/// <summary>
/// Finds the closest contact in the network. Does several round trips to the network
/// </summary>
/// <param name="target">The target.</param>
/// <returns>an IEnumerable<contact> in order of distance from the target. Can be cast into a GetClosestNodes.ClosestResults</contact></returns>
public IEnumerable <Contact> GetClosestContacts(Identifier512 target, Func <Contact, bool> terminate = null)
{
MinMaxHeap <Contact> heap = new MinMaxHeap <Contact>(new ContactComparer(target), contacts.ClosestNodes(target).Take(RoutingTable.Configuration.LookupConcurrency));
HashSet <Identifier512> contacted = new HashSet <Identifier512>();
contacted.Add(RoutingTable.LocalIdentifier);
int iterations = 0;
HashSet <Contact> uniqueDiscoveries;
do
{
iterations++;
uniqueDiscoveries = new HashSet <Contact>( //hashet means we only get each result once
heap //from the set of results we know about
.Where(c => !contacted.Contains(c.Identifier)) //which we have not already contacted
.SelectMany(c =>
{
try { return(RemoteGetClosest(RoutingTable.LocalContact, c, target, RoutingTable.Configuration.LookupConcurrency, RoutingTable.Configuration.LookupTimeout)); }
catch (TimeoutException) { return(null); }
}) //select the closest ones they know about
.Where(n => n != null)
.Where(r => !heap.Contains(r))); //remove the results we already know about
//Make the system aware of these potentially new nodes
foreach (var c in uniqueDiscoveries)
{
contacts.Update(c);
}
//make sure we never contact these nodes again
contacted.UnionWith(heap.Select(a => a.Identifier));
//add the new results
heap.AddMany(uniqueDiscoveries);
while (heap.Count > RoutingTable.Configuration.LookupConcurrency)
{
heap.RemoveMax();
}
if (terminate != null)
{
if (uniqueDiscoveries.Where(a => terminate(a)).FirstOrDefault() != null)
{
break;
}
}
}while (uniqueDiscoveries.Count != 0 && heap.Minimum.Identifier != target);
return(new ClosestResults(heap, iterations));
//while (heap.Count > 0)
// yield return heap.RemoveMin();
}
