Groupex

Syncronization primitive that allows acquire lock by index.

RawGroupex is implementation of this primitive. Its size the same as usize's size. It is being locked by index and panics when index out of this range. Range depends on size of usize, i.e. depends on the platform. It uses parking_lot internally for parking threads.

This crate provides GroupexMap and GroupexVec structs - hash table and dynamic array.

Let's talk about GroupexMap first. It includes HashMap. Its cells can be locked by keys. For this GroupexMap computes hash of the key and calculates the remainder of the division this hash by usize's size - 64 on amd64. So it locks not only the element connected to the key but all other elements that collides to that key. Thus it's dangerous to lock another cell when one lock already acquired in the thread. So, this is some kind of Bloom filter.

GroupexVec works similar to the previous one but includes Vec and its cells can be locked just by index. It's also dangerous to lock another cell when one lock already acquired in the thread because different indexes can be collided due to size of the RawGroupex.

Take into account that using just HashMap<_, Mutex<_>> is faster than GroupexMap. The second one is your choice only if you need more space-efficient solution.