Rearchitect router internals.

[CathalMullan]

Some work to be done on the performance side of things.

Assuming that due to moving the data out of the node, our cache locality is worse. Plus now we need a hashmap lookup per match.

Instead of a hashmap, we could use a vec + index approach. But would make updates/deletes painful.

We could just change NodeData into an enum?

/// Holds data associated with a given node.
#[derive(Clone, Debug, Eq, PartialEq)]
pub enum NodeData<T> {
    /// Data is stored inline.
    Inline(T),

    /// Data is stored at the router level, as it's shared between 2 or more nodes.
    Reference(Arc<str>),
}

EDIT: Yes, much better. Happy to take a 5% hit for this, down from 20%.

We still need to actually disconnect the end-node -> data relationship. Right now, we've just moved it elsewhere.

EDIT: Also, should ensure we use constant terms. I've mixed up path and route multiple times in the docs.

This is only really a 'part 1'. We'll flesh out the finer details as part of the optional params support.

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 73.91304% with 6 lines in your changes missing coverage. Please review.

:white_check_mark: All tests successful. No failed tests found.

Files with missing lines	Patch %	Lines
src/router.rs	73.91%	5 Missing and 1 partial :warning:

Files with missing lines	Coverage Δ
src/node/search.rs	78.11% <ø> (ø)
src/router.rs	88.88% <73.91%> (-1.95%)	:arrow_down:

[codspeed-hq[bot]]

CodSpeed Performance Report

Merging #144 will degrade performances by 5.39%

_{Comparing 143-reconsider-router-internal-structure (02687bf) with main (15dd3fe)}

Summary

❌ 1 regressions ✅ 15 untouched benchmarks

:warning: Please fix the performance issues or acknowledge them on CodSpeed.

Benchmarks breakdown

	Benchmark	main	143-reconsider-router-internal-structure	Change
❌	path-tree benchmarks/wayfind	66.5 µs	70.2 µs	-5.39%