priority buckets:
  std::array [ differentiated service ]
fairness buckets:
  intrusive unordered set [ source address ]
  intrusive unordered set [ dest address ]
  intrusive unordered set [ protocol, port pair ]
per-bucket queue:
  intrusive doubly linked list
global size queue (for binpacking):
  intrusive multiset [ packet size ]

siphash for unordered sets

pop algorithm:
  find first non-empty priority
  keep iterator to 3 tiers of next bucket in rotation
  pop first N from bucket queue until picking next packet would exceed size limit
  use global size queue find packets with size <= remaining space; largest-first binpacking


HonestQueue
  std::array[ differentiated service ] -> PriorityBucket
    intrusive unordered set [ source address ] -> FairSrcBucket
      intrusive unordered set [ dest address ] -> FairDestBucket
        intrusive unordered set [ protocol, port pair ] -> FairFlowBucket
          intrusive double-linked list -> Packet
    statistics

  intrusive multiset [ packet size ] -> Packet

  statistics