Metrognome

A simple repeating task scheduler for Rails applications

Installation

Add this line to your application's Gemfile:

gem 'metrognome'

And then execute:

$ bundle install

Or install it yourself as:

$ gem install metrognome

To start the metrognome, run:

$ bundle exec rake metrognome:start

In production, use RAILS_ENV to let Rails know to start the right environment:

$ bundle exec rake RAILS_ENV=production metrognome:start

To stop the metrognome, run:

$ bundle exec rake metrognome:stop

Schedulers are registered with metrognome and run on a periodic basis. Schedulers are .rb files read from the folder config/metrognome

All schedulers are instances of Metrognome::Scheduler, initialized like:

beeper = Metrognome::Scheduler.new(10.seconds)

The beeper task will be executed every 10 seconds beginning when the metrognome starts. To define the task to execute, pass a block to beeper.task:

beeper.task do
  puts "Beep!"
end

Finally, register the task with Metrognome::Registrar.register:

Metrognome::Registrar.register beeper

Most schedulers can benefit from some persistence, or at least some setup. Let's have our beeper keep track of how many times it's beeped.

Accessors can be declared when the scheduler is initialized:

beeper = Metrognome::Scheduler.new(10.seconds, :counter)

The counter can be given an initial value by passing a block to beeper.setup:

beeper.setup do
  self.counter = 0
end

Finally, the counter can be used in the task block:

beeper.task do
  self.counter += 1
  logger.info "Beep! #{counter} time(s)"
end

TODO: Commit message/code style guidelines