class ActiveSupport::Notifications::Instrumenter

Instrumenters are stored in a thread local.

def finish(name, payload)

Send a finish notification with +name+ and +payload+. 
def finish(name, payload)
  @notifier.finish name, @id, payload
end

def finish_with_state(listeners_state, name, payload) 

def finish_with_state(listeners_state, name, payload)
  @notifier.finish name, @id, payload, listeners_state
end

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={})
  # some of the listeners might have state
  listeners_state = start name, payload
  begin
    yield payload
  rescue Exception => e
    payload[:exception] = [e.class.name, e.message]
    payload[:exception_object] = e
    raise e
  ensure
    finish_with_state listeners_state, name, payload
  end
end

def start(name, payload)

Send a start notification with +name+ and +payload+. 
def start(name, payload)
  @notifier.start name, @id, payload
end

def unique_id 

def unique_id
  SecureRandom.hex(10)
end