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<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>
<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 timestamp
the most recent event loop iteration began. This timestamp is
taken right after returning from the event sleep, and before
dispatching any event sources. The <parameter>event</parameter>
parameter takes the even 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 its equivalent
<constant>CLOCK_REALTIME_ALARM</constant>),
<constant>CLOCK_MONOTONIC</constant> or
<constant>CLOCK_BOOTTIME</constant> (or its equivalent
<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 non-zero in this case, while it is zero when the returned
timestamp refers to the 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> returns the requested
timestamp in <parameter>usec</parameter> and returns a positive,
non-zero return value. Otherwise, on success it will return the
iteration's timestamp in <parameter>usec</parameter> and 0 as
return value. On failure, the call returns a negative errno-style
error code.</para>
</refsect1>
<refsect1>
<title>Errors</title>
<para>Returned errors 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>
<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>