systemd/man/sd_journal_get_cutoff_realtime_usec.xml
Zbigniew Jędrzejewski-Szmek 1651e2c61e man,journal: add note about sd_journal_get_cutoff_monotonic_usec return value
Also modify the function itself to be a bit simpler to read.
2014-07-18 21:44:36 -04:00

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<?xml version='1.0'?> <!--*-nxml-*-->
<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
<!--
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Copyright 2012 Lennart Poettering
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under the terms of the GNU Lesser General Public License as published by
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You should have received a copy of the GNU Lesser General Public License
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<refentry id="sd_journal_get_cutoff_realtime_usec">
<refentryinfo>
<title>sd_journal_get_cutoff_realtime_usec</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_journal_get_cutoff_realtime_usec</refentrytitle>
<manvolnum>3</manvolnum>
</refmeta>
<refnamediv>
<refname>sd_journal_get_cutoff_realtime_usec</refname>
<refname>sd_journal_get_cutoff_monotonic_usec</refname>
<refpurpose>Read cut-off timestamps from the current journal entry</refpurpose>
</refnamediv>
<refsynopsisdiv>
<funcsynopsis>
<funcsynopsisinfo>#include &lt;systemd/sd-journal.h&gt;</funcsynopsisinfo>
<funcprototype>
<funcdef>int <function>sd_journal_get_cutoff_realtime_usec</function></funcdef>
<paramdef>sd_journal *<parameter>j</parameter></paramdef>
<paramdef>uint64_t *<parameter>from</parameter></paramdef>
<paramdef>uint64_t *<parameter>to</parameter></paramdef>
</funcprototype>
<funcprototype>
<funcdef>int <function>sd_journal_get_cutoff_monotonic_usec</function></funcdef>
<paramdef>sd_journal *<parameter>j</parameter></paramdef>
<paramdef>sd_id128_t <parameter>boot_id</parameter></paramdef>
<paramdef>uint64_t *<parameter>from</parameter></paramdef>
<paramdef>uint64_t *<parameter>to</parameter></paramdef>
</funcprototype>
</funcsynopsis>
</refsynopsisdiv>
<refsect1>
<title>Description</title>
<para><function>sd_journal_get_cutoff_realtime_usec()</function>
retrieves the realtime (wallclock) timestamps of the
first and last entries accessible in the journal. It
takes three arguments: the journal context object
<parameter>j</parameter> and two pointers
<parameter>from</parameter> and
<parameter>to</parameter> pointing at 64-bit unsigned
integers to store the timestamps in. The timestamps
are in microseconds since the epoch,
i.e. <constant>CLOCK_REALTIME</constant>. Either one
of the two timestamp arguments may be passed as
<constant>NULL</constant> in case the timestamp is not
needed, but not both.</para>
<para><function>sd_journal_get_cutoff_monotonic_usec()</function>
retrieves the monotonic timestamps of the first and
last entries accessible in the journal. It takes three
arguments: the journal context object
<parameter>j</parameter>, a 128-bit identifier for the
boot <parameter>boot_id</parameter>, and two pointers
to 64-bit unsigned integers to store the timestamps,
<parameter>from</parameter> and
<parameter>to</parameter>. The timestamps are in
microseconds since boot-up of the specific boot,
i.e. <constant>CLOCK_MONOTONIC</constant>. Since the
monotonic clock begins new with every reboot it only
defines a well-defined point in time when used
together with an identifier identifying the boot, see
<citerefentry><refentrytitle>sd_id128_get_boot</refentrytitle><manvolnum>3</manvolnum></citerefentry>
for more information. The function will return the
timestamps for the boot identified by the passed boot
ID. Either one of the two timestamp arguments may be
passed as <constant>NULL</constant> in case the
timestamp is not needed, but not both.</para>
</refsect1>
<refsect1>
<title>Return Value</title>
<para><function>sd_journal_get_cutoff_realtime_usec()</function>
and
<function>sd_journal_get_cutoff_monotonic_usec()</function>
return 1 on success, 0 if not suitable entries are in
the journal or a negative errno-style error code.</para>
<para>Locations pointed to by parameters
<parameter>from</parameter> and
<parameter>to</parameter> will be set only if the
return value is positive, and obviously, the
parameters are non-null.</para>
</refsect1>
<refsect1>
<title>Notes</title>
<para>The
<function>sd_journal_get_cutoff_realtime_usec()</function>
and
<function>sd_journal_get_cutoff_monotonic_usec()</function>
interfaces are available as a shared library, which can
be compiled and linked to with the
<constant>libsystemd</constant> <citerefentry project='die-net'><refentrytitle>pkg-config</refentrytitle><manvolnum>1</manvolnum></citerefentry>
file.</para>
</refsect1>
<refsect1>
<title>See Also</title>
<para>
<citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
<citerefentry><refentrytitle>sd-journal</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
<citerefentry><refentrytitle>sd_journal_open</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
<citerefentry><refentrytitle>sd_journal_get_realtime_usec</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
<citerefentry><refentrytitle>sd_id128_get_boot</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
<citerefentry><refentrytitle>clock_gettime</refentrytitle><manvolnum>2</manvolnum></citerefentry>
</para>
</refsect1>
</refentry>