This module is used to encapsulate access to thread local variables.
Instead of polluting the thread locals namespace:
you define a class that extends this module:
module ActiveRecord class RuntimeRegistry extend ActiveSupport::PerThreadRegistry attr_accessor :connection_handler end end
and invoke the declared instance accessors as class methods. So
ActiveRecord::RuntimeRegistry.connection_handler = connection_handler
sets a connection handler local to the current thread, and
returns a connection handler local to the current thread.
This feature is accomplished by instantiating the class and storing the instance as a thread local keyed by the class name. In the example above a key “ActiveRecord::RuntimeRegistry” is stored in Thread.current. The class methods proxy to said thread local instance.
If the class has an initializer, it must accept no arguments.