man: document message timestamping/sequence number API
This commit is contained in:
Lennart Poettering
parent
1fedcf59e0
commit
3736955368
|
|
@ -26,6 +26,7 @@ MANPAGES += \
|
|||
man/sd_bus_error.3 \
|
||||
man/sd_bus_label_escape.3 \
|
||||
man/sd_bus_message_get_cookie.3 \
|
||||
man/sd_bus_message_get_monotonic_usec.3 \
|
||||
man/sd_bus_new.3 \
|
||||
man/sd_bus_open_user.3 \
|
||||
man/sd_bus_request_name.3 \
|
||||
|
|
@ -180,7 +181,9 @@ MANPAGES_ALIAS += \
|
|||
man/sd_bus_error_set_errno.3 \
|
||||
man/sd_bus_error_set_errnof.3 \
|
||||
man/sd_bus_label_unescape.3 \
|
||||
man/sd_bus_message_get_realtime_usec.3 \
|
||||
man/sd_bus_message_get_reply_cookie.3 \
|
||||
man/sd_bus_message_get_seqnum.3 \
|
||||
man/sd_bus_open_system.3 \
|
||||
man/sd_bus_open_system_container.3 \
|
||||
man/sd_bus_open_system_remote.3 \
|
||||
|
|
@ -327,7 +330,9 @@ man/sd_bus_error_set_const.3: man/sd_bus_error.3
|
|||
man/sd_bus_error_set_errno.3: man/sd_bus_error.3
|
||||
man/sd_bus_error_set_errnof.3: man/sd_bus_error.3
|
||||
man/sd_bus_label_unescape.3: man/sd_bus_label_escape.3
|
||||
man/sd_bus_message_get_realtime_usec.3: man/sd_bus_message_get_monotonic_usec.3
|
||||
man/sd_bus_message_get_reply_cookie.3: man/sd_bus_message_get_cookie.3
|
||||
man/sd_bus_message_get_seqnum.3: man/sd_bus_message_get_monotonic_usec.3
|
||||
man/sd_bus_open_system.3: man/sd_bus_open_user.3
|
||||
man/sd_bus_open_system_container.3: man/sd_bus_open_user.3
|
||||
man/sd_bus_open_system_remote.3: man/sd_bus_open_user.3
|
||||
|
|
@ -606,9 +611,15 @@ man/sd_bus_error_set_errnof.html: man/sd_bus_error.html
|
|||
man/sd_bus_label_unescape.html: man/sd_bus_label_escape.html
|
||||
$(html-alias)
|
||||
|
||||
man/sd_bus_message_get_realtime_usec.html: man/sd_bus_message_get_monotonic_usec.html
|
||||
$(html-alias)
|
||||
|
||||
man/sd_bus_message_get_reply_cookie.html: man/sd_bus_message_get_cookie.html
|
||||
$(html-alias)
|
||||
|
||||
man/sd_bus_message_get_seqnum.html: man/sd_bus_message_get_monotonic_usec.html
|
||||
$(html-alias)
|
||||
|
||||
man/sd_bus_open_system.html: man/sd_bus_open_user.html
|
||||
$(html-alias)
|
||||
|
||||
|
|
@ -1340,6 +1351,7 @@ EXTRA_DIST += \
|
|||
man/sd_bus_error.xml \
|
||||
man/sd_bus_label_escape.xml \
|
||||
man/sd_bus_message_get_cookie.xml \
|
||||
man/sd_bus_message_get_monotonic_usec.xml \
|
||||
man/sd_bus_new.xml \
|
||||
man/sd_bus_open_user.xml \
|
||||
man/sd_bus_request_name.xml \
|
||||
|
|
|
|||
|
|
@ -0,0 +1,183 @@
|
|||
<?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 <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 sending userspace.</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>
|
||||
Loading…
Reference in New Issue