public function save($content, $lock = LOCK_EX)
 {
     $this->_open("w+");
     $lock = new Lock($this);
     switch (LOCK_SH) {
         case LOCK_NB:
             $lock->nb();
             break;
         case LOCK_EX:
             $lock->ex();
             break;
         default:
             $lock->ex();
     }
     if (!$this->_fileModeInfo($this->fileName)) {
         throw new Exception("Cache File " . realpath($this->fileName) . "  Can't write'");
     }
     $result = fwrite($this->handle, $content);
     $lock->unlock();
     $this->_close();
     return $result;
 }