module ActiveJob::Callbacks::ClassMethods

end
end
Video.find(video_id).process
def perform(video_id)

end
UserMailer.notify_video_started_processing(job.arguments.first)
before_perform do |job|

queue_as :default
class VideoProcessJob < ActiveJob::Base

job's perform method is executed.
Defines a callback that will get called right before the

def before_perform(*filters, &blk)
  set_callback(:perform, :before, *filters, &blk)
end