2. Usage

3. Implementation

4. Problems

5. Future Development

6. Lessons Learnt

8. I searched Thesaurus.com

10. Uses Redis which is fast and persistent

11. Allows expiry of aging data

12. Great for caching

14. Set Frivol::Config.redis_config= in environment.rb

15. include Frivol or Frivol::Config.include_in

16. Simply use store and retrieve methods

17. Stored keys are merged, not overwritten

18. expire_storage and delete_storage

19. Override storage_key if not using ActiveRecord

20. Usage – Example from Mad Mimi # environment.rb # Each environment has a REDIS_CONFIG, eg. development.rb: # REDIS_CONFIG = { :host => &quot;localhost&quot;, :port => 6379 } Frivol::Config.redis_config = REDIS_CONFIG # Frivol could be included in all AR models using: # Frivol::Config.include_in ActiveRecord::Base, 10.minutes # audience_list.rb class AudienceList < ActiveRecord::Base include Frivol storage_expires_in 1.day has_many :memberships, :dependent => :destroy has_many :audience_members, :through => :memberships # ... def list_size retrieve :list_size => :force_list_size_update end def force_list_size_update new_size = audience_members.size store :list_size => new_size new_size end # ... end

22. Uses Module#included (class methods)

24. Resolves symbols vs strings for keys

25. Json storage (network latency)

26. Implementation – Config & Included module Config def self.redis_config=(config) @@redis = Redis.new(config) end def self.redis @@redis end def self.include_in(host_class, storage_expires_in = nil) host_class.send(:include, Frivol) host_class.storage_expires_in storage_expires_in if storage_expires_in end end module ClassMethods def storage_expires_in(time) @frivol_storage_expiry = time end def storage_expiry @frivol_storage_expiry end end def self.included(host) host.extend(ClassMethods) end

27. Implementation - Helpers module Helpers def self.store_hash(instance) hash = instance.instance_variable_get(:@frivol_hash) is_new = instance.instance_variable_get(:@frivol_is_new) key = instance.send(:storage_key) Frivol::Config.redis[key] = hash.to_json if is_new instance.expire_storage instance.class.storage_expiry instance.instance_variable_set :@frivol_is_new, false end end def self.retrieve_hash(instance) return instance.instance_variable_get(:@frivol_hash) => if instance.instance_variable_defined? :@frivol_hash key = instance.send(:storage_key) json = Frivol::Config.redis[key] instance.instance_variable_set :@frivol_is_new, json.nil? hash = json.nil? ? {} : JSON.parse(json) instance.instance_variable_set :@frivol_hash, hash hash end def self.delete_hash(instance) key = instance.send(:storage_key) Frivol::Config.redis.del key instance.instance_variable_set :@frivol_hash, {} end end

28. Implementation – Instance Methods def store(keys_and_values) Frivol::Helpers.retrieve_hash self keys_and_values.each do |key, value| @frivol_hash[key.to_s] = value end Frivol::Helpers.store_hash self end def retrieve(keys_and_defaults) Frivol::Helpers.retrieve_hash self result = keys_and_defaults.map do |key, default| @frivol_hash[ key.to_s ] || ( default.is_a?(Symbol) && respond_to?(default) && => send(default) ) || default end return result.first if result.size == 1 result end def delete_storage Frivol::Helpers.delete_hash self end def expire_storage(time) return if time.nil? Frivol::Config.redis.expire storage_key, time end def storage_key @frivol_key ||= &quot;#{self.class.name}-#{id}&quot; end

32. retrieve with a splat, instead of hash

35. retrieve_default method to override class set default

39. OpenOffice is pretty aweful for creating presentations (but it works)