This is Belated, a new Ruby backend job library! It supports running procs, lambdas and classes in the background. To deal with restarts, it uses YAML for the current jobs in the queue waiting to be processed and PStore for the future jobs to load the queues into a file, which it then calls at startup to find the previous jobs. There is no way in Ruby to save procs or lambdas to a file, so they are discarded when the process restarts.

Belated uses the Ruby Queue class, so it's First In, First Out (FIFO), unless of course you want to run the job in the future. In that case the order is decided by the time the job is scheduled to be executed.

It uses dRuby to do the communication! Which is absolute great. No need for Redis or PostgreSQL, just Ruby standard libraries.

Can be used with or without Rails.

Can be used if you're on a normal instance such as EC2 or Digital Ocean drop. Not if you're on a Heroku or Docker, or anything with ephemeral storage.

TODO LIST:

• Have a web UI with job history.
• Deploy a Rails app to production that is using Belated and mention it in the readme. (Capistrano support?) (Wasurechatta deployed, still need to setup Capistrano)

If you can, definitely use Sidekiq!!! Belated is supposed to be used if you can't get anything else to work. Like if you want to use SQLite in a Rails app and don't want to have Redis running. Or maybe you just want to run procs in the background?

Add this line to your application's Gemfile:

gem 'belated'

And then execute:

$ bundle install

Or install it yourself as:

$ gem install belated

Start up Belated!

$ belated

If you're using Rails, just set Belated to be the ActiveJob adapter like below:

config.active_job.adapter = :belated

And you're good to go!

If not, in your non-ActiveJob using program, connect to Belated and give it a job to do. Sample below:

class DumDum
  # classes need to have a perform method
  def perform
    5 / 4
  end
end

client = Belated::Client.new
client.perform_belated(proc { 2 / 1 })
client.perform_belated(DumDum.new)
# client.perform, client.perform_later are also good
# if you want to do something later:
client.perform_belated(DumDum.new, at: Time.now + 5 * 60)
# max retries:
client.perform_belated(DumDum.new, max_retries: 3) # default 5

You can also fetch jobs from the future jobs queue:

job = client.perform_belated(proc { 0 / 0 }, at: Time.now + 5 * 60)
job = Belated.find job.id # Find the job if it's in the future queue
# Oh no, that job looks a bit weird!
# Let's delete it:
client.perform_belated(
  Belated.delete job.id
)
# Yeah... currently you have to send the command through the client like this as a job. :/
# Maybe the client should handle the deletion?

Belated runs on localhost, port 8788 by default, but the port is configurable, see below.

Usage with Rails: First, start up Belated. Then,

# Get the client
client = Belated::Client.instance

and you can use the client! Note that the client is a singleton. This means that you can only have one client running at a time, but it also means you only have one connection to dRuby, and that the number of threads in charge of queuing the jobs is only one.

Call

job = proc { 2 / 1 }
client.perform_belated(job)

If you want to pass a job to Belated.

If you don't want the job to run right away, you can also pass it a keyword param at: like so:

client.perform_belated(job, Time.now + 1.month)

The client also holds references to the jobs that are instances of Proc that have been pushed so that they are not collected by GC. This is because procs are passed by reference, and the client needs to keep them alive. They are removed from the list when the job is done.

There is also a rudimentary admin panel:

1. Mount the engine routes

# routes.rb
mount Belated::Engine => '/belated'

Then access it at /belated/ for job search based on id or see future jobs at /belated/future_jobs. Warning: Very rudimentary.

Configuring Belated:

Belated.configure do |config|
  config.env = 'production' # Defaults to production
  config.rails = false # default is true
  config.rails_path = # './dummy' default is '.'
  config.connect = false # Connect to dRuby, default is true, useful for testing only
  config.workers = 2 # default is 1
  config.basic_auth.user = 'user' # default is Belated
  config.basic_auth.password = 'password' # default is Belated123
  # Set nil for both if you don't want basic auth
end

From command line:

$ bundle exec belated --rails=true

Use Rails or not.

$ bundle exec belated --rails_path=/my_rails_project

Path to Rails project.

$ bundle exec belated --workers=10

Other available settings:

$ bundle exec belated --host=1.1.1.1 --port=1234 
# druby://1.1.1.1:1234
$ bundle exec belated --env=test
# environment
$ bundle exec belated --client_heartbeat=10
# how often client sends jobs to server, default is once every 5 seconds

Number of workers.

When testing, you can require belated/testing and then call Belated::Testing.inline! to make your jobs perform inline.

`belated/testing`
c = Belated::Client.instance
c.perform(proc { 2/ 1}) # Tries to push the job to the drb backend
# <Belated::JobWrapper:0x00005654bc2db1f0 @at=nil, @completed=false, @id="95e4dc6a-1876-4adf-ae0f-5ae902f5f024", @job=#<Proc:0x00005654bc2db330 (irb):3>, @max_retries=5, @proc_klass=true, @retries=0>
Belated::Testing.inline! # Sidekiq-inspired, now jobs run inline
c.perform(proc { 2/ 1}) # Returns 2 right away
# 2
Belated::Client.test_mode_off! # Turn off inline job processing

After checking out the repo, run bin/setup to install dependencies. Then, run rake spec to run the tests. You can also run bin/console for an interactive prompt that will allow you to experiment. On Ubuntu, if you have an SQLite install error, try sudo apt-get install libsqlite3-dev.

To install this gem onto your local machine, run bundle exec rake install. To release a new version, update the version number in version.rb, and then run bundle exec rake release, which will create a git tag for the version, push git commits and the created tag, and push the .gem file to rubygems.org.

If you have the port 8788 already in use, you can check the ports in use in Linux with the following command:

$ sudo lsof -i -P -n | grep LISTEN

Bug reports, questions and pull requests are welcome on GitHub at https://github.com/sampokuokkanen/belated. This project is intended to be a safe, welcoming space for collaboration, and contributors are expected to adhere to the code of conduct.

The gem is available as open source under the terms of the MIT License.

Everyone interacting in the Belated project's codebases, issue trackers, chat rooms and mailing lists is expected to follow the code of conduct.