Working With Rails

Template Optimizer

Welcome to the Rails Template Optimizer

The Rails Template Optimizer was designed to greatly enhance the performance of the rendering engine built into Rails.

The Rails Template Optimizer is available under the GPL LICENCE.

Requirements

The template optimizer depends on the functionality of Ryan Davis’ ParseTree package, which in turn requires his RubyInline package.

You can either download and install these, or obtain a standalone version of ParseTree from http://www.railsexpress.de/downloads.

The advantage of the second option is that you won’t need a C compiler on your production system.

Getting started

1. Install the software package into some directory of your choice <dir>. 2. Add "require <dir>/init.rb" to the end of RAILS_ROOT/config/environment.rb. 3. Create directory RAILS_ROOT/tmp/templates with appropriate permissions. 4. Optional: add configuration code to RAILS_ROOT/config/environment.rb

Alternatively you can install the template optimizer in the plugin directory of your Rails app.

NOTE: plugin support is currently broken, but will be fixed eventually.

How it works

Whenever the code for a Rails template gets compiled, the Rails Template Optimizer gets invoked in the context of the current controller’s view class, with the name of the compiled render method. It then retrieves the abstract syntax tree of the render method, processes it according to a set of configured optimization options, creates Ruby source code from the transformed tree and evaluates the new source to obtain an optimized version of the original method.

NOTE: you might want to make sure that the Template Optimizer doesn’t run in development mode.

Watching it perform

The original source code of a render method m gets logged to RAILS_ROOT/tmp/templates/m.src. The code for the optimized method is written to RAILS_ROOT/tmp/templates/m.rb.

Log information produced by the template optimizer is prefixed by the string "TO: ", which makes it easy to seach your log for optimizer problems.

Safety hazards

The original render method will be used by your app if optimization raises an exception. In rare cases, where the improved code doesn’t perform the way it should (raises exceptions or produces wrong results), optimization can be turned off for selected templates by specifying a list of regular expressions for method names which should be exempted from optimization.

NOTE: This description has been extracted from the Plugin README and so the formatting may need updating to make browser friendly