<?xml version='1.0'?> <!--*- Mode: nxml; nxml-child-indent: 2; indent-tabs-mode: nil -*--> <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN" "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd"> <!-- This file is part of systemd. Copyright 2015 Lennart Poettering systemd is free software; you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation; either version 2.1 of the License, or (at your option) any later version. systemd is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details. You should have received a copy of the GNU Lesser General Public License along with systemd; If not, see <http://www.gnu.org/licenses/>. --> <refentry id="sd_event_now" xmlns:xi="http://www.w3.org/2001/XInclude"> <refentryinfo> <title>sd_event_now</title> <productname>systemd</productname> <authorgroup> <author> <contrib>Developer</contrib> <firstname>Lennart</firstname> <surname>Poettering</surname> <email>lennart@poettering.net</email> </author> </authorgroup> </refentryinfo> <refmeta> <refentrytitle>sd_event_now</refentrytitle> <manvolnum>3</manvolnum> </refmeta> <refnamediv> <refname>sd_event_now</refname> <refpurpose>Retrieve current event loop iteration timestamp</refpurpose> </refnamediv> <refsynopsisdiv> <funcsynopsis> <funcsynopsisinfo>#include <systemd/sd-event.h></funcsynopsisinfo> <funcprototype> <funcdef>int <function>sd_event_now</function></funcdef> <paramdef>sd_event *<parameter>event</parameter></paramdef> <paramdef>clockid_t <parameter>clock</parameter></paramdef> <paramdef>uint64_t *<parameter>usec</parameter></paramdef> </funcprototype> </funcsynopsis> </refsynopsisdiv> <refsect1> <title>Description</title> <para><function>sd_event_now()</function> returns the time when the most recent event loop iteration began. A timestamp is taken right after returning from the event sleep, and before dispatching any event sources. The <parameter>event</parameter> parameter specifies the event loop object to retrieve the timestamp from. The <parameter>clock</parameter> parameter specifies the clock to retrieve the timestamp for, and is one of <constant>CLOCK_REALTIME</constant> (or equivalently <constant>CLOCK_REALTIME_ALARM</constant>), <constant>CLOCK_MONOTONIC</constant>, or <constant>CLOCK_BOOTTIME</constant> (or equivalently <constant>CLOCK_BOOTTIME_ALARM</constant>), see <citerefentry project='man-pages'><refentrytitle>clock_gettime</refentrytitle><manvolnum>2</manvolnum></citerefentry> for more information on the various clocks. The retrieved timestamp is stored in the <parameter>usec</parameter> parameter, in µs since the clock's epoch. If this function is invoked before the first event loop iteration, the current time is returned, as reported by <function>clock_gettime()</function>. To distinguish this case from a regular invocation the return value will be positive, and zero when the returned timestamp refers to an actual event loop iteration.</para> </refsect1> <refsect1> <title>Return Value</title> <para>If the first event loop iteration has not run yet <function>sd_event_now()</function> writes current time to <parameter>usec</parameter> and returns a positive return value. Otherwise, it will write the requested timestamp to <parameter>usec</parameter> and return 0. On failure, the call returns a negative errno-style error code.</para> </refsect1> <refsect1> <title>Errors</title> <para>Returned values may indicate the following problems:</para> <variablelist> <varlistentry> <term><constant>-EINVAL</constant></term> <listitem><para>An invalid parameter was passed.</para></listitem> </varlistentry> <varlistentry> <term><constant>-EOPNOTSUPP</constant></term> <listitem><para>Unsupported clock type. </para></listitem> </varlistentry> <varlistentry> <term><constant>-ECHILD</constant></term> <listitem><para>The event loop object was created in a different process.</para></listitem> </varlistentry> </variablelist> </refsect1> <xi:include href="libsystemd-pkgconfig.xml" /> <refsect1> <title>See Also</title> <para> <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>, <citerefentry><refentrytitle>sd-event</refentrytitle><manvolnum>3</manvolnum></citerefentry>, <citerefentry><refentrytitle>sd_event_new</refentrytitle><manvolnum>3</manvolnum></citerefentry>, <citerefentry><refentrytitle>sd_event_add_time</refentrytitle><manvolnum>3</manvolnum></citerefentry>, <citerefentry project='man-pages'><refentrytitle>clock_gettime</refentrytitle><manvolnum>2</manvolnum></citerefentry> </para> </refsect1> </refentry>