class ActiveSupport::Notifications::Instrumenter

def initialize(notifier) 

def initialize(notifier)
  @id = unique_id
  @notifier = notifier
end

def instrument(name, payload={})

in the passed-in block
and publish it. Notice that events get sent even if an error occurs
Instrument the given block by measuring the time taken to execute it 
def instrument(name, payload={})
  started = Time.now
  begin
    yield
  rescue Exception => e
    payload[:exception] = [e.class.name, e.message]
    raise e
  ensure
    @notifier.publish(name, started, Time.now, @id, payload)
  end
end

def unique_id 

def unique_id
  SecureRandom.hex(10)
end