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<div class="section" id="clocks-and-synchronization-kombu-clocks">
<h1>Clocks and Synchronization - kombu.clocks<a class="headerlink" href="#clocks-and-synchronization-kombu-clocks" title="Permalink to this headline">¶</a></h1>
<span class="target" id="module-kombu.clocks"></span><dl class="class">
<dt id="kombu.clocks.LamportClock">
<em class="property">class </em><tt class="descclassname">kombu.clocks.</tt><tt class="descname">LamportClock</tt><big>(</big><em>initial_value=0</em><big>)</big><a class="headerlink" href="#kombu.clocks.LamportClock" title="Permalink to this definition">¶</a></dt>
<dd><p>Lamport’s logical clock.</p>
<p>From Wikipedia:</p>
<p>“A Lamport logical clock is a monotonically incrementing software counter
maintained in each process. It follows some simple rules:</p>
<blockquote>
<div><ul class="simple">
<li>A process increments its counter before each event in that process;</li>
<li>When a process sends a message, it includes its counter value with
the message;</li>
<li>On receiving a message, the receiver process sets its counter to be
greater than the maximum of its own value and the received value
before it considers the message received.</li>
</ul>
</div></blockquote>
<p>Conceptually, this logical clock can be thought of as a clock that only
has meaning in relation to messages moving between processes. When a
process receives a message, it resynchronizes its logical clock with
the sender.</p>
<div class="admonition-see-also admonition seealso">
<p class="first admonition-title">See also</p>
<p><a class="reference external" href="http://en.wikipedia.org/wiki/Lamport_timestamps">http://en.wikipedia.org/wiki/Lamport_timestamps</a>
<a class="reference external" href="http://en.wikipedia.org/wiki/Lamport">http://en.wikipedia.org/wiki/Lamport</a>‘<a href="#id1"><span class="problematic" id="id2">s_Distributed_</span></a></p>
<blockquote class="last">
<div>Mutual_Exclusion_Algorithm</div></blockquote>
</div>
<p><em>Usage</em></p>
<p>When sending a message use <a class="reference internal" href="#kombu.clocks.LamportClock.forward" title="kombu.clocks.LamportClock.forward"><tt class="xref py py-meth docutils literal"><span class="pre">forward()</span></tt></a> to increment the clock,
when receiving a message use <a class="reference internal" href="#kombu.clocks.LamportClock.adjust" title="kombu.clocks.LamportClock.adjust"><tt class="xref py py-meth docutils literal"><span class="pre">adjust()</span></tt></a> to sync with
the time stamp of the incoming message.</p>
<dl class="method">
<dt id="kombu.clocks.LamportClock.adjust">
<tt class="descname">adjust</tt><big>(</big><em>other</em><big>)</big><a class="headerlink" href="#kombu.clocks.LamportClock.adjust" title="Permalink to this definition">¶</a></dt>
<dd></dd></dl>
<dl class="method">
<dt id="kombu.clocks.LamportClock.forward">
<tt class="descname">forward</tt><big>(</big><big>)</big><a class="headerlink" href="#kombu.clocks.LamportClock.forward" title="Permalink to this definition">¶</a></dt>
<dd></dd></dl>
<dl class="attribute">
<dt id="kombu.clocks.LamportClock.value">
<tt class="descname">value</tt><a class="headerlink" href="#kombu.clocks.LamportClock.value" title="Permalink to this definition">¶</a></dt>
<dd><p>The clocks current value.</p>
</dd></dl>
</dd></dl>
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