<?php
/**
 * Caching: cache driver Memcache
 *
 * $Id$
 *
 * @author gERD Schaufelberger <gerd@php-tools.net>
 * @license PHP License
 * @package WB
 * @subpackage base
 */

/**
 * load base class
 */
WBClass::load('WBCache_Driver');

/**
 * Caching: cache driver Memcache
 *
 * Use MemCache-Daemon to store cache data
 *
 * http://www.php.net/memcache and
 * http://pecl.php.net/package/memcache
 *
 * Memcached is a caching daemon designed especially for dynamic web applications
 * to decrease database load by storing objects in memory. The extension allows
 * you to work with memcached through handy OO and procedural interfaces.
 *
 * @version 0.1.1
 * @package WB
 * @subpackage base
 */
class WBCache_Driver_Memcache extends WBCache_Driver
{
   /**
    * memcache
    * @var Memcache
    */
    protected $mc;

    /**
     * cache key prefix
     * @var string
     */
    protected $prefix;

   /**
    * constructor
    *
    * Load index file
    */
    public function __construct()
    {
        // start memcache
        $host       =   WBParam::get('wb/cache/memcache/host', 'localhost');
        $port       =   WBParam::get('wb/cache/memcache/host', 11211);
        $this->mc   =   new Memcache();
        $this->mc->connect($host, $port);

        // load index
        $this->_index   =   array();
        $this->prefix   =   WBParam::get('wb/dir/base') . '/';
        $index          =   $this->mc->get($this->prefix . '_index');
        if (strlen($index)) {
            $this->_index   =   unserialize($index);
        }
    }

   /**
    * destruct
    *
    * Save index in memcache
    */
    public function __destruct()
    {
        $this->set($this->prefix . '_index', $this->_index);
    }

   /**
    * fetch cached data
    *
    * @param string $id cache id
    * @return mixed return data or null if not cached yet
    */
    public function get($id)
    {
        $cnt    =   $this->mc->set($this->prefix . $id);
        if (!$cnt) {
            return null;
        }

        return unserialize($cnt);
    }

   /**
    * store data in cache
    *
    * @param string $id cache id
    * @return mixed return data or null if not cached yet
    */
    public function set($id, $data)
    {
        $cnt    =   serialize($data);
        if (!$this->mc->replace($this->prefix . $id, $cnt)) {
            $this->mc->set($this->prefix . $id, $cnt);
        }
        return true;
    }

   /**
    * flush cached data
    *
    * @param string $id cache id
    * @return bool true on success
    */
    public function flush($id)
    {
        $this->mc->delete($this->prefix . $id);
        return true;
    }
}
?>