How to manage Rufus scheduler at runtime

Question

I schedule a job using Rufus-scheduler in Ruby from a simple controller's action. Later I want to call another action in which I will un-schedule the job that was executing up until that moment in time. Of course, I need to keep a reference to my scheduler alive during many sessions that may occur between starting and stopping the scheduler. An obvious choice would be some kind of a singleton class which would keep that reference to the scheduler.

Is that an OK approach?

If yes, here is how I handled it...

Beside folders like 'controllers', 'models', 'views'... I created folder 'domain' in which I created AppConfig singleton class that has property of class Rufus::Scheduler.

My singleton class looks like this:

require 'singleton'
require 'rufus/scheduler'

class AppConfig
  include Singleton

  attr_accessor :scheduler

  def self.instance
    @@instance ||= new
  end

  def initialize
    @scheduler = Rufus::Scheduler.start_new
  end
end

And my actions that use this scheduler are like this:

        # ...
  # someController
  def start_actions
    scheduler = AppConfig.instance.scheduler

    scheduler.every('30s') do
      SomeModel.some_method
    end

  end

  def stop_actions
    scheduler = AppConfig.instance.scheduler
    scheduler.stop(:terminate => true)
  end

Am I missing something here? Is this an OK approach?

Answer 1

the problem I see with your approach: when you stop the scheduler, @@instance doesn't become nil, so the next time the controller needs a scheduler it will get one, the same one, which is stopped.

Most of the time, people start a scheduler in config/initializers/scheduler.rb and place it in a global var (or a singleton). That scheduler lives as long as the Ruby on Rails process lives. The controller place (or remove) jobs in the scheduler, they never stop it.