Add overflow strategy for pending messages queue.

2026-10-25 07:41:32 +08:00 · 2018-05-11 20:49:31 +02:00
parent 57287a5303
commit e14ea9a240
10 changed files with 103 additions and 71 deletions
@@ -6,6 +6,7 @@ namespace MQTTnet.Server
    {
        int ConnectionBacklog { get; }
        int MaxPendingMessagesPerClient { get; }
+        MqttPendingMessagesOverflowStrategy PendingMessagesOverflowStrategy { get; }

        TimeSpan DefaultCommunicationTimeout { get; }

@@ -59,7 +59,7 @@ namespace MQTTnet.Server
                    // Values described here: [MQTT-3.1.2-24].
                    if (_lastPacketReceivedTracker.Elapsed.TotalSeconds > keepAlivePeriod * 1.5D)
                    {
-                        _logger.Warning<MqttClientSession>("Client '{0}': Did not receive any packet or keep alive signal.", _clientId);
+                        _logger.Warning(this, null, "Client '{0}': Did not receive any packet or keep alive signal.", _clientId);

                        _timeoutCallback?.Invoke();

@@ -74,11 +74,11 @@ namespace MQTTnet.Server
            }
            catch (Exception exception)
            {
-                _logger.Error<MqttClientSession>(exception, "Client '{0}': Unhandled exception while checking keep alive timeouts.", _clientId);
+                _logger.Error(this, exception, "Client '{0}': Unhandled exception while checking keep alive timeouts.", _clientId);
            }
            finally
            {
-                _logger.Verbose<MqttClientSession>("Client {0}: Stopped checking keep alive timeout.", _clientId);
+                _logger.Verbose(this, "Client {0}: Stopped checking keep alive timeout.", _clientId);
            }
        }

@@ -50,25 +50,27 @@ namespace MQTTnet.Server
            }
        }

-        public async Task DropPacket()
-        {
-            MqttBasePacket packet = null;
-            await _queueWaitSemaphore.WaitAsync().ConfigureAwait(false);
-            if (!_queue.TryDequeue(out packet))
-            {
-                throw new InvalidOperationException(); // should not happen
-            }
-            _queueWaitSemaphore.Release(); 
-        }
-
        public void Enqueue(MqttBasePacket packet)
        {
            if (packet == null) throw new ArgumentNullException(nameof(packet));

+            if (_queue.Count >= _options.MaxPendingMessagesPerClient)
+            {
+                if (_options.PendingMessagesOverflowStrategy == MqttPendingMessagesOverflowStrategy.DropNewMessage)
+                {
+                    return;
+                }
+
+                if (_options.PendingMessagesOverflowStrategy == MqttPendingMessagesOverflowStrategy.DropOldestQueuedMessage)
+                {
+                    _queue.TryDequeue(out _);
+                }
+            }
+
            _queue.Enqueue(packet);
            _queueAutoResetEvent.Set();

-            _logger.Verbose<MqttClientPendingMessagesQueue>("Enqueued packet (ClientId: {0}).", _clientSession.ClientId);
+            _logger.Verbose(this, "Enqueued packet (ClientId: {0}).", _clientSession.ClientId);
        }

        private async Task SendQueuedPacketsAsync(IMqttChannelAdapter adapter, CancellationToken cancellationToken)
@@ -77,7 +79,7 @@ namespace MQTTnet.Server
            {
                while (!cancellationToken.IsCancellationRequested)
                {
-                    await SendNextQueuedPacketAsync(adapter, cancellationToken).ConfigureAwait(false);
+                    await TrySendNextQueuedPacketAsync(adapter, cancellationToken).ConfigureAwait(false);
                }
            }
            catch (OperationCanceledException)
@@ -85,19 +87,23 @@ namespace MQTTnet.Server
            }
            catch (Exception exception)
            {
-                _logger.Error<MqttClientPendingMessagesQueue>(exception, "Unhandled exception while sending enqueued packet (ClientId: {0}).", _clientSession.ClientId);
+                _logger.Error(this, exception, "Unhandled exception while sending enqueued packet (ClientId: {0}).", _clientSession.ClientId);
            }
        }

-        private async Task SendNextQueuedPacketAsync(IMqttChannelAdapter adapter, CancellationToken cancellationToken)
+        private async Task TrySendNextQueuedPacketAsync(IMqttChannelAdapter adapter, CancellationToken cancellationToken)
        {
            MqttBasePacket packet = null;
            try
            {
-                await _queueAutoResetEvent.WaitOneAsync(cancellationToken).ConfigureAwait(false);
+                if (_queue.IsEmpty)
+                {
+                    await _queueAutoResetEvent.WaitOneAsync(cancellationToken).ConfigureAwait(false);
+                }
+
                if (!_queue.TryDequeue(out packet))
                {
-                    throw new InvalidOperationException(); // should not happen
+                    return;
                }

                if (cancellationToken.IsCancellationRequested)
@@ -107,24 +113,25 @@ namespace MQTTnet.Server

                await adapter.SendPacketsAsync(_options.DefaultCommunicationTimeout, new[] { packet }, cancellationToken).ConfigureAwait(false);

-                _logger.Verbose<MqttClientPendingMessagesQueue>("Enqueued packet sent (ClientId: {0}).", _clientSession.ClientId);
+                _logger.Verbose<MqttClientPendingMessagesQueue>("Enqueued packet sent (ClientId: {0}).",
+                    _clientSession.ClientId);
            }
            catch (Exception exception)
            {
                if (exception is MqttCommunicationTimedOutException)
                {
-                    _logger.Warning<MqttClientPendingMessagesQueue>(exception, "Sending publish packet failed due to timeout (ClientId: {0}).", _clientSession.ClientId);
+                    _logger.Warning(this, exception, "Sending publish packet failed: Timeout (ClientId: {0}).", _clientSession.ClientId);
                }
                else if (exception is MqttCommunicationException)
                {
-                    _logger.Warning<MqttClientPendingMessagesQueue>(exception, "Sending publish packet failed due to communication exception (ClientId: {0}).", _clientSession.ClientId);
+                    _logger.Warning(this, exception, "Sending publish packet failed: Communication exception (ClientId: {0}).", _clientSession.ClientId);
                }
                else if (exception is OperationCanceledException)
                {
                }
                else
                {
-                    _logger.Error<MqttClientPendingMessagesQueue>(exception, "Sending publish packet failed (ClientId: {0}).", _clientSession.ClientId);
+                    _logger.Error(this, exception, "Sending publish packet failed (ClientId: {0}).", _clientSession.ClientId);
                }

                if (packet is MqttPublishPacket publishPacket)
@@ -147,10 +147,7 @@ namespace MQTTnet.Server
            {
                publishPacket.PacketIdentifier = _packetIdentifierProvider.GetNewPacketIdentifier();
            }
-            if (_options.MaxPendingMessagesPerClient <= PendingMessagesQueue.Count)
-            {  
-                await PendingMessagesQueue.DropPacket(); 
-            }
+
            PendingMessagesQueue.Enqueue(publishPacket);
        }

@@ -276,7 +273,7 @@ namespace MQTTnet.Server
                return Task.FromResult(0);
            }

-            _logger.Warning<MqttClientSession>("Client '{0}': Received not supported packet ({1}). Closing connection.", ClientId, packet);
+            _logger.Warning(this, null, "Client '{0}': Received not supported packet ({1}). Closing connection.", ClientId, packet);
            Stop(MqttClientDisconnectType.NotClean);

            return Task.FromResult(0);
@@ -0,0 +1,8 @@
+namespace MQTTnet.Server
+{
+    public enum MqttPendingMessagesOverflowStrategy
+    {
+        DropOldestQueuedMessage,
+        DropNewMessage
+    }
+}
@@ -11,7 +11,9 @@ namespace MQTTnet.Server
        public int ConnectionBacklog { get; set; } = 10;

        public int MaxPendingMessagesPerClient { get; set; } = 250;
-        
+
+        public MqttPendingMessagesOverflowStrategy PendingMessagesOverflowStrategy { get; set; } = MqttPendingMessagesOverflowStrategy.DropOldestQueuedMessage;
+
        public TimeSpan DefaultCommunicationTimeout { get; set; } = TimeSpan.FromSeconds(15);

        public Action<MqttConnectionValidatorContext> ConnectionValidator { get; set; }