Do not create string objects from consumerTag, exchange and routingKey, or get them from a string cache.

projects/Benchmarks/ConsumerDispatching/AsyncBasicConsumerFake.cs

@@ -18,7 +18,7 @@ public AsyncBasicConsumerFake(ManualResetEventSlim autoResetEvent)
             _autoResetEvent = autoResetEvent;
         }
 
-        public Task HandleBasicDeliver(string consumerTag, ulong deliveryTag, bool redelivered, string exchange, string routingKey, in ReadOnlyBasicProperties properties, ReadOnlyMemory<byte> body)
+        public Task HandleBasicDeliver(string consumerTag, ulong deliveryTag, bool redelivered, ReadOnlyMemory<byte> exchange, ReadOnlyMemory<byte> routingKey, in ReadOnlyBasicProperties properties, ReadOnlyMemory<byte> body)
         {
             if (Interlocked.Increment(ref _current) == Count)
             {
@@ -28,7 +28,7 @@ public Task HandleBasicDeliver(string consumerTag, ulong deliveryTag, bool redel
             return Task.CompletedTask;
         }
 
-        void IBasicConsumer.HandleBasicDeliver(string consumerTag, ulong deliveryTag, bool redelivered, string exchange, string routingKey,
+        void IBasicConsumer.HandleBasicDeliver(string consumerTag, ulong deliveryTag, bool redelivered, ReadOnlyMemory<byte> exchange, ReadOnlyMemory<byte> routingKey,
             in ReadOnlyBasicProperties properties, ReadOnlyMemory<byte> body)
         {
             if (Interlocked.Increment(ref _current) == Count)

projects/Benchmarks/ConsumerDispatching/ConsumerDispatcher.cs

@@ -1,4 +1,5 @@
-using System.Threading;
+using System.Text;
+using System.Threading;
 using BenchmarkDotNet.Attributes;
 using RabbitMQ.Client;
 using RabbitMQ.Client.ConsumerDispatching;
@@ -14,9 +15,10 @@ public class ConsumerDispatcherBase
         private protected IConsumerDispatcher _dispatcher;
         private protected readonly AsyncBasicConsumerFake _consumer = new AsyncBasicConsumerFake(_autoResetEvent);
         protected readonly string _consumerTag = "ConsumerTag";
+        protected static readonly byte[] _consumerTagBytes = Encoding.UTF8.GetBytes("ConsumerTag");
         protected readonly ulong _deliveryTag = 500UL;
-        protected readonly string _exchange = "Exchange";
-        protected readonly string _routingKey = "RoutingKey";
+        protected static readonly byte[] _exchange = Encoding.UTF8.GetBytes("Exchange");
+        protected static readonly byte[] _routingKey = Encoding.UTF8.GetBytes("RoutingKey");
         protected readonly ReadOnlyBasicProperties _properties = new ReadOnlyBasicProperties();
         protected readonly byte[] _body = new byte[512];
     }
@@ -41,7 +43,7 @@ public void AsyncConsumerDispatcher()
         {
             for (int i = 0; i < Count; i++)
             {
-                _dispatcher.HandleBasicDeliver(_consumerTag, _deliveryTag, false, _exchange, _routingKey, _properties, _body, _body);
+                _dispatcher.HandleBasicDeliver(_consumerTagBytes, _deliveryTag, false, _exchange, _routingKey, _properties, _body, _body);
             }
             _autoResetEvent.Wait();
             _autoResetEvent.Reset();
@@ -59,7 +61,7 @@ public void ConsumerDispatcher()
         {
             for (int i = 0; i < Count; i++)
             {
-                _dispatcher.HandleBasicDeliver(_consumerTag, _deliveryTag, false, _exchange, _routingKey, _properties, _body, _body);
+                _dispatcher.HandleBasicDeliver(_consumerTagBytes, _deliveryTag, false, _exchange, _routingKey, _properties, _body, _body);
             }
             _autoResetEvent.Wait();
             _autoResetEvent.Reset();

projects/Benchmarks/WireFormatting/MethodSerialization.cs

@@ -45,7 +45,7 @@ public override void SetUp()
         }
 
         [Benchmark]
-        public object BasicDeliverRead() => new BasicDeliver(_buffer.Span)._consumerTag; // return one property to not box when returning an object instead
+        public object BasicDeliverRead() => new BasicDeliver(_buffer)._consumerTag; // return one property to not box when returning an object instead
 
         [Benchmark]
         public int BasicPublishWrite() => _basicPublish.WriteTo(_buffer.Span);

projects/RabbitMQ.Client/client/api/AsyncDefaultBasicConsumer.cs

@@ -110,8 +110,8 @@ public virtual Task HandleBasicConsumeOk(string consumerTag)
         public virtual Task HandleBasicDeliver(string consumerTag,
             ulong deliveryTag,
             bool redelivered,
-            string exchange,
-            string routingKey,
+            ReadOnlyMemory<byte> exchange,
+            ReadOnlyMemory<byte> routingKey,
             in ReadOnlyBasicProperties properties,
             ReadOnlyMemory<byte> body)
         {
@@ -165,7 +165,7 @@ void IBasicConsumer.HandleBasicConsumeOk(string consumerTag)
             throw new InvalidOperationException("Should never be called. Enable 'DispatchConsumersAsync'.");
         }
 
-        void IBasicConsumer.HandleBasicDeliver(string consumerTag, ulong deliveryTag, bool redelivered, string exchange, string routingKey, in ReadOnlyBasicProperties properties, ReadOnlyMemory<byte> body)
+        void IBasicConsumer.HandleBasicDeliver(string consumerTag, ulong deliveryTag, bool redelivered, ReadOnlyMemory<byte> exchange, ReadOnlyMemory<byte> routingKey, in ReadOnlyBasicProperties properties, ReadOnlyMemory<byte> body)
         {
             throw new InvalidOperationException("Should never be called. Enable 'DispatchConsumersAsync'.");
         }

projects/RabbitMQ.Client/client/api/DefaultBasicConsumer.cs

@@ -150,8 +150,8 @@ public virtual void HandleBasicConsumeOk(string consumerTag)
         public virtual void HandleBasicDeliver(string consumerTag,
             ulong deliveryTag,
             bool redelivered,
-            string exchange,
-            string routingKey,
+            ReadOnlyMemory<byte> exchange,
+            ReadOnlyMemory<byte> routingKey,
             in ReadOnlyBasicProperties properties,
             ReadOnlyMemory<byte> body)
         {

projects/RabbitMQ.Client/client/api/IAsyncBasicConsumer.cs

@@ -49,8 +49,8 @@ public interface IAsyncBasicConsumer
         Task HandleBasicDeliver(string consumerTag,
             ulong deliveryTag,
             bool redelivered,
-            string exchange,
-            string routingKey,
+            ReadOnlyMemory<byte> exchange,
+            ReadOnlyMemory<byte> routingKey,
             in ReadOnlyBasicProperties properties,
             ReadOnlyMemory<byte> body);
 

projects/RabbitMQ.Client/client/api/IBasicConsumer.cs

@@ -92,8 +92,8 @@ public interface IBasicConsumer
         void HandleBasicDeliver(string consumerTag,
             ulong deliveryTag,
             bool redelivered,
-            string exchange,
-            string routingKey,
+            ReadOnlyMemory<byte> exchange,
+            ReadOnlyMemory<byte> routingKey,
             in ReadOnlyBasicProperties properties,
             ReadOnlyMemory<byte> body);
 

projects/RabbitMQ.Client/client/events/AsyncEventingBasicConsumer.cs

@@ -71,7 +71,7 @@ public override async Task HandleBasicConsumeOk(string consumerTag)
         }
 
         ///<summary>Fires the Received event.</summary>
-        public override Task HandleBasicDeliver(string consumerTag, ulong deliveryTag, bool redelivered, string exchange, string routingKey, in ReadOnlyBasicProperties properties, ReadOnlyMemory<byte> body)
+        public override Task HandleBasicDeliver(string consumerTag, ulong deliveryTag, bool redelivered, ReadOnlyMemory<byte> exchange, ReadOnlyMemory<byte> routingKey, in ReadOnlyBasicProperties properties, ReadOnlyMemory<byte> body)
         {
             // No need to call base, it's empty.
             return _receivedWrapper.InvokeAsync(this, new BasicDeliverEventArgs(consumerTag, deliveryTag, redelivered, exchange, routingKey, properties, body));

projects/RabbitMQ.Client/client/events/BasicDeliverEventArgs.cs

@@ -47,8 +47,8 @@ public BasicDeliverEventArgs()
         public BasicDeliverEventArgs(string consumerTag,
             ulong deliveryTag,
             bool redelivered,
-            string exchange,
-            string routingKey,
+            ReadOnlyMemory<byte> exchange,
+            ReadOnlyMemory<byte> routingKey,
             in ReadOnlyBasicProperties properties,
             ReadOnlyMemory<byte> body)
         {
@@ -77,13 +77,13 @@ public BasicDeliverEventArgs(string consumerTag,
 
         ///<summary>The exchange the message was originally published
         ///to.</summary>
-        public string Exchange { get; set; }
+        public ReadOnlyMemory<byte> Exchange { get; set; }
 
         ///<summary>The AMQP "redelivered" flag.</summary>
         public bool Redelivered { get; set; }
 
         ///<summary>The routing key used when the message was
         ///originally published.</summary>
-        public string RoutingKey { get; set; }
+        public ReadOnlyMemory<byte> RoutingKey { get; set; }
     }
 }

projects/RabbitMQ.Client/client/events/EventingBasicConsumer.cs

@@ -84,7 +84,7 @@ public override void HandleBasicConsumeOk(string consumerTag)
         /// Accessing the body at a later point is unsafe as its memory can
         /// be already released.
         /// </remarks>
-        public override void HandleBasicDeliver(string consumerTag, ulong deliveryTag, bool redelivered, string exchange, string routingKey, in ReadOnlyBasicProperties properties, ReadOnlyMemory<byte> body)
+        public override void HandleBasicDeliver(string consumerTag, ulong deliveryTag, bool redelivered, ReadOnlyMemory<byte> exchange, ReadOnlyMemory<byte> routingKey, in ReadOnlyBasicProperties properties, ReadOnlyMemory<byte> body)
         {
             base.HandleBasicDeliver(consumerTag, deliveryTag, redelivered, exchange, routingKey, properties, body);
             Received?.Invoke(

projects/RabbitMQ.Client/client/framing/BasicDeliver.cs

@@ -30,27 +30,26 @@
 //---------------------------------------------------------------------------
 
 using System;
-
 using RabbitMQ.Client.client.framing;
 using RabbitMQ.Client.Impl;
 
 namespace RabbitMQ.Client.Framing.Impl
 {
     internal readonly struct BasicDeliver : IAmqpMethod
     {
-        public readonly string _consumerTag;
+        public readonly ReadOnlyMemory<byte> _consumerTag;
         public readonly ulong _deliveryTag;
         public readonly bool _redelivered;
-        public readonly string _exchange;
-        public readonly string _routingKey;
+        public readonly ReadOnlyMemory<byte> _exchange;
+        public readonly ReadOnlyMemory<byte> _routingKey;
 
-        public BasicDeliver(ReadOnlySpan<byte> span)
+        public BasicDeliver(ReadOnlyMemory<byte> data)
         {
-            int offset = WireFormatting.ReadShortstr(span, out _consumerTag);
-            offset += WireFormatting.ReadLonglong(span.Slice(offset), out _deliveryTag);
-            offset += WireFormatting.ReadBits(span.Slice(offset), out _redelivered);
-            offset += WireFormatting.ReadShortstr(span.Slice(offset), out _exchange);
-            WireFormatting.ReadShortstr(span.Slice(offset), out _routingKey);
+            int offset = WireFormatting.ReadShortMemory(data, out _consumerTag);
+            offset += WireFormatting.ReadLonglong(data.Span.Slice(offset), out _deliveryTag);
+            offset += WireFormatting.ReadBits(data.Span.Slice(offset), out _redelivered);
+            offset += WireFormatting.ReadShortMemory(data.Slice(offset), out _exchange);
+            WireFormatting.ReadShortMemory(data.Slice(offset), out _routingKey);
         }
 
         public ProtocolCommandId ProtocolCommandId => ProtocolCommandId.BasicDeliver;

projects/RabbitMQ.Client/client/impl/ConsumerDispatching/ConsumerDispatcherBase.cs

@@ -1,53 +1,88 @@
-using System.Collections.Generic;
+using System;
+using System.Collections.Generic;
 using System.Runtime.CompilerServices;
+using System.Text;
 using System.Threading.Tasks;
+using RabbitMQ.Util;
 
 namespace RabbitMQ.Client.ConsumerDispatching
 {
 #nullable enable
     internal abstract class ConsumerDispatcherBase
     {
         private static readonly FallbackConsumer fallbackConsumer = new FallbackConsumer();
-        private readonly Dictionary<string, IBasicConsumer> _consumers;
+        private readonly Dictionary<ReadOnlyMemory<byte>, (IBasicConsumer consumer, string consumerTag)> _consumers;
 
         public IBasicConsumer? DefaultConsumer { get; set; }
 
         protected ConsumerDispatcherBase()
         {
-            _consumers = new Dictionary<string, IBasicConsumer>();
+            _consumers = new Dictionary<ReadOnlyMemory<byte>, (IBasicConsumer, string)>(MemoryOfByteEqualityComparer.Instance);
         }
 
         protected void AddConsumer(IBasicConsumer consumer, string tag)
         {
             lock (_consumers)
             {
-                _consumers[tag] = consumer;
+                var tagBytes = Encoding.UTF8.GetBytes(tag);
+                _consumers[tagBytes] = (consumer, tag);
             }
         }
 
-        protected IBasicConsumer GetConsumerOrDefault(string tag)
+        protected (IBasicConsumer consumer, string consumerTag) GetConsumerOrDefault(ReadOnlyMemory<byte> tag)
         {
             lock (_consumers)
             {
-                return _consumers.TryGetValue(tag, out var consumer) ? consumer : GetDefaultOrFallbackConsumer();
+                if (_consumers.TryGetValue(tag, out var consumerPair))
+                {
+                    return consumerPair;
+                }
+
+#if NETCOREAPP
+                var consumerTag = Encoding.UTF8.GetString(tag.Span);
+#else
+                string consumerTag;
+                unsafe
+                {
+                    fixed (byte* bytes = tag.Span)
+                    {
+                        consumerTag = Encoding.UTF8.GetString(bytes, tag.Length);
+                    }
+                }
+#endif
+
+                return (GetDefaultOrFallbackConsumer(), consumerTag);
             }
         }
 
         public IBasicConsumer GetAndRemoveConsumer(string tag)
         {
             lock (_consumers)
             {
-                return _consumers.Remove(tag, out var consumer) ? consumer : GetDefaultOrFallbackConsumer();
+                var utf8 = Encoding.UTF8;
+#if NETCOREAPP
+                var pool = ArrayPool<byte>.Shared;
+                var buf = pool.Rent(utf8.GetMaxByteCount(tag.Length));
+                int count = utf8.GetBytes(tag, buf);
+                var memory = buf.AsMemory(0, count);
+#else
+                var memory = utf8.GetBytes(tag).AsMemory();
+#endif
+                var result = _consumers.Remove(memory, out var consumerPair) ? consumerPair.consumer : GetDefaultOrFallbackConsumer();
+#if NETCOREAPP
+                pool.Return(buf);
+#endif
+                return result;
             }
         }
 
         public Task ShutdownAsync(ShutdownEventArgs reason)
         {
             lock (_consumers)
             {
-                foreach (KeyValuePair<string, IBasicConsumer> pair in _consumers)
+                foreach (KeyValuePair<ReadOnlyMemory<byte>, (IBasicConsumer consumer, string consumerTag)> pair in _consumers)
                 {
-                    ShutdownConsumer(pair.Value, reason);
+                    ShutdownConsumer(pair.Value.consumer, reason);
                 }
                 _consumers.Clear();
             }

projects/RabbitMQ.Client/client/impl/ConsumerDispatching/ConsumerDispatcherChannelBase.cs

@@ -53,12 +53,13 @@ public void HandleBasicConsumeOk(IBasicConsumer consumer, string consumerTag)
             }
         }
 
-        public void HandleBasicDeliver(string consumerTag, ulong deliveryTag, bool redelivered,
-            string exchange, string routingKey, in ReadOnlyBasicProperties basicProperties, ReadOnlyMemory<byte> body, byte[] rentedArray)
+        public void HandleBasicDeliver(ReadOnlyMemory<byte> consumerTag, ulong deliveryTag, bool redelivered,
+            ReadOnlyMemory<byte> exchange, ReadOnlyMemory<byte> routingKey, in ReadOnlyBasicProperties basicProperties, ReadOnlyMemory<byte> body, byte[] rentedArray)
         {
             if (!IsShutdown)
             {
-                _writer.TryWrite(new WorkStruct(GetConsumerOrDefault(consumerTag), consumerTag, deliveryTag, redelivered, exchange, routingKey, basicProperties, body, rentedArray));
+                var consumerPair = GetConsumerOrDefault(consumerTag);
+                _writer.TryWrite(new WorkStruct(consumerPair.consumer, consumerPair.consumerTag, deliveryTag, redelivered, exchange, routingKey, basicProperties, body, rentedArray));
             }
         }
 
@@ -108,8 +109,8 @@ protected readonly struct WorkStruct
             public readonly string? ConsumerTag;
             public readonly ulong DeliveryTag;
             public readonly bool Redelivered;
-            public readonly string? Exchange;
-            public readonly string? RoutingKey;
+            public readonly ReadOnlyMemory<byte> Exchange;
+            public readonly ReadOnlyMemory<byte> RoutingKey;
             public readonly ReadOnlyBasicProperties BasicProperties;
             public readonly ReadOnlyMemory<byte> Body;
             public readonly byte[]? RentedArray;
@@ -133,7 +134,7 @@ public WorkStruct(IBasicConsumer consumer, ShutdownEventArgs reason)
             }
 
             public WorkStruct(IBasicConsumer consumer, string consumerTag, ulong deliveryTag, bool redelivered,
-                string exchange, string routingKey, in ReadOnlyBasicProperties basicProperties, ReadOnlyMemory<byte> body, byte[] rentedArray)
+                ReadOnlyMemory<byte> exchange, ReadOnlyMemory<byte> routingKey, in ReadOnlyBasicProperties basicProperties, ReadOnlyMemory<byte> body, byte[] rentedArray)
             {
                 WorkType = WorkType.Deliver;
                 Consumer = consumer;

projects/RabbitMQ.Client/client/impl/ConsumerDispatching/FallbackConsumer.cs

@@ -37,7 +37,7 @@ void IBasicConsumer.HandleBasicConsumeOk(string consumerTag)
             ESLog.Info($"Unhandled {nameof(IBasicConsumer.HandleBasicConsumeOk)} for tag {consumerTag}");
         }
 
-        void IBasicConsumer.HandleBasicDeliver(string consumerTag, ulong deliveryTag, bool redelivered, string exchange, string routingKey, in ReadOnlyBasicProperties properties,
+        void IBasicConsumer.HandleBasicDeliver(string consumerTag, ulong deliveryTag, bool redelivered, ReadOnlyMemory<byte> exchange, ReadOnlyMemory<byte> routingKey, in ReadOnlyBasicProperties properties,
             ReadOnlyMemory<byte> body)
         {
             ESLog.Info($"Unhandled {nameof(IBasicConsumer.HandleBasicDeliver)} for tag {consumerTag}");
@@ -66,7 +66,7 @@ Task IAsyncBasicConsumer.HandleBasicConsumeOk(string consumerTag)
             return Task.CompletedTask;
         }
 
-        Task IAsyncBasicConsumer.HandleBasicDeliver(string consumerTag, ulong deliveryTag, bool redelivered, string exchange, string routingKey, in ReadOnlyBasicProperties properties,
+        Task IAsyncBasicConsumer.HandleBasicDeliver(string consumerTag, ulong deliveryTag, bool redelivered, ReadOnlyMemory<byte> exchange, ReadOnlyMemory<byte> routingKey, in ReadOnlyBasicProperties properties,
             ReadOnlyMemory<byte> body)
         {
             ((IBasicConsumer)this).HandleBasicDeliver(consumerTag, deliveryTag, redelivered, exchange, routingKey, properties, body);

projects/RabbitMQ.Client/client/impl/ConsumerDispatching/IConsumerDispatcher.cs

@@ -45,11 +45,11 @@ internal interface IConsumerDispatcher
 
         void HandleBasicConsumeOk(IBasicConsumer consumer, string consumerTag);
 
-        void HandleBasicDeliver(string consumerTag,
+        void HandleBasicDeliver(ReadOnlyMemory<byte> consumerTag,
                             ulong deliveryTag,
                             bool redelivered,
-                            string exchange,
-                            string routingKey,
+                            ReadOnlyMemory<byte> exchange,
+                            ReadOnlyMemory<byte> routingKey,
                             in ReadOnlyBasicProperties basicProperties,
                             ReadOnlyMemory<byte> body,
                             byte[] rentedArray);

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

@@ -573,8 +573,7 @@ protected void HandleBasicConsumeOk(in IncomingCommand cmd)
 
         protected void HandleBasicDeliver(in IncomingCommand cmd)
         {
-            var method = new Client.Framing.Impl.BasicDeliver(cmd.MethodBytes.Span);
-            cmd.ReturnMethodBuffer();
+            var method = new Client.Framing.Impl.BasicDeliver(cmd.MethodBytes);
             var header = new ReadOnlyBasicProperties(cmd.HeaderBytes.Span);
             cmd.ReturnHeaderBuffer();
 
@@ -587,6 +586,8 @@ protected void HandleBasicDeliver(in IncomingCommand cmd)
                     header,
                     cmd.Body,
                     cmd.TakeoverBody());
+
+            cmd.ReturnMethodBuffer();
         }
 
         protected void HandleBasicGetOk(in IncomingCommand cmd)