1 <?xml version='1.0'?> <!--*- Mode: nxml; nxml-child-indent: 2; indent-tabs-mode: nil -*-->
2 <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
3 "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
6 This file is part of elogind.
7 SPDX-License-Identifier: LGPL-2.1+
10 Copyright 2015 Lennart Poettering
13 <refentry id="sd_event_source_get_pending" xmlns:xi="http://www.w3.org/2001/XInclude">
16 <title>sd_event_source_get_pending</title>
17 <productname>elogind</productname>
21 <contrib>Developer</contrib>
22 <firstname>Lennart</firstname>
23 <surname>Poettering</surname>
24 <email>lennart@poettering.net</email>
30 <refentrytitle>sd_event_source_get_pending</refentrytitle>
31 <manvolnum>3</manvolnum>
35 <refname>sd_event_source_get_pending</refname>
37 <refpurpose>Determine pending state of event sources</refpurpose>
42 <funcsynopsisinfo>#include <elogind/sd-event.h></funcsynopsisinfo>
45 <funcdef>int <function>sd_event_source_get_pending</function></funcdef>
46 <paramdef>sd_event_source *<parameter>source</parameter></paramdef>
53 <title>Description</title>
55 <para><function>sd_event_source_get_pending()</function> may be
56 used to determine whether the event source object specified as
57 <parameter>source</parameter> has seen events but has not been
58 dispatched yet (and thus is marked "pending").</para>
60 <para>Event source objects initially are not marked pending, when
61 they are created with calls such as
62 <citerefentry><refentrytitle>sd_event_add_io</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
63 <citerefentry><refentrytitle>sd_event_add_time</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
64 with the exception of those created with
65 <citerefentry><refentrytitle>sd_event_add_defer</refentrytitle><manvolnum>3</manvolnum></citerefentry>
66 which are immediately marked pending, and
67 <citerefentry><refentrytitle>sd_event_add_exit</refentrytitle><manvolnum>3</manvolnum></citerefentry>
68 for which the "pending" concept is not defined. For details see
69 the respective manual pages.</para>
71 <para>In each event loop iteration one event source of those
72 marked pending is dispatched, in the order defined by the event
73 source priority, as set with
74 <citerefentry><refentrytitle>sd_event_source_set_priority</refentrytitle><manvolnum>3</manvolnum></citerefentry>.</para>
76 <para>For I/O event sources, as created with
77 <citerefentry><refentrytitle>sd_event_add_io</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
79 <citerefentry><refentrytitle>sd_event_source_get_io_revents</refentrytitle><manvolnum>3</manvolnum></citerefentry>
80 may be used to query the type of event pending in more
86 <title>Return Value</title>
89 <function>sd_event_source_get_pending()</function> returns an
90 integer greater than zero when the event source is marked pending,
91 and zero when the event source is not marked pending. On failure,
92 it returns a negative errno-style error code.</para>
98 <para>Returned errors may indicate the following problems:</para>
102 <term><constant>-EINVAL</constant></term>
104 <listitem><para><parameter>source</parameter> is not a valid
105 pointer to an <structname>sd_event_source</structname>
106 object.</para></listitem>
110 <term><constant>-EDOM</constant></term>
112 <listitem><para><parameter>source</parameter> refers to an
113 event source object created with
114 <citerefentry><refentrytitle>sd_event_add_exit</refentrytitle><manvolnum>3</manvolnum></citerefentry>.</para></listitem>
118 <term><constant>-ENOMEM</constant></term>
120 <listitem><para>Not enough memory.</para></listitem>
124 <term><constant>-ESTALE</constant></term>
126 <listitem><para>The event loop is already terminated.</para></listitem>
131 <term><constant>-ECHILD</constant></term>
133 <listitem><para>The event loop has been created in a different process.</para></listitem>
140 <xi:include href="libelogind-pkgconfig.xml" />
143 <title>See Also</title>
146 <citerefentry><refentrytitle>sd-event</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
147 <citerefentry><refentrytitle>sd_event_add_io</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
148 <citerefentry><refentrytitle>sd_event_add_time</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
149 <citerefentry><refentrytitle>sd_event_add_child</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
150 <citerefentry><refentrytitle>sd_event_add_signal</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
151 <citerefentry><refentrytitle>sd_event_add_defer</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
152 <citerefentry><refentrytitle>sd_event_source_unref</refentrytitle><manvolnum>3</manvolnum></citerefentry>