What does "stale, valid, store" mean when accessing a cache in Rails?

Question

In my log I have many things like this:

cache: [GET /assets/widget.png] stale, valid, store

What does it mean? Is it a cache miss or hit? What does it mean to be stale and also valid?

Answer 1

What it means is that the entry was stale and a conditional request was issued (a request with If-Modified-Since header). The origin server responded with a 304 (Not Modified) status code, implying that the cache entry is valid.

In other words the origin server was reached (miss?) BUT it didn't send the object again, it just validated it since it was not modified.