private async Task <ImmutableList <BoundPeer> > QueryNeighborsAsync(
Address target,
TimeSpan?timeout,
CancellationToken cancellationToken)
{
List <BoundPeer> neighbors = _routing.Neighbors(target, _bucketSize).ToList();
var found = new List <BoundPeer>();
int count = (neighbors.Count < Kademlia.FindConcurrency)
? neighbors.Count
: Kademlia.FindConcurrency;
bool timeoutOccurred = true;
for (int i = 0; i < count; i++)
{
try
{
found.AddRange(
await GetNeighbors(neighbors[i], target, timeout, cancellationToken));
timeoutOccurred = false;
}
catch (TimeoutException)
{
continue;
}
}
if (count != 0 && timeoutOccurred)
{
_logger.Debug($"Timeout occurred during {nameof(QueryNeighborsAsync)}.");
throw new TimeoutException(
$"Timeout occurred during {nameof(QueryNeighborsAsync)}.");
}
return(found.ToImmutableList());
}
private async Task <IEnumerable <BoundPeer> > QueryNeighborsAsync(
ConcurrentBag <BoundPeer> history,
Address target,
TimeSpan?timeout,
CancellationToken cancellationToken)
{
List <BoundPeer> neighbors = _routing.Neighbors(target, _bucketSize).ToList();
var found = new List <BoundPeer>();
int count = neighbors.Count < Kademlia.FindConcurrency
? neighbors.Count
: Kademlia.FindConcurrency;
var timeoutOccurred = true;
for (var i = 0; i < count; i++)
{
try
{
var peers =
await GetNeighbors(neighbors[i], target, timeout, cancellationToken);
history.Add(neighbors[i]);
found.AddRange(peers.Where(peer => !found.Contains(peer)));
timeoutOccurred = false;
}
catch (TimeoutException)
{
}
}
if (count != 0 && timeoutOccurred)
{
_logger.Debug($"Timeout occurred during {nameof(QueryNeighborsAsync)}.");
throw new TimeoutException(
$"Timeout occurred during {nameof(QueryNeighborsAsync)}.");
}
return(found);
}
/// <summary>
/// Use <see cref="FindNeighbors"/> messages to to find a <see cref="BoundPeer"/> with
/// <see cref="Address"/> of <paramref name="target"/>.
/// </summary>
/// <param name="target">The <see cref="Address"/> to find.</param>
/// <param name="depth">Target depth of recursive operation.</param>
/// <param name="timeout"><see cref="TimeSpan"/> for waiting reply of
/// <see cref="FindNeighbors"/>.</param>
/// <param name="cancellationToken">A cancellation token used to propagate notification
/// that this operation should be canceled.</param>
/// <returns>A <see cref="BoundPeer"/> with <see cref="Address"/> of
/// <paramref name="target"/>.</returns>
public async Task <BoundPeer> FindSpecificPeerAsync(
Address target,
int depth,
TimeSpan?timeout,
CancellationToken cancellationToken)
{
_logger.Verbose(
$"{nameof(FindSpecificPeerAsync)}() with {{Target}}. " +
"(depth: {Depth})",
target,
depth);
if (_table.GetPeer(target) is BoundPeer boundPeer)
{
try
{
await PingAsync(boundPeer, _requestTimeout, cancellationToken);
}
catch (PingTimeoutException)
{
var msg =
"{BoundPeer}, a target peer, is in the routing table does not respond.";
_logger.Verbose(msg, boundPeer);
RemovePeer(boundPeer);
return(null);
}
_logger.Verbose(
"{BoundPeer}, a target peer, is in the routing table.",
boundPeer);
return(boundPeer);
}
var history = new ConcurrentBag <BoundPeer>();
var peersToFind = new ConcurrentQueue <Tuple <BoundPeer, int> >();
foreach (BoundPeer peer in _table.Neighbors(target, _findConcurrency, false))
{
peersToFind.Enqueue(new Tuple <BoundPeer, int>(peer, 0));
}
while (peersToFind.Any())
{
cancellationToken.ThrowIfCancellationRequested();
if (!peersToFind.TryDequeue(out Tuple <BoundPeer, int> tuple))
{
continue;
}
tuple.Deconstruct(out BoundPeer viaPeer, out int curDepth);
_logger.Debug("ViaPeer: {Peer}, curDepth: {curDepth}", viaPeer, curDepth);
if (depth != -1 && curDepth >= depth)
{
continue;
}
history.Add(viaPeer);
IEnumerable <BoundPeer> foundPeers =
await GetNeighbors(viaPeer, target, timeout, cancellationToken);
IEnumerable <BoundPeer> filteredPeers = foundPeers
.Where(peer =>
!history.Contains(peer) &&
!peersToFind.Any(t => t.Item1.Equals(peer)) &&
!peer.Address.Equals(_address))
.Take(_findConcurrency);
int count = 0;
foreach (var found in filteredPeers)
{
try
{
await PingAsync(found, _requestTimeout, cancellationToken);
if (found.Address.Equals(target))
{
return(found);
}
peersToFind.Enqueue(new Tuple <BoundPeer, int>(found, curDepth + 1));
if (count++ >= _findConcurrency)
{
break;
}
}
catch (TaskCanceledException)
{
throw new TaskCanceledException(
$"Task is cancelled during {nameof(FindSpecificPeerAsync)}()");
}
catch (PingTimeoutException)
{
// Ignore peer not responding
}
finally
{
history.Add(found);
}
}
}
return(null);
}