Intelligent routing

[sanity]

• Greedy routing will always pick the closest peer to the desired location.
• But optimal strategy is to pick the peer that will complete the request fastest
• Use isotonic regression to estimate response time from a peer based on its ring distance from the target location of the request
• For each peer, track the average delta between iso estimated response time and actual response time
• Intelligent routing, for a given request, uses the iso to estimate response time for each peer then adjust by average delta
• Pick the peer with the lowest estimated response time

[sanity]

Need to consider how failed requests are accounted for to discourage the use of peers that have an improbably low success rate.

[github-actions]

Pivotal Tracker story: https://www.pivotaltracker.com/story/show/184058033