1 files changed, 56 insertions, 13 deletions
diff --git a/actionpack/lib/action_dispatch/middleware/session/abstract_store.rb b/actionpack/lib/action_dispatch/middleware/session/abstract_store.rb
index e82132b445..56c71b962a 100644
--- a/actionpack/lib/action_dispatch/middleware/session/abstract_store.rb
+++ b/actionpack/lib/action_dispatch/middleware/session/abstract_store.rb
@@ -18,19 +18,6 @@ module ActionDispatch
       end
     end
 
-    module DestroyableSession
-      def destroy
-        clear
-        options = @env[Rack::Session::Abstract::ENV_SESSION_OPTIONS_KEY] if @env
-        options ||= {}
-        @by.send(:destroy_session, @env, options[:id], options) if @by
-        options[:id] = nil
-        @loaded = false
-      end
-    end
-
-    ::Rack::Session::Abstract::SessionHash.send :include, DestroyableSession
-
     module Compatibility
       def initialize(app, options = {})
         options[:key] ||= '_session_id'
@@ -81,12 +68,68 @@ module ActionDispatch
       include Compatibility
       include StaleSessionCheck
 
+      ENV_SESSION_KEY         = Rack::Session::Abstract::ENV_SESSION_KEY # :nodoc:
+      ENV_SESSION_OPTIONS_KEY = Rack::Session::Abstract::ENV_SESSION_OPTIONS_KEY # :nodoc:
+
       private
 
+      module DestroyableSession
+        def destroy
+          clear
+          options = @env[Rack::Session::Abstract::ENV_SESSION_OPTIONS_KEY] if @env
+          options ||= {}
+          @by.send(:destroy_session, @env, options[:id], options) if @by
+          options[:id] = nil
+          @loaded = false
+        end
+      end
+
+      ::Rack::Session::Abstract::SessionHash.send :include, DestroyableSession
+
+      def prepare_session(env)
+        session_was                  = env[ENV_SESSION_KEY]
+        env[ENV_SESSION_KEY]         = Rack::Session::Abstract::SessionHash.new(self, env)
+        env[ENV_SESSION_OPTIONS_KEY] = Request::Session::Options.new(self, env, @default_options)
+        env[ENV_SESSION_KEY].merge! session_was if session_was
+      end
+
       def set_cookie(env, session_id, cookie)
         request = ActionDispatch::Request.new(env)
         request.cookie_jar[key] = cookie
       end
     end
   end
+
+  class Request
+    # SessionHash is responsible to lazily load the session from store.
+    class Session
+      class Options #:nodoc:
+        def initialize(by, env, default_options)
+          @by                = by
+          @env               = env
+          @session_id_loaded = false
+          @delegate          = default_options
+        end
+
+        def [](key)
+          load_session_id! if key == :id && session_id_not_loaded?
+          @delegate[key]
+        end
+
+        def []=(k,v);        @delegate[k] = v; end
+        def to_hash;         @delegate.dup; end
+        def values_at(*args) @delegate.values_at(*args); end
+
+        private
+        def session_id_not_loaded?
+          !(@session_id_loaded || @delegate.key?(:id))
+        end
+
+        def load_session_id!
+          @delegate[:id] = @by.send(:extract_session_id, @env)
+          @session_id_loaded = true
+        end
+      end
+    end
+  end
 end