Getting most recent paths visited across sessions in Rails app

Question

I have a simple rails app with no database and no controllers. It uses High Voltage for routing queries, then uses javascript to go get data using the params hash.

A typical URL looks like this:

http://example.com/?id=37ed660aa222e61ebbbc02db

I'd like to grab the ten unique URLs users have most recently visited and pass them to a view. Note that I said users, preferably across concurrent sessions.

Is there a way to retrieve this using ActiveSupport::Notifications or Production.log? Any examples, including where the code should best go, would be greatly appreciated!

Answer 1

I think that Redis would be ideally suited to this. It's one of the NoSQL key-value store db's, but its support for the value part being an ordered list, queue, etc. should make it easy to store unique urls in a FIFO list as they are visited, limit the size of that list (discard urls at the 'old' end of the list), and retrieve the most recent N urls to pass to your view. Your list should stay small enough that it would all stay in memory and be very fast. You might be able to do this with memcached or mongo or another one as well; I think it would be best though if the solution kept the stored values in memory.

If you aren't already using redis (or similar), it might seem like overkill to set it up and maintain just for this feature. But you can make it pay for itself by also using it for caching, background job processing (Resque / Sidekiq), and probably other things in your app.