Feedpoint (source) is a blog aggregator written with Ruby on Rails deployed on a linux server. It retrieves RSS content from blogs and displays them sorted by date at http://feedpoint.hertler.org. Retrieving the RSS content is an expensive step and caching is needed to speed up HTTP requests. Google searching for a way to expire page caching on a timed interval did not yield promising results so I developed a very easy custom strategy through the use of Linux cron jobs.

The Rails code for the page caching is in home_controller.rb.



caches_page and expire_page  are ActionController methods. caches_page caches the the :index and :planet_redpoint actions and expire_page expires them.

With this setup, http://feedpoint.hertler.org/home/ will load the :index into page cache and http://feedpoint.hertler.org/home/expire_cache will expire the cache. At this point, monkeys could be trained to navigate to the expire_cache URL every ten minutes or a cron job could be set up. This post will focus on setting up the cron job.

The cron job was configured by entering crontab -e from a terminal and then adding the following line:


This job uses cURL to call the expire_page action every ten minutes. Good cron tutorials are all over the web and beyond the scope of this post.

One added benefit of this approach is that if a blogger is anxious for a recently posted blog to show up on the world famous http://feedpoint.hertler.org site, it can manually be refreshed right away!

Labels: Rails, Ruby