Change the modules map to use &'static str instead of String.

[Rylan W. Yancey]

The CudaDevice stores the modules in an RwLock<BTreeMap<String, CudaModule>>. This makes me concerned, since I will have ~100 modules loaded for my application and comparing heap strings this way is a very slow process. I suggest using &'static str and a HashMap. This will allow us to avoid uneccessary heap allocations and decrease the number of comparisons needed when searching for a module.

pub struct CudaDevice {
     modules: RwLock<HashMap<&'static str, CudaModule>>,
     ... etc
}

Benchmarking is obviously required to be certain. I look forward to hearing your thoughts, I'm a college student and would love to understand your process.

It is also entirely possible the compiler is doing all of this for us.

[Corey Lowman]

You can't use dynamically constructed names for your modules with &'static str. For you case, in general 100 strings isn't going to add much overhead, so I wouldn't worry about that!