app.rb

class Bench
  def counter
    @@counter ||= 0
  end

  def call(env)
    STDOUT.puts "beginning request #{counter}"
    sleep 45 if env['PATH_INFO'] == '/timeout'
    body = 'OK'
    headers = {
      'Content-Type'   => 'text/html; charset=utf-8',
      'Content-Length' => body.size.to_s,
      'Cache-Control'  => 'private, no-store'
    }
    STDOUT.puts "finished request #{counter}"
    @@counter += 1
    [200, headers, [body]]
  end
end