module ActiveSupport::PerThreadRegistry

NOTE: This approach has been deprecated for end-user code in favor of thread_mattr_accessor and friends. Please use that approach instead.

This module is used to encapsulate access to thread local variables.

Instead of polluting the thread locals namespace:

Thread.current[:connection_handler]

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

ActiveRecord::RuntimeRegistry.connection_handler

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.

Public Class Methods

extended(object) click to toggle source
# File lib/active_support/per_thread_registry.rb, line 42
def self.extended(object)
  object.instance_variable_set :@per_thread_registry_key, object.name.freeze
end

Public Instance Methods

instance() click to toggle source
# File lib/active_support/per_thread_registry.rb, line 46
def instance
  Thread.current[@per_thread_registry_key] ||= new
end

Private Instance Methods

method_missing(name, *args, &block) click to toggle source
# File lib/active_support/per_thread_registry.rb, line 51
def method_missing(name, *args, &block)
  # Caches the method definition as a singleton method of the receiver.
  #
  # By letting #delegate handle it, we avoid an enclosure that'll capture args.
  singleton_class.delegate name, to: :instance

  send(name, *args, &block)
end