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));
}
/// <summary>
/// Find the closest k closest nodes to the given key (using <see cref = "NodeLookUp" />) and stores
/// the (<paramref name = "key" />,<paramref name = "value" />) pair in those nodes.
/// </summary>
/// <param name = "key"></param>
/// <param name = "value"></param>
public void StoreLookUp(TKey key, TValue value)
{
// the calls to Store in the nodes can be asynchronous
NodeLookUp(key).ToObservable()
.Subscribe(node =>
{
try
{
IKadNode <TKey, TValue> client = CreateClientFromNodeId(node);
client.Store(key, value, NodeIdentifier);
}
catch (CommunicationException e)
{
}
});
}
/// <summary>
/// This method returns the value associated with the given key.
/// </summary>
/// <remarks>
/// It's similar to the <see cref = "NodeLookUp" /> method but using <see cref = "FindValue" />.
/// </remarks>
/// <param name = "key"></param>
/// <returns></returns>
public TValue ValueLookUp(TKey key)
{
// IEnumerable<NodeIdentifier<TKey>> closestNodes = NodeLookUp(key).ToList();
foreach (var nodeIdentifier in NodeLookUp(key))
{
try
{
IKadNode <TKey, TValue> client = CreateClientFromNodeId(nodeIdentifier);
FindValueResult <TKey, TValue> findValueResult = client.FindValue(key, NodeIdentifier);
if (findValueResult.HasValue)
{
return(findValueResult.Value);
}
}
catch (CommunicationException e)
{
// the service isn't working properly or doesn't contain the given key
}
}
throw new KeyNotFoundException("The key doesn't exist in the network.");
}
