Move synchronize to setup method and make CONFIG private

lib/active_model/serializer.rb

@@ -3,6 +3,8 @@ require 'active_model/serializable'
 require 'active_model/serializer/associations'
 require 'active_model/serializer/config'
 
+require 'thread'
+
 module ActiveModel
   class Serializer
     include Serializable
@@ -14,8 +16,10 @@ module ActiveModel
       end
 
       def setup
+        Mutex.new.synchronize do
           yield CONFIG
         end
+      end
 
       def embed(type, options={})
         CONFIG.embed = type

lib/active_model/serializer/config.rb

@@ -1,27 +1,19 @@
-require 'thread'
-
 module ActiveModel
   class Serializer
     class Config
-      def initialize
+      def initialize(data = {})
-        @data = {}
+        @data = data
-        @mutex = Mutex.new
       end
 
       def each(&block)
-        @mutex.synchronize do
         @data.each(&block)
       end
-      end
 
       def clear
-        @mutex.synchronize do
         @data.clear
       end
-      end
 
       def method_missing(name, *args)
-        @mutex.synchronize do
         name = name.to_s
         return @data[name] if @data.include?(name)
         match = name.match(/\A(.*?)([?=]?)\Z/)
@@ -33,9 +25,7 @@ module ActiveModel
         end
       end
     end
-    end
 
-    CONFIG = Config.new
+    CONFIG = Config.new('embed' => :objects) # :nodoc:
-    CONFIG.embed = :objects
   end
 end