public async Task DispatchApplicationMessage(string senderId, MqttApplicationMessage applicationMessage)
{
try
{
if (applicationMessage.Retain)
{
await _retainedMessagesManager.UpdateMessage(senderId, applicationMessage).ConfigureAwait(false);
}
var deliveryCount = 0;
List <MqttSession> subscriberSessions;
lock (_sessionsManagementLock)
{
// only subscriber clients are of interest here.
subscriberSessions = _subscriberSessions.ToList();
}
// Calculate application message topic hash once for subscription checks
MqttSubscription.CalculateTopicHash(applicationMessage.Topic, out var topicHash, out _, out _);
foreach (var session in subscriberSessions)
{
var checkSubscriptionsResult = session.SubscriptionsManager.CheckSubscriptions(
applicationMessage.Topic,
topicHash,
applicationMessage.QualityOfServiceLevel,
senderId);
if (!checkSubscriptionsResult.IsSubscribed)
{
continue;
}
var newPublishPacket = _packetFactories.Publish.Create(applicationMessage);
newPublishPacket.QualityOfServiceLevel = checkSubscriptionsResult.QualityOfServiceLevel;
newPublishPacket.SubscriptionIdentifiers = checkSubscriptionsResult.SubscriptionIdentifiers;
if (newPublishPacket.QualityOfServiceLevel > 0)
{
newPublishPacket.PacketIdentifier = session.PacketIdentifierProvider.GetNextPacketIdentifier();
}
if (checkSubscriptionsResult.RetainAsPublished)
{
// Transfer the original retain state from the publisher. This is a MQTTv5 feature.
newPublishPacket.Retain = applicationMessage.Retain;
}
else
{
newPublishPacket.Retain = false;
}
session.EnqueueDataPacket(new MqttPacketBusItem(newPublishPacket));
deliveryCount++;
_logger.Verbose("Client '{0}': Queued PUBLISH packet with topic '{1}'.", session.Id, applicationMessage.Topic);
}
await FireApplicationMessageNotConsumedEvent(applicationMessage, deliveryCount, senderId);
}
catch (Exception exception)
{
_logger.Error(exception, "Unhandled exception while processing next queued application message.");
}
}
CreateSubscriptionResult CreateSubscription(MqttTopicFilter topicFilter, uint subscriptionIdentifier, MqttSubscribeReasonCode reasonCode)
{
MqttQualityOfServiceLevel grantedQualityOfServiceLevel;
if (reasonCode == MqttSubscribeReasonCode.GrantedQoS0)
{
grantedQualityOfServiceLevel = MqttQualityOfServiceLevel.AtMostOnce;
}
else if (reasonCode == MqttSubscribeReasonCode.GrantedQoS1)
{
grantedQualityOfServiceLevel = MqttQualityOfServiceLevel.AtLeastOnce;
}
else if (reasonCode == MqttSubscribeReasonCode.GrantedQoS2)
{
grantedQualityOfServiceLevel = MqttQualityOfServiceLevel.ExactlyOnce;
}
else
{
throw new InvalidOperationException();
}
var subscription = new MqttSubscription(
topicFilter.Topic,
topicFilter.NoLocal,
topicFilter.RetainHandling,
topicFilter.RetainAsPublished,
grantedQualityOfServiceLevel,
subscriptionIdentifier);
bool isNewSubscription;
// Add to subscriptions and maintain topic hash dictionaries
_subscriptionsLock.Wait();
try
{
MqttSubscription.CalculateTopicHash(topicFilter.Topic, out var topicHash, out var topicHashMask, out var hasWildcard);
if (_subscriptions.TryGetValue(topicFilter.Topic, out var existingSubscription))
{
// must remove object from topic hash dictionary first
if (hasWildcard)
{
if (_wildcardSubscriptionsByTopicHash.TryGetValue(topicHash, out var subs))
{
subs.Subscriptions.Remove(existingSubscription);
// no need to remove empty entry because we'll be adding subscription again below
}
}
else
{
if (_noWildcardSubscriptionsByTopicHash.TryGetValue(topicHash, out var subscriptions))
{
subscriptions.Remove(existingSubscription);
// no need to remove empty entry because we'll be adding subscription again below
}
}
}
isNewSubscription = existingSubscription == null;
_subscriptions[topicFilter.Topic] = subscription;
// Add or re-add to topic hash dictionary
if (hasWildcard)
{
if (!_wildcardSubscriptionsByTopicHash.TryGetValue(topicHash, out var subscriptions))
{
subscriptions = new TopicHashMaskSubscriptions(topicHashMask);
_wildcardSubscriptionsByTopicHash.Add(topicHash, subscriptions);
}
subscriptions.Subscriptions.Add(subscription);
}
else
{
if (!_noWildcardSubscriptionsByTopicHash.TryGetValue(topicHash, out var subscriptions))
{
subscriptions = new HashSet <MqttSubscription>();
_noWildcardSubscriptionsByTopicHash.Add(topicHash, subscriptions);
}
subscriptions.Add(subscription);
}
}
finally
{
_subscriptionsLock.Release();
}
return(new CreateSubscriptionResult
{
IsNewSubscription = isNewSubscription,
Subscription = subscription
});
}