private IEnumerable <NodeIdentifier <TKey> > NodeLookUp(TKey key,
IEnumerable <NodeIdentifier <TKey> > knownClosestNodes)
{
// convert the closest nodes to a list to prevent multiple enumerations
List <NodeIdentifier <TKey> > closestNodes = knownClosestNodes.ToList();
List <NodeIdentifier <TKey> > orderedNodes = closestNodes.ToObservable()
.CachedSelectMany(nodeId =>
{
IKadNode <TKey, TValue> client = CreateClientFromNodeId(nodeId);
FindNodeResult <TKey> nodes = client.FindNode(key, NodeIdentifier);
return(Observable.Return(nodes));
}, maxConcurrent: Settings.Cita)
.SelectMany(findNodeResult => findNodeResult.Nodes)
.Merge(closestNodes.ToObservable())
.Distinct()
.Do(RegisterNewNode)
.Timeout(Settings.ClientTimeOut)
.OnErrorResumeNext(Observable.Empty <NodeIdentifier <TKey> >())
.ToEnumerable()
.OrderBy(nodeId => nodeId.NodeId,
new LamdaComparer <TKey>((n1, n2) => RoutingTable.DistanceComparer(n1, n2, key)))
.Take(Settings.K)
.ToList();
return(orderedNodes.SequenceEqual(closestNodes)
? orderedNodes
: NodeLookUp(key, orderedNodes));
}
