use cached empty BasicProperties when null

Author: bollhals

projects/RabbitMQ.Client/client/impl/BasicPublishBatch.cs

@@ -63,15 +63,14 @@ public void Add(string exchange, string routingKey, bool mandatory, IBasicProper
 
         public void Add(string exchange, string routingKey, bool mandatory, IBasicProperties basicProperties, ReadOnlyMemory<byte> body)
         {
-            IBasicProperties bp = basicProperties ?? _model.CreateBasicProperties();
             var method = new BasicPublish
             {
                 _exchange = exchange,
                 _routingKey = routingKey,
                 _mandatory = mandatory
             };
 
-            _commands.Add(new Command(method, (ContentHeaderBase)bp, body, false));
+            _commands.Add(new Command(method, (ContentHeaderBase)(basicProperties ?? _model._emptyBasicProperties), body, false));
         }
 
         public void Publish()

projects/RabbitMQ.Client/client/impl/ModelBase.cs

@@ -58,6 +58,7 @@ abstract class ModelBase : IFullModel, IRecoverable
         ///<summary>Only used to kick-start a connection open
         ///sequence. See <see cref="Connection.Open"/> </summary>
         public BlockingCell<ConnectionStartDetails> m_connectionStartCell = null;
+        internal readonly IBasicProperties _emptyBasicProperties;
 
         private readonly Dictionary<string, IBasicConsumer> _consumers = new Dictionary<string, IBasicConsumer>();
 
@@ -72,7 +73,6 @@ abstract class ModelBase : IFullModel, IRecoverable
         private readonly object _confirmLock = new object();
         private readonly LinkedList<ulong> _pendingDeliveryTags = new LinkedList<ulong>();
         private readonly CountdownEvent _deliveryTagsCountdown = new CountdownEvent(0);
-
         private EventHandler<ShutdownEventArgs> _modelShutdown;
 
         private bool _onlyAcksReceived = true;
@@ -93,6 +93,7 @@ public ModelBase(ISession session, ConsumerWorkService workService)
                 ConsumerDispatcher = new ConcurrentConsumerDispatcher(this, workService);
             }
 
+            _emptyBasicProperties = CreateBasicProperties();
             Initialise(session);
         }
 
@@ -1111,7 +1112,7 @@ public void BasicPublish(string exchange,
 
             if (basicProperties == null)
             {
-                basicProperties = CreateBasicProperties();
+                basicProperties = _emptyBasicProperties;
             }
 
             if (NextPublishSeqNo > 0)