CodeIgniter Caching Class Subfolder Driver

<?php if ( ! defined('BASEPATH')) exit('No direct script access allowed');
/**
 * CodeIgniter
 *
 * An open source application development framework for PHP 4.3.2 or newer
 *
 * @package     CodeIgniter
 * @author      ExpressionEngine Dev Team
 * @copyright   Copyright (c) 2006 - 2012 EllisLab, Inc.
 * @license     http://codeigniter.com/user_guide/license.html
 * @link        http://codeigniter.com
 * @since       Version 2.0
 * @filesource
 */

// ------------------------------------------------------------------------

/**
 * CodeIgniter Memcached Caching Class
 *
 * @package     CodeIgniter
 * @subpackage  Libraries
 * @category    Core
 * @author      ExpressionEngine Dev Team
 * @link
 */

class CI_Cache_file extends CI_Driver {

    protected $_cache_path;

    /**
     * Constructor
     */
    public function __construct()
    {
        $CI =& get_instance();
        $CI->load->helper('file');

        $path = $CI->config->item('cache_path');

        $this->_cache_path = ($path == '') ? APPPATH.'cache/' : $path;
    }

    // ------------------------------------------------------------------------

    /**
     * Fetch from cache
     *
     * @param   mixed       unique key id
     * @return  mixed       data on success/false on failure
     */
    public function get($id)
    {
        if ( ! file_exists($this->_cache_path.$id))
        {
            return FALSE;
        }

        $data = read_file($this->_cache_path.$id);
        $data = unserialize($data);

        if (time() >  $data['time'] + $data['ttl'])
        {
            unlink($this->_cache_path.$id);
            return FALSE;
        }

        return $data['data'];
    }

    // ------------------------------------------------------------------------

    /**
     * Save into cache
     *
     * @param   string      unique key
     * @param   mixed       data to store
     * @param   int         length of time (in seconds) the cache is valid
     *                      - Default is 60 seconds
     * @return  boolean     true on success/false on failure
     */
    public function save($id, $data, $ttl = 60)
    {
        $contents = array(
                'time'      => time(),
                'ttl'       => $ttl,
                'data'      => $data
            );

        if (write_file($this->_cache_path.$id, serialize($contents)))
        {
            @chmod($this->_cache_path.$id, 0777);
            return TRUE;
        }

        return FALSE;
    }

    // ------------------------------------------------------------------------

    /**
     * Delete from Cache
     *
     * @param   mixed       unique identifier of item in cache
     * @return  boolean     true on success/false on failure
     */
    public function delete($id)
    {
        return @unlink($this->_cache_path.$id);
    }

    // ------------------------------------------------------------------------

    /**
     * Clean the Cache
     *
     * @return  boolean     false on failure/true on success
     */
    public function clean()
    {
        return delete_files($this->_cache_path);
    }

    // ------------------------------------------------------------------------

    /**
     * Cache Info
     *
     * Not supported by file-based caching
     *
     * @param   string  user/filehits
     * @return  mixed   FALSE
     */
    public function cache_info($type = NULL)
    {
        return get_dir_file_info($this->_cache_path);
    }

    // ------------------------------------------------------------------------

    /**
     * Get Cache Metadata
     *
     * @param   mixed       key to get cache metadata on
     * @return  mixed       FALSE on failure, array on success.
     */
    public function get_metadata($id)
    {
        if ( ! file_exists($this->_cache_path.$id))
        {
            return FALSE;
        }

        $data = read_file($this->_cache_path.$id);
        $data = unserialize($data);

        if (is_array($data))
        {
            $mtime = filemtime($this->_cache_path.$id);

            if ( ! isset($data['ttl']))
            {
                return FALSE;
            }

            return array(
                'expire'    => $mtime + $data['ttl'],
                'mtime'     => $mtime
            );
        }

        return FALSE;
    }

    // ------------------------------------------------------------------------

    /**
     * Is supported
     *
     * In the file driver, check to see that the cache directory is indeed writable
     *
     * @return boolean
     */
    public function is_supported()
    {
        return is_really_writable($this->_cache_path);
    }

    // ------------------------------------------------------------------------
}
// End Class

/* End of file Cache_file.php */
/* Location: ./system/libraries/Cache/drivers/Cache_file.php */