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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 | ||
72 | <para>On success, | |
73 | <function>sd_event_source_get_pending()</function> returns an | |
74 | integer greater than zero when the event source is marked pending, | |
75 | and zero when the event source is not marked pending. On failure, | |
76 | it returns a negative errno-style error code.</para> | |
77 | </refsect1> | |
78 | ||
79 | <refsect1> | |
80 | <title>Errors</title> | |
81 | ||
82 | <para>Returned errors may indicate the following problems:</para> | |
83 | ||
84 | <variablelist> | |
85 | <varlistentry> | |
86 | <term><constant>-EINVAL</constant></term> | |
87 | ||
88 | <listitem><para><parameter>source</parameter> is not a valid | |
89 | pointer to an <structname>sd_event_source</structname> | |
90 | object.</para></listitem> | |
91 | </varlistentry> | |
92 | ||
93 | <varlistentry> | |
94 | <term><constant>-EDOM</constant></term> | |
95 | ||
96 | <listitem><para><parameter>source</parameter> refers to an | |
97 | event source object created with | |
98 | <citerefentry><refentrytitle>sd_event_add_exit</refentrytitle><manvolnum>3</manvolnum></citerefentry>.</para></listitem> | |
99 | </varlistentry> | |
100 | ||
101 | <varlistentry> | |
102 | <term><constant>-ENOMEM</constant></term> | |
103 | ||
104 | <listitem><para>Not enough memory.</para></listitem> | |
105 | </varlistentry> | |
106 | ||
107 | <varlistentry> | |
108 | <term><constant>-ESTALE</constant></term> | |
109 | ||
110 | <listitem><para>The event loop is already terminated.</para></listitem> | |
111 | ||
112 | </varlistentry> | |
113 | ||
114 | <varlistentry> | |
115 | <term><constant>-ECHILD</constant></term> | |
116 | ||
117 | <listitem><para>The event loop has been created in a different process.</para></listitem> | |
118 | ||
119 | </varlistentry> | |
120 | ||
121 | </variablelist> | |
122 | </refsect1> | |
123 | ||
124 | <xi:include href="libsystemd-pkgconfig.xml" /> | |
125 | ||
126 | <refsect1> | |
127 | <title>See Also</title> | |
128 | ||
129 | <para> | |
130 | <citerefentry><refentrytitle>sd-event</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
131 | <citerefentry><refentrytitle>sd_event_add_io</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
132 | <citerefentry><refentrytitle>sd_event_add_time</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
dc83f27a | 133 | <citerefentry><refentrytitle>sd_event_add_signal</refentrytitle><manvolnum>3</manvolnum></citerefentry>, |
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134 | <citerefentry><refentrytitle>sd_event_add_child</refentrytitle><manvolnum>3</manvolnum></citerefentry>, |
135 | <citerefentry><refentrytitle>sd_event_add_inotify</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
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136 | <citerefentry><refentrytitle>sd_event_add_defer</refentrytitle><manvolnum>3</manvolnum></citerefentry>, |
137 | <citerefentry><refentrytitle>sd_event_source_unref</refentrytitle><manvolnum>3</manvolnum></citerefentry> | |
138 | </para> | |
139 | </refsect1> | |
140 | ||
141 | </refentry> |