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diff --git a/src/libsystemd/sd_bus_message_get_monotonic_usec.xml b/src/libsystemd/sd_bus_message_get_monotonic_usec.xml new file mode 100644 index 0000000000..2c0a8a5d54 --- /dev/null +++ b/src/libsystemd/sd_bus_message_get_monotonic_usec.xml @@ -0,0 +1,181 @@ +<?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 systemd. + + Copyright 2013 Lennart Poettering + + systemd 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. + + systemd 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 systemd; 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>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 <systemd/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>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-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> |