fix: Do not attempt to process Memcache clients with DalliProxy

gemfiles/activesupport3.2.gemfile

@@ -3,5 +3,6 @@
 source "https://rubygems.org"
 
 gem "activesupport", "~> 3.2.0"
+gem "memcache-client"
 
 gemspec :path => "../"

lib/rack/attack/store_proxy.rb

@@ -8,11 +8,16 @@ module Rack
         # (method has an arity of 2; must call #expire separately
         if (defined?(::ActiveSupport::Cache::RedisStore) && store.is_a?(::ActiveSupport::Cache::RedisStore)) ||
           (defined?(::ActiveSupport::Cache::MemCacheStore) && store.is_a?(::ActiveSupport::Cache::MemCacheStore))
-          # ActiveSupport::Cache::RedisStore doesn't expose any way to set an expiry,
-          # so use the raw Redis::Store instead
-          store = store.instance_variable_get(:@data)
-        end
 
+          # ActiveSupport::Cache::RedisStore doesn't expose any way to set an expiry,
+          # so use the raw Redis::Store instead.
+          # We also want to use the underlying Dalli client instead of ::ActiveSupport::Cache::MemCacheStore,
+          # but not the Memcache client if using Rails 3.x
+          client = store.instance_variable_get(:@data)
+          if client.is_a?(Redis::Store) || client.is_a?(Dalli::Client)
+            store = store.instance_variable_get(:@data)
+          end
+        end
         klass = PROXIES.find { |proxy| proxy.handle?(store) }
         klass ? klass.new(store) : store
       end

lib/rack/attack/store_proxy/dalli_proxy.rb

@@ -12,7 +12,7 @@ module Rack
           if defined?(::ConnectionPool) && store.is_a?(::ConnectionPool)
             store.with { |conn| conn.is_a?(::Dalli::Client) }
           else
-            store.is_a?(::Dalli::Client) || store.is_a?(::ActiveSupport::Cache::MemCacheStore)
+            store.is_a?(::Dalli::Client)
           end
         end