#title=FCSH for ASC 2.0 Compiler
#preview=air.jpg
#tags=#Actionscript,#Mobile,#Linux,#Windows,#Mac,#AIR,#Compiler

<p>If you remember how the fcsh / fcshd compiler wrappers sped up the Flex SDK compiler (or if you've noticed that the Flash Builder compiler is much faster than, say, Flash Develop), read on.  Your AS3 workflow may get a performance boost from my new tools, ascsh and ascshd.<span class="break"/></p>

<h2>Backstory</h2>

<a href="http://www.adobe.com/products/air.html"><img class="thumbnail" src="./sm.air.jpg"></a>

<p>Under the hood, Flash Builder has access to a memory-resident compiler that incrementally recompiles ActionScript 3 much faster than spinning up the compiler each time.  In the old Flex SDK, Adobe delivered a tool called fcsh (flex compiler shell) that allowed command line and third party workflows (aka Flash Develop) access to this fast compilation mechanism.  Some clever coders wrapped this tool in something called <span class="cmd">fcshd</span> (fcsh daemon) that converted the awkward shell interface into a slick compiler service.  And the as3 developers rejoiced.</p>

<p>Fast forward to present day, and the <a href="http://www.bytearray.org/?p=4789">newer ASC 2.0 compiler</a> in the AIR SDK is replacing the old Flex SDK compiler.  As cool as this slick new compiler is (with bug fixes and features like inlining and advanced telemetry), it doesn't include a tool like fcsh to expose fast compilation outside Flash Builder.  I'm not sure if this was an oversight, a simplification, or an effort to differentiate Flash Builder.  But as you know I'm an <a href="http://jcward.com/Adobe+AIR+Mobile+Development+On+Linux">avid command line workflow user</a>, and I've been quite frustrated by this omission... Until now!</p>

<pre>#IrritatedHackerEqualsProblemSolved =D</pre>

<h2>Hacking ascsh and ascshd</h2>

<p>Looking into the ASC 2.0 compiler.jar, I noticed that the MXMLC and COMPC classes (those that compile SWFs and SWCs, respectively) have a <span class="cmd">staticMainNoExit(args)</span> function.  This is envoked when you type mxmlc on the command line.  A quick wrapper around this call reveals that calling this function repeatedly (without exiting) did indeed pick up new code changes and reduce compile times significantly.  Adding a simple shell interface around this (to parse arguments), ascsh was born.  And just as fcshd is a socket-server wrapper around fcsh, ascshd maintains the ascsh shell in a background thread and passes compilation jobs to it.</p>

<p>I've open-sourced the <a href="https://github.com/jcward/ascsh">ascsh and ascshd project on github</a>.  It includes setup and usage instructions and scripts.</p>

<p>The idea is that you can replace <span class="cmd">mxmlc ...</span> in your build scripts with <span class="cmd">ascshd mxmlc ...</span>, and the scripts maintain a background compiler process that makes your builds faster.  In a simple test project and a large project, I've seen up to 4X improvement in compile times:</p>

<div class="image"><img src="./ascsh.png"/></div>

<p>The tools should work under Windows*, Mac, and of course, Linux.  Ideally Flash Develop users may be able to tweak their .bat scripts to use them as well, though the current implementation of ascshd may not be Windows-friendly (see below.)

<h2>Disclaimers</h2>

<p>Ok, a couple disclaimers:</p>

<ul>
<li>At this time, while ascsh is Java and works fine in Windows, ascshd is written in Ruby, and it uses process I/O, sockets, and forks a background thread.  I've had problems getting it to work in Windows.  If anyone wants to contribute a working ascshd wrapper (in any language) for Windows, that'd be swell.  I'm not sure how fcsh worked with Flash Develop, but potentially ascsh should be able to work the same way.</li>
<li>ascsh is a very simple wrapper around mxmlc and compc, and this is all somewhat of a hack.  All the magic happens in the MXMLC/COMPC classes.  Adobe could change the SDK at any point to break these tools.  But it works great through AIR SDK 3.9, and is likely to continue working (assuming Flash Builder relies on the same functionality.)</li>
<li>These tools are in an early stage.  For instance, fcsh had a target/compile id feature, and I didn't implement that.  It didn't seem to be necessary in my usecases.  Please report any issues on github.  Use it to speed up your development workflows, but I suggest you build your final production SWFs with Adobe's tools directly.</li>
<li>I've occasionally seen issues running ascshd from a Ruby build script even in Linux, and I've had to manually start/kill the ascshd server.  This level of fiddling wasn't uncommon in the days of fcshd.  Someone can probably help me solidify the Ruby socket server.</li>
</ul>