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<?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.
*
* $Id$
*
* @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 tags for this item
* @param integer number of seconds until the cache expires
* @return boolean
*/
function set($id, $data, array $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, $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
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