Order processing from the database based on status

Order.rb

class Order

  def self.ready_to_queue
    where(status: new_states)
  end

  def self.new_states
    ['created', '', nil]
  end

  # This will select the next available order to be processed and queue it for
  # sidekiq ensuring that it's not already being processed
  def self.queue_next_order
    Order.transaction do
      order = Order.lock.ready_to_queue.first
      if new_states.include?(order.status)
        order.status = 'queued' && order.save!
        SendOrderWorker.perform_async(order.id)
      else
        queue_next_order
    end
  end
end

SendOrderWorker.rb

class SendOrderWorker
  include Sidekiq::Worker

  def perform(order_id)
    order = Order.find(order_id)
    order.status = 'running' && order.save
    # serialze and send the order
    order.status = 'success' && order.save
  rescue
    order.status = 'error' && order.save
  ensure
    # This queues the next job once this worker is done
    Order.queue_next_order
  end
end