2 <!DOCTYPE refentry PUBLIC
"-//OASIS//DTD DocBook XML V4.5//EN"
3 "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
4 <!-- SPDX-License-Identifier: LGPL-2.1+ -->
6 <refentry id=
"sd_event_source_get_pending" xmlns:
xi=
"http://www.w3.org/2001/XInclude">
9 <title>sd_event_source_get_pending
</title>
10 <productname>systemd
</productname>
14 <refentrytitle>sd_event_source_get_pending
</refentrytitle>
15 <manvolnum>3</manvolnum>
19 <refname>sd_event_source_get_pending
</refname>
21 <refpurpose>Determine pending state of event sources
</refpurpose>
26 <funcsynopsisinfo>#include
<systemd/sd-event.h
></funcsynopsisinfo>
29 <funcdef>int
<function>sd_event_source_get_pending
</function></funcdef>
30 <paramdef>sd_event_source *
<parameter>source
</parameter></paramdef>
37 <title>Description
</title>
39 <para><function>sd_event_source_get_pending()
</function> may be
40 used to determine whether the event source object specified as
41 <parameter>source
</parameter> has seen events but has not been
42 dispatched yet (and thus is marked
"pending").
</para>
44 <para>Event source objects initially are not marked pending, when
45 they are created with calls such as
46 <citerefentry><refentrytitle>sd_event_add_io
</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
47 <citerefentry><refentrytitle>sd_event_add_time
</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
48 with the exception of those created with
49 <citerefentry><refentrytitle>sd_event_add_defer
</refentrytitle><manvolnum>3</manvolnum></citerefentry>
50 which are immediately marked pending, and
51 <citerefentry><refentrytitle>sd_event_add_exit
</refentrytitle><manvolnum>3</manvolnum></citerefentry>
52 for which the
"pending" concept is not defined. For details see
53 the respective manual pages.
</para>
55 <para>In each event loop iteration one event source of those
56 marked pending is dispatched, in the order defined by the event
57 source priority, as set with
58 <citerefentry><refentrytitle>sd_event_source_set_priority
</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
</para>
60 <para>For I/O event sources, as created with
61 <citerefentry><refentrytitle>sd_event_add_io
</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
63 <citerefentry><refentrytitle>sd_event_source_get_io_revents
</refentrytitle><manvolnum>3</manvolnum></citerefentry>
64 may be used to query the type of event pending in more
70 <title>Return Value
</title>
72 <para>On success,
<function>sd_event_source_get_pending()
</function> returns an integer greater than zero
73 when the event source is marked pending, and zero when the event source is not marked pending. On
74 failure, it returns a negative errno-style error code.
</para>
79 <para>Returned errors may indicate the following problems:
</para>
83 <term><constant>-EINVAL
</constant></term>
85 <listitem><para><parameter>source
</parameter> is not a valid pointer to an
86 <structname>sd_event_source
</structname> object.
</para></listitem>
90 <term><constant>-EDOM
</constant></term>
92 <listitem><para><parameter>source
</parameter> refers to an event source object created with
93 <citerefentry><refentrytitle>sd_event_add_exit
</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
</para></listitem>
97 <term><constant>-ENOMEM
</constant></term>
99 <listitem><para>Not enough memory.
</para></listitem>
103 <term><constant>-ESTALE
</constant></term>
105 <listitem><para>The event loop is already terminated.
</para></listitem>
110 <term><constant>-ECHILD
</constant></term>
112 <listitem><para>The event loop has been created in a different process.
</para></listitem>
120 <xi:include href=
"libsystemd-pkgconfig.xml" />
123 <title>See Also
</title>
126 <citerefentry><refentrytitle>sd-event
</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
127 <citerefentry><refentrytitle>sd_event_add_io
</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
128 <citerefentry><refentrytitle>sd_event_add_time
</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
129 <citerefentry><refentrytitle>sd_event_add_signal
</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
130 <citerefentry><refentrytitle>sd_event_add_child
</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
131 <citerefentry><refentrytitle>sd_event_add_inotify
</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
132 <citerefentry><refentrytitle>sd_event_add_defer
</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
133 <citerefentry><refentrytitle>sd_event_source_unref
</refentrytitle><manvolnum>3</manvolnum></citerefentry>