module ActiveSupport # 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 Active Record subscriber responsible for collecting # statistics about queries: # # module ActiveRecord # class StatsSubscriber < ActiveSupport::Subscriber # def sql(event) # Statsd.timing("sql.#{event.payload[:name]}", event.duration) # end # end # end # # And it's finally registered as: # # ActiveRecord::StatsSubscriber.attach_to :active_record # # Since we need to know all instance methods before attaching the log # subscriber, the line above should be called after your subscriber definition. # # After configured, whenever a "sql.active_record" notification is published, # it will properly dispatch the event (ActiveSupport::Notifications::Event) to # the +sql+ method. class Subscriber class << self # Attach the subscriber to a namespace. def attach_to(namespace, subscriber=new, notifier=ActiveSupport::Notifications) subscribers << subscriber subscriber.public_methods(false).each do |event| next if %w{ start finish }.include?(event.to_s) notifier.subscribe("#{event}.#{namespace}", subscriber) end end def subscribers @@subscribers ||= [] end end def initialize @queue_key = [self.class.name, object_id].join "-" super end def start(name, id, payload) e = ActiveSupport::Notifications::Event.new(name, Time.now, nil, id, payload) parent = event_stack.last parent << e if parent event_stack.push e end def finish(name, id, payload) finished = Time.now event = event_stack.pop event.end = finished event.payload.merge!(payload) method = name.split('.').first send(method, event) end private def event_stack Thread.current[@queue_key] ||= [] end end end