RFC - Efficient Targeting Service

A targeting object represents a set of rules that need to be evaluated, which outputs the best-fit variation for a particular flag. Rulesets need to be evaluated in priority order. The first matching rule will dictate the resulting output (i.e. the recommended variation).

Evaluation Engine

The ruleset evaluation engine essentially selects the variation in which the first rule is satisfied. It can be defined recursively in 4 lines. Note that the following below is just pseudo-code aimed to illustrate the core logic that is used for flag evaluation.

evaluate(ruleset, fallthrough_variation) :: (Ruleset, Variation) -> Variation
  if (ruleset is empty) return fallthrough_variation
  cons {condition, identity, segement, variation} = ruleset.pop()
  if (<condition> matches <identity | segment>) then return variation
  return evaluate(ruleset, fallthrough_variation)

Data Models