docs: function defRoute(session, msg, context, cb) {
      const list = context.getServersByType(msg.serverType);
      if (!list || !list.length) {
          cb(new Error(`can not find server info for type:${msg.serverType}`));
          return;
      }
      const uid = session ? (session.uid || '') : '';
      const index = Math.abs(crc.crc32(uid.toString())) % list.length;
      utils.invokeCallback(cb, null, list[index].id);
  }