<"Error:dir is not exist.";
   $result = 0;
  }
  return $result;
 }
 /**
  * @return array 
  *   0 no cache
  *    1 cached
  *    2 overdue
  */
 public function getCache ($key) {
  $cache_file = $this->cache_dir . '/xzcache_' . md5($key);
  if (is_dir($this->cache_dir) && is_file($cache_file)) {
   $timedif = @(time() - filemtime($cache_file));
   if ($timedif >= $this->cache_time) {
    $result['cached'] = 2;
   }else{
    // cached file is fresh enough, return cached array
    $result['value'] = unserialize(file_get_contents($cache_file));
    $result['cached'] = 1;
   }
  }else {
   echo "Error:no cache";
   $result['cached'] = 0;
  }
  return $result;
 }
} //end of class

$cache = new XZCache();
$key = 'global';
$value = $GLOBALS;
$cache->saveCache($key, $value);
$result = $cache->getCache($key);
var_dump($result);