Can I use store.log to figure out if a response was cachable?
Sort of. You can use store.log to find out if a particular response was cached. Cached responses are logged with the SWAPOUT tag. Uncached responses are logged with the RELEASE tag. However, your analysis must also consider that when a cached response is removed from the cache (for example due to cache replacement) it is also logged in store.log with the RELEASE tag. To differentiate these two, you can look at the filenumber (3rd) field. When an uncachable response is released, the filenumber is FFFFFFFF (-1). Any other filenumber indicates a cached response was released.
