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 Lennart Poettering
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_now" xmlns:
xi=
"http://www.w3.org/2001/XInclude">
29 <title>sd_event_now
</title>
30 <productname>systemd
</productname>
34 <contrib>Developer
</contrib>
35 <firstname>Lennart
</firstname>
36 <surname>Poettering
</surname>
37 <email>lennart@poettering.net
</email>
43 <refentrytitle>sd_event_now
</refentrytitle>
44 <manvolnum>3</manvolnum>
48 <refname>sd_event_now
</refname>
50 <refpurpose>Retrieve current event loop iteration timestamp
</refpurpose>
55 <funcsynopsisinfo>#include
<systemd/sd-event.h
></funcsynopsisinfo>
58 <funcdef>int
<function>sd_event_now
</function></funcdef>
59 <paramdef>sd_event *
<parameter>event
</parameter></paramdef>
60 <paramdef>clockid_t
<parameter>clock
</parameter></paramdef>
61 <paramdef>uint64_t *
<parameter>usec
</parameter></paramdef>
68 <title>Description
</title>
70 <para><function>sd_event_now()
</function> returns the time when
71 the most recent event loop iteration began. A timestamp
72 is taken right after returning from the event sleep, and before
73 dispatching any event sources. The
<parameter>event
</parameter>
74 parameter specifies the event loop object to retrieve the timestamp
75 from. The
<parameter>clock
</parameter> parameter specifies the clock to
76 retrieve the timestamp for, and is one of
77 <constant>CLOCK_REALTIME
</constant> (or equivalently
78 <constant>CLOCK_REALTIME_ALARM
</constant>),
79 <constant>CLOCK_MONOTONIC
</constant>, or
80 <constant>CLOCK_BOOTTIME
</constant> (or equivalently
81 <constant>CLOCK_BOOTTIME_ALARM
</constant>), see
82 <citerefentry project='man-pages'
><refentrytitle>clock_gettime
</refentrytitle><manvolnum>2</manvolnum></citerefentry>
83 for more information on the various clocks. The retrieved
84 timestamp is stored in the
<parameter>usec
</parameter> parameter,
85 in µs since the clock's epoch. If this function is invoked before
86 the first event loop iteration, the current time is returned, as
87 reported by
<function>clock_gettime()
</function>. To distinguish
88 this case from a regular invocation the return value will be
89 positive, and zero when the returned timestamp refers to an actual
90 event loop iteration.
</para>
94 <title>Return Value
</title>
96 <para>If the first event loop iteration has not run yet
97 <function>sd_event_now()
</function> writes current time to
98 <parameter>usec
</parameter> and returns a positive return value.
99 Otherwise, it will write the requested timestamp to
<parameter>usec
</parameter>
100 and return
0. On failure, the call returns a negative errno-style
105 <title>Errors
</title>
107 <para>Returned values may indicate the following problems:
</para>
111 <term><constant>-EINVAL
</constant></term>
113 <listitem><para>An invalid parameter was
114 passed.
</para></listitem>
119 <term><constant>-EOPNOTSUPP
</constant></term>
121 <listitem><para>Unsupported clock type.
126 <term><constant>-ECHILD
</constant></term>
128 <listitem><para>The event loop object was created in a
129 different process.
</para></listitem>
134 <xi:include href=
"libsystemd-pkgconfig.xml" />
137 <title>See Also
</title>
140 <citerefentry><refentrytitle>systemd
</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
141 <citerefentry><refentrytitle>sd-event
</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
142 <citerefentry><refentrytitle>sd_event_new
</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
143 <citerefentry><refentrytitle>sd_event_add_time
</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
144 <citerefentry project='man-pages'
><refentrytitle>clock_gettime
</refentrytitle><manvolnum>2</manvolnum></citerefentry>