cache.rb

module Virt
  class Cache
    attr_accessor :ttl

    def initialize args
      # default TTL is one hour
      @ttl = args[:ttl] || 3600
      reset
    end

    def store key, value
      @data[key] = [current_time, value]
      true
    end

    def read key
      find(key)[1] unless expired?(key)
    end

    def clear key
      @data[key] = nil if key
    end

    def expired? key
      if value = find(key)
        current_time - value[0] <= ttl
      else
        clear(key)
      end
    end

    def size
      @data.keys.size
    end

    def reset
      @data = {}
    end

    def [] key
      read(key)
    end

    def []= key,value
      store(key, value)
    end

    private # -------------------------------

    def current_time
      Time.now
    end

    def find key
      return unless value = @data[key]
      return clear(key) unless value[0].is_a?(Time)
      value
    end

  end
end