Consider using xxHash instead of fnv64-1a

[dashpole]

Problem Statement

In #7175, we adopted fnv-1a for the hash algorithm without a deep investigation into alternatives. Based on feedback prometheus maintainers in that PR, we should strongly consider xxhash as an alternative.

Proposed Solution

Implement and benchmark hashing using github.com/cespare/xxhash.

[pree-dew]

@dashpole @MrAlias @pellared @dmathieu can I take this up?

[pellared]

@pree-dew, note that this issue includes investigating (e.g. benchmarking and testing the collision rates) whether xxhash is actually a better alternative.

[pree-dew]

Noted @pellared
From what I understand that we have already implemented a hashing mechanism, we have to find out that xxhash is a better alternative as compared to what is already implemented in terms of collision rates. It will only go in production if it turns out to be better than existing one.

Let me know if I have missed anything or if you want me to take care of any specifics while evaluating it.

[pree-dew]

@dmathieu @pellared @dashpole
Created a PR just to share the approach that I am taking to evaluate this (not added any package etc required to run this, wanted to share the method only)
#7497

Currently tested upto 100M, if the approach looks okay, I will continue with higher input and better distribution metrics, along with that look at resource benchmarks also.