refentrytitle>sd_event_source_set_enabled</refentrytitle><manvolnum>3</manvolnum></citerefentry>
+    </para>
+  </refsect1>
+
+</refentry>