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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" | |
12b42c76 | 3 | "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd"> |
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4 | |
5 | <!-- | |
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6 | SPDX-License-Identifier: LGPL-2.1+ |
7 | ||
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8 | This file is part of systemd. |
9 | ||
10 | Copyright 2015 Zbigniew Jędrzejewski-Szmek | |
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11 | --> |
12 | ||
dc83f27a | 13 | <refentry id="sd_event_run" xmlns:xi="http://www.w3.org/2001/XInclude"> |
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14 | |
15 | <refentryinfo> | |
16 | <title>sd_event_run</title> | |
17 | <productname>systemd</productname> | |
18 | ||
19 | <authorgroup> | |
20 | <author> | |
21 | <contrib>Developer</contrib> | |
22 | <firstname>Tom</firstname> | |
23 | <surname>Gundersen</surname> | |
24 | <email>teg@jklm.no</email> | |
25 | </author> | |
26 | </authorgroup> | |
27 | </refentryinfo> | |
28 | ||
29 | <refmeta> | |
30 | <refentrytitle>sd_event_run</refentrytitle> | |
31 | <manvolnum>3</manvolnum> | |
32 | </refmeta> | |
33 | ||
34 | <refnamediv> | |
35 | <refname>sd_event_run</refname> | |
36 | <refname>sd_event_loop</refname> | |
37 | ||
dc83f27a | 38 | <refpurpose>Run an event loop</refpurpose> |
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39 | </refnamediv> |
40 | ||
41 | <refsynopsisdiv> | |
42 | <funcsynopsis> | |
43 | <funcsynopsisinfo>#include <systemd/sd-event.h></funcsynopsisinfo> | |
44 | ||
45 | <funcprototype> | |
46 | <funcdef>int <function>sd_event_run</function></funcdef> | |
47 | <paramdef>sd_event *<parameter>event</parameter></paramdef> | |
dc83f27a | 48 | <paramdef>uint64_t <parameter>usec</parameter></paramdef> |
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49 | </funcprototype> |
50 | ||
51 | <funcprototype> | |
52 | <funcdef>int <function>sd_event_loop</function></funcdef> | |
53 | <paramdef>sd_event *<parameter>event</parameter></paramdef> | |
54 | </funcprototype> | |
55 | </funcsynopsis> | |
56 | </refsynopsisdiv> | |
57 | ||
58 | <refsect1> | |
59 | <title>Description</title> | |
60 | ||
dc83f27a LP |
61 | <para><function>sd_event_run()</function> may be used to run a single |
62 | iteration of the event loop specified in the | |
63 | <parameter>event</parameter> parameter. The function waits until an event to | |
64 | process is available, and dispatches the registered handler for | |
65 | it. The <parameter>usec</parameter> parameter specifies the | |
66 | maximum time (in microseconds) to wait for an event. Use | |
67 | <constant>(uint64_t) -1</constant> to specify an infinite | |
68 | timeout.</para> | |
69 | ||
70 | <para><function>sd_event_loop()</function> invokes | |
71 | <function>sd_event_run()</function> in a loop, thus implementing | |
72 | the actual event loop. The call returns as soon as exiting was | |
73 | requested using | |
74 | <citerefentry><refentrytitle>sd_event_exit</refentrytitle><manvolnum>3</manvolnum></citerefentry>.</para> | |
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75 | |
76 | <para>The event loop object <parameter>event</parameter> is | |
77 | created with | |
dc83f27a LP |
78 | <citerefentry><refentrytitle>sd_event_new</refentrytitle><manvolnum>3</manvolnum></citerefentry>. |
79 | Events sources to wait for and their handlers may be registered | |
80 | with | |
81 | <citerefentry><refentrytitle>sd_event_add_io</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
82 | <citerefentry><refentrytitle>sd_event_add_time</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
83 | <citerefentry><refentrytitle>sd_event_add_signal</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
84 | <citerefentry><refentrytitle>sd_event_add_child</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
85 | <citerefentry><refentrytitle>sd_event_add_defer</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
86 | <citerefentry><refentrytitle>sd_event_add_post</refentrytitle><manvolnum>3</manvolnum></citerefentry> | |
42f1ab50 | 87 | and |
dc83f27a | 88 | <citerefentry><refentrytitle>sd_event_add_exit</refentrytitle><manvolnum>3</manvolnum></citerefentry>. |
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89 | </para> |
90 | ||
dc83f27a LP |
91 | <para>For low-level control of event loop execution, use |
92 | <citerefentry><refentrytitle>sd_event_prepare</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
93 | <citerefentry><refentrytitle>sd_event_wait</refentrytitle><manvolnum>3</manvolnum></citerefentry> | |
94 | and | |
95 | <citerefentry><refentrytitle>sd_event_dispatch</refentrytitle><manvolnum>3</manvolnum></citerefentry> | |
96 | which are wrapped by <function>sd_event_run()</function>. Along | |
97 | with | |
98 | <citerefentry><refentrytitle>sd_event_get_fd</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
99 | these functions allow integration of an | |
100 | <citerefentry><refentrytitle>sd-event</refentrytitle><manvolnum>3</manvolnum></citerefentry> | |
101 | event loop into foreign event loop implementations.</para> | |
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102 | </refsect1> |
103 | ||
104 | <refsect1> | |
105 | <title>Return Value</title> | |
106 | ||
dc83f27a LP |
107 | <para>On failure, these functions return a negative errno-style |
108 | error code. <function>sd_event_run()</function> returns a | |
109 | positive, non-zero integer if an event source was dispatched, and | |
110 | zero when the specified timeout hit before an event source has | |
111 | seen any event, and hence no event source was | |
112 | dispatched. <function>sd_event_loop()</function> returns the exit | |
113 | code specified when invoking | |
114 | <function>sd_event_exit()</function>.</para> | |
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115 | </refsect1> |
116 | ||
117 | <refsect1> | |
118 | <title>Errors</title> | |
119 | ||
120 | <para>Returned errors may indicate the following problems:</para> | |
121 | ||
122 | <variablelist> | |
123 | <varlistentry> | |
124 | <term><constant>-EINVAL</constant></term> | |
125 | ||
a8eaaee7 | 126 | <listitem><para>The <parameter>event</parameter> parameter is |
dc83f27a | 127 | invalid or <constant>NULL</constant>.</para></listitem> |
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128 | </varlistentry> |
129 | ||
130 | <varlistentry> | |
131 | <term><constant>-EBUSY</constant></term> | |
132 | ||
133 | <listitem><para>The event loop object is not in the right | |
134 | state (see | |
135 | <citerefentry><refentrytitle>sd_event_prepare</refentrytitle><manvolnum>3</manvolnum></citerefentry> | |
136 | for an explanation of possible states).</para></listitem> | |
137 | </varlistentry> | |
138 | ||
139 | <varlistentry> | |
140 | <term><constant>-ESTALE</constant></term> | |
141 | ||
142 | <listitem><para>The event loop is already terminated.</para></listitem> | |
143 | ||
144 | </varlistentry> | |
145 | ||
146 | <varlistentry> | |
147 | <term><constant>-ECHILD</constant></term> | |
148 | ||
149 | <listitem><para>The event loop has been created in a different process.</para></listitem> | |
150 | ||
151 | </varlistentry> | |
152 | ||
153 | </variablelist> | |
154 | ||
b938cb90 | 155 | <para>Other errors are possible, too.</para> |
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156 | </refsect1> |
157 | ||
dc83f27a | 158 | <xi:include href="libsystemd-pkgconfig.xml" /> |
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159 | |
160 | <refsect1> | |
161 | <title>See Also</title> | |
162 | ||
163 | <para> | |
164 | <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>, | |
165 | <citerefentry><refentrytitle>sd_event_new</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
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166 | <citerefentry><refentrytitle>sd_event_add_io</refentrytitle><manvolnum>3</manvolnum></citerefentry>, |
167 | <citerefentry><refentrytitle>sd_event_add_time</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
168 | <citerefentry><refentrytitle>sd_event_add_signal</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
169 | <citerefentry><refentrytitle>sd_event_add_defer</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
170 | <citerefentry><refentrytitle>sd_event_add_exit</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
c268628a | 171 | <citerefentry><refentrytitle>sd_event_add_post</refentrytitle><manvolnum>3</manvolnum></citerefentry>, |
dc83f27a LP |
172 | <citerefentry><refentrytitle>sd_event_exit</refentrytitle><manvolnum>3</manvolnum></citerefentry>, |
173 | <citerefentry><refentrytitle>sd_event_get_fd</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
174 | <citerefentry><refentrytitle>sd_event_wait</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
a8eaaee7 | 175 | <ulink url="https://developer.gnome.org/glib/unstable/glib-The-Main-Event-Loop.html">GLib Main Event Loop</ulink>. |
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176 | </para> |
177 | </refsect1> | |
178 | ||
179 | </refentry> |