The new option allows any Ruby namespace to be registered and set
up for eager load. We are effectively exposing the structure existing
in Rails since v3.0 for all developers in order to make their applications
thread-safe and CoW friendly.
This is a private place to put those AS features that are used
by every component. Nowadays we cherry-pick individual files
wherever they are used, but that it is not worth the effort
for stuff that is going to be loaded for sure sooner or later,
like blank?, autoload, concern, etc.
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
* A new module (ActiveSupport::Autoload) is provide that extends
autoloading with new behavior.
* All autoloads in modules that have extended ActiveSupport::Autoload
will be eagerly required in threadsafe environments
* Autoloads can optionally leave off the path if the path is the same
as full_constant_name.underscore
* It is possible to specify that a group of autoloads live under an
additional path. For instance, all of ActionDispatch's middlewares
are ActionDispatch::MiddlewareName, but they live under
"action_dispatch/middlewares/middleware_name"
* It is possible to specify that a group of autoloads are all found
at the same path. For instance, a number of exceptions might all
be declared there.
* One consequence of this is that testing-related constants are not
autoloaded. To get the testing helpers for a given component,
require "component_name/test_case". For instance, "action_controller/test_case".
* test_help.rb, which is automatically required by a Rails application's
test helper, requires the test_case.rb for all active components, so
this change will not be disruptive in existing or new applications.
