* activesupport cache with cas first implemented

* tests for single cas

lib/active_support/cache/redis_store_with_cas.rb

+require 'active_support'
+require 'redis-store-with-cas'
+require 'active_support/cache/redis_store'
+
+module ActiveSupport
+  module Cache
+    module RedisStoreCas
+
+      attr_accessor :read_only
+
+      def cas name,options=nil
+        options = merged_options(options)
+        key = normalize_key(name, options)
+        instrument(:cas, name, options) do
+          ttl = cas_expiration options
+          @data.cas(key,ttl) do |entry|
+            value = yield entry.value
+            break true if read_only
+            options[:raw].present? ? value : Entry.new(value, options)
+          end
+        end
+      end
+
+      def cas_muli
+
+      end
+
+      private
+
+      def cas_expiration(options)
+        if options[:expires_in].present? && options[:race_condition_ttl].present? && options[:raw].blank?
+          options[:expires_in].to_f + options[:race_condition_ttl].to_f
+        else
+          nil
+        end
+      end
+
+    end
+
+    class RedisStoreWithCas < RedisStore
+
+      def initialize(*adresses)
+        super adresses
+        check_and_extend_cas
+      end
+
+      def candocas?
+        @data.is_a?(Redis::Store) && @data.respond_to?(:cas)
+      end
+
+      private
+
+      def check_and_extend_cas
+        extend RedisStoreCas if candocas?
+      end
+
+    end
+  end
+end

lib/active_support/redis-activesupport-with-cas.rb

+require 'redis-store-with-cas'
+require 'active_support'
+require 'active_support/cache/redis_store_with_cas'

test/active_support/cache/redis_store_with_cas_test.rb

+require 'active_support/test_helper'
+require 'ostruct'
+
+describe "ActiveSupport::Cache::RedisStoreWithCas" do
+
+  def setup
+    @store  = ActiveSupport::Cache::RedisStoreWithCas.new "redis://127.0.0.1:6379/5/cachetest"
+    @dstore = ActiveSupport::Cache::RedisStoreWithCas.new "redis://127.0.0.1:6379/5", "redis://127.0.0.1:6379/6"
+
+    @rabbit = OpenStruct.new :name => "bunny"
+    @white_rabbit = OpenStruct.new :color => "white"
+    @black_rabbit = OpenStruct.new :color => 'black'
+
+  end
+
+  def teardown
+    @store.instance_variable_get("@data").flushdb
+    @dstore.instance_variable_get("@data").flushdb
+  end
+
+  describe "Single cas " do
+    it "should not swap missing key" do
+      refute @store.cas('rabbit') { |_value| flunk }
+    end
+
+    it "should correct swap value" do
+      @store.write "rabbit", @rabbit
+      assert(@store.cas('rabbit') do |value|
+        assert_equal @rabbit, value
+        @white_rabbit
+      end)
+      @store.read("rabbit").must_equal(@white_rabbit)
+    end
+
+    it "should not swap if value changes" do
+      @store.write('rabbit', @rabbit)
+      refute @store.cas('rabbit') { |_value|
+        @store.write('rabbit', @black_rabbit)
+        @white_rabbit
+      }
+      @store.read("rabbit").must_equal(@black_rabbit)
+    end
+
+  end
+
+end
\ No newline at end of file

test/active_support/test_helper.rb

+require 'bundler/setup'
+require 'minitest/autorun'
+require 'mocha/setup'
+require 'active_support'
+require 'active_support/cache/redis_store_with_cas'
+
+puts "Testing against ActiveSupport v.#{ActiveSupport::VERSION::STRING}"
\ No newline at end of file