<h4>Pre-Submission Checklist</h4>
<ul>
<li>[ X] Commit message has the format required by CONTRIBUTING guide</li>
<li>[ X] Commits are split per component (core, individual modules, libs, utils, ...)</li>
<li>[ X] Each component has a single commit (if not, squash them into one commit)</li>
<li>[ X] No commits to README files for modules (changes must be done to docbook files<br>
in <code>doc/</code> subfolder, the README file is autogenerated)</li>
</ul>
<h4>Type Of Change</h4>
<ul class="contains-task-list">
<li class="task-list-item"><input type="checkbox" class="task-list-item-checkbox" disabled=""> Small bug fix (non-breaking change which fixes an issue)</li>
<li>[ X] New feature (non-breaking change which adds new functionality)</li>
<li class="task-list-item"><input type="checkbox" class="task-list-item-checkbox" disabled=""> Breaking change (fix or feature that would change existing functionality)</li>
</ul>
<h4>Checklist:</h4>
<ul class="contains-task-list">
<li class="task-list-item"><input type="checkbox" class="task-list-item-checkbox" disabled=""> PR should be backported to stable branches</li>
<li>[ X] Tested changes locally</li>
<li class="task-list-item"><input type="checkbox" class="task-list-item-checkbox" disabled=""> Related to issue #XXXX (replace XXXX with an open issue number)</li>
</ul>
<h4>Description</h4>
<p>With the proposed modification the dispatcher can now compute the latency of all the nodes it is pinging and also report timeouts counts.</p>
<p>Default module behavior is unchanged, the stats needs to be explicitly activated.</p>
<p>In this first stage, the objective is to start to monitor latency and intermittent timeouts and share the result to be used by an external monitoring system.</p>
<p>The metrics are only expose using <code>kamcmd dispatcher.list</code> maybe they should be made available elsewhere, for example from the routing script ? but this can be done later ...</p>
<pre><code>DEST: {
URI: sip:1.2.3.4
FLAGS: AX
PRIORITY: 9
LATENCY: {
AVG: 24.250000 # weigthed moving average for the last few weeks
STD: 1.035000 # standard deviation of AVG
EST: 25.000000 # short term estimate, see parameter: ds_latency_estimator_alpha
MAX: 26 # maximun value seen
TIMEOUT: 0 # count of ping timeouts
}
}
</code></pre>
<p>Another stage would probably be to adjust the load distribution/weight considering the latency estimator, the dispatcher would be able to detect intermittent remote server lags and minimize the impact.</p>
<p>tested :</p>
<p>Some tests done on the calculation generating billions of fake samples to verify calculations.</p>
<p>ds_reload :</p>
<ul>
<li>safe because it is using a blue/green update keeping the active version while creating the new one</li>
<li>this will currently reset the stats</li>
</ul>
<hr>
<h4>You can view, comment on, or merge this pull request online at:</h4>
<p> <a href='https://github.com/kamailio/kamailio/pull/1234'>https://github.com/kamailio/kamailio/pull/1234</a></p>
<h4>Commit Summary</h4>
<ul>
<li>dispatcher: latency statistics</li>
</ul>
<h4>File Changes</h4>
<ul>
<li>
<strong>M</strong>
<a href="https://github.com/kamailio/kamailio/pull/1234/files#diff-0">src/modules/dispatcher/dispatch.c</a>
(87)
</li>
<li>
<strong>M</strong>
<a href="https://github.com/kamailio/kamailio/pull/1234/files#diff-1">src/modules/dispatcher/dispatch.h</a>
(13)
</li>
<li>
<strong>M</strong>
<a href="https://github.com/kamailio/kamailio/pull/1234/files#diff-2">src/modules/dispatcher/dispatcher.c</a>
(28)
</li>
<li>
<strong>M</strong>
<a href="https://github.com/kamailio/kamailio/pull/1234/files#diff-3">src/modules/dispatcher/doc/dispatcher.xml</a>
(9)
</li>
<li>
<strong>M</strong>
<a href="https://github.com/kamailio/kamailio/pull/1234/files#diff-4">src/modules/dispatcher/doc/dispatcher_admin.xml</a>
(75)
</li>
</ul>
<h4>Patch Links:</h4>
<ul>
<li><a href='https://github.com/kamailio/kamailio/pull/1234.patch'>https://github.com/kamailio/kamailio/pull/1234.patch</a></li>
<li><a href='https://github.com/kamailio/kamailio/pull/1234.diff'>https://github.com/kamailio/kamailio/pull/1234.diff</a></li>
</ul>
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