Rate limiting specific Rails routes

rate-limit-routes.rb

class RateConstraint
  def matches?(request)
    last_request = request.session[:request_time]
    request.session[:request_time] = Time.now
    !(last_request and (Time.now - last_request < 2.second))
  end
end

Application.routes.draw do
  constraints RateConstraint.new do
    # Routes within this constraint will fail if the requests occur within 2 seconds of each other.
    # This should be faster than rate limiting using the controllers and models.
    # Rack middleware would probably be faster still, but I prefer the routes approach.
  end
end