@Override
  public void onResponse(ReplicaId replicaId, TrackedRequestFinalState trackedRequestFinalState) {
    super.onResponse(replicaId, trackedRequestFinalState);
    String dcName = replicaId.getDataNodeId().getDatacenterName();
    if (trackedRequestFinalState == TrackedRequestFinalState.SUCCESS) {
      numSuccessInDcs.put(dcName, numSuccessInDcs.getOrDefault(dcName, 0) + 1);
    } else {
      numFailureInDcs.put(dcName, numFailureInDcs.getOrDefault(dcName, 0) + 1);
    }
  }
Constructs an {@link UndeleteOperationTracker}
@param routerConfig The {@link RouterConfig} containing the configs for operation tracker.
@param partitionId The partition on which the operation is performed.
@param originatingDcName name of originating DC whose replicas should be tried first.
@param routerMetrics
ambry-router/src/main/java/com/github/ambry/router/UndeleteOperationTracker.java