Quick braindump on how would one implement a mint store in rack:cache, I haven't tested this, so it probably doesn't work :-)

gistfile1.rb

# NB: I just wrote this to see how one would go about writing a mint store in rack cache and
# how hard it would be. I haven't tested it or even runned it so it most probably doesn't work (I'll
# play with it when I have more time)

module Rack::Cache
  class MetaStore
    # Stores request/response pairs in memcached. Keys are not stored
    # directly since memcached has a 250-byte limit on key names. Instead,
    # the SHA1 hexdigest of the key is used.
    # Uses the mint store algorithm
    class MintStore < Memcache
      attr_reader :options
      
      def initialize(server="localhost:11211", options={})
        @options = {:refresh_delay => 30}
        @options.merge!(options.only(:refresh_delay))
        super(server, options)
      end
      
      def lookup(request, entity_store)
        response = super        
        if response && response.freshness_information? && response.stale?
          response.max_age += options[:refresh_delay]
          self.store(request, response, entity_store)
          nil
        else
          response
        end
      end

      extend Rack::Utils

      # Create Mintstorn store for the given URI. The URI must specify
      # a host and may specify a port, namespace, and options:
      #
      # memcached://example.com:11211/namespace?opt1=val1&opt2=val2
      #
      # Query parameter names and values are documented with the memcached
      # library: http://tinyurl.com/4upqnd
      def self.resolve(uri)
        server = "#{uri.host}:#{uri.port || '11211'}"
        options = parse_query(uri.query)
        options.keys.each do |key|
          value =
            case value = options.delete(key)
            when 'true' ; true
            when 'false' ; false
            else value.to_sym
            end
          options[k.to_sym] = value
        end
        options[:namespace] = uri.path.sub(/^\//, '')
        new server, options
      end
    end
  end
end