use Session.instance rather than Session.new for easier code

2 files changed, 9 insertions, 25 deletions

diff --git a/lib/arel/algebra/relations/relation.rb b/lib/arel/algebra/relations/relation.rb
index 0332482066..34181beea2 100644
--- a/lib/arel/algebra/relations/relation.rb
+++ b/lib/arel/algebra/relations/relation.rb
@@ -3,7 +3,7 @@ module Arel
     attr_reader :count
 
     def session
-      Session.new
+      Session.instance
     end
 
     def call
diff --git a/lib/arel/session.rb b/lib/arel/session.rb
index e6da825b97..622ca090f8 100644
--- a/lib/arel/session.rb
+++ b/lib/arel/session.rb
@@ -1,30 +1,14 @@
 module Arel
   class Session
-    class << self
-      attr_accessor :instance
-      alias_method :manufacture, :new
+    def self.instance
+      @instance || new
+    end
 
-      def start
-        if defined?(@started) && @started
-          yield
-        else
-          begin
-            @started = true
-            @instance = manufacture
-            singleton_class.class_eval do
-              undef :new
-              alias_method :new, :instance
-            end
-            yield
-          ensure
-            singleton_class.class_eval do
-              undef :new
-              alias_method :new, :manufacture
-            end
-            @started = false
-          end
-        end
-      end
+    def self.start
+      @instance ||= new
+      yield @instance
+    ensure
+      @instance = nil
     end
 
     module CRUD