<?php
/**
 * Class Minify_Cache_APC
 * @package Minify
 */

/**
 * APC-based cache class for Minify
 * 
 * <code>
 * Minify::setCache(new Minify_Cache_APC());
 * </code>
 * 
 * @package Minify
 * @author Chris Edwards
 **/
class Minify_Cache_APC {

 /**
 * Create a Minify_Cache_APC object, to be passed to
 * Minify::setCache().
 *
 *
 * @param int $expire seconds until expiration (default = 0
 * meaning the item will not get an expiration date)
 *
 * @return null
 */
 public function __construct($expire = 0)
 {
 $this->_exp = $expire;
 }

 /**
 * Write data to cache.
 *
 * @param string $id cache id
 *
 * @param string $data
 *
 * @return bool success
 */
 public function store($id, $data)
 {
 return apc_store($id, "{$_SERVER['REQUEST_TIME']}|{$data}", $this->_exp);
 }

 /**
 * Get the size of a cache entry
 *
 * @param string $id cache id
 *
 * @return int size in bytes
 */
 public function getSize($id)
 {
 if (! $this->_fetch($id)) {
 return false;
 }
 return (function_exists('mb_strlen') && ((int)ini_get('mbstring.func_overload') & 2))
 ? mb_strlen($this->_data, '8bit')
 : strlen($this->_data);
 }

 /**
 * Does a valid cache entry exist?
 *
 * @param string $id cache id
 *
 * @param int $srcMtime mtime of the original source file(s)
 *
 * @return bool exists
 */
 public function isValid($id, $srcMtime)
 {
 return ($this->_fetch($id) && ($this->_lm >= $srcMtime));
 }

 /**
 * Send the cached content to output
 *
 * @param string $id cache id
 */
 public function display($id)
 {
 echo $this->_fetch($id)
 ? $this->_data
 : '';
 }

 /**
 * Fetch the cached content
 *
 * @param string $id cache id
 *
 * @return string
 */
 public function fetch($id)
 {
 return $this->_fetch($id)
 ? $this->_data
 : '';
 }

 private $_exp = null;

 // cache of most recently fetched id
 private $_lm = null;
 private $_data = null;
 private $_id = null;

 /**
 * Fetch data and timestamp from apc, store in instance
 *
 * @param string $id
 *
 * @return bool success
 */
 private function _fetch($id)
 {
 if ($this->_id === $id) {
 return true;
 }
 $ret = apc_fetch($id);
 if (false === $ret) {
 $this->_id = null;
 return false;
 }
 list($this->_lm, $this->_data) = explode('|', $ret, 2);
 $this->_id = $id;
 return true;
 }
}