Check if cache empty?

Is there are way to detect when a bigcache instance is completely empty? I have a use case where I store about a dozen cache items which are read in from a file bundled with my application. After the invalidation interval elapses, I have an OnRemove() handler set up to listen for the evictions. I want to rehydrate the cache from the original file I mentioned earlier, but I don't want to do that until all the cache items have been removed. Any thoughts or perhaps suggestions on a different strategy?