public async Task <MessageRelayConnection> SelectNextConnectionAsync()
{
IReadOnlyList <MessageRelayRecord> allRecords = await this.messageRelayRecords.GetAllMessageRelayRecordsAsync();
if (allRecords.Count == 0)
{
this.logger.LogWarning("No relay addresses in the store - can't select a connection candidate!");
return(null);
}
// peers, shortest success ago first
var hottestRecords = allRecords
.Where(x => !IsExcluded(x)) // e.g. if we are already connected, or the last error is less than a certain time ago
.OrderBy(x => DateTimeOffset.UtcNow - x.LastSeenUtc) // then, try the best candidates first
.ThenByDescending(x => DateTimeOffset.UtcNow - x.LastErrorUtc) // then, try the candidates where the last error is longest ago
.ToList();
if (hottestRecords.Count == 0)
{
this.logger.LogDebug("After applying the filtering rules, no connection candidates remain for selection.");
return(null);
}
MessageRelayRecord messageRelayRecord = hottestRecords[0];
this.logger.LogDebug($"Selected connection candidate {messageRelayRecord}, last seen {DateTimeOffset.UtcNow - messageRelayRecord.LastSeenUtc} ago, last error {DateTimeOffset.UtcNow - messageRelayRecord.LastErrorUtc} ago.");
var messageRelayConnection = new MessageRelayConnection(messageRelayRecord, this.cancellation.Token);
bool addSuccess = this.connections.TryAdd(messageRelayRecord.Id, messageRelayConnection);
Debug.Assert(addSuccess, $"Bug: Peer {messageRelayRecord} was already in the ConnectedPeers dictionary - that should not happen.");
return(messageRelayConnection);
}
public MessageRelayConnection(MessageRelayRecord messageMessageRelayRecord, CancellationToken cancellationToken)
{
this.MessageRelayRecord = messageMessageRelayRecord;
this.TcpClient = new TcpClient(AddressFamily.InterNetworkV6);
this.TcpClient.Client.SetSocketOption(SocketOptionLevel.IPv6, SocketOptionName.IPv6Only, false);
this.cancellationToken = cancellationToken;
}
bool IsExcluded(MessageRelayRecord relay)
{
if (this.connections.ContainsKey(relay.Id))
{
this.logger.LogDebug($"Peer {relay} is excluded, because it's in the list of connected peers.");
return(true);
}
if (relay.LastErrorUtc != default)
{
var timeSinceLastError = DateTimeOffset.UtcNow - relay.LastErrorUtc;
if (timeSinceLastError <= TimeSpan.FromSeconds(60))
{
this.logger.LogDebug(
$"Peer (MessageRelay) {relay} is excluded, because it's last error is only {timeSinceLastError} ago.");
return(true);
}
}
return(false);
}
