A Rails Fake Cron

07 Jun 2012

Recently I've been working on a project on which a simple cron job was not an option, while it would have been the perfect solution for the task given. Since we were sure that we were not dealing with long running jobs we decided that it could run during a user's request. But not on every request, only every so often would be just fine. A fake cron job is the solution I came up with... (it goes into the ApplicationController)

  before_filter :fake_cron_job
  
  # checks on every request if the last check is
  # older than one hour, if so, yields block
  def fake_cron_job
    periodic_check(:interval => 1.hour,
                   :path => '/tmp/project_name_fake_cron_check') do
      # add tasks to perform periodically here...
      Milestone.check_for_over_due!
    end
  end
  
  def periodic_check(options)
    defaults = {
      :interval => 12.hours,
      :path => File.join(Rails.root, 'tmp', 'periodic')
    }
    options.reverse_merge! defaults
    path = options[:path]
    return if File.exist?(path) and
      Time.now - File.mtime(path) < options[:interval]
    yield
    FileUtils.touch(path)
  end

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A Rails Fake Cron