Name cache by the hash of a file

It would be incredible if we could name the cache based off of the hash of the contents of a file. Primarily because if the file doesn't change then the hash will be the same, therefore we know there is no need to update the cache as well is if we should retrieve the cache.

For example:
Say I have a package.json that contains a list of js dependencies for my project. At the beginning of the pipeline there is a check that hashes the contents of my package.json and if it matches any of my caches then it will pull it down. Otherwise cache won't be pulled down and on completion of a pipeline a new cache will be created.

As a result we ensure we always have the proper dependencies and potentially speed up the pipeline as well.

To solve the problem of potential lingering cache we can delete cache that was using this method after a given period of time like a week or two.