/// <summary>
/// Invoked when a router gets a message.
/// </summary>
/// <param name="sender">
/// The <see cref="IMessageRouter"/>.
/// </param>
/// <param name="msg">
/// The message.
/// </param>
/// <remarks>
/// Invokes any topic handlers and publishes the messages on the other routers.
/// </remarks>
private void Router_MessageReceived(object sender, PublishedMessage msg)
{
++MesssagesReceived;
// Check for duplicate message.
if (_tracker.RecentlySeen(msg.MessageId))
{
++DuplicateMesssagesReceived;
return;
}
// Call local topic handlers.
var handlers = _topicHandlers.Values
.Where(th => msg.Topics.Contains(th.Topic));
foreach (var handler in handlers)
{
try
{
handler.Handler(msg);
}
catch (Exception e)
{
_log.Error($"Topic handler for '{handler.Topic}' failed.", e);
}
}
// Tell other message routers.
_ = Task.WhenAll(Routers
.Where(r => r != sender)
.Select(r => r.PublishAsync(msg, CancellationToken.None))
);
}
/// <inheritdoc />
public Task PublishAsync(PublishedMessage message, CancellationToken cancel)
{
cancel.ThrowIfCancellationRequested();
if (!_tracker.RecentlySeen(message.MessageId))
{
MessageReceived?.Invoke(this, message);
}
return(Task.CompletedTask);
}
/// <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[] { message }
};
return(SendAsync(forward, peers, cancel));
}