Allow users to choose when to eager_load the application or not.

Previously, the eager load behavior was mostly coupled to
config.cache_classes, however this was suboptimal since in
some environments a developer may want to cache classes but
not necessarily load them all on boot (for example, test env).

This pull request also promotes the use of config.eager_load
set to true by default in production. In the majority of the
cases, this is the behavior you want since it will copy most
of your app into memory on boot (which was also the previous
behavior).

Finally, this fix a long standing Rails bug where it was
impossible to access a model in a rake task when Rails was
set as thread safe.

3 files changed, 19 insertions, 6 deletions

diff --git a/railties/lib/rails/application/bootstrap.rb b/railties/lib/rails/application/bootstrap.rb
index e567df7162..1e5f95336f 100644
--- a/railties/lib/rails/application/bootstrap.rb
+++ b/railties/lib/rails/application/bootstrap.rb
@@ -13,6 +13,20 @@ module Rails
         require "active_support/all" unless config.active_support.bare
       end
 
+      initializer :set_eager_load, :group => :all do
+        if config.eager_load.nil?
+          warn <<-INFO
+config.eager_load is set to nil. Please update your config/environments file accordingly:
+
+  * development - set it to false
+  * test - set it to false (unless you use a tool that preloads your test environment)
+  * production - set it to true
+
+INFO
+          config.eager_load = config.cache_classes
+        end
+      end
+
       # Preload all frameworks specified by the Configuration#frameworks.
       # Used by Passenger to ensure everything's loaded before forking and
       # to avoid autoload race conditions in JRuby.
@@ -60,7 +74,6 @@ module Rails
       end
 
       # Sets the dependency loading mechanism.
-      # TODO: Remove files from the $" and always use require.
       initializer :initialize_dependency_mechanism, :group => :all do
         ActiveSupport::Dependencies.mechanism = config.cache_classes ? :require : :load
       end
diff --git a/railties/lib/rails/application/configuration.rb b/railties/lib/rails/application/configuration.rb
index 2b36cc9d0d..7dffe91bb9 100644
--- a/railties/lib/rails/application/configuration.rb
+++ b/railties/lib/rails/application/configuration.rb
@@ -7,7 +7,7 @@ module Rails
     class Configuration < ::Rails::Engine::Configuration
       attr_accessor :allow_concurrency, :asset_host, :asset_path, :assets, :autoflush_log,
                     :cache_classes, :cache_store, :consider_all_requests_local, :console,
-                    :dependency_loading, :exceptions_app, :file_watcher, :filter_parameters,
+                    :eager_load, :exceptions_app, :file_watcher, :filter_parameters,
                     :force_ssl, :helpers_paths, :logger, :log_formatter, :log_tags,
                     :preload_frameworks, :railties_order, :relative_url_root, :secret_token,
                     :serve_static_assets, :ssl_options, :static_cache_control, :session_options,
@@ -24,7 +24,6 @@ module Rails
         @consider_all_requests_local   = false
         @filter_parameters             = []
         @helpers_paths                 = []
-        @dependency_loading            = true
         @serve_static_assets           = true
         @static_cache_control          = nil
         @force_ssl                     = false
@@ -45,6 +44,7 @@ module Rails
         @log_formatter                 = ActiveSupport::Logger::SimpleFormatter.new
         @queue                         = Rails::Queueing::Queue
         @queue_consumer                = Rails::Queueing::ThreadedConsumer
+        @eager_load                    = nil
 
         @assets = ActiveSupport::OrderedOptions.new
         @assets.enabled                  = false
@@ -98,7 +98,7 @@ module Rails
       def threadsafe!
         @preload_frameworks = true
         @cache_classes = true
-        @dependency_loading = false
+        @eager_load = true
         @allow_concurrency = true
         self
       end
diff --git a/railties/lib/rails/application/finisher.rb b/railties/lib/rails/application/finisher.rb
index 60aa40b92f..ba9f501546 100644
--- a/railties/lib/rails/application/finisher.rb
+++ b/railties/lib/rails/application/finisher.rb
@@ -50,7 +50,7 @@ module Rails
       end
 
       initializer :eager_load! do
-        if config.cache_classes && !(defined?($rails_rake_task) && $rails_rake_task)
+        if config.eager_load
           ActiveSupport.run_load_hooks(:before_eager_load, self)
           eager_load!
         end
@@ -91,7 +91,7 @@ module Rails
 
       # Disable dependency loading during request cycle
       initializer :disable_dependency_loading do
-        if config.cache_classes && !config.dependency_loading
+        if config.eager_load
           ActiveSupport::Dependencies.unhook!
         end
       end