Module: ActiveSupport::Notifications

Defined in:
lib/active_support/notifications.rb,
lib/active_support/notifications/fanout.rb,
lib/active_support/notifications/instrumenter.rb

Overview

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.

Defined Under Namespace

Classes: Event, Fanout, Instrumenter

Class Attribute Summary collapse

Class Method Summary collapse

Class Attribute Details

.notifier ⇒ Object 



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# File 'lib/active_support/notifications.rb', line 69

def notifier
  @notifier ||= Fanout.new
end

Class Method Details

.instrument(name, payload = {}) ⇒ Object 



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# File 'lib/active_support/notifications.rb', line 50

def instrument(name, payload = {})
  if @instrumenters[name]
    instrumenter.instrument(name, payload) { yield payload if block_given? }
  else
    yield payload if block_given?
  end
end

.instrumenter ⇒ Object 



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# File 'lib/active_support/notifications.rb', line 73

def instrumenter
  Thread.current[:"instrumentation_#{notifier.object_id}"] ||= Instrumenter.new(notifier)
end

.subscribe(*args, &block) ⇒ Object 



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# File 'lib/active_support/notifications.rb', line 58

def subscribe(*args, &block)
  notifier.subscribe(*args, &block).tap do
    @instrumenters.clear
  end
end

.unsubscribe(*args) ⇒ Object 



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# File 'lib/active_support/notifications.rb', line 64

def unsubscribe(*args)
  notifier.unsubscribe(*args)
  @instrumenters.clear
end