#pragma warning disable VSTHRD100 // Avoid async void methods
/// <summary>
/// Raised when a connection is established to a remote peer.
/// </summary>
/// <param name="sender"></param>
/// <param name="connection"></param>
/// <remarks>
/// Sends the hello message to the remote peer. The message contains
/// all topics that are of interest to the local peer.
/// </remarks>
async void Swarm_ConnectionEstablished(object sender, PeerConnection connection)
#pragma warning restore VSTHRD100 // Avoid async void methods
{
if (localTopics.Count == 0)
{
return;
}
try
{
var hello = new PubSubMessage
{
Subscriptions = localTopics.Values
.Select(topic => new Subscription
{
Subscribe = true,
Topic = topic
})
.ToArray()
};
await SendAsync(hello, new Peer[] { connection.RemotePeer }, CancellationToken.None).ConfigureAwait(false);
}
catch (Exception e)
{
log.Warn("Sending hello message failed", e);
}
}
/// <inheritdoc />
public async Task LeaveTopicAsync(string topic, CancellationToken cancel)
{
localTopics.TryRemove(topic, out _);
var msg = new PubSubMessage
{
Subscriptions = new Subscription[]
{
new Subscription
{
Topic = topic,
Subscribe = false
}
}
};
try
{
var peers = Swarm.KnownPeers.Where(p => p.ConnectedAddress != null);
await SendAsync(msg, peers, cancel).ConfigureAwait(false);
}
catch (Exception e)
{
log.Warn("Leave topic failed.", e);
}
}
Task SendAsync(PubSubMessage msg, IEnumerable<Peer> peers, CancellationToken cancel)
{
// Get binary representation
byte[] bin;
using (var ms = new MemoryStream())
{
Serializer.SerializeWithLengthPrefix(ms, msg, PrefixStyle.Base128);
bin = ms.ToArray();
}
return Task.WhenAll(peers.Select(p => SendAsync(bin, p, cancel)));
}
/// <inheritdoc />
public Task PublishAsync(PublishedMessage message, CancellationToken cancel)
{
if (tracker.RecentlySeen(message.MessageId))
return Task.CompletedTask;
// Find a set of peers that are interested in the topic(s).
// Exclude author and sender
var peers = message.Topics
.SelectMany(topic => RemoteTopics.GetPeers(topic))
.Where(peer => peer != message.Sender)
.Where(peer => peer != message.Forwarder);
// Forward the message.
var forward = new PubSubMessage
{
PublishedMessages = new PublishedMessage[] { message }
};
return SendAsync(forward, peers, cancel);
}