How do I test if Rack::Cache is functioning with Sinatra app on Heroku with memcache?

Question

I'm making a web app where many users will be viewing a Google map, with updates on the map pulled in through ajax requests to the server. I want the response that is sent to the users to be cached, because it involves scraping data from an outside server, and it only needs to update every 2-3 minutes.

So, as soon as one person requests the data, I want all subsequent requests from all other users to be pulled in from the cache for the next 2-3 minutes. I followed this tutorial , which details how to set up Rack::Cache and the Dalli gem in Sinatra with Heroku, and when I ran a test on a page set up with the following,

cache_control :public, max_age: 3000

I can see the cache headers come through correctly (using Google Chrome Developer Tools), but if I hit refresh, or if I request the page from another computer, the content was clearly regenerated (I put a Time.now output). However, if I go to another page, then retype the URL, the content is not regenerated. I think the browser is caching the result, but not the memcache server? Do I have a fundamental misunderstanding of how caching works?

Answer 1

For people who come upon this question, here are some threads which may help you solve your issue (helped me).

"refresh" in your browser, causes a "Cache-Control: max-age=0": https://groups.google.com/forum/#!topic/rack-cache/sWHyu4pYwKw

Clearing cache and removing cache directory (this worked for me): https://github.com/rails/rails/issues/5245

Adding specs for it with rspec / other Sinatra, Rack::Test, and Conditional GET requests