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"
3 "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
6 SPDX-License-Identifier: LGPL-2.1+
8 This file is part of systemd.
10 Copyright 2015 Zbigniew Jędrzejewski-Szmek
12 systemd is free software; you can redistribute it and/or modify it
13 under the terms of the GNU Lesser General Public License as published by
14 the Free Software Foundation; either version 2.1 of the License, or
15 (at your option) any later version.
17 systemd is distributed in the hope that it will be useful, but
18 WITHOUT ANY WARRANTY; without even the implied warranty of
19 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
20 Lesser General Public License for more details.
22 You should have received a copy of the GNU Lesser General Public License
23 along with systemd; If not, see <http://www.gnu.org/licenses/>.
26 <refentry id=
"sd_event_run" xmlns:
xi=
"http://www.w3.org/2001/XInclude">
29 <title>sd_event_run
</title>
30 <productname>systemd
</productname>
34 <contrib>Developer
</contrib>
35 <firstname>Tom
</firstname>
36 <surname>Gundersen
</surname>
37 <email>teg@jklm.no
</email>
43 <refentrytitle>sd_event_run
</refentrytitle>
44 <manvolnum>3</manvolnum>
48 <refname>sd_event_run
</refname>
49 <refname>sd_event_loop
</refname>
51 <refpurpose>Run an event loop
</refpurpose>
56 <funcsynopsisinfo>#include
<systemd/sd-event.h
></funcsynopsisinfo>
59 <funcdef>int
<function>sd_event_run
</function></funcdef>
60 <paramdef>sd_event *
<parameter>event
</parameter></paramdef>
61 <paramdef>uint64_t
<parameter>usec
</parameter></paramdef>
65 <funcdef>int
<function>sd_event_loop
</function></funcdef>
66 <paramdef>sd_event *
<parameter>event
</parameter></paramdef>
72 <title>Description
</title>
74 <para><function>sd_event_run()
</function> may be used to run a single
75 iteration of the event loop specified in the
76 <parameter>event
</parameter> parameter. The function waits until an event to
77 process is available, and dispatches the registered handler for
78 it. The
<parameter>usec
</parameter> parameter specifies the
79 maximum time (in microseconds) to wait for an event. Use
80 <constant>(uint64_t) -
1</constant> to specify an infinite
83 <para><function>sd_event_loop()
</function> invokes
84 <function>sd_event_run()
</function> in a loop, thus implementing
85 the actual event loop. The call returns as soon as exiting was
87 <citerefentry><refentrytitle>sd_event_exit
</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
</para>
89 <para>The event loop object
<parameter>event
</parameter> is
91 <citerefentry><refentrytitle>sd_event_new
</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
92 Events sources to wait for and their handlers may be registered
94 <citerefentry><refentrytitle>sd_event_add_io
</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
95 <citerefentry><refentrytitle>sd_event_add_time
</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
96 <citerefentry><refentrytitle>sd_event_add_signal
</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
97 <citerefentry><refentrytitle>sd_event_add_child
</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
98 <citerefentry><refentrytitle>sd_event_add_defer
</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
99 <citerefentry><refentrytitle>sd_event_add_post
</refentrytitle><manvolnum>3</manvolnum></citerefentry>
101 <citerefentry><refentrytitle>sd_event_add_exit
</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
104 <para>For low-level control of event loop execution, use
105 <citerefentry><refentrytitle>sd_event_prepare
</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
106 <citerefentry><refentrytitle>sd_event_wait
</refentrytitle><manvolnum>3</manvolnum></citerefentry>
108 <citerefentry><refentrytitle>sd_event_dispatch
</refentrytitle><manvolnum>3</manvolnum></citerefentry>
109 which are wrapped by
<function>sd_event_run()
</function>. Along
111 <citerefentry><refentrytitle>sd_event_get_fd
</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
112 these functions allow integration of an
113 <citerefentry><refentrytitle>sd-event
</refentrytitle><manvolnum>3</manvolnum></citerefentry>
114 event loop into foreign event loop implementations.
</para>
118 <title>Return Value
</title>
120 <para>On failure, these functions return a negative errno-style
121 error code.
<function>sd_event_run()
</function> returns a
122 positive, non-zero integer if an event source was dispatched, and
123 zero when the specified timeout hit before an event source has
124 seen any event, and hence no event source was
125 dispatched.
<function>sd_event_loop()
</function> returns the exit
126 code specified when invoking
127 <function>sd_event_exit()
</function>.
</para>
131 <title>Errors
</title>
133 <para>Returned errors may indicate the following problems:
</para>
137 <term><constant>-EINVAL
</constant></term>
139 <listitem><para>The
<parameter>event
</parameter> parameter is
140 invalid or
<constant>NULL
</constant>.
</para></listitem>
144 <term><constant>-EBUSY
</constant></term>
146 <listitem><para>The event loop object is not in the right
148 <citerefentry><refentrytitle>sd_event_prepare
</refentrytitle><manvolnum>3</manvolnum></citerefentry>
149 for an explanation of possible states).
</para></listitem>
153 <term><constant>-ESTALE
</constant></term>
155 <listitem><para>The event loop is already terminated.
</para></listitem>
160 <term><constant>-ECHILD
</constant></term>
162 <listitem><para>The event loop has been created in a different process.
</para></listitem>
168 <para>Other errors are possible, too.
</para>
171 <xi:include href=
"libsystemd-pkgconfig.xml" />
174 <title>See Also
</title>
177 <citerefentry><refentrytitle>systemd
</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
178 <citerefentry><refentrytitle>sd_event_new
</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
179 <citerefentry><refentrytitle>sd_event_add_io
</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
180 <citerefentry><refentrytitle>sd_event_add_time
</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
181 <citerefentry><refentrytitle>sd_event_add_signal
</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
182 <citerefentry><refentrytitle>sd_event_add_defer
</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
183 <citerefentry><refentrytitle>sd_event_add_exit
</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
184 <citerefentry><refentrytitle>sd_event_add_post
</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
185 <citerefentry><refentrytitle>sd_event_exit
</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
186 <citerefentry><refentrytitle>sd_event_get_fd
</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
187 <citerefentry><refentrytitle>sd_event_wait
</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
188 <ulink url=
"https://developer.gnome.org/glib/unstable/glib-The-Main-Event-Loop.html">GLib Main Event Loop
</ulink>.