code: @Override
  	public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
  		HttpServletRequest req = HttpServletRequest.class.cast(request);
  		long start = System.currentTimeMillis();
  
  		try {
  			chain.doFilter(request, response);
  		} finally {
  			long delta = System.currentTimeMillis() - start;
  			HttpServletResponse resp = HttpServletResponse.class.cast(response);
  
  			updateCounters(req, resp, delta);
  		}
  	}
docs: Updates performance counters using the Argus monitoring service.
  
  @param   request   The HTTP request.
  @param   response  The HTTP response.
  @param   chain     The filter chain to execute.
  
  @throws  IOException       If an I/O error occurs.
  @throws  ServletException  If an unknown error occurs.