public void Enqueue(MqttQueuedApplicationMessage queuedApplicationMessage)
{
if (queuedApplicationMessage == null)
{
throw new ArgumentNullException(nameof(queuedApplicationMessage));
}
lock (_messageQueue)
{
if (_messageQueue.Count >= _options.MaxPendingMessagesPerClient)
{
if (_options.PendingMessagesOverflowStrategy == MqttPendingMessagesOverflowStrategy.DropNewMessage)
{
return;
}
if (_options.PendingMessagesOverflowStrategy == MqttPendingMessagesOverflowStrategy.DropOldestQueuedMessage)
{
_messageQueue.TryDequeue();
}
}
_messageQueue.Enqueue(queuedApplicationMessage);
}
}
async Task SendPendingPacketsAsync(CancellationToken cancellationToken)
{
MqttQueuedApplicationMessage queuedApplicationMessage = null;
MqttPublishPacket publishPacket = null;
try
{
while (!cancellationToken.IsCancellationRequested)
{
queuedApplicationMessage = await Session.ApplicationMessagesQueue.DequeueAsync(cancellationToken).ConfigureAwait(false);
if (queuedApplicationMessage == null)
{
return;
}
if (cancellationToken.IsCancellationRequested)
{
return;
}
publishPacket = _dataConverter.CreatePublishPacket(queuedApplicationMessage.ApplicationMessage);
publishPacket.QualityOfServiceLevel = queuedApplicationMessage.SubscriptionQualityOfServiceLevel;
// Set the retain flag to true according to [MQTT-3.3.1-8] and [MQTT-3.3.1-9].
publishPacket.Retain = queuedApplicationMessage.IsRetainedMessage;
if (_serverOptions.ClientMessageQueueInterceptor != null)
{
var context = new MqttClientMessageQueueInterceptorContext(
queuedApplicationMessage.SenderClientId,
ClientId,
queuedApplicationMessage.ApplicationMessage,
queuedApplicationMessage.SubscriptionQualityOfServiceLevel);
if (_serverOptions.ClientMessageQueueInterceptor != null)
{
await _serverOptions.ClientMessageQueueInterceptor.InterceptClientMessageQueueEnqueueAsync(context).ConfigureAwait(false);
}
if (!context.AcceptEnqueue || context.ApplicationMessage == null)
{
return;
}
publishPacket.Topic = context.ApplicationMessage.Topic;
publishPacket.Payload = context.ApplicationMessage.Payload;
publishPacket.QualityOfServiceLevel = context.SubscriptionQualityOfServiceLevel;
}
if (publishPacket.QualityOfServiceLevel > 0)
{
publishPacket.PacketIdentifier = _packetIdentifierProvider.GetNextPacketIdentifier();
}
if (publishPacket.QualityOfServiceLevel == MqttQualityOfServiceLevel.AtMostOnce)
{
await SendAsync(publishPacket, cancellationToken).ConfigureAwait(false);
}
else if (publishPacket.QualityOfServiceLevel == MqttQualityOfServiceLevel.AtLeastOnce)
{
var awaiter = _packetDispatcher.AddAwaiter <MqttPubAckPacket>(publishPacket.PacketIdentifier);
await SendAsync(publishPacket, cancellationToken).ConfigureAwait(false);
await awaiter.WaitOneAsync(_serverOptions.DefaultCommunicationTimeout).ConfigureAwait(false);
}
else if (publishPacket.QualityOfServiceLevel == MqttQualityOfServiceLevel.ExactlyOnce)
{
using (var awaiter1 = _packetDispatcher.AddAwaiter <MqttPubRecPacket>(publishPacket.PacketIdentifier))
using (var awaiter2 = _packetDispatcher.AddAwaiter <MqttPubCompPacket>(publishPacket.PacketIdentifier))
{
await SendAsync(publishPacket, cancellationToken).ConfigureAwait(false);
await awaiter1.WaitOneAsync(_serverOptions.DefaultCommunicationTimeout).ConfigureAwait(false);
await SendAsync(new MqttPubRelPacket
{
PacketIdentifier = publishPacket.PacketIdentifier,
ReasonCode = MqttPubRelReasonCode.Success
}, cancellationToken).ConfigureAwait(false);
await awaiter2.WaitOneAsync(_serverOptions.DefaultCommunicationTimeout).ConfigureAwait(false);
}
}
_logger.Verbose("Queued application message sent (ClientId: {0}).", ClientId);
}
}
catch (Exception exception)
{
if (exception is OperationCanceledException)
{
}
else if (exception is MqttCommunicationTimedOutException)
{
_logger.Warning(exception, "Sending publish packet failed: Timeout (ClientId: {0}).", ClientId);
}
else if (exception is MqttCommunicationException)
{
_logger.Warning(exception, "Sending publish packet failed: Communication exception (ClientId: {0}).", ClientId);
}
else
{
_logger.Error(exception, "Sending publish packet failed (ClientId: {0}).", ClientId);
}
if (publishPacket?.QualityOfServiceLevel > MqttQualityOfServiceLevel.AtMostOnce)
{
queuedApplicationMessage.IsDuplicate = true;
Session.ApplicationMessagesQueue.Enqueue(queuedApplicationMessage);
}
StopInternal();
}
}