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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" | |
3 | "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd"> | |
4 | ||
5 | <!-- | |
6 | This file is part of systemd. | |
7 | ||
8 | Copyright 2015 Lennart Poettering | |
9 | ||
10 | systemd is free software; you can redistribute it and/or modify it | |
11 | under the terms of the GNU Lesser General Public License as published by | |
12 | the Free Software Foundation; either version 2.1 of the License, or | |
13 | (at your option) any later version. | |
14 | ||
15 | systemd is distributed in the hope that it will be useful, but | |
16 | WITHOUT ANY WARRANTY; without even the implied warranty of | |
17 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
18 | Lesser General Public License for more details. | |
19 | ||
20 | You should have received a copy of the GNU Lesser General Public License | |
21 | along with systemd; If not, see <http://www.gnu.org/licenses/>. | |
22 | --> | |
23 | ||
24 | <refentry id="sd_event_now" xmlns:xi="http://www.w3.org/2001/XInclude"> | |
25 | ||
26 | <refentryinfo> | |
27 | <title>sd_event_now</title> | |
28 | <productname>systemd</productname> | |
29 | ||
30 | <authorgroup> | |
31 | <author> | |
32 | <contrib>Developer</contrib> | |
33 | <firstname>Lennart</firstname> | |
34 | <surname>Poettering</surname> | |
35 | <email>lennart@poettering.net</email> | |
36 | </author> | |
37 | </authorgroup> | |
38 | </refentryinfo> | |
39 | ||
40 | <refmeta> | |
41 | <refentrytitle>sd_event_now</refentrytitle> | |
42 | <manvolnum>3</manvolnum> | |
43 | </refmeta> | |
44 | ||
45 | <refnamediv> | |
46 | <refname>sd_event_now</refname> | |
47 | ||
48 | <refpurpose>Retrieve current event loop iteration timestamp</refpurpose> | |
49 | </refnamediv> | |
50 | ||
51 | <refsynopsisdiv> | |
52 | <funcsynopsis> | |
53 | <funcsynopsisinfo>#include <systemd/sd-event.h></funcsynopsisinfo> | |
54 | ||
55 | <funcprototype> | |
56 | <funcdef>int <function>sd_event_now</function></funcdef> | |
57 | <paramdef>sd_event *<parameter>event</parameter></paramdef> | |
58 | <paramdef>clockid_t <parameter>clock</parameter></paramdef> | |
59 | <paramdef>uint64_t *<parameter>usec</parameter></paramdef> | |
60 | </funcprototype> | |
61 | ||
62 | </funcsynopsis> | |
63 | </refsynopsisdiv> | |
64 | ||
65 | <refsect1> | |
66 | <title>Description</title> | |
67 | ||
f23e83b1 ZJS |
68 | <para><function>sd_event_now()</function> returns the time when |
69 | the most recent event loop iteration began. A timestamp | |
70 | is taken right after returning from the event sleep, and before | |
dc83f27a | 71 | dispatching any event sources. The <parameter>event</parameter> |
f23e83b1 | 72 | parameter specifies the event loop object to retrieve the timestamp |
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73 | from. The <parameter>clock</parameter> parameter specifies the clock to |
74 | retrieve the timestamp for, and is one of | |
f23e83b1 | 75 | <constant>CLOCK_REALTIME</constant> (or equivalently |
dc83f27a | 76 | <constant>CLOCK_REALTIME_ALARM</constant>), |
f23e83b1 ZJS |
77 | <constant>CLOCK_MONOTONIC</constant>, or |
78 | <constant>CLOCK_BOOTTIME</constant> (or equivalently | |
79 | <constant>CLOCK_BOOTTIME_ALARM</constant>), see | |
80 | <citerefentry project='man-pages'><refentrytitle>clock_gettime</refentrytitle><manvolnum>2</manvolnum></citerefentry> | |
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81 | for more information on the various clocks. The retrieved |
82 | timestamp is stored in the <parameter>usec</parameter> parameter, | |
83 | in µs since the clock's epoch. If this function is invoked before | |
f23e83b1 | 84 | the first event loop iteration, the current time is returned, as |
dc83f27a LP |
85 | reported by <function>clock_gettime()</function>. To distinguish |
86 | this case from a regular invocation the return value will be | |
f23e83b1 ZJS |
87 | positive, and zero when the returned timestamp refers to an actual |
88 | event loop iteration.</para> | |
dc83f27a LP |
89 | </refsect1> |
90 | ||
91 | <refsect1> | |
92 | <title>Return Value</title> | |
93 | ||
94 | <para>If the first event loop iteration has not run yet | |
f23e83b1 ZJS |
95 | <function>sd_event_now()</function> writes current time to |
96 | <parameter>usec</parameter> and returns a positive return value. | |
97 | Otherwise, it will write the requested timestamp to <parameter>usec</parameter> | |
98 | and return 0. On failure, the call returns a negative errno-style | |
dc83f27a LP |
99 | error code.</para> |
100 | </refsect1> | |
101 | ||
102 | <refsect1> | |
103 | <title>Errors</title> | |
104 | ||
f23e83b1 | 105 | <para>Returned values may indicate the following problems:</para> |
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106 | |
107 | <variablelist> | |
108 | <varlistentry> | |
109 | <term><constant>-EINVAL</constant></term> | |
110 | ||
111 | <listitem><para>An invalid parameter was | |
112 | passed.</para></listitem> | |
113 | ||
114 | </varlistentry> | |
115 | ||
2c86ba5a ZJS |
116 | <varlistentry> |
117 | <term><constant>-EOPNOTSUPP</constant></term> | |
118 | ||
119 | <listitem><para>Unsupported clock type. | |
120 | </para></listitem> | |
121 | </varlistentry> | |
122 | ||
dc83f27a LP |
123 | <varlistentry> |
124 | <term><constant>-ECHILD</constant></term> | |
125 | ||
126 | <listitem><para>The event loop object was created in a | |
127 | different process.</para></listitem> | |
128 | </varlistentry> | |
dc83f27a LP |
129 | </variablelist> |
130 | </refsect1> | |
131 | ||
132 | <xi:include href="libsystemd-pkgconfig.xml" /> | |
133 | ||
134 | <refsect1> | |
135 | <title>See Also</title> | |
136 | ||
137 | <para> | |
138 | <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>, | |
139 | <citerefentry><refentrytitle>sd-event</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
140 | <citerefentry><refentrytitle>sd_event_new</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
141 | <citerefentry><refentrytitle>sd_event_add_time</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
142 | <citerefentry project='man-pages'><refentrytitle>clock_gettime</refentrytitle><manvolnum>2</manvolnum></citerefentry> | |
143 | </para> | |
144 | </refsect1> | |
145 | ||
146 | </refentry> |