1 <?xml version='
1.0'
?> <!--*-nxml-*-->
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 2012 Lennart Poettering
13 <refentry id=
"sd_journal_get_realtime_usec"
14 xmlns:
xi=
"http://www.w3.org/2001/XInclude">
17 <title>sd_journal_get_realtime_usec
</title>
18 <productname>systemd
</productname>
22 <contrib>Developer
</contrib>
23 <firstname>Lennart
</firstname>
24 <surname>Poettering
</surname>
25 <email>lennart@poettering.net
</email>
31 <refentrytitle>sd_journal_get_realtime_usec
</refentrytitle>
32 <manvolnum>3</manvolnum>
36 <refname>sd_journal_get_realtime_usec
</refname>
37 <refname>sd_journal_get_monotonic_usec
</refname>
38 <refpurpose>Read timestamps from the current journal entry
</refpurpose>
43 <funcsynopsisinfo>#include
<systemd/sd-journal.h
></funcsynopsisinfo>
46 <funcdef>int
<function>sd_journal_get_realtime_usec
</function></funcdef>
47 <paramdef>sd_journal *
<parameter>j
</parameter></paramdef>
48 <paramdef>uint64_t *
<parameter>usec
</parameter></paramdef>
52 <funcdef>int
<function>sd_journal_get_monotonic_usec
</function></funcdef>
53 <paramdef>sd_journal *
<parameter>j
</parameter></paramdef>
54 <paramdef>uint64_t *
<parameter>usec
</parameter></paramdef>
55 <paramdef>sd_id128_t *
<parameter>boot_id
</parameter></paramdef>
62 <title>Description
</title>
64 <para><function>sd_journal_get_realtime_usec()
</function> gets the
65 realtime (wallclock) timestamp of the current journal entry. It
66 takes two arguments: the journal context object and a pointer to a
67 64-bit unsigned integer to store the timestamp in. The timestamp
68 is in microseconds since the epoch, i.e.
69 <constant>CLOCK_REALTIME
</constant>.
</para>
71 <para><function>sd_journal_get_monotonic_usec()
</function> gets
72 the monotonic timestamp of the current journal entry. It takes
73 three arguments: the journal context object, a pointer to a
64-bit
74 unsigned integer to store the timestamp in, as well as a
128-bit
75 ID buffer to store the boot ID of the monotonic timestamp. The
76 timestamp is in microseconds since boot-up of the specific boot,
77 i.e.
<constant>CLOCK_MONOTONIC
</constant>. Since the monotonic
78 clock begins new with every reboot, it only defines a well-defined
79 point in time when used together with an identifier identifying
81 <citerefentry><refentrytitle>sd_id128_get_boot
</refentrytitle><manvolnum>3</manvolnum></citerefentry>
82 for more information. If the boot ID parameter is passed
83 <constant>NULL
</constant>, the function will fail if the monotonic
84 timestamp of the current entry is not of the current system
87 <para>Note that these functions will not work before
88 <citerefentry><refentrytitle>sd_journal_next
</refentrytitle><manvolnum>3</manvolnum></citerefentry>
89 (or related call) has been called at least
90 once, in order to position the read pointer at a valid entry.
</para>
94 <title>Return Value
</title>
96 <para><function>sd_journal_get_realtime_usec()
</function> and
97 <function>sd_journal_get_monotonic_usec()
</function> returns
0 on
98 success or a negative errno-style error code. If the boot ID
99 parameter was passed
<constant>NULL
</constant> and the monotonic
100 timestamp of the current journal entry is not of the current
101 system boot,
<constant>-ESTALE
</constant> is returned by
102 <function>sd_journal_get_monotonic_usec()
</function>.
</para>
105 <xi:include href=
"libsystemd-pkgconfig.xml" />
108 <title>See Also
</title>
111 <citerefentry><refentrytitle>systemd
</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
112 <citerefentry><refentrytitle>sd-journal
</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
113 <citerefentry><refentrytitle>sd_journal_open
</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
114 <citerefentry><refentrytitle>sd_journal_next
</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
115 <citerefentry><refentrytitle>sd_journal_get_data
</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
116 <citerefentry><refentrytitle>sd_id128_get_boot
</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
117 <citerefentry><refentrytitle>clock_gettime
</refentrytitle><manvolnum>2</manvolnum></citerefentry>,
118 <citerefentry><refentrytitle>sd_journal_get_cutoff_realtime_usec
</refentrytitle><manvolnum>3</manvolnum></citerefentry>