private async Task ProcessDeltaAsync(CancellationToken cancellationToken)
{
while (true)
{
PeerSetDelta delta;
while (!_deltas.TryDequeue(out delta, TimeSpan.FromMilliseconds(100)))
{
await Task.Delay(100, cancellationToken);
}
Peer sender = delta.Sender;
PublicKey senderKey = sender.PublicKey;
if (!_peers.ContainsKey(sender) && _peers.Keys.All(p => senderKey != p.PublicKey))
{
delta = new PeerSetDelta(
delta.Sender,
delta.Timestamp,
delta.AddedPeers.Add(sender),
delta.RemovedPeers,
delta.ExistingPeers
);
}
_logger.Debug($"Received the delta[{delta}].");
using (await _receiveMutex.LockAsync(cancellationToken))
{
DeltaReceived.Reset();
_logger.Debug($"Trying to apply the delta[{delta}]...");
await ApplyDelta(delta, cancellationToken);
LastReceived = delta.Timestamp;
LastSeenTimestamps[delta.Sender] = delta.Timestamp;
DeltaReceived.Set();
}
_logger.Debug($"The delta[{delta}] has been applied.");
}
}
private async Task ApplyDelta(PeerSetDelta delta, CancellationToken cancellationToken)
{
PublicKey senderPublicKey = delta.Sender.PublicKey;
bool firstEncounter = _peers.Keys.All(p => p.PublicKey != senderPublicKey);
RemovePeers(delta.RemovedPeers, delta.Timestamp);
var addedPeers = new HashSet <Peer>(delta.AddedPeers);
if (delta.ExistingPeers != null)
{
ImmutableHashSet <PublicKey> removedPublicKeys = _removedPeers
.Keys.Select(p => p.PublicKey)
.ToImmutableHashSet();
addedPeers.UnionWith(
delta.ExistingPeers.Where(
p => !removedPublicKeys.Contains(p.PublicKey)
)
);
}
_logger.Debug("Trying to add peers...");
ISet <Peer> added = await AddPeersAsync(
addedPeers, delta.Timestamp, cancellationToken);
if (_logger.IsEnabled(LogEventLevel.Debug))
{
DumpDiffs(
delta,
added,
addedPeers.Except(added),
delta.RemovedPeers
);
}
if (firstEncounter)
{
await DistributeDeltaAsync(true, cancellationToken);
}
}
private void DumpDiffs(
PeerSetDelta delta,
IEnumerable <Peer> added,
IEnumerable <Peer> existing,
IEnumerable <Peer> removed)
{
DateTime timestamp = delta.Timestamp;
foreach (Peer peer in added)
{
_logger.Debug($"{timestamp} {delta.Sender} > +{peer}");
}
foreach (Peer peer in existing)
{
_logger.Debug($"{timestamp} {delta.Sender} > {peer}");
}
foreach (Peer peer in removed)
{
_logger.Debug($"{timestamp} {delta.Sender} > -{peer}");
}
}