Make many parts of Rails lazy. In order to facilitate this,

add lazy_load_hooks.rb, which allows us to declare code that
should be run at some later time. For instance, this allows
us to defer requiring ActiveRecord::Base at boot time purely
to apply configuration. Instead, we register a hook that should
apply configuration once ActiveRecord::Base is loaded.

With these changes, brings down total boot time of a
new app to 300ms in production and 400ms in dev.

TODO: rename base_hook

4 files changed, 4 insertions, 4 deletions

diff --git a/actionpack/lib/action_dispatch/middleware/params_parser.rb b/actionpack/lib/action_dispatch/middleware/params_parser.rb
index 522982e202..f4c4324fb0 100644
--- a/actionpack/lib/action_dispatch/middleware/params_parser.rb
+++ b/actionpack/lib/action_dispatch/middleware/params_parser.rb
@@ -1,4 +1,3 @@
-require 'active_support/json'
 require 'action_dispatch/http/request'
 
 module ActionDispatch
diff --git a/actionpack/lib/action_dispatch/middleware/session/cookie_store.rb b/actionpack/lib/action_dispatch/middleware/session/cookie_store.rb
index db64711052..22da82479e 100644
--- a/actionpack/lib/action_dispatch/middleware/session/cookie_store.rb
+++ b/actionpack/lib/action_dispatch/middleware/session/cookie_store.rb
@@ -1,5 +1,4 @@
 require 'active_support/core_ext/hash/keys'
-require 'rack/request'
 
 module ActionDispatch
   module Session
diff --git a/actionpack/lib/action_dispatch/middleware/stack.rb b/actionpack/lib/action_dispatch/middleware/stack.rb
index 18a2922fa7..c52c8c0e6a 100644
--- a/actionpack/lib/action_dispatch/middleware/stack.rb
+++ b/actionpack/lib/action_dispatch/middleware/stack.rb
@@ -58,7 +58,7 @@ module ActionDispatch
           if lazy_compare?(@klass) && lazy_compare?(middleware)
             normalize(@klass) == normalize(middleware)
           else
-            klass == ActiveSupport::Inflector.constantize(middleware.to_s)
+            klass.name == middleware.to_s
           end
         end
       end
diff --git a/actionpack/lib/action_dispatch/routing/mapper.rb b/actionpack/lib/action_dispatch/routing/mapper.rb
index 52e7b0e77d..52a8df4273 100644
--- a/actionpack/lib/action_dispatch/routing/mapper.rb
+++ b/actionpack/lib/action_dispatch/routing/mapper.rb
@@ -1,3 +1,5 @@
+require "active_support/core_ext/hash/except"
+
 module ActionDispatch
   module Routing
     class Mapper
@@ -85,7 +87,7 @@ module ActionDispatch
           end
 
           def requirements
-            @requirements ||= returning(@options[:constraints] || {}) do |requirements|
+            @requirements ||= (@options[:constraints] || {}).tap do |requirements|
               requirements.reverse_merge!(@scope[:constraints]) if @scope[:constraints]
               @options.each { |k, v| requirements[k] = v if v.is_a?(Regexp) }
             end