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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">
+
+<!--
+ This file is part of elogind.
+
+ Copyright 2013 Lennart Poettering
+
+ elogind is free software; you can redistribute it and/or modify it
+ under the terms of the GNU Lesser General Public License as published by
+ the Free Software Foundation; either version 2.1 of the License, or
+ (at your option) any later version.
+
+ elogind is distributed in the hope that it will be useful, but
+ WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public License
+ along with elogind; If not, see <http://www.gnu.org/licenses/>.
+-->
+
+<refentry id="sd_bus_message_get_monotonic_usec">
+
+ <refentryinfo>
+ <title>sd_bus_message_get_monotonic_usec</title>
+ <productname>elogind</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 <elogind/sd-bus.h></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
+ <constant>CLOCK_MONOTONIC</constant> epoch, see
+ <citerefentry><refentrytitle>clock_gettime</refentrytitle><manvolnum>2</manvolnum></citerefentry>
+ for details.</para>
+
+ <para>Similarly,
+ <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 <constant>CLOCK_REALTIME</constant> 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
+ transmitted on the local system, at the time the message was sent.
+ This sequence number is useful for determining message send order,
+ even across different buses 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>Note that the sending order and receiving order of messages
+ might differ, in particular for broadcast messages. This means
+ that the sequence number and the timestamps of messages a client
+ reads are not necessarily monotonically increasing.</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><constant>-EINVAL</constant></term>
+
+ <listitem><para>A specified parameter is
+ invalid.</para></listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term><constant>-ENODATA</constant></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>libelogind</constant> <citerefentry project='die-net'><refentrytitle>pkg-config</refentrytitle><manvolnum>1</manvolnum></citerefentry>
+ file.</para>
+ </refsect1>
+
+ <refsect1>
+ <title>See Also</title>
+
+ <para>
+ <citerefentry><refentrytitle>elogind</refentrytitle><manvolnum>8</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>
~ianmdlvl / elogind.git / blobdiff