[thirdparty/systemd.git] / man / sd_bus_message_get_monotonic_usec.xml

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<refentry id="sd_bus_message_get_monotonic_usec">

        <refentryinfo>
                <title>sd_bus_message_get_monotonic_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_bus_message_get_monotonic_usec</refentrytitle>
                <manvolnum>3</manvolnum>
        </refmeta>

        <refnamediv>
                <refname>sd_bus_message_get_monotonic_usec</refname>
                <refname>sd_bus_message_get_realtime_usec</refname>
                <refname>sd_bus_message_get_seqnum</refname>
                <refpurpose>Retrieve the sender timestamps and sequence number of a message</refpurpose>
        </refnamediv>

        <refsynopsisdiv>
                <funcsynopsis>
                        <funcsynopsisinfo>#include &lt;systemd/sd-bus.h&gt;</funcsynopsisinfo>

                        <funcprototype>
                                <funcdef>int <function>sd_bus_message_get_monotonic_usec</function></funcdef>
                                <paramdef>sd_bus_message* <parameter>message</parameter></paramdef>
                                <paramdef>uint64_t* <parameter>usec</parameter></paramdef>
                        </funcprototype>

                        <funcprototype>
                                <funcdef>int <function>sd_bus_message_get_realtime_usec</function></funcdef>
                                <paramdef>sd_bus_message* <parameter>message</parameter></paramdef>
                                <paramdef>uint64_t* <parameter>usec</parameter></paramdef>
                        </funcprototype>

                        <funcprototype>
                                <funcdef>int <function>sd_bus_message_get_seqnum</function></funcdef>
                                <paramdef>sd_bus_message* <parameter>message</parameter></paramdef>
                                <paramdef>uint64_t* <parameter>seqnum</parameter></paramdef>
                        </funcprototype>
                </funcsynopsis>
        </refsynopsisdiv>

        <refsect1>
                <title>Description</title>

                <para><function>sd_bus_message_get_monotonic_usec()</function>
                returns the monotonic timestamp of the time the
                message was sent. This value is in microseconds since
                the <literal>CLOCK_MONOTONIC</literal> epoch, see
                <citerefentry><refentrytitle>clock_gettime</refentrytitle><manvolnum>2</manvolnum></citerefentry>
                for details.</para>

                <para>Similar,
                <function>sd_bus_message_get_realtime_usec()</function>
                returns the realtime (wallclock) timestamp of the time
                the message was sent. This value is in microseconds
                since Jan 1st, 1970, i.e. in the
                <literal>CLOCK_REALTIME</literal> clock.</para>

                <para><function>sd_bus_message_get_seqnum()</function>
                returns the kernel-assigned sequence number of the
                message. The kernel assigns a global monotonically increasing
                sequence number to all messages sent on the local
                system. This sequence number is useful for determining
                message send order, even across different busses of
                the local system. The sequence number combined with
                the boot ID of the system (as returned by
                <citerefentry><refentrytitle>sd_id128_get_boot</refentrytitle><manvolnum>3</manvolnum></citerefentry>)
                is a suitable globally unique identifier for bus
                messages.</para>

                <para>These timestamps and the sequence number are
                attached to each message by the kernel and cannot be
                manipulated by the sender.</para>

                <para>Note that these timestamps are only available on
                some bus transports, and only after support for them
                has been negotiated with the
                <citerefentry><refentrytitle>sd_bus_negotiate_timestamp</refentrytitle><manvolnum>3</manvolnum></citerefentry>
                call.</para>
        </refsect1>

        <refsect1>
                <title>Return Value</title>

                <para>On success, these calls return 0 or a positive
                integer. On failure, these calls return a negative
                errno-style error code.</para>

                <para>On success, the timestamp or sequence number is
                returned in the specified 64-bit unsigned integer
                variable.</para>
        </refsect1>

        <refsect1>
                <title>Errors</title>

                <para>Returned errors may indicate the following problems:</para>

                <variablelist>
                        <varlistentry>
                                <term><varname>-EINVAL</varname></term>

                                <listitem><para>A specified parameter
                                is invalid.</para></listitem>
                        </varlistentry>

                        <varlistentry>
                                <term><varname>-ENODATA</varname></term>

                                <listitem><para>No timestamp or
                                sequence number information is
                                attached to the passed message. This
                                error is returned if the underlying
                                transport does not support
                                timestamping or assigning of sequence
                                numbers, or if this feature has not
                                been negotiated with
                                <citerefentry><refentrytitle>sd_bus_negotiate_timestamp</refentrytitle><manvolnum>3</manvolnum></citerefentry>.</para></listitem>
                        </varlistentry>
                </variablelist>
        </refsect1>

        <refsect1>
                <title>Notes</title>

                <para>The
                <function>sd_bus_message_get_monotonic_usec()</function>,
                <function>sd_bus_message_get_realtime_usec()</function>,
                and <function>sd_bus_message_get_seqnum()</function>
                interfaces are available as a shared library, which
                can be compiled and linked to with the
                <constant>libsystemd</constant> <citerefentry><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-bus</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
                        <citerefentry><refentrytitle>sd_bus_new</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
                        <citerefentry><refentrytitle>sd_bus_negotiate_timestamp</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
                        <citerefentry><refentrytitle>clock_gettime</refentrytitle><manvolnum>2</manvolnum></citerefentry>,
                        <citerefentry><refentrytitle>sd_id128_get_boot</refentrytitle><manvolnum>3</manvolnum></citerefentry>
                </para>
        </refsect1>

</refentry>
Commit	Line	Data
37369553 LP	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">
	4
	5	<!--
	6	This file is part of systemd.
	7
	8	Copyright 2013 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_bus_message_get_monotonic_usec">
	25
	26	<refentryinfo>
	27	<title>sd_bus_message_get_monotonic_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_bus_message_get_monotonic_usec</refentrytitle>
	42	<manvolnum>3</manvolnum>
	43	</refmeta>
	44
	45	<refnamediv>
	46	<refname>sd_bus_message_get_monotonic_usec</refname>
	47	<refname>sd_bus_message_get_realtime_usec</refname>
	48	<refname>sd_bus_message_get_seqnum</refname>
	49	<refpurpose>Retrieve the sender timestamps and sequence number of a message</refpurpose>
	50	</refnamediv>
	51
	52	<refsynopsisdiv>
	53	<funcsynopsis>
	54	<funcsynopsisinfo>#include <systemd/sd-bus.h></funcsynopsisinfo>
	55
	56	<funcprototype>
	57	<funcdef>int <function>sd_bus_message_get_monotonic_usec</function></funcdef>
	58	<paramdef>sd_bus_message* <parameter>message</parameter></paramdef>
	59	<paramdef>uint64_t* <parameter>usec</parameter></paramdef>
	60	</funcprototype>
	61
	62	<funcprototype>
	63	<funcdef>int <function>sd_bus_message_get_realtime_usec</function></funcdef>
	64	<paramdef>sd_bus_message* <parameter>message</parameter></paramdef>
65	<paramdef>uint64_t* <parameter>usec</parameter></paramdef>
66	</funcprototype>
67
68	<funcprototype>
69	<funcdef>int <function>sd_bus_message_get_seqnum</function></funcdef>
70	<paramdef>sd_bus_message* <parameter>message</parameter></paramdef>
71	<paramdef>uint64_t* <parameter>seqnum</parameter></paramdef>
72	</funcprototype>
73	</funcsynopsis>
74	</refsynopsisdiv>
75
76	<refsect1>
77	<title>Description</title>
78
79	<para><function>sd_bus_message_get_monotonic_usec()</function>
80	returns the monotonic timestamp of the time the
81	message was sent. This value is in microseconds since
82	the <literal>CLOCK_MONOTONIC</literal> epoch, see
83	<citerefentry><refentrytitle>clock_gettime</refentrytitle><manvolnum>2</manvolnum></citerefentry>
84	for details.</para>
85
86	<para>Similar,
87	<function>sd_bus_message_get_realtime_usec()</function>
88	returns the realtime (wallclock) timestamp of the time
89	the message was sent. This value is in microseconds
90	since Jan 1st, 1970, i.e. in the
91	<literal>CLOCK_REALTIME</literal> clock.</para>
92
93	<para><function>sd_bus_message_get_seqnum()</function>
94	returns the kernel-assigned sequence number of the
95	message. The kernel assigns a global monotonically increasing
96	sequence number to all messages sent on the local
97	system. This sequence number is useful for determining
98	message send order, even across different busses of
99	the local system. The sequence number combined with
100	the boot ID of the system (as returned by
101	<citerefentry><refentrytitle>sd_id128_get_boot</refentrytitle><manvolnum>3</manvolnum></citerefentry>)
102	is a suitable globally unique identifier for bus
103	messages.</para>
104
105	<para>These timestamps and the sequence number are
106	attached to each message by the kernel and cannot be
dc968941	107	manipulated by the sender.</para>
37369553 LP	108
	109	<para>Note that these timestamps are only available on
	110	some bus transports, and only after support for them
	111	has been negotiated with the
	112	<citerefentry><refentrytitle>sd_bus_negotiate_timestamp</refentrytitle><manvolnum>3</manvolnum></citerefentry>
	113	call.</para>
	114	</refsect1>
	115
	116	<refsect1>
	117	<title>Return Value</title>
	118
	119	<para>On success, these calls return 0 or a positive
	120	integer. On failure, these calls return a negative
	121	errno-style error code.</para>
	122
	123	<para>On success, the timestamp or sequence number is
	124	returned in the specified 64-bit unsigned integer
	125	variable.</para>
	126	</refsect1>
	127
	128	<refsect1>
	129	<title>Errors</title>
	130
	131	<para>Returned errors may indicate the following problems:</para>
	132
	133	<variablelist>
	134	<varlistentry>
	135	<term><varname>-EINVAL</varname></term>
	136
	137	<listitem><para>A specified parameter
	138	is invalid.</para></listitem>
	139	</varlistentry>
	140
	141	<varlistentry>
	142	<term><varname>-ENODATA</varname></term>
	143
	144	<listitem><para>No timestamp or
	145	sequence number information is
	146	attached to the passed message. This
	147	error is returned if the underlying
	148	transport does not support
	149	timestamping or assigning of sequence
	150	numbers, or if this feature has not
	151	been negotiated with
	152	<citerefentry><refentrytitle>sd_bus_negotiate_timestamp</refentrytitle><manvolnum>3</manvolnum></citerefentry>.</para></listitem>
	153	</varlistentry>
	154	</variablelist>
	155	</refsect1>
	156
	157	<refsect1>
	158	<title>Notes</title>
	159
	160	<para>The
	161	<function>sd_bus_message_get_monotonic_usec()</function>,
	162	<function>sd_bus_message_get_realtime_usec()</function>,
	163	and <function>sd_bus_message_get_seqnum()</function>
	164	interfaces are available as a shared library, which
	165	can be compiled and linked to with the
	166	<constant>libsystemd</constant> <citerefentry><refentrytitle>pkg-config</refentrytitle><manvolnum>1</manvolnum></citerefentry>
	167	file.</para>
	168	</refsect1>
	169
	170	<refsect1>
	171	<title>See Also</title>
172
173	<para>
174	<citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
175	<citerefentry><refentrytitle>sd-bus</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
176	<citerefentry><refentrytitle>sd_bus_new</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
177	<citerefentry><refentrytitle>sd_bus_negotiate_timestamp</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
178	<citerefentry><refentrytitle>clock_gettime</refentrytitle><manvolnum>2</manvolnum></citerefentry>,
179	<citerefentry><refentrytitle>sd_id128_get_boot</refentrytitle><manvolnum>3</manvolnum></citerefentry>
180	</para>
181	</refsect1>
182
183	</refentry>