Benjamin Sago aa94ee89db Return Arcs instead of clones, and take &self ...

The primary goal of this commit was to avoid having to clone the users and groups it produces. The old implementation was written by me when I hadn't *fully* internalised how lifetimes worked, and just used `clone` to get around the error messages. It was only later that I realised how inefficient this actually is -- the values stored in the cache are never used, only their clones are!

Several attempt at this later, I settled on using `Arc` for everything and cloning *those* values instead.

All the gory details of what happened are written in a comment in the OS module. The short version is that it's now possible to change the `Users` trait's methods from taking `&mut self` to just taking `&self`. This is within the allowed uses of `Cell`: implementation details of a method that does actually return the same thing each time, which this is.

The main casualty is that the user now has to know about `Arc` and initialise a user with a username in such a container, which I hope to solve in a later commit.

2016-01-14 23:15:02 -10:00

..

example.rs

Return Arcs instead of clones, and take &self

2016-01-14 23:15:02 -10:00

threading.rs

Return Arcs instead of clones, and take &self

2016-01-14 23:15:02 -10:00