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1 | <?xml version='1.0'?> <!--*-nxml-*--> |
2 | <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN" | |
12b42c76 | 3 | "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd"> |
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4 | |
5 | <!-- | |
6 | This file is part of systemd. | |
7 | ||
8 | Copyright 2012 Lennart Poettering | |
9 | ||
10 | systemd is free software; you can redistribute it and/or modify it | |
11 | under the terms of the GNU Lesser General Public License as published by | |
12 | the Free Software Foundation; either version 2.1 of the License, or | |
13 | (at your option) any later version. | |
14 | ||
15 | systemd is distributed in the hope that it will be useful, but | |
16 | WITHOUT ANY WARRANTY; without even the implied warranty of | |
17 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
18 | Lesser General Public License for more details. | |
19 | ||
20 | You should have received a copy of the GNU Lesser General Public License | |
21 | along with systemd; If not, see <http://www.gnu.org/licenses/>. | |
22 | --> | |
23 | ||
24 | <refentry id="sd_journal_get_realtime_usec"> | |
25 | ||
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26 | <refentryinfo> |
27 | <title>sd_journal_get_realtime_usec</title> | |
28 | <productname>systemd</productname> | |
29 | ||
30 | <authorgroup> | |
31 | <author> | |
32 | <contrib>Developer</contrib> | |
33 | <firstname>Lennart</firstname> | |
34 | <surname>Poettering</surname> | |
35 | <email>lennart@poettering.net</email> | |
36 | </author> | |
37 | </authorgroup> | |
38 | </refentryinfo> | |
39 | ||
40 | <refmeta> | |
41 | <refentrytitle>sd_journal_get_realtime_usec</refentrytitle> | |
42 | <manvolnum>3</manvolnum> | |
43 | </refmeta> | |
44 | ||
45 | <refnamediv> | |
46 | <refname>sd_journal_get_realtime_usec</refname> | |
47 | <refname>sd_journal_get_monotonic_usec</refname> | |
48 | <refpurpose>Read timestamps from the current journal entry</refpurpose> | |
49 | </refnamediv> | |
50 | ||
51 | <refsynopsisdiv> | |
52 | <funcsynopsis> | |
53 | <funcsynopsisinfo>#include <systemd/sd-journal.h></funcsynopsisinfo> | |
54 | ||
55 | <funcprototype> | |
56 | <funcdef>int <function>sd_journal_get_realtime_usec</function></funcdef> | |
57 | <paramdef>sd_journal *<parameter>j</parameter></paramdef> | |
58 | <paramdef>uint64_t *<parameter>usec</parameter></paramdef> | |
59 | </funcprototype> | |
60 | ||
61 | <funcprototype> | |
62 | <funcdef>int <function>sd_journal_get_monotonic_usec</function></funcdef> | |
63 | <paramdef>sd_journal *<parameter>j</parameter></paramdef> | |
64 | <paramdef>uint64_t *<parameter>usec</parameter></paramdef> | |
65 | <paramdef>sd_id128_t *<parameter>boot_id</parameter></paramdef> | |
66 | </funcprototype> | |
67 | ||
68 | </funcsynopsis> | |
69 | </refsynopsisdiv> | |
70 | ||
71 | <refsect1> | |
72 | <title>Description</title> | |
73 | ||
74 | <para><function>sd_journal_get_realtime_usec()</function> gets the | |
75 | realtime (wallclock) timestamp of the current journal entry. It | |
76 | takes two arguments: the journal context object and a pointer to a | |
77 | 64-bit unsigned integer to store the timestamp in. The timestamp | |
78 | is in microseconds since the epoch, i.e. | |
79 | <constant>CLOCK_REALTIME</constant>.</para> | |
80 | ||
81 | <para><function>sd_journal_get_monotonic_usec()</function> gets | |
82 | the monotonic timestamp of the current journal entry. It takes | |
83 | three arguments: the journal context object, a pointer to a 64-bit | |
84 | unsigned integer to store the timestamp in, as well as a 128-bit | |
85 | ID buffer to store the boot ID of the monotonic timestamp. The | |
86 | timestamp is in microseconds since boot-up of the specific boot, | |
87 | i.e. <constant>CLOCK_MONOTONIC</constant>. Since the monotonic | |
88 | clock begins new with every reboot, it only defines a well-defined | |
89 | point in time when used together with an identifier identifying | |
90 | the boot. See | |
91 | <citerefentry><refentrytitle>sd_id128_get_boot</refentrytitle><manvolnum>3</manvolnum></citerefentry> | |
92 | for more information. If the boot ID parameter is passed | |
93 | <constant>NULL</constant>, the function will fail if the monotonic | |
94 | timestamp of the current entry is not of the current system | |
95 | boot.</para> | |
96 | ||
97 | <para>Note that these functions will not work before | |
98 | <citerefentry><refentrytitle>sd_journal_next</refentrytitle><manvolnum>3</manvolnum></citerefentry> | |
99 | (or related call) has been called at least | |
100 | once, in order to position the read pointer at a valid entry.</para> | |
101 | </refsect1> | |
102 | ||
103 | <refsect1> | |
104 | <title>Return Value</title> | |
105 | ||
106 | <para><function>sd_journal_get_realtime_usec()</function> and | |
107 | <function>sd_journal_get_monotonic_usec()</function> returns 0 on | |
108 | success or a negative errno-style error code. If the boot ID | |
109 | parameter was passed <constant>NULL</constant> and the monotonic | |
110 | timestamp of the current journal entry is not of the current | |
111 | system boot, <constant>-ESTALE</constant> is returned by | |
112 | <function>sd_journal_get_monotonic_usec()</function>.</para> | |
113 | </refsect1> | |
114 | ||
115 | <refsect1> | |
116 | <title>Notes</title> | |
117 | ||
118 | <para>The <function>sd_journal_get_realtime_usec()</function> and | |
119 | <function>sd_journal_get_monotonic_usec()</function> interfaces | |
120 | are available as a shared library, which can be compiled and | |
121 | linked to with the | |
122 | <constant>libsystemd</constant> <citerefentry project='die-net'><refentrytitle>pkg-config</refentrytitle><manvolnum>1</manvolnum></citerefentry> | |
123 | file.</para> | |
124 | </refsect1> | |
125 | ||
126 | <refsect1> | |
127 | <title>See Also</title> | |
128 | ||
129 | <para> | |
130 | <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>, | |
131 | <citerefentry><refentrytitle>sd-journal</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
132 | <citerefentry><refentrytitle>sd_journal_open</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
133 | <citerefentry><refentrytitle>sd_journal_next</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
134 | <citerefentry><refentrytitle>sd_journal_get_data</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
135 | <citerefentry><refentrytitle>sd_id128_get_boot</refentrytitle><manvolnum>3</manvolnum></citerefentry>, | |
136 | <citerefentry><refentrytitle>clock_gettime</refentrytitle><manvolnum>2</manvolnum></citerefentry>, | |
137 | <citerefentry><refentrytitle>sd_journal_get_cutoff_realtime_usec</refentrytitle><manvolnum>3</manvolnum></citerefentry> | |
138 | </para> | |
139 | </refsect1> | |
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140 | |
141 | </refentry> |