Cache some records

[denismo]

It is obvious from the logs that Fuse performs some operations several times in a row. For example, getattr is called multiple times for the same file.

This presents significant opportunities for optimisation by caching, especially for any simple records like directory or file descriptor (but not data).

[denismo]

https://github.com/stucchio/Python-LRU-cache https://github.com/jlhutch/pylru https://github.com/repoze/repoze.lru