Pub/Sub using ActiveSupport::Notifications

publisher.rb

module Publisher
  extend self

  def broadcast_event(event_name, payload={})
    if block_given?
      ActiveSupport::Notifications.instrument(event_name, payload) do
        yield
      end
    else
      ActiveSupport::Notifications.instrument(event_name, payload)
    end
  end

end

# Usage
if user.save 
  Publisher.broadcast_event('user.created', user: user)
end

# Usage with block
def create_user(params)
  user = User.new(params)
  
  Publisher.broadcast_event('user.created', user: user) do 
    User.save!
    # do some more important stuff here
  end
end

subscriber.rb

module Subscriber

  def self.subscribe(event_name)
    if block_given?
      ActiveSupport::Notifications.subscribe(event_name) do |*args|
        event = ActiveSupport::Notifications::Event.new(*args)
        yield(event)
      end
    end
  end

end

# Usage
Subscriber.subscribe('user.created') do |event|
  error = "Error: #{event.payload[:exception].first}" if event.payload[:exception]
  puts "#{event.transaction_id} | #{event.name} | #{event.time} | #{event.duration} | #{event.payload[:user].id} | #{error}"
end