Add ActiveJob

[zaratan]

Why ?

Sending an email (see ticket #46) with Sendgrid take 1 to 2 sec each time. The user doesn't need to wait and the email can be sent asynchronously.

Must have

• Sidekiq must be configured to work with ActiveJob
• All emails should be delivered later through Sidekiq/ActiveJob
• Plug it in Heroku
• If you have it make it work in Docker

Todo

• Configure sidekiq to work with active record (in dev) (see documentation lower)
• For processing emails with sidekiq dont forget to tell sidekiq that you want to process the mailer queue (-q default -q mailers)
• Email sent by devise token auth are sent with a deliver_now. To send them through sidekiq, define this in the User model:

def send_devise_notification(notification, *args)
  devise_mailer.send(notification, self, *args).deliver_later
end

• A worker and the main rails process doesn't share a SQL Transaction. So if you sent the emails in an after_create, you might have some fun and your worker might not find the invitation. Use after_commit instead (cf doc lower).
• To test and NOT use the sidekiq queue add at the end of your rails_helper.rb:

ActiveJob::Base.queue_adapter = :test

• When it's working in dev the fun part begin: Add Redis as an add-on to all of your heroku apps
• Add a worker line in your profile to launch sidekiq
• Each worker will connect to the DB and the number of connection is limited in a free heroku postgresql so limit the number of sidekiq workers to 10 (-c 10)
• Try your heroku config with heroku local worker (more info on this here: https://devcenter.heroku.com/articles/heroku-local)
• Deploy in staging and test it, then deploy in production.

Reading List

• https://edgeguides.rubyonrails.org/active_job_basics.html;
• https://github.com/mperham/sidekiq/wiki/Active-Job;
• https://www.zaratan.fr/blog/2018/03/23/la-theorie-des-background-jobs/ (IE: why are we doing it this way);
• https://www.zaratan.fr/blog/2018/03/16/turtle-family-3-background-jobs/ (an example in turtle app).
• https://guides.rubyonrails.org/active_record_callbacks.html#transaction-callbacks