ri > ActiveSupport::Subscriber

= ActiveSupport::Subscriber < Object

(from /home/chedong/.local/share/rdoc)
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ActiveSupport::Subscriber is an object set to consume
ActiveSupport::Notifications. The subscriber dispatches notifications to
a registered object based on its given namespace.

An example would be an Active Record subscriber responsible for
collecting statistics about queries:

  module ActiveRecord
    class StatsSubscriber < ActiveSupport::Subscriber
      attach_to :active_record

      def sql(event)
        Statsd.timing("sql.#{event.payload[:name]}", event.duration)
      end
    end
  end

After configured, whenever a "sql.active_record" notification is
published, it will properly dispatch the event
(ActiveSupport::Notifications::Event) to the sql method.

We can detach a subscriber as well:

  ActiveRecord::StatsSubscriber.detach_from(:active_record)
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= Class methods:

  add_event_subscriber
  attach_to
  detach_from
  method_added
  new
  remove_event_subscriber
  subscribers

= Instance methods:

  finish
  start