class ActiveSupport::Subscriber

the sql method.
it will properly dispatch the event (ActiveSupport::Notifications::Event) to
After configured, whenever a “sql.active_record” notification is published,
end
end
end
Statsd.timing(“sql.#{event.payload}”, event.duration)
def sql(event)
attach_to :active_record
class StatsSubscriber < ActiveSupport::Subscriber
module ActiveRecord
statistics about queries:
An example would be an Active Record subscriber responsible for collecting
a registered object based on its given namespace.
ActiveSupport::Notifications. The subscriber dispatches notifications to
ActiveSupport::Subscriber is an object set to consume

def add_event_subscriber(event)

def add_event_subscriber(event)
  return if %w{ start finish }.include?(event.to_s)
  pattern = "#{event}.#{namespace}"
  # Don't add multiple subscribers (eg. if methods are redefined).
  return if subscriber.patterns.include?(pattern)
  subscriber.patterns << pattern
  notifier.subscribe(pattern, subscriber)
end

def attach_to(namespace, subscriber=new, notifier=ActiveSupport::Notifications)

Attach the subscriber to a namespace.

def attach_to(namespace, subscriber=new, notifier=ActiveSupport::Notifications)
  @namespace  = namespace
  @subscriber = subscriber
  @notifier   = notifier
  subscribers << subscriber
  # Add event subscribers for all existing methods on the class.
  subscriber.public_methods(false).each do |event|
    add_event_subscriber(event)
  end
end

def event_stack

def event_stack
  SubscriberQueueRegistry.instance.get_queue(@queue_key)
end

def finish(name, id, payload)

def finish(name, id, payload)
  finished  = Time.now
  event     = event_stack.pop
  event.end = finished
  event.payload.merge!(payload)
  method = name.split('.'.freeze).first
  send(method, event)
end

def initialize

def initialize
  @queue_key = [self.class.name, object_id].join "-"
  @patterns  = []
  super
end

def method_added(event)

Adds event subscribers for all new methods added to the class.

def method_added(event)
  # Only public methods are added as subscribers, and only if a notifier
  # has been set up. This means that subscribers will only be set up for
  # classes that call #attach_to.
  if public_method_defined?(event) && notifier
    add_event_subscriber(event)
  end
end

def start(name, id, payload)

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 subscribers

def subscribers
  @@subscribers ||= []
end

Modules

Classes