Creating a class to build the default middleware stack.

A lot of logic for building the default middleware stack is currently
kept in Application class, but this can be encapsulated and made more
modular by being moved to its own class. Also refactored a couple of the
helper methods.

2 files changed, 109 insertions, 95 deletions

diff --git a/railties/lib/rails/application.rb b/railties/lib/rails/application.rb
index 753e870a8c..a39ac304f2 100644
--- a/railties/lib/rails/application.rb
+++ b/railties/lib/rails/application.rb
@@ -52,11 +52,12 @@ module Rails
   #   11) Run config.after_initialize callbacks
   #
   class Application < Engine
-    autoload :Bootstrap,      'rails/application/bootstrap'
-    autoload :Configuration,  'rails/application/configuration'
-    autoload :Finisher,       'rails/application/finisher'
-    autoload :Railties,       'rails/engine/railties'
-    autoload :RoutesReloader, 'rails/application/routes_reloader'
+    autoload :Bootstrap,              'rails/application/bootstrap'
+    autoload :Configuration,          'rails/application/configuration'
+    autoload :DefaultMiddlewareStack, 'rails/application/default_middleware_stack'
+    autoload :Finisher,               'rails/application/finisher'
+    autoload :Railties,               'rails/engine/railties'
+    autoload :RoutesReloader,         'rails/application/routes_reloader'
 
     class << self
       def inherited(base)
@@ -102,7 +103,6 @@ module Rails
       routes_reloader.reload!
     end
 
-
     # Return the application's KeyGenerator
     def key_generator
       # number of iterations selected based on consultation with the google security
@@ -298,96 +298,9 @@ module Rails
       initializers
     end
 
-    def reload_dependencies? #:nodoc:
-      config.reload_classes_only_on_change != true || reloaders.map(&:updated?).any?
-    end
-
     def default_middleware_stack #:nodoc:
-      ActionDispatch::MiddlewareStack.new.tap do |middleware|
-        app = self
-
-        if rack_cache = load_rack_cache
-          require "action_dispatch/http/rack_cache"
-          middleware.use ::Rack::Cache, rack_cache
-        end
-
-        if config.force_ssl
-          middleware.use ::ActionDispatch::SSL, config.ssl_options
-        end
-
-        if config.action_dispatch.x_sendfile_header.present?
-          middleware.use ::Rack::Sendfile, config.action_dispatch.x_sendfile_header
-        end
-
-        if config.serve_static_assets
-          middleware.use ::ActionDispatch::Static, paths["public"].first, config.static_cache_control
-        end
-
-        middleware.use ::Rack::Lock unless allow_concurrency?
-        middleware.use ::Rack::Runtime
-        middleware.use ::Rack::MethodOverride
-        middleware.use ::ActionDispatch::RequestId
-
-        # Must come after Rack::MethodOverride to properly log overridden methods
-        middleware.use ::Rails::Rack::Logger, config.log_tags
-        middleware.use ::ActionDispatch::ShowExceptions, show_exceptions_app
-        middleware.use ::ActionDispatch::DebugExceptions, app
-        middleware.use ::ActionDispatch::RemoteIp, config.action_dispatch.ip_spoofing_check, config.action_dispatch.trusted_proxies
-
-        unless config.cache_classes
-          middleware.use ::ActionDispatch::Reloader, lambda { app.reload_dependencies? }
-        end
-
-        middleware.use ::ActionDispatch::Callbacks
-        middleware.use ::ActionDispatch::Cookies
-
-        if config.session_store
-          if config.force_ssl && !config.session_options.key?(:secure)
-            config.session_options[:secure] = true
-          end
-          middleware.use config.session_store, config.session_options
-          middleware.use ::ActionDispatch::Flash
-        end
-
-        middleware.use ::ActionDispatch::ParamsParser
-        middleware.use ::Rack::Head
-        middleware.use ::Rack::ConditionalGet
-        middleware.use ::Rack::ETag, "no-cache"
-      end
-    end
-
-    def allow_concurrency?
-      if config.allow_concurrency.nil?
-        config.cache_classes
-      else
-        config.allow_concurrency
-      end
-    end
-
-    def load_rack_cache
-      rack_cache = config.action_dispatch.rack_cache
-      return unless rack_cache
-
-      begin
-        require 'rack/cache'
-      rescue LoadError => error
-        error.message << ' Be sure to add rack-cache to your Gemfile'
-        raise
-      end
-
-      if rack_cache == true
-        {
-          metastore: "rails:/",
-          entitystore: "rails:/",
-          verbose: false
-        }
-      else
-        rack_cache
-      end
-    end
-
-    def show_exceptions_app
-      config.exceptions_app || ActionDispatch::PublicExceptions.new(Rails.public_path)
+      default_stack = DefaultMiddlewareStack.new(self, config, paths)
+      default_stack.build_stack
     end
 
     def build_original_fullpath(env) #:nodoc:
diff --git a/railties/lib/rails/application/default_middleware_stack.rb b/railties/lib/rails/application/default_middleware_stack.rb
new file mode 100644
index 0000000000..370c906086
--- /dev/null
+++ b/railties/lib/rails/application/default_middleware_stack.rb
@@ -0,0 +1,101 @@
+module Rails
+  class Application
+    class DefaultMiddlewareStack
+      attr_reader :config, :paths, :app
+
+      def initialize(app, config, paths)
+        @app = app
+        @config = config
+        @paths = paths
+      end
+
+      def build_stack
+        ActionDispatch::MiddlewareStack.new.tap do |middleware|
+          if rack_cache = load_rack_cache
+            require "action_dispatch/http/rack_cache"
+            middleware.use ::Rack::Cache, rack_cache
+          end
+
+          if config.force_ssl
+            middleware.use ::ActionDispatch::SSL, config.ssl_options
+          end
+
+          if config.action_dispatch.x_sendfile_header.present?
+            middleware.use ::Rack::Sendfile, config.action_dispatch.x_sendfile_header
+          end
+
+          if config.serve_static_assets
+            middleware.use ::ActionDispatch::Static, paths["public"].first, config.static_cache_control
+          end
+
+          middleware.use ::Rack::Lock unless allow_concurrency?
+          middleware.use ::Rack::Runtime
+          middleware.use ::Rack::MethodOverride
+          middleware.use ::ActionDispatch::RequestId
+
+          # Must come after Rack::MethodOverride to properly log overridden methods
+          middleware.use ::Rails::Rack::Logger, config.log_tags
+          middleware.use ::ActionDispatch::ShowExceptions, show_exceptions_app
+          middleware.use ::ActionDispatch::DebugExceptions, app
+          middleware.use ::ActionDispatch::RemoteIp, config.action_dispatch.ip_spoofing_check, config.action_dispatch.trusted_proxies
+
+          unless config.cache_classes
+            middleware.use ::ActionDispatch::Reloader, lambda { reload_dependencies? }
+          end
+
+          middleware.use ::ActionDispatch::Callbacks
+          middleware.use ::ActionDispatch::Cookies
+
+          if config.session_store
+            if config.force_ssl && !config.session_options.key?(:secure)
+              config.session_options[:secure] = true
+            end
+            middleware.use config.session_store, config.session_options
+            middleware.use ::ActionDispatch::Flash
+          end
+
+          middleware.use ::ActionDispatch::ParamsParser
+          middleware.use ::Rack::Head
+          middleware.use ::Rack::ConditionalGet
+          middleware.use ::Rack::ETag, "no-cache"
+        end
+      end
+
+      private
+
+        def reload_dependencies?
+          config.reload_classes_only_on_change != true || app.reloaders.map(&:updated?).any?
+        end
+
+        def allow_concurrency?
+          config.allow_concurrency.nil? ? config.cache_classes : config.allow_concurrency
+        end
+
+        def load_rack_cache
+          rack_cache = config.action_dispatch.rack_cache
+          return unless rack_cache
+
+          begin
+            require 'rack/cache'
+          rescue LoadError => error
+            error.message << ' Be sure to add rack-cache to your Gemfile'
+            raise
+          end
+
+          if rack_cache == true
+            {
+              metastore: "rails:/",
+              entitystore: "rails:/",
+              verbose: false
+            }
+          else
+            rack_cache
+          end
+        end
+
+        def show_exceptions_app
+          config.exceptions_app || ActionDispatch::PublicExceptions.new(Rails.public_path)
+        end
+    end
+  end
+end