rails--rails/activejob

Active Job -- Make work happen later

Active Job is a framework for declaring jobs and making them run on a variety of queueing backends. These jobs can be everything from regularly scheduled clean-ups, to billing charges, to mailings. Anything that can be chopped up into small units of work and run in parallel, really.

It also serves as the backend for Action Mailer's #deliver_later functionality that makes it easy to turn any mailing into a job for running later. That's one of the most common jobs in a modern web application: sending emails outside of the request-response cycle, so the user doesn't have to wait on it.

The main point is to ensure that all Rails apps will have a job infrastructure in place, even if it's in the form of an "immediate runner". We can then have framework features and other gems build on top of that, without having to worry about API differences between Delayed Job and Resque. Picking your queuing backend becomes more of an operational concern, then. And you'll be able to switch between them without having to rewrite your jobs.

Usage

To learn how to use your preferred queueing backend see its adapter documentation at ActiveJob::QueueAdapters.

Declare a job like so:

class MyJob < ActiveJob::Base
  queue_as :my_jobs

  def perform(record)
    record.do_work
  end
end

Enqueue a job like so:

MyJob.perform_later record  # Enqueue a job to be performed as soon as the queueing system is free.

MyJob.set(wait_until: Date.tomorrow.noon).perform_later(record)  # Enqueue a job to be performed tomorrow at noon.

MyJob.set(wait: 1.week).perform_later(record) # Enqueue a job to be performed 1 week from now.

That's it!

Supported types for arguments

ActiveJob supports the following types of arguments by default:

• Standard types (NilClass, String, Integer, Fixnum, Bignum, Float, BigDecimal, TrueClass, FalseClass)
• Hash. Keys should be of String or Symbol type
• ActiveSupport::HashWithIndifferentAccess
• Array

GlobalID support

Active Job supports GlobalID serialization for parameters. This makes it possible to pass live Active Record objects to your job instead of class/id pairs, which you then have to manually deserialize. Before, jobs would look like this:

class TrashableCleanupJob
  def perform(trashable_class, trashable_id, depth)
    trashable = trashable_class.constantize.find(trashable_id)
    trashable.cleanup(depth)
  end
end

Now you can simply do:

class TrashableCleanupJob
  def perform(trashable, depth)
    trashable.cleanup(depth)
  end
end

This works with any class that mixes in GlobalID::Identification, which by default has been mixed into Active Record classes.

Serializers

You can extend list of supported types for arguments. You just need to define your own serializer.

class MySpecialSerializer
  class << self
    # Check if this object should be serialized using this serializer
    def serialize?(argument)
      object.is_a? MySpecialValueObject
    end

    # Convert an object to a simpler representative using supported object types.
    # The recommended representative is a Hash with a specific key. Keys can be of basic types only
    def serialize(object)
      {
        key => ActiveJob::Serializers.serialize(object.value)
        'another_attribute' => ActiveJob::Serializers.serialize(object.another_attribute)
      }
    end

    # Check if this serialized value be deserialized using this serializer
    def deserialize?(argument)
      object.is_a?(Hash) && object.keys == [key, 'another_attribute']
    end

    # Convert serialized value into a proper object
    def deserialize(object)
      value = ActiveJob::Serializers.deserialize(object[key])
      another_attribute = ActiveJob::Serializers.deserialize(object['another_attribute'])
      MySpecialValueObject.new value, another_attribute
    end

    # Define this method if you are using a hash as a representative.
    # This key will be added to a list of restricted keys for hashes. Use basic types only
    def key
      "_aj_custom_dummy_value_object"
    end
  end
end

And now you just need to add this serializer to a list:

ActiveJob::Base.add_serializers(MySpecialSerializer)

Supported queueing systems

Active Job has built-in adapters for multiple queueing backends (Sidekiq, Resque, Delayed Job and others). To get an up-to-date list of the adapters see the API Documentation for ActiveJob::QueueAdapters.

Auxiliary gems

• activejob-stats

Download and installation

The latest version of Active Job can be installed with RubyGems:

  $ gem install activejob

Source code can be downloaded as part of the Rails project on GitHub:

• https://github.com/rails/rails/tree/master/activejob

License

Active Job is released under the MIT license:

• https://opensource.org/licenses/MIT

Support

API documentation is at:

• http://api.rubyonrails.org

Bug reports for the Ruby on Rails project can be filed here:

• https://github.com/rails/rails/issues

Feature requests should be discussed on the rails-core mailing list here:

• https://groups.google.com/forum/?fromgroups#!forum/rubyonrails-core