@@ -79,6 +79,15 @@ With a limit attribute, indices will only store limit + buffer in the cache. As `Message.count(:all, :conditions => {:sender_id => ...})` will use the cache rather than the database. This happens for "free" -- no additional declarations are necessary. +### Version Numbers ### + + class User + version 7 + index ... + end + +You can increment the version number as you migrate your schema. + ### Transactions ### Because of the parallel requests writing to the same indices, race conditions are possible. We have created a pessimistic "transactional" memcache client to handle the locking issues. @@ -136,7 +145,6 @@ Sometimes your code will request the same cache key twice in one request. You ca #### Step 1: `config/initializers/cache_money.rb` #### Place this in `config/initializers/cache_money.rb` - require 'cache_money' config = YAML.load(IO.read(File.join(RAILS_ROOT, "config", "memcache.yml")))[RAILS_ENV] README.markdown @@ -66,7 +66,7 @@ module Cash end def cache_key(key) - "#{name}/#{key.to_s.gsub(' ', '+')}" + "#{name}:#{cache_config.version}/#{key.to_s.gsub(' ', '+')}" end end lib/cash/accessor.rb @@ -10,6 +10,7 @@ module Cash module ClassMethods def self.extended(a_class) class << a_class + attr_reader :cache_config delegate :repository, :indices, :to => :@cache_config alias_method_chain :inherited, :cache_config end @@ -25,6 +26,10 @@ module Cash (@cache_config.indices.unshift(Index.new(@cache_config, self, attributes, options))).uniq! end + def version(number) + @cache_config.options[:version] = number + end + def cache_config=(config) @cache_config = config end @@ -50,6 +55,10 @@ module Cash @options[:ttl] end + def version + @options[:version] || 1 + end + def indices @indices ||= active_record == ActiveRecord::Base ? [] : [Index.new(self, active_record, active_record.primary_key)] end lib/cash/config.rb @@ -22,8 +22,8 @@ module Cash describe 'when there is a total cache miss' do it 'yields the keys to the block' do Story.fetch(["yabba", "dabba"]) { |*missing_ids| ["doo", "doo"] }.should == { - "Story/yabba" => "doo", - "Story/dabba" => "doo" + "Story:1/yabba" => "doo", + "Story:1/dabba" => "doo" } end end @@ -32,8 +32,8 @@ module Cash it 'yields just the missing ids to the block' do Story.set("yabba", "dabba") Story.fetch(["yabba", "dabba"]) { |*missing_ids| "doo" }.should == { - "Story/yabba" => "dabba", - "Story/dabba" => "doo" + "Story:1/yabba" => "dabba", + "Story:1/dabba" => "doo" } end end @@ -145,5 +145,15 @@ module Cash end end end + + describe '#cache_key' do + it 'uses the version number' do + Story.version 1 + Story.cache_key("foo").should == "Story:1/foo" + + Story.version 2 + Story.cache_key("foo").should == "Story:2/foo" + end + end end end spec/cash/accessor_spec.rb 1024a91c27c795df01837e2de24c70b37fc3349e Nick Kallen nkallen@nick-kallens-computer-2.local http://github.com/brynary/cache-money/commit/6af729a08644a6e0aa361d901d223865249b1f3f 6af729a08644a6e0aa361d901d223865249b1f3f 2008-12-11T21:52:14-08:00 2008-12-11T21:52:14-08:00 version numbers 44f34a4de4478fb2f9440c25056ea6f89a147650 Nick Kallen nkallen@nick-kallens-computer-2.local