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514094f9 | 1 | <?xml version='1.0'?> |
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2 | <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN" |
3 | "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd"> | |
0307f791 | 4 | <!-- SPDX-License-Identifier: LGPL-2.1+ --> |
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5 | |
6 | <refentry id="sd_event_source_get_pending" xmlns:xi="http://www.w3.org/2001/XInclude"> | |
7 | ||
8 | <refentryinfo> | |
9 | <title>sd_event_source_get_pending</title> | |
10 | <productname>systemd</productname> | |
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11 | </refentryinfo> |
12 | ||
13 | <refmeta> | |
14 | <refentrytitle>sd_event_source_get_pending</refentrytitle> | |
15 | <manvolnum>3</manvolnum> | |
16 | </refmeta> | |
17 | ||
18 | <refnamediv> | |
19 | <refname>sd_event_source_get_pending</refname> | |
20 | ||
21 | <refpurpose>Determine pending state of event sources</refpurpose> | |
22 | </refnamediv> | |
23 | ||
24 | <refsynopsisdiv> | |
25 | <funcsynopsis> | |
26 | <funcsynopsisinfo>#include <systemd/sd-event.h></funcsynopsisinfo> | |
27 | ||
28 | <funcprototype> | |
29 | <funcdef>int <function>sd_event_source_get_pending</function></funcdef> | |
30 | <paramdef>sd_event_source *<parameter>source</parameter></paramdef> | |
31 | </funcprototype> | |
32 | ||
33 | </funcsynopsis> | |
34 | </refsynopsisdiv> | |
35 | ||
36 | <refsect1> | |
37 | <title>Description</title> | |
38 | ||
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> | |
43 | ||
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> | |
54 | ||
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> | |
59 | ||
60 | <para>For I/O event sources, as created with | |
61 | <citerefentry><refentrytitle>sd_event_add_io</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
62 | the call | |
a3972469 | 63 | <citerefentry><refentrytitle>sd_event_source_get_io_revents</refentrytitle><manvolnum>3</manvolnum></citerefentry> |
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64 | may be used to query the type of event pending in more |
65 | detail.</para> | |
66 | ||
67 | </refsect1> | |
68 | ||
69 | <refsect1> | |
70 | <title>Return Value</title> | |
71 | ||
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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> | |
dc83f27a | 75 | |
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76 | <refsect2> |
77 | <title>Errors</title> | |
dc83f27a | 78 | |
b1de39de | 79 | <para>Returned errors may indicate the following problems:</para> |
dc83f27a | 80 | |
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81 | <variablelist> |
82 | <varlistentry> | |
83 | <term><constant>-EINVAL</constant></term> | |
dc83f27a | 84 | |
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85 | <listitem><para><parameter>source</parameter> is not a valid pointer to an |
86 | <structname>sd_event_source</structname> object.</para></listitem> | |
87 | </varlistentry> | |
dc83f27a | 88 | |
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89 | <varlistentry> |
90 | <term><constant>-EDOM</constant></term> | |
dc83f27a | 91 | |
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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> | |
94 | </varlistentry> | |
dc83f27a | 95 | |
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96 | <varlistentry> |
97 | <term><constant>-ENOMEM</constant></term> | |
dc83f27a | 98 | |
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99 | <listitem><para>Not enough memory.</para></listitem> |
100 | </varlistentry> | |
dc83f27a | 101 | |
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102 | <varlistentry> |
103 | <term><constant>-ESTALE</constant></term> | |
dc83f27a | 104 | |
b1de39de | 105 | <listitem><para>The event loop is already terminated.</para></listitem> |
dc83f27a | 106 | |
b1de39de | 107 | </varlistentry> |
dc83f27a | 108 | |
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109 | <varlistentry> |
110 | <term><constant>-ECHILD</constant></term> | |
dc83f27a | 111 | |
b1de39de | 112 | <listitem><para>The event loop has been created in a different process.</para></listitem> |
dc83f27a | 113 | |
b1de39de | 114 | </varlistentry> |
dc83f27a | 115 | |
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116 | </variablelist> |
117 | </refsect2> | |
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118 | </refsect1> |
119 | ||
120 | <xi:include href="libsystemd-pkgconfig.xml" /> | |
121 | ||
122 | <refsect1> | |
123 | <title>See Also</title> | |
124 | ||
125 | <para> | |
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>, | |
dc83f27a | 129 | <citerefentry><refentrytitle>sd_event_add_signal</refentrytitle><manvolnum>3</manvolnum></citerefentry>, |
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130 | <citerefentry><refentrytitle>sd_event_add_child</refentrytitle><manvolnum>3</manvolnum></citerefentry>, |
131 | <citerefentry><refentrytitle>sd_event_add_inotify</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
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132 | <citerefentry><refentrytitle>sd_event_add_defer</refentrytitle><manvolnum>3</manvolnum></citerefentry>, |
133 | <citerefentry><refentrytitle>sd_event_source_unref</refentrytitle><manvolnum>3</manvolnum></citerefentry> | |
134 | </para> | |
135 | </refsect1> | |
136 | ||
137 | </refentry> |