/**
  * Push the client to the pending client queue
  * @param  array $client
  * @author Devin.Jin
  */
 public static function enQueue($client)
 {
     if (empty(self::findOne(['openId' => $client['openId']]))) {
         $pendingClient = new PendingClient();
         $pendingClient->load($client, '');
         $pendingClient->lastPingTime = TimeUtil::msTime();
         if (!$pendingClient->save()) {
             LogUtil::error(['error' => 'Save pending client failed', 'errors' => $pendingClient->getErrors()], 'helpdesk');
             throw new ServerErrorHttpException("failed to save pending client for unknown reason");
         }
     }
 }