1 files changed, 85 insertions, 11 deletions

diff --git a/actionpack/lib/action_dispatch/middleware/session/abstract_store.rb b/actionpack/lib/action_dispatch/middleware/session/abstract_store.rb
index 3e8d64b0c6..7623a94234 100644
--- a/actionpack/lib/action_dispatch/middleware/session/abstract_store.rb
+++ b/actionpack/lib/action_dispatch/middleware/session/abstract_store.rb
@@ -12,6 +12,37 @@ module ActionDispatch
       ENV_SESSION_KEY = 'rack.session'.freeze
       ENV_SESSION_OPTIONS_KEY = 'rack.session.options'.freeze
 
+      # thin wrapper around Hash that allows us to lazily
+      # load session id into session_options
+      class OptionsHash < Hash
+        def initialize(by, env, default_options)
+          @by = by
+          @env = env
+          merge!(default_options)
+          @session_id_loaded = false
+        end
+
+        alias_method :get_without_session_load, :[]
+
+        def [](key)
+          if key == :id
+            load_session_id! unless has_session_id?
+          end
+          super(key)
+        end
+
+        private
+
+          def has_session_id?
+            get_without_session_load(:id).present? || @session_id_loaded
+          end
+
+          def load_session_id!
+            self[:id] = @by.send(:extract_session_id, @env)
+            @session_id_loaded = true
+          end
+      end
+
       class SessionHash < Hash
         def initialize(by, env)
           super()
@@ -21,45 +52,71 @@ module ActionDispatch
         end
 
         def [](key)
-          load! unless @loaded
+          load_for_read!
+          super(key.to_s)
+        end
+
+        def has_key?(key)
+          load_for_read!
           super(key.to_s)
         end
 
         def []=(key, value)
-          load! unless @loaded
+          load_for_write!
           super(key.to_s, value)
         end
 
         def to_hash
+          load_for_read!
           h = {}.replace(self)
           h.delete_if { |k,v| v.nil? }
           h
         end
 
         def update(hash)
-          load! unless @loaded
+          load_for_write!
           super(hash.stringify_keys)
         end
 
         def delete(key)
-          load! unless @loaded
+          load_for_write!
           super(key.to_s)
         end
 
         def inspect
-          load! unless @loaded
+          load_for_read!
           super
         end
 
+        def exists?
+          @by.send(:exists?, @env)
+        end
+
         def loaded?
           @loaded
         end
 
+        def destroy
+          clear
+          @by.send(:destroy, @env) if @by
+          @env[ENV_SESSION_OPTIONS_KEY].delete(:id) if @env && @env[ENV_SESSION_OPTIONS_KEY]
+          @loaded = false
+        end
+
         private
+
+          def load_for_read!
+            load! if !loaded? && exists?
+          end
+
+          def load_for_write!
+            load! unless loaded?
+          end
+
           def load!
             stale_session_check! do
               id, session = @by.send(:load_session, @env)
-              (@env[ENV_SESSION_OPTIONS_KEY] ||= {})[:id] = id
+              @env[ENV_SESSION_OPTIONS_KEY][:id] = id
               replace(session.stringify_keys)
               @loaded = true
             end
@@ -75,7 +132,6 @@ module ActionDispatch
               rescue LoadError, NameError => const_error
                 raise ActionDispatch::Session::SessionRestoreError, "Session contains objects whose class definition isn't available.\nRemember to require the classes for all objects kept in the session.\n(Original exception: #{const_error.message} [#{const_error.class}])\n"
               end
-
               retry
             else
               raise
@@ -133,7 +189,7 @@ module ActionDispatch
 
         def prepare!(env)
           env[ENV_SESSION_KEY] = SessionHash.new(self, env)
-          env[ENV_SESSION_OPTIONS_KEY] = @default_options.dup
+          env[ENV_SESSION_OPTIONS_KEY] = OptionsHash.new(self, env, @default_options.dup)
         end
 
         def generate_sid
@@ -145,13 +201,22 @@ module ActionDispatch
         end
 
         def load_session(env)
-          request = Rack::Request.new(env)
-          sid   = request.cookies[@key]
-          sid ||= request.params[@key] unless @cookie_only
+          sid = current_session_id(env)
           sid, session = get_session(env, sid)
           [sid, session]
         end
 
+        def extract_session_id(env)
+          request = Rack::Request.new(env)
+          sid = request.cookies[@key]
+          sid ||= request.params[@key] unless @cookie_only
+          sid
+        end
+
+        def current_session_id(env)
+          env[ENV_SESSION_OPTIONS_KEY][:id]
+        end
+
         def ensure_session_key!
           if @key.blank?
             raise ArgumentError, 'A key is required to write a ' +
@@ -161,6 +226,10 @@ module ActionDispatch
           end
         end
 
+        def exists?(env)
+          current_session_id(env).present?
+        end
+
         def get_session(env, sid)
           raise '#get_session needs to be implemented.'
         end
@@ -169,6 +238,11 @@ module ActionDispatch
           raise '#set_session needs to be implemented and should return ' <<
             'the value to be stored in the cookie (usually the sid)'
         end
+
+        def destroy(env)
+          raise '#destroy needs to be implemented.'
+        end
+
     end
   end
 end