MongoDB Output Cache for CodeIgniter
by James Constable
me@jamesconstable.co.uk
@weejames

06/07/2010

Intro:
This library allows you to use MongoDB as a frontend caching mechanism for CodeIgniter.  It overrides the underlying functions associated with the standard web page caching functionaloty described 
here: http://codeigniter.com/user_guide/general/caching.html

Requirements:
Existing MongoDB Server
CodeIgniter 1.7.2
PHP 5.2 (not a requirement but that's all i've tested with)
PHP MongoDB extention (pecl install mongo)

Usage:

1) Place MY_Output.php in application/libraries/ (if you've changed the subclass_prefix configuration you may need to alter the filename).
2) Place the mongodb.php in application/config/ and fill in the values appropriately.
3) Enable caching in the appropriate controllers.

The functions are syntactically compatible with the existing cache functionality and caches are still enabled using $this->output->cache(n) within your controllers. Cached pages will still persist 
until expiration, or the cache is cleared.

Note: Unlike the CodeIgniter library, this modification also takes into account the contents of the $_GET and $_POST arrays when caching data.