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<?xml version='1.0'?>
<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
<!-- SPDX-License-Identifier: LGPL-2.1-or-later -->
<refentry id="sd_event_now" xmlns:xi="http://www.w3.org/2001/XInclude">
<refentryinfo>
<title>sd_event_now</title>
<productname>systemd</productname>
</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>
<refsect2>
<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, library or module instance.</para></listitem>
</varlistentry>
</variablelist>
</refsect2>
</refsect1>
<xi:include href="libsystemd-pkgconfig.xml" />
<refsect1>
<title>History</title>
<para><function>sd_event_now()</function> was added in version 229.</para>
</refsect1>
<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>
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