Caching the response for a single page in Sinatra.

sinatra_page_cache.rb

get '/' do
  if !File.exist?('cache') || (File.mtime('cache') < (Time.now - 1800))
    puts "**********CACHE MISS**********"
    data = erb(:index)
    File.open('cache',"w"){ |f| f << data }
  else
    puts "**********CACHE HIT**********"
  end
  send_file 'cache', :type => 'html'
end