/// <summary>
/// Handler for device config change events.
/// </summary>
/// <param name="changeEvent">The change event to handle.</param>
private async void HandleConfigSubscriptionChange(ConfigSubscriptionChangeEvent changeEvent)
{
// Stop listening to removed topics
foreach (var topic in changeEvent.DeletedSubscriptions.Distinct())
{
// Check if actually subscribed and remove MQTT subscription
if (SubscribedTopics.Contains(topic))
{
_log.LogInformation("MQTT unsubscribing to the following topic: {Topic}", topic);
await MqttClient.UnsubscribeAsync(new List <string> {
topic
});
SubscribedTopics.Remove(topic);
}
// Check that state cache actually contains topic
if (_stateCache.ContainsKey(topic))
{
if (_stateCache.TryRemove(topic, out string _))
{
_log.LogInformation("Successfully removed topic {Topic} from internal state cache", topic);
}
else
{
_log.LogWarning("Failed to remove topic {Topic} from internal state cache", topic);
}
}
}
// Begin listening to added topics
foreach (var topic in changeEvent.AddedSubscriptions.Distinct())
{
// Ensure the that state cache doesn't contain topic and add
if (!_stateCache.ContainsKey(topic))
{
if (_stateCache.TryAdd(topic, string.Empty))
{
_log.LogInformation("Successfully added topic {Topic} to internal state cache", topic);
}
else
{
_log.LogWarning("Failed to add topic {Topic} to internal state cache", topic);
}
}
// Check if already subscribed and subscribe to MQTT topic
if (!SubscribedTopics.Contains(topic))
{
_log.LogInformation("MQTT subscribing to the following topic: {Topic}", topic);
await MqttClient.SubscribeAsync(
new List <MqttTopicFilter>
{
new MqttTopicFilterBuilder()
.WithTopic(topic)
.WithAtLeastOnceQoS()
.Build()
});
SubscribedTopics.Add(topic);
}
}
}
