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1 | <?xml version='1.0'?> | |
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+ --> | |
5 | ||
6 | <refentry id="sd_event_run" xmlns:xi="http://www.w3.org/2001/XInclude"> | |
7 | ||
8 | <refentryinfo> | |
9 | <title>sd_event_run</title> | |
10 | <productname>systemd</productname> | |
11 | </refentryinfo> | |
12 | ||
13 | <refmeta> | |
14 | <refentrytitle>sd_event_run</refentrytitle> | |
15 | <manvolnum>3</manvolnum> | |
16 | </refmeta> | |
17 | ||
18 | <refnamediv> | |
19 | <refname>sd_event_run</refname> | |
20 | <refname>sd_event_loop</refname> | |
21 | ||
22 | <refpurpose>Run an event loop</refpurpose> | |
23 | </refnamediv> | |
24 | ||
25 | <refsynopsisdiv> | |
26 | <funcsynopsis> | |
27 | <funcsynopsisinfo>#include <systemd/sd-event.h></funcsynopsisinfo> | |
28 | ||
29 | <funcprototype> | |
30 | <funcdef>int <function>sd_event_run</function></funcdef> | |
31 | <paramdef>sd_event *<parameter>event</parameter></paramdef> | |
32 | <paramdef>uint64_t <parameter>usec</parameter></paramdef> | |
33 | </funcprototype> | |
34 | ||
35 | <funcprototype> | |
36 | <funcdef>int <function>sd_event_loop</function></funcdef> | |
37 | <paramdef>sd_event *<parameter>event</parameter></paramdef> | |
38 | </funcprototype> | |
39 | </funcsynopsis> | |
40 | </refsynopsisdiv> | |
41 | ||
42 | <refsect1> | |
43 | <title>Description</title> | |
44 | ||
45 | <para><function>sd_event_run()</function> may be used to run a single | |
46 | iteration of the event loop specified in the | |
47 | <parameter>event</parameter> parameter. The function waits until an event to | |
48 | process is available, and dispatches the registered handler for | |
49 | it. The <parameter>usec</parameter> parameter specifies the | |
50 | maximum time (in microseconds) to wait for an event. Use | |
51 | <constant>(uint64_t) -1</constant> to specify an infinite | |
52 | timeout.</para> | |
53 | ||
54 | <para><function>sd_event_loop()</function> invokes | |
55 | <function>sd_event_run()</function> in a loop, thus implementing | |
56 | the actual event loop. The call returns as soon as exiting was | |
57 | requested using | |
58 | <citerefentry><refentrytitle>sd_event_exit</refentrytitle><manvolnum>3</manvolnum></citerefentry>.</para> | |
59 | ||
60 | <para>The event loop object <parameter>event</parameter> is | |
61 | created with | |
62 | <citerefentry><refentrytitle>sd_event_new</refentrytitle><manvolnum>3</manvolnum></citerefentry>. | |
63 | Events sources to wait for and their handlers may be registered | |
64 | with | |
65 | <citerefentry><refentrytitle>sd_event_add_io</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
66 | <citerefentry><refentrytitle>sd_event_add_time</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
67 | <citerefentry><refentrytitle>sd_event_add_signal</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
68 | <citerefentry><refentrytitle>sd_event_add_child</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
69 | <citerefentry><refentrytitle>sd_event_add_defer</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
70 | <citerefentry><refentrytitle>sd_event_add_post</refentrytitle><manvolnum>3</manvolnum></citerefentry> | |
71 | and | |
72 | <citerefentry><refentrytitle>sd_event_add_exit</refentrytitle><manvolnum>3</manvolnum></citerefentry>. | |
73 | </para> | |
74 | ||
75 | <para>For low-level control of event loop execution, use | |
76 | <citerefentry><refentrytitle>sd_event_prepare</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
77 | <citerefentry><refentrytitle>sd_event_wait</refentrytitle><manvolnum>3</manvolnum></citerefentry> | |
78 | and | |
79 | <citerefentry><refentrytitle>sd_event_dispatch</refentrytitle><manvolnum>3</manvolnum></citerefentry> | |
80 | which are wrapped by <function>sd_event_run()</function>. Along | |
81 | with | |
82 | <citerefentry><refentrytitle>sd_event_get_fd</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
83 | these functions allow integration of an | |
84 | <citerefentry><refentrytitle>sd-event</refentrytitle><manvolnum>3</manvolnum></citerefentry> | |
85 | event loop into foreign event loop implementations.</para> | |
86 | </refsect1> | |
87 | ||
88 | <refsect1> | |
89 | <title>Return Value</title> | |
90 | ||
91 | <para>On failure, these functions return a negative errno-style | |
92 | error code. <function>sd_event_run()</function> returns a | |
93 | positive, non-zero integer if an event source was dispatched, and | |
94 | zero when the specified timeout hit before an event source has | |
95 | seen any event, and hence no event source was | |
96 | dispatched. <function>sd_event_loop()</function> returns the exit | |
97 | code specified when invoking | |
98 | <function>sd_event_exit()</function>.</para> | |
99 | ||
100 | <refsect2> | |
101 | <title>Errors</title> | |
102 | ||
103 | <para>Returned errors may indicate the following problems:</para> | |
104 | ||
105 | <variablelist> | |
106 | <varlistentry> | |
107 | <term><constant>-EINVAL</constant></term> | |
108 | ||
109 | <listitem><para>The <parameter>event</parameter> parameter is invalid or | |
110 | <constant>NULL</constant>.</para></listitem> | |
111 | </varlistentry> | |
112 | ||
113 | <varlistentry> | |
114 | <term><constant>-EBUSY</constant></term> | |
115 | ||
116 | <listitem><para>The event loop object is not in the right | |
117 | state (see | |
118 | <citerefentry><refentrytitle>sd_event_prepare</refentrytitle><manvolnum>3</manvolnum></citerefentry> | |
119 | for an explanation of possible states).</para></listitem> | |
120 | </varlistentry> | |
121 | ||
122 | <varlistentry> | |
123 | <term><constant>-ESTALE</constant></term> | |
124 | ||
125 | <listitem><para>The event loop is already terminated.</para></listitem> | |
126 | ||
127 | </varlistentry> | |
128 | ||
129 | <varlistentry> | |
130 | <term><constant>-ECHILD</constant></term> | |
131 | ||
132 | <listitem><para>The event loop has been created in a different process.</para></listitem> | |
133 | ||
134 | </varlistentry> | |
135 | ||
136 | </variablelist> | |
137 | ||
138 | <para>Other errors are possible, too.</para> | |
139 | </refsect2> | |
140 | </refsect1> | |
141 | ||
142 | <xi:include href="libsystemd-pkgconfig.xml" /> | |
143 | ||
144 | <refsect1> | |
145 | <title>See Also</title> | |
146 | ||
147 | <para> | |
148 | <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>, | |
149 | <citerefentry><refentrytitle>sd-event</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
150 | <citerefentry><refentrytitle>sd_event_new</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
151 | <citerefentry><refentrytitle>sd_event_add_io</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
152 | <citerefentry><refentrytitle>sd_event_add_time</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
153 | <citerefentry><refentrytitle>sd_event_add_signal</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
154 | <citerefentry><refentrytitle>sd_event_add_child</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
155 | <citerefentry><refentrytitle>sd_event_add_inotify</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
156 | <citerefentry><refentrytitle>sd_event_add_defer</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
157 | <citerefentry><refentrytitle>sd_event_exit</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
158 | <citerefentry><refentrytitle>sd_event_get_fd</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
159 | <citerefentry><refentrytitle>sd_event_wait</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
160 | <ulink url="https://developer.gnome.org/glib/unstable/glib-The-Main-Event-Loop.html">GLib Main Event Loop</ulink> | |
161 | </para> | |
162 | </refsect1> | |
163 | ||
164 | </refentry> |