Setup

ChronoTrigger is designed to work with Rails 5.2 and beyond. It has minimal gem dependencies and no infrastructure dependencies.

bundle add chrono_trigger
mkdir app/events

In the app/events folder, we will create an ApplicationEvent class for our Event classes to inherit from:

app/events/application_event.rb

class ApplicationEvent < ChronoTrigger::Event
  include CableReady::Broadcaster
  # delegate :render, to: ApplicationController
end

While you can use ChronoTrigger to run any code, it has been designed to work with CableReady. Including CableReady::Broadcaster makes the cable_ready method available to all of your Event classes.

If you plan to use CableReady to send rendered HTML, you might wish to delegate render to ApplicationController.

Finally, you need to start the Clock! The best place to do this is after Puma starts up:

config/puma.rb

# place this at the bottom of puma.rb
ChronoTrigger::Clock.start

Optional: Create an initializer

Today, it's possible to configure the resolution of the timer, but the 100ms default is likely fine. There will be additional options added in the future:

config/initializers/chrono_trigger.rb

ChronoTrigger.configure do |config|
  config.interval = 0.1 # 100ms
end

You might be wondering: why not start the Clock in the initializer? The reason is that you only want to run ChronoTrigger in the web server process - not Sidekiq, console, when running migrations and other rake tasks...