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<h1>9 Testing and tools</h1>
<h3><a name="id67998">9.1
Tracing</a></h3>
<p>We have instrumented our code in order to enable
tracing. Running the application with tracing deactivated,
causes a negligible performance overhead (an external call to a
function which returns an atom). Activation of tracing does not
require any recompilation of the code, since we rely on
Erlang/OTP's built in support for dynamic trace activation. In
our case tracing of calls to a given external function.</p>
<p>Event traces can be viewed in a generic message sequence chart
tool, <span class="code">et</span>, or as standard output (events are written to stdio). </p>
<p>See <span class="bold_code"><a href="megaco.html#enable_trace">enable_trace</a></span>,
<span class="bold_code"><a href="megaco.html#disable_trace">disable_trace</a></span> and
<span class="bold_code"><a href="megaco.html#set_trace">set_trace</a></span> for
more info. </p>
<h3><a name="id68043">9.2
Measurement and transformation</a></h3>
<p>We have included some simple tool(s) for codec measurement (meas),
performance tests (mstone1 and mstone2) and message transformation.</p>
<p>The tool(s) are located in the example/meas directory.</p>
<h4>Requirement</h4>
<ul>
<li>
<p>Erlang/OTP, version R13B01 or later.</p>
</li>
<li>
<p>Version 3.11 or later of <strong>this</strong> application.</p>
</li>
<li>
<p>Version 1.6.10 or later of the <strong>asn1</strong> application. </p>
</li>
<li>
<p>The flex libraries. Without it, the flex powered codecs cannot
be used.</p>
</li>
</ul>
<h4>Meas results</h4>
<p>The results from the measurement run (meas) is four
excel-compatible textfiles: </p>
<ul>
<li>
<p>decode_time.xls -> Decoding result</p>
</li>
<li>
<p>encode_time.xls -> Encoding result</p>
</li>
<li>
<p>total_time.xls -> Total (Decoding+encoding) result</p>
</li>
<li>
<p>message_size.xls -> Message size</p>
</li>
</ul>
<h4>Instruction</h4>
<p>The tool contain four things:
</p>
<ul>
<li>
<p>The transformation module</p>
</li>
<li>
<p>The measurement (meas) module(s)</p>
</li>
<li>
<p>The mstone (mstone1 and mstone2) module(s)</p>
</li>
<li>
<p>The basic message file</p>
</li>
</ul>
<h4>Message Transformation</h4>
<p>The messages used by the different tools are contained in
single message package file (see below for more info). The messages
in this file is encoded with just one codec. During
measurement initiation, the messages are read and then transformed to all
codec formats used in the measurement. </p>
<p>The message transformation is done by the transformation module.
It is used to transform a set of messages encoded with one codec
into the other base codec's.</p>
<h4>Measurement(s)</h4>
<p>There are two different measurement tools: </p>
<ul>
<li>
<p><strong>meas</strong>: </p>
<p>Used to perform codec measurements. That is, to see what
kind of performance can be expected by the different codecs
provided by the megaco application. </p>
<p>The measurement is done by iterating over the decode/encode
function for approx 2 seconds per message and counting
the number of decodes/encodes.</p>
<p>Is best run by modifying the meas.sh.skel skeleton script
provided by the tool.</p>
<p>To run it manually do the following: </p>
<div class="example"><pre>
% erl -pa <path-megaco-ebin-dir> -pa <path-to-meas-module-dir>
Erlang (BEAM) emulator version 5.6 [source]
Eshell V5.7.1 (abort with ^G)
1> megaco_codec_meas:start().
...
2> halt().
</pre></div>
<p>or to make it even easier, assuming a measure shall be
done on all the codecs (as above):</p>
<div class="example"><pre>
% erl -noshell -pa <path-megaco-ebin-dir> \\
-pa <path-to-meas-module-dir> \\
-s megaco_codec_meas -s init stop
</pre></div>
<p>When run as above (this will take some time), the measurement
process is done as follows:</p>
<div class="example"><pre>
For each codec:
For each message:
Read the message from the file
Detect message version
Measure decode
Measure encode
Write results, encode, decode and total, to file
</pre></div>
</li>
<li>
<p><strong>mstone1 and mstone2</strong>: </p>
<p>These are two different SMP performance monitoring tool(s). </p>
<p><strong>mstone1</strong> creates a process for each codec config supported by
the megaco application and let them run for a specific
time (all at the same time), encoding and decoding
megaco messages. The number of messages processed in total
is the mstone1(1) value. </p>
<p>There are different ways to run the mstone1 tool, e.g. with or without
the use of drivers, with <strong>only</strong> flex-empowered configs. </p>
<p>Is best run by modifying the mstone1.sh.skel skeleton script
provided by the tool.</p>
<p>The <strong>mstone2</strong> is similar to the <strong>mstone1</strong> tool,
but in this case, each created process makes only <strong>one</strong> run
through the messages and then exits. A soon as a process exits,
a new process (with the same config and messages) is created to takes
its place.
The number of messages processed in total
is the mstone2(1) value. </p>
</li>
</ul>
<p>Both these tools use the message package (time_test.msgs) provided
with the tool(s), although it can run on any message package as long as
it has the same structure. </p>
<h4>Message package file</h4>
<p>This is simply an erlang compatible text-file with the following
structure: <span class="code">{codec_name(), messages_list()}</span>. </p>
<div class="example"><pre>
codec_name() = pretty | compact | ber | per | erlang (how the messages are encoded)
messages_list() = [{message_name(), message()}]
message_name() = atom()
message() = binary()
</pre></div>
<p>The codec name is the name of the codec with which all messages in
the <span class="code">message_list()</span> has been encoded. </p>
<p>This file can be <span class="code">exported</span> to a file structure by calling the
<span class="bold_code"><a href="megaco_codec_transform.html#export_messages">export_messages</a></span>
function. This can be usefull if a measurement shall be done with
an external tool. Exporting the messages creates a directory tree
with the following structure:
</p>
<div class="example"><pre>
<message package>/pretty/<message-files>
compact/
per/
ber/<message-files>
erlang/
</pre></div>
<p>The file includes both version 1, 2 and version 3 messages.</p>
<h4>Notes</h4>
<h4>Binary codecs</h4>
<p>There are two basic ways to use the binary encodings:
With package related name and termination id transformation
(the 'native' encoding config) or without. This transformation
converts package related names and termination id's to a more
convenient internal form (equivalent with the decoded text message).</p>
<p>The transformation is done _after_ the actual decode has been
done.</p>
<p>Furthermore, it is possible to make use of a linked in driver that
performs some of the decode/encode, decode for ber and encode for per
(the 'driver' encoding config).</p>
<p>Therefor in the tests, binary codecs are tested with four
different encoding configs to determine exactly how the
different options effect the performance: with transformation and
without driver ([]), without transformation and without driver
([native]), with transformation and with driver ([driver]) and
finally without transformation and with driver ([driver,native]).</p>
<h4>Included test messages</h4>
<p>Some of these messages are ripped from the call flow examples
in an old version of the RFC and others are created to test
a specific feature of megaco. </p>
<h4>Measurement tool directory name</h4>
<p>Be sure <strong>not</strong> no name the directory containing the measurement
binaries starting with 'megaco-', e.g. megaco-meas. This will
confuse the erlang application loader (erlang applications
are named, e.g. megaco-1.0.2).</p>
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