Notifications provides an instrumentation API for Ruby. To instrument an action in Ruby you just need to do: 

  ActiveSupport::Notifications.instrument(:render, :extra => :information) do
    render :text => "Foo"
  end

You can consume those events and the information they provide by registering a log subscriber. For instance, let’s store all instrumented events in an array: 

  @events = []

  ActiveSupport::Notifications.subscribe do |*args|
    @events << ActiveSupport::Notifications::Event.new(*args)
  end

  ActiveSupport::Notifications.instrument(:render, :extra => :information) do
    render :text => "Foo"
  end

  event = @events.first
  event.name      # => :render
  event.duration  # => 10 (in milliseconds)
  event.payload   # => { :extra => :information }

When subscribing to Notifications, you can pass a pattern, to only consume events that match the pattern: 

  ActiveSupport::Notifications.subscribe(/render/) do |event|
    @render_events << event
  end

Notifications ships with a queue implementation that consumes and publish events to log subscribers in a thread. You can use any queue implementation you want.

Methods
Attributes
[W] notifier
Public Class methods
instrument(name, payload = {})

[ show source ]

      # File activesupport/lib/active_support/notifications.rb, line 50
50:       def instrument(name, payload = {})
51:         if @instrumenters[name]
52:           instrumenter.instrument(name, payload) { yield payload if block_given? }
53:         else
54:           yield payload if block_given?
55:         end
56:       end
instrumenter()

[ show source ]

      # File activesupport/lib/active_support/notifications.rb, line 73
73:       def instrumenter
74:         Thread.current[:"instrumentation_#{notifier.object_id}"] ||= Instrumenter.new(notifier)
75:       end
notifier()

[ show source ]

      # File activesupport/lib/active_support/notifications.rb, line 69
69:       def notifier
70:         @notifier ||= Fanout.new
71:       end
subscribe(*args, &block)

[ show source ]

      # File activesupport/lib/active_support/notifications.rb, line 58
58:       def subscribe(*args, &block)
59:         notifier.subscribe(*args, &block).tap do
60:           @instrumenters.clear
61:         end
62:       end
unsubscribe(*args)

[ show source ]

      # File activesupport/lib/active_support/notifications.rb, line 64
64:       def unsubscribe(*args)
65:         notifier.unsubscribe(*args)
66:         @instrumenters.clear
67:       end