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<div class="section" id="trial-error-prototyping-continous-integration">
<span id="phk-trialerror"></span><h1>Trial&Error - Prototyping - Continous Integration<a class="headerlink" href="#trial-error-prototyping-continous-integration" title="Permalink to this headline">¶</a></h1>
<p>The other day I chatted to a friend who wrote his phd thesis with
<a class="reference external" href="https://en.wikipedia.org/wiki/David_Wheeler_(British_computer_scientist)">David Wheeler</a> as his advisor, that made me feel young, because Wheeler
was the guy who invented the subroutine.</p>
<p>No, not ‘a subroutine’ but ‘the subroutine’.</p>
<p>In the 1980’ies, right when I had started in IT, there was the new
fashion: “Prototyping”.</p>
<p>It was all over the place, in 1983 Datamation you could about <em>“Data
driven prototyping”</em>, and by 1990 it had bubbled up to management
and Information and Software Technology could publish <em>“Organization
and Management of Systems Prototyping”</em> etc. etc.</p>
<p>The grey-beard at my workplace laconically said <em>“We already do that,
only we call it Trial&Error.”</em></p>
<p>Programming has always been Trial&Error, and probably always will.</p>
<p>All the early pioneers, like Wheeler, complained about how
batch-scheduling of machine resources removed the “intimate” contact
with the running program and argued that it prolonged the debugging
process.</p>
<p>Practically all the oral histories from back then are about people
sneaking in to university or work at night, to get the computer for
themselves.</p>
<p>But we could call it “Prototyping” if that sounded better, and now
that the history-deficient dot-com generation has “invented” it,
we can call it “Continous Integration”.</p>
<p>I don’t care - it’s still Trial&Error to me.</p>
<p>They guy I chatted with told how after his phd thesis he
<em>“swore to never again attempt to solve a problem with inadequate
tools”</em>.</p>
<p>That is sound advice, and we all tend to forget it all the time,
so reminded, I did a mental inventory on the train home: Which tools
do I use even though I find them inadequate.</p>
<p>And then I decided to do something about them.</p>
<p>First thing was my lab which has - erhh… evolved? - over the last 15 years.</p>
<p>Some of the original assumptions were plain wrong, and a lot of “As
a temporary solution I can …” hacks became permanent, and so on.</p>
<p>I spent two days cleaning, moving, shuffling and generally tidying
my lab, (Amongst other discoveries: The original two SCSI disks
from the first “freefall.freebsd.org” machine built by Rod Grimes.)
and it is now a lot more pleasant for the work I do these days.</p>
<p>Second thing was the Jenkins and Travis we use for Tria^H^H^H^Continuous
Integration in the Varnish Project.</p>
<p>Jenkins and Travis are both general purpose
program-test-framework-cloud-thingies, and they’re fine up to a
point, but they are inadequate tools for me in too many ways.</p>
<p>Jenkins is written in Java, which is not something I want to inflict
on computers volutarily, in particular not on computers people lend
us to test varnish on.</p>
<p>Travis is Linux only, which is fine if you run Linux only, but I don’t.</p>
<p>But worst of all: Neither of them fully understand of our varnishtest
tool, and therefore their failure reports are tedious and cumbersome
to use.</p>
<p>So, taking my friends advice, I sat down and wrote VTEST, which
consists of two small pieces of code: Tester and Reporter.</p>
<p>The tester is a small, 173 lines, <a class="reference external" href="https://github.com/varnishcache/varnish-cache/blob/master/tools/vtest.sh">portable and simple shell script</a>
which runs on the computer, physical or virtual, where we want
to test Varnish.</p>
<p>It obviously needs the compilers and tools we require to compile
Varnish, (autocrap, sphinx, graphviz) but it doesn’t anything
beyond that, in particular it does not need a java runtime, a
GUI or a hole in your firewall.</p>
<p>The tester sends a report to the project server with ssh(1), and
the reporter, which is just 750 lines of python code, ingests and
digests the report and spits out some <a class="reference external" href="http://varnish-cache.org/vtest/">pidgin HTML</a> with the information I actually
want to see.</p>
<p>And just like with the varnishtest program before it, once I
had done it, my first thought was <em>“Why didn’t I do that long time ago?”</em></p>
<p>So it is only fair to dedicate VTEST to the friend I chatted with:</p>
<img alt="../_images/bjarne.jpeg" src="../_images/bjarne.jpeg" />
<p><a class="reference external" href="http://www.stroustrup.com/">Bjarne</a> tried to model how to best
distribute operating system kernels across a network, wrote a
adequate programming language tool for the job, which was also
an adequate tool for a lot of other programming jobs.</p>
<p>Thanks Bjarne!</p>
<p>Poul-Henning, 2016-11-21</p>
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