DC Pagecache

A simple page caching for kohana.

When to use?

When you are serving mostly static content
When content does not change for a long period
When you simply want page caching and knows when to clear cache

How to use?

Simple. For a given URI (request), you will capture the output and feed it to the pagecache object. The pagecache will then save the output to a directory. The next time the user requests the same URI, your webserver will serve the cached content without bothering Kohana.

You will just need to configure the following:

Publicly accessible directory where you save the cached content
A certain URI pattern that can actually match a valid filename (ex: no space)
A RewriteRule that will serve the cached content for a given URI
A controller that will capture the output of the request and will save it to cache

Configuration

The default cache directory is at DOCROOT/media/pagecache but you can change it anytime. This is the default config at MODPATH/pagecache/config/pagecache.php

return array(
	'cache_dir'		=> DOCROOT.'media/pagecache'
);

Assuming that DOCROOT/media is accessible directly from the outside world.

URI pattern

It is assumed that your URI can be directly mapped to a valid filename. Ex:

/ will map to /index.html
/contact will map to /contact/index.html
/about/mission will map to /about/mission/index.html

Using the default config, it will map to:

/ will map to /media/pagecache/index.html
/contact will map to /media/pagecache/contact/index.html
/about/mission will map to /media/pagecache/about/mission/index.html

Simple isn't it?

The Rewrite Rule

# BEGIN Page cache

RewriteRule ^/(.*)/$ /$1 [QSA]
RewriteRule ^$ media/pagecache/index.html [QSA]
RewriteRule ^([^.]+)/$ media/pagecache/$1/index.html [QSA]
RewriteRule ^([^.]+)$ media/pagecache/$1/index.html [QSA]

 # END Page cache

The Rewrite rule above will accomplish the URI pattern matching. However, you must configure Kohana so that it will hide index.php from the URL by setting index_file in bootstrap to FALSE.

The above rewrite rule will need the following rewrite rule for Kohana:

# Protect application and system files from being viewed
RewriteRule ^(?:application|modules|system)\b - [F,L]

RewriteCond %{REQUEST_FILENAME} -s [OR]
RewriteCond %{REQUEST_FILENAME} -l [OR]
RewriteCond %{REQUEST_FILENAME} -d

RewriteRule ^.*$ - [NC,L]
RewriteRule ^.*$ index.php [NC,L]

If I'm not mistaken, the above rewrite rule is from either an old version of Kohana's rewrite rule or it may came from Zend Framework style rewrite. Below is the current rewrite sample for Kohana 3.1.2 which does not work for the Pagecache.

# Protect application and system files from being viewed
RewriteRule ^(?:application|modules|system)\b.* index.php/$0 [L]

# Allow any files or directories that exist to be displayed directly
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d

# Rewrite all other URLs to index.php/URL
RewriteRule .* index.php/$0 [PT]

Capturing and saving output / page

The basic usage goes like this:

Pagecache::factory('/the/requested/uri')
	->write($the_page_output);

Currently, I used a controller to facilitate the page caching. Once a controller extends to this controller, it will automatically trigger output to be cached.

abstract class Controller_Cached extends Controller_Template {
	
	public function after()
	{
		parent::after();

		$uri = Arr::get($_SERVER, 'REQUEST_URI', $this->request->uri());

		Pagecache::factory($uri)
			->write($this->response->body());
	}
}

It assumes that the controller uses a template. Once the after() method is called, it will capture the response and save it to cache using the current request URI.

For example you have a controller Controller_Faq, you can serve cached page by extending the Controller_Cached.

class Controller_Faq extends Controller_Cached {
	// The rest of the code here

Cleaning up

To clear your cached files, call Pagecache::cleanup(). You can schedule clearing the cache via CRON, whatever fits your need. Note that cleanup() will delete all the cached pages, which effectively refreshes your pages contents.

Currently, there is no such thing as garbage collection (as you may observe on several caching solutions such as WP Super Cache. This feature may be added in the future if need arises.

Web Administration

In development environment, you can administer the Pagecache module by visiting /pagecache/console. Currently, it has two operations:

Test cache - to test it page caching works in your current setup
Clear cache - clears / deletes all cached pages

It can only be accessible when Kohana::$environment === Kohana::DEVELOPMENT.

Tests?

Yes, there are tests for the code Pagecache class.

avillagran/pagecache