This policy encapsulates another policy. The resulting policy works in the following way:

• the distance method is inherited from the child policy.
• the iterator return by the newQueryPlan method will first return the LOCAL replicas for the query (based on Statement.GetRoutingKey) if possible (i.e. if the query getRoutingKey method doesn't return null and if GetReplicas(String, Byte) returns a non empty set of replicas for that partition key). If no local replica can be either found or successfully contacted, the rest of the query plan will fallback to one of the child policy.

Do note that only replica for which the child policy distance method returns HostDistance.Local will be considered having priority. For example, if you wrap DCAwareRoundRobinPolicy with this token aware policy, replicas from remote data centers may only be returned after all the host of the local data center.