Rename 'kohana' to 'system' to conform to the Kohana filesystem layout. I'm comfortable with us not clearly drawing the distinction about the fact that it's Kohana.

system/libraries/Cache.php

@@ -0,0 +1,208 @@
+<?php defined('SYSPATH') OR die('No direct access allowed.');
+/**
+ * Provides a driver-based interface for finding, creating, and deleting cached
+ * resources. Caches are identified by a unique string. Tagging of caches is
+ * also supported, and caches can be found and deleted by id or tag.
+ *
+ * $Id: Cache.php 4321 2009-05-04 01:39:44Z kiall $
+ *
+ * @package    Cache
+ * @author     Kohana Team
+ * @copyright  (c) 2007-2008 Kohana Team
+ * @license    http://kohanaphp.com/license.html
+ */
+class Cache_Core {
+
+	protected static $instances = array();
+
+	// For garbage collection
+	protected static $loaded;
+
+	// Configuration
+	protected $config;
+
+	// Driver object
+	protected $driver;
+
+	/**
+	 * Returns a singleton instance of Cache.
+	 *
+	 * @param   string  configuration
+	 * @return  Cache_Core
+	 */
+	public static function & instance($config = FALSE)
+	{
+		if ( ! isset(Cache::$instances[$config]))
+		{
+			// Create a new instance
+			Cache::$instances[$config] = new Cache($config);
+		}
+
+		return Cache::$instances[$config];
+	}
+
+	/**
+	 * Loads the configured driver and validates it.
+	 *
+	 * @param   array|string  custom configuration or config group name
+	 * @return  void
+	 */
+	public function __construct($config = FALSE)
+	{
+		if (is_string($config))
+		{
+			$name = $config;
+
+			// Test the config group name
+			if (($config = Kohana::config('cache.'.$config)) === NULL)
+				throw new Kohana_Exception('cache.undefined_group', $name);
+		}
+
+		if (is_array($config))
+		{
+			// Append the default configuration options
+			$config += Kohana::config('cache.default');
+		}
+		else
+		{
+			// Load the default group
+			$config = Kohana::config('cache.default');
+		}
+
+		// Cache the config in the object
+		$this->config = $config;
+
+		// Set driver name
+		$driver = 'Cache_'.ucfirst($this->config['driver']).'_Driver';
+
+		// Load the driver
+		if ( ! Kohana::auto_load($driver))
+			throw new Kohana_Exception('core.driver_not_found', $this->config['driver'], get_class($this));
+
+		// Initialize the driver
+		$this->driver = new $driver($this->config['params']);
+
+		// Validate the driver
+		if ( ! ($this->driver instanceof Cache_Driver))
+			throw new Kohana_Exception('core.driver_implements', $this->config['driver'], get_class($this), 'Cache_Driver');
+
+		Kohana::log('debug', 'Cache Library initialized');
+
+		if (Cache::$loaded !== TRUE)
+		{
+			$this->config['requests'] = (int) $this->config['requests'];
+
+			if ($this->config['requests'] > 0 AND mt_rand(1, $this->config['requests']) === 1)
+			{
+				// Do garbage collection
+				$this->driver->delete_expired();
+
+				Kohana::log('debug', 'Cache: Expired caches deleted.');
+			}
+
+			// Cache has been loaded once
+			Cache::$loaded = TRUE;
+		}
+	}
+
+	/**
+	 * Fetches a cache by id. NULL is returned when a cache item is not found.
+	 *
+	 * @param   string  cache id
+	 * @return  mixed   cached data or NULL
+	 */
+	public function get($id)
+	{
+		// Sanitize the ID
+		$id = $this->sanitize_id($id);
+
+		return $this->driver->get($id);
+	}
+
+	/**
+	 * Fetches all of the caches for a given tag. An empty array will be
+	 * returned when no matching caches are found.
+	 *
+	 * @param   string  cache tag
+	 * @return  array   all cache items matching the tag
+	 */
+	public function find($tag)
+	{
+		return $this->driver->find($tag);
+	}
+
+	/**
+	 * Set a cache item by id. Tags may also be added and a custom lifetime
+	 * can be set. Non-string data is automatically serialized.
+	 *
+	 * @param   string        unique cache id
+	 * @param   mixed         data to cache
+	 * @param   array|string  tags for this item
+	 * @param   integer       number of seconds until the cache expires
+	 * @return  boolean
+	 */
+	function set($id, $data, $tags = NULL, $lifetime = NULL)
+	{
+		if (is_resource($data))
+			throw new Kohana_Exception('cache.resources');
+
+		// Sanitize the ID
+		$id = $this->sanitize_id($id);
+
+		if ($lifetime === NULL)
+		{
+			// Get the default lifetime
+			$lifetime = $this->config['lifetime'];
+		}
+
+		return $this->driver->set($id, $data, (array) $tags, $lifetime);
+	}
+
+	/**
+	 * Delete a cache item by id.
+	 *
+	 * @param   string   cache id
+	 * @return  boolean
+	 */
+	public function delete($id)
+	{
+		// Sanitize the ID
+		$id = $this->sanitize_id($id);
+
+		return $this->driver->delete($id);
+	}
+
+	/**
+	 * Delete all cache items with a given tag.
+	 *
+	 * @param   string   cache tag name
+	 * @return  boolean
+	 */
+	public function delete_tag($tag)
+	{
+		return $this->driver->delete($tag, TRUE);
+	}
+
+	/**
+	 * Delete ALL cache items items.
+	 *
+	 * @return  boolean
+	 */
+	public function delete_all()
+	{
+		return $this->driver->delete(TRUE);
+	}
+
+	/**
+	 * Replaces troublesome characters with underscores.
+	 *
+	 * @param   string   cache id
+	 * @return  string
+	 */
+	protected function sanitize_id($id)
+	{
+		// Change slashes and spaces to underscores
+		return str_replace(array('/', '\\', ' '), '_', $id);
+	}
+
+} // End Cache