sheen.rb

class Sheen
  include Celluloid

  def initialize(name)
    @name = name
  end

  def set_status(status)
    @status = status
  end

  def report
    Rails.cache.fetch(:report, expires_in: 20.seconds) do
      puts "Taking a nap..."
      sleep(5)
      "#{@name} is #{@status}"
    end
  end
end

So you want to cache the output of future.report and next time report is called, not actually run the method?