# File lib/caches/cachetastic_caches_base.rb, line 153
    def calculate_expiry_time(expiry) # :doc:
      exp_swing = adapter.all_options["expiry_swing"]
      if exp_swing
        swing = rand(exp_swing.to_i)
        case rand(2)
        when 0
          expiry = (expiry.to_i + swing)
        when 1
          expiry = (expiry.to_i - swing)
        end
      end
      expiry
    end