The policy cache is a two-level nested cache, with one hash map contained inside the other. The top level cache is the resource cache. The session cache is a second hash map inside the resource cache.
A hash map whose key is resource/rule name and the value is hash map of policy session cache.
A hash map whose key is sessionid and the value is map of policy decision objects. For each new resource a new hash map of session cache is created and stored in the policy resource cache.