Adding clockwork to recurrently fetch feeds

It will replace Scheduler (for deployment on Heroku), so that no extra step is
needed due to another spawn command being called on unicorn.rb starting
clockwork.

Still on Heroku, Procfile is updated, describing the worker and clock
components (if the user wants a more robust architecture).
This fixes #411

Also, for development environments, it will allow fetching feeds without
having to manually running rake commands.

The default interval for fetching feeds is 10 min and it can be customized
by env var FETCH_INTERVAL.

Author: fearenales

Diff for: Gemfile

@@ -27,6 +27,7 @@ end
 gem "activerecord", "~> 4.1.11"
 gem "arel", "~> 5.0"
 gem "bcrypt-ruby", "~> 3.1.2"
+gem "clockwork", "~> 1.2"
 gem "delayed_job", "~> 4.1"
 gem "delayed_job_active_record", "~> 4.1"
 gem "feedbag", "~> 0.9.2"

Diff for: Gemfile.lock

@@ -30,6 +30,9 @@ GEM
       rack (>= 1.0.0)
       rack-test (>= 0.5.4)
       xpath (~> 2.0)
+    clockwork (1.2.0)
+      activesupport
+      tzinfo
     coderay (1.1.0)
     columnize (0.3.6)
     coveralls (0.7.0)
@@ -187,6 +190,7 @@ DEPENDENCIES
   arel (~> 5.0)
   bcrypt-ruby (~> 3.1.2)
   capybara (~> 2.4.1)
+  clockwork (~> 1.2.0)
   coveralls (~> 0.7)
   delayed_job (~> 4.1)
   delayed_job_active_record (~> 4.1)
@@ -217,3 +221,6 @@ DEPENDENCIES
   timecop (~> 0.7.1)
   unicorn (~> 4.7)
   will_paginate (~> 3.0, >= 3.0.5)
+
+BUNDLED WITH
+   1.11.2

Diff for: Procfile

@@ -1,2 +1,4 @@
 web: bundle exec unicorn -p $PORT -c ./config/unicorn.rb
+worker: bundle exec rake work_jobs
+clock: bundle exec clockwork lib/clock.rb
 console: bundle exec racksh

Diff for: config/unicorn.rb

@@ -2,14 +2,17 @@
 timeout 30
 preload_app true
 
-@delayed_job_pid = nil
+work_pids = {}
 
 before_fork do |_server, _worker|
   # the following is highly recommended for Rails + "preload_app true"
   # as there's no need for the master process to hold a connection
   ActiveRecord::Base.connection.disconnect! if defined?(ActiveRecord::Base)
 
-  @delayed_job_pid ||= spawn("bundle exec rake work_jobs")
+  unless ENV["WORKER_EMBEDDED"] == "false"
+    work_pids[:delayed_job] ||= spawn("bundle exec rake work_jobs")
+    work_pids[:recurring_jobs] ||= spawn("bundle exec clockwork lib/clock.rb")
+  end
 
   sleep 1
 end

Diff for: lib/clock.rb

@@ -0,0 +1,16 @@
+require "clockwork"
+require "delayed_job"
+require "delayed_job_active_record"
+
+require_relative "../app"
+require_relative "../app/jobs/fetch_feed_job"
+require_relative "../app/repositories/feed_repository"
+
+include Clockwork
+
+fetch_interval = (ENV["FETCH_INTERVAL"] || 10*60).to_i # Fetch every 10 minutes by default
+every(fetch_interval.seconds, "clockwork.frequent") do
+  FeedRepository.list.each do |feed|
+    Delayed::Job.enqueue FetchFeedJob.new(feed.id)
+  end
+end