simplifies ActiveRecord::ExplainSubscriber [José Valim & Xavier Noria]

activerecord/lib/active_record/explain_subscriber.rb

-module ActiveRecord
-  class ExplainSubscriber < ActiveSupport::LogSubscriber
-    def sql(event)
-      ActiveRecord::Base.collect_queries_for_explain(event.payload)
-    end
+require 'active_support/notifications'
 
-    def logger
-      ActiveRecord::Base.logger
+module ActiveRecord
+  class ExplainSubscriber
+    def call(*args)
+      ActiveRecord::Base.collect_queries_for_explain(args.last)
     end
 
-    attach_to :active_record
+    ActiveSupport::Notifications.subscribe("sql.active_record", new)
   end
 end