code: func newMeteredConn(conn net.Conn, ingress bool, ip net.IP) net.Conn {
  	// Short circuit if metrics are disabled
  	if !metrics.Enabled {
  		return conn
  	}
  	if ip.IsUnspecified() {
  		log.Warn("Peer IP is unspecified")
  		return conn
  	}
  	// Bump the connection counters and wrap the connection
  	if ingress {
  		ingressConnectMeter.Mark(1)
  	} else {
  		egressConnectMeter.Mark(1)
  	}
  	return &meteredConn{
  		Conn:      conn,
  		ip:        ip,
  		connected: time.Now(),
  	}
  }
docs: // newMeteredConn creates a new metered connection, bumps the ingress or egress
  // connection meter and also increases the metered peer count. If the metrics
  // system is disabled or the IP address is unspecified, this function returns
  // the original object.