Prefix-tree router

[ikitommi]

Background

• https://en.wikipedia.org/wiki/Radix_tree
• https://en.wikipedia.org/wiki/Deterministic_acyclic_finite_state_automaton
• https://github.com/julienschmidt/httprouter#how-does-it-work
• https://github.com/pedestal/pedestal/blob/master/route/src/io/pedestal/http/route/prefix_tree.clj

Based on Pedestal

But rewritten for speed and (IMO) correctness.

Speed?

4x better perf than the :linear-router (or the pedestal prefix-tree router) on the opensensor routing test.

Here are the steps for perf improvement:

  ;; 3.1ms
  ;; 2.5ms (string equals)
  ;; 2.5ms (protocol)
  ;; 2.3ms (nil childs)
  ;; 2.0ms (rando impros)
  ;; 1.9ms (wild & catch shortcuts)
  ;; 1.5ms (inline child fetching)
  ;; 1.5ms (WildNode also backtracks)
  ;; 1.4ms (precalculate segment-size)
  ;; 1.3ms (fast-map)
  ;; 1.3ms (dissoc wild & catch-all from children)
  ;; 1.3ms (reified protocols)
  ;; 0.8ms (flattened matching)
  ;; 0.8ms (return route-data)
  ;; 0.8ms (fix payloads)

Should this be merged?

Not yet, need more tests.