mirror of
https://git.proxmox.com/git/systemd
synced 2025-06-03 12:02:58 +00:00
81 lines
8.8 KiB
HTML
81 lines
8.8 KiB
HTML
<html><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8"><title>sd_bus_message_get_monotonic_usec</title><meta name="generator" content="DocBook XSL Stylesheets V1.78.1"></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><style>
|
||
a.headerlink {
|
||
color: #c60f0f;
|
||
font-size: 0.8em;
|
||
padding: 0 4px 0 4px;
|
||
text-decoration: none;
|
||
visibility: hidden;
|
||
}
|
||
|
||
a.headerlink:hover {
|
||
background-color: #c60f0f;
|
||
color: white;
|
||
}
|
||
|
||
h1:hover > a.headerlink, h2:hover > a.headerlink, h3:hover > a.headerlink, dt:hover > a.headerlink {
|
||
visibility: visible;
|
||
}
|
||
</style><a href="index.html">Index </a>·
|
||
<a href="systemd.directives.html">Directives </a>·
|
||
<a href="../python-systemd/index.html">Python </a>·
|
||
<a href="../libudev/index.html">libudev </a>·
|
||
<a href="../libudev/index.html">gudev </a><span style="float:right">systemd 217</span><hr><div class="refentry"><a name="sd_bus_message_get_monotonic_usec"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p>sd_bus_message_get_monotonic_usec, sd_bus_message_get_realtime_usec, sd_bus_message_get_seqnum — Retrieve the sender timestamps and sequence number of a message</p></div><div class="refsynopsisdiv"><h2>Synopsis</h2><div class="funcsynopsis"><pre class="funcsynopsisinfo">#include <systemd/sd-bus.h></pre><table border="0" class="funcprototype-table" summary="Function synopsis" style="cellspacing: 0; cellpadding: 0;"><tr><td><code class="funcdef">int <b class="fsfunc">sd_bus_message_get_monotonic_usec</b>(</code></td><td>sd_bus_message *<var class="pdparam">message</var>, </td></tr><tr><td> </td><td>uint64_t *<var class="pdparam">usec</var><code>)</code>;</td></tr></table><div class="funcprototype-spacer"> </div><table border="0" class="funcprototype-table" summary="Function synopsis" style="cellspacing: 0; cellpadding: 0;"><tr><td><code class="funcdef">int <b class="fsfunc">sd_bus_message_get_realtime_usec</b>(</code></td><td>sd_bus_message *<var class="pdparam">message</var>, </td></tr><tr><td> </td><td>uint64_t *<var class="pdparam">usec</var><code>)</code>;</td></tr></table><div class="funcprototype-spacer"> </div><table border="0" class="funcprototype-table" summary="Function synopsis" style="cellspacing: 0; cellpadding: 0;"><tr><td><code class="funcdef">int <b class="fsfunc">sd_bus_message_get_seqnum</b>(</code></td><td>sd_bus_message *<var class="pdparam">message</var>, </td></tr><tr><td> </td><td>uint64_t *<var class="pdparam">seqnum</var><code>)</code>;</td></tr></table><div class="funcprototype-spacer"> </div></div></div><div class="refsect1"><a name="idm214192513472"></a><h2 id="Description">Description<a class="headerlink" title="Permalink to this headline" href="#Description">¶</a></h2><p><code class="function">sd_bus_message_get_monotonic_usec()</code>
|
||
returns the monotonic timestamp of the time the
|
||
message was sent. This value is in microseconds since
|
||
the "<code class="literal">CLOCK_MONOTONIC</code>" epoch, see
|
||
<a href="http://man7.org/linux/man-pages/man2/clock_gettime.2.html"><span class="citerefentry"><span class="refentrytitle">clock_gettime</span>(2)</span></a>
|
||
for details.</p><p>Similar,
|
||
<code class="function">sd_bus_message_get_realtime_usec()</code>
|
||
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
|
||
"<code class="literal">CLOCK_REALTIME</code>" clock.</p><p><code class="function">sd_bus_message_get_seqnum()</code>
|
||
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 busses of
|
||
the local system. The sequence number combined with
|
||
the boot ID of the system (as returned by
|
||
<a href="sd_id128_get_boot.html"><span class="citerefentry"><span class="refentrytitle">sd_id128_get_boot</span>(3)</span></a>)
|
||
is a suitable globally unique identifier for bus
|
||
messages.</p><p>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.</p><p>These timestamps and the sequence number are
|
||
attached to each message by the kernel and cannot be
|
||
manipulated by the sender.</p><p>Note that these timestamps are only available on
|
||
some bus transports, and only after support for them
|
||
has been negotiated with the
|
||
<a href="sd_bus_negotiate_timestamp.html"><span class="citerefentry"><span class="refentrytitle">sd_bus_negotiate_timestamp</span>(3)</span></a>
|
||
call.</p></div><div class="refsect1"><a name="idm214196401632"></a><h2 id="Return Value">Return Value<a class="headerlink" title="Permalink to this headline" href="#Return%20Value">¶</a></h2><p>On success, these calls return 0 or a positive
|
||
integer. On failure, these calls return a negative
|
||
errno-style error code.</p><p>On success, the timestamp or sequence number is
|
||
returned in the specified 64-bit unsigned integer
|
||
variable.</p></div><div class="refsect1"><a name="idm214196399728"></a><h2 id="Errors">Errors<a class="headerlink" title="Permalink to this headline" href="#Errors">¶</a></h2><p>Returned errors may indicate the following problems:</p><div class="variablelist"><dl class="variablelist"><dt id="-EINVAL"><span class="term"><code class="constant">-EINVAL</code></span><a class="headerlink" title="Permalink to this term" href="#-EINVAL">¶</a></dt><dd><p>A specified parameter
|
||
is invalid.</p></dd><dt id="-ENODATA"><span class="term"><code class="constant">-ENODATA</code></span><a class="headerlink" title="Permalink to this term" href="#-ENODATA">¶</a></dt><dd><p>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
|
||
<a href="sd_bus_negotiate_timestamp.html"><span class="citerefentry"><span class="refentrytitle">sd_bus_negotiate_timestamp</span>(3)</span></a>.</p></dd></dl></div></div><div class="refsect1"><a name="idm214196393904"></a><h2 id="Notes">Notes<a class="headerlink" title="Permalink to this headline" href="#Notes">¶</a></h2><p>The
|
||
<code class="function">sd_bus_message_get_monotonic_usec()</code>,
|
||
<code class="function">sd_bus_message_get_realtime_usec()</code>,
|
||
and <code class="function">sd_bus_message_get_seqnum()</code>
|
||
interfaces are available as a shared library, which
|
||
can be compiled and linked to with the
|
||
<code class="constant">libsystemd</code> <a href="http://linux.die.net/man/1/pkg-config"><span class="citerefentry"><span class="refentrytitle">pkg-config</span>(1)</span></a>
|
||
file.</p></div><div class="refsect1"><a name="idm214196381440"></a><h2 id="See Also">See Also<a class="headerlink" title="Permalink to this headline" href="#See%20Also">¶</a></h2><p>
|
||
<a href="systemd.html"><span class="citerefentry"><span class="refentrytitle">systemd</span>(1)</span></a>,
|
||
<a href="sd-bus.html"><span class="citerefentry"><span class="refentrytitle">sd-bus</span>(3)</span></a>,
|
||
<a href="sd_bus_new.html"><span class="citerefentry"><span class="refentrytitle">sd_bus_new</span>(3)</span></a>,
|
||
<a href="sd_bus_negotiate_timestamp.html"><span class="citerefentry"><span class="refentrytitle">sd_bus_negotiate_timestamp</span>(3)</span></a>,
|
||
<a href="http://man7.org/linux/man-pages/man2/clock_gettime.2.html"><span class="citerefentry"><span class="refentrytitle">clock_gettime</span>(2)</span></a>,
|
||
<a href="sd_id128_get_boot.html"><span class="citerefentry"><span class="refentrytitle">sd_id128_get_boot</span>(3)</span></a>
|
||
</p></div></div></body></html>
|