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authorLennart Poettering <lennart@poettering.net>2015-11-19 23:38:54 +0100
committerLennart Poettering <lennart@poettering.net>2015-11-19 23:38:54 +0100
commitdc83f27a7cf03757dec11a69ec18504ad4ea8f89 (patch)
tree54af47fe95cdaa44ea4f0e3c0c3482e40c46edc3 /man/sd_event_source_set_enabled.xml
parent0be6c2f617732902921d42bb0705f016b2838aba (diff)
man: fully document sd-event interfaces
This completes the set of man pages for sd-event and contains some minor other fixes for other man pages too. The sd_event_set_name(3) man page is renamed to sd_event_source_set_description(3), which is the correct name of the concept today.
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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_set_enabled" xmlns:xi="http://www.w3.org/2001/XInclude">
+
+ <refentryinfo>
+ <title>sd_event_source_set_enabled</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_set_enabled</refentrytitle>
+ <manvolnum>3</manvolnum>
+ </refmeta>
+
+ <refnamediv>
+ <refname>sd_event_source_set_enabled</refname>
+ <refname>sd_event_source_get_enabled</refname>
+ <refname>SD_EVENT_ON</refname>
+ <refname>SD_EVENT_OFF</refname>
+ <refname>SD_EVENT_ONESHOT</refname>
+
+ <refpurpose>Enable or disable event sources</refpurpose>
+ </refnamediv>
+
+ <refsynopsisdiv>
+ <funcsynopsis>
+ <funcsynopsisinfo>#include &lt;systemd/sd-event.h&gt;</funcsynopsisinfo>
+
+ <funcsynopsisinfo><token>enum</token> {
+ <constant>SD_EVENT_OFF</constant> = 0,
+ <constant>SD_EVENT_ON</constant> = 1,
+ <constant>SD_EVENT_ONESHOT</constant> = -1,
+};</funcsynopsisinfo>
+
+ <funcprototype>
+ <funcdef>int <function>sd_event_source_set_enabled</function></funcdef>
+ <paramdef>sd_event_source *<parameter>source</parameter></paramdef>
+ <paramdef>int <parameter>enabled</parameter></paramdef>
+ </funcprototype>
+
+ <funcprototype>
+ <funcdef>int <function>sd_event_source_get_enabled</function></funcdef>
+ <paramdef>sd_event_source *<parameter>source</parameter></paramdef>
+ <paramdef>int *<parameter>enabled</parameter></paramdef>
+ </funcprototype>
+
+ </funcsynopsis>
+ </refsynopsisdiv>
+
+ <refsect1>
+ <title>Description</title>
+
+ <para><function>sd_event_source_set_enabled()</function> may be
+ used to enable or disable the event source object specified as
+ <parameter>source</parameter>. The <parameter>enabled</parameter>
+ parameter takes one of <constant>SD_EVENT_ON</constant> (to
+ enable), <constant>SD_EVENT_OFF</constant> (to disable) or
+ <constant>SD_EVENT_ONESHOT</constant>. If invoked with
+ <constant>SD_EVENT_ONESHOT</constant> the event source will be
+ enabled but automatically reset to
+ <constant>SD_EVENT_OFF</constant> after the event source was
+ dispatched once.</para>
+
+ <para>Event sources that are disabled will not result in event
+ loop wakeups and will not be dispatched, until they are enabled
+ again.</para>
+
+ <para><function>sd_event_source_get_enabled()</function> may be
+ used to query whether the event source object
+ <parameter>source</parameter> is currently enabled or not. It
+ returns the enablement state in
+ <parameter>enabled</parameter>.</para>
+
+ <para>Event source objects are enabled when they are first created
+ with calls such as
+ <citerefentry><refentrytitle>sd_event_add_io</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
+ <citerefentry><refentrytitle>sd_event_add_time</refentrytitle><manvolnum>3</manvolnum></citerefentry>. However,
+ depending on the event source type they are enabled continously
+ (<constant>SD_EVENT_ON</constant>) or only for a single invocation
+ of the event source handler
+ (<constant>SD_EVENT_ONESHOT</constant>). For details see the
+ respective manual pages.</para>
+
+ <para>As event source objects stay active and may be dispatched as
+ long as there is at least one reference to them, in many cases it
+ is a good idea to combine a call to
+ <citerefentry><refentrytitle>sd_event_source_unref</refentrytitle><manvolnum>3</manvolnum></citerefentry>
+ with a prior call to
+ <function>sd_event_source_set_enabled()</function> with
+ <constant>SD_EVENT_OFF</constant>, to ensure the event source is
+ not dispatched again until all other remaining references are dropped.</para>
+ </refsect1>
+
+ <refsect1>
+ <title>Return Value</title>
+
+ <para>On success, <function>sd_event_source_set_enabled()</function> and
+ <function>sd_event_source_get_enabled()</function> return a
+ non-negative integer. On failure, they return a negative
+ errno-style error code.</para>
+ </refsect1>
+
+ <refsect1>
+ <title>Errors</title>
+
+ <para>Returned errors may indicate the following problems:</para>
+
+ <variablelist>
+ <varlistentry>
+ <term><constant>-EINVAL</constant></term>
+
+ <listitem><para><parameter>source</parameter> is not a valid
+ pointer to an <structname>sd_event_source</structname>
+ object.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><constant>-ENOMEM</constant></term>
+
+ <listitem><para>Not enough memory.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><constant>-ECHILD</constant></term>
+
+ <listitem><para>The event loop has been created in a different process.</para></listitem>
+
+ </varlistentry>
+
+ </variablelist>
+ </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_unref</refentrytitle><manvolnum>3</manvolnum></citerefentry>
+ </para>
+ </refsect1>
+
+</refentry>