Module: ActiveSupport::Notifications

### Home Classes Methods

### In Files

- lib/active_support/notifications.rb
- lib/active_support/notifications/fanout.rb
- lib/active_support/notifications/instrumenter.rb

### Namespace

- CLASS ActiveSupport::Notifications::Event
- CLASS ActiveSupport::Notifications::Fanout
- CLASS ActiveSupport::Notifications::Instrumenter

### Methods

- ::instrument
- ::instrumenter
- ::notifier
- ::subscribe
- ::unsubscribe

### Class/Module Index

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No matching classes.

# ActiveSupport::Notifications

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.

### Attributes

notifier[W]

### Public Class Methods

instrument(name, payload = {}) click to toggle source

    # 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() click to toggle source

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

notifier() click to toggle source

    # File lib/active_support/notifications.rb, line 69
    def notifier
      @notifier ||= Fanout.new
    end

subscribe(*args, &block) click to toggle source

    # File lib/active_support/notifications.rb, line 58
    def subscribe(*args, &block)
      notifier.subscribe(*args, &block).tap do
        @instrumenters.clear
      end
    end

unsubscribe(*args) click to toggle source

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

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