Code cleanups and performance optimizations.

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

@@ -30,6 +30,8 @@
 //---------------------------------------------------------------------------
 
 using System;
+using System.Runtime.CompilerServices;
+
 using RabbitMQ.Client.client.framing;
 using RabbitMQ.Client.Framing.Impl;
 
@@ -54,10 +56,13 @@ internal sealed class Protocol : ProtocolBase
 
         internal override Client.Impl.MethodBase DecodeMethodFrom(ReadOnlySpan<byte> span)
         {
-            var commandId = (ProtocolCommandId)Util.NetworkOrderDeserializer.ReadUInt32(span);
+            ProtocolCommandId commandId = ReadCommandId(span);
             return DecodeMethodFrom(commandId, span.Slice(4));
         }
 
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        public static ProtocolCommandId ReadCommandId(ReadOnlySpan<byte> span) => (ProtocolCommandId)Util.NetworkOrderDeserializer.ReadUInt32(span);
+
         private static Client.Impl.MethodBase DecodeMethodFrom(ProtocolCommandId commandId, ReadOnlySpan<byte> span)
         {
             switch (commandId)

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

@@ -1,5 +1,5 @@
 using System;
-using System.Buffers;
+using System.Runtime.CompilerServices;
 using System.Threading.Tasks;
 
 namespace RabbitMQ.Client.Impl
@@ -67,6 +67,7 @@ public void HandleModelShutdown(IBasicConsumer consumer, ShutdownEventArgs reaso
             Schedule(new ModelShutdown(consumer, reason, _model));
         }
 
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
         private void ScheduleUnlessShuttingDown(Work work)
         {
             if (!IsShutdown)
@@ -75,6 +76,7 @@ private void ScheduleUnlessShuttingDown(Work work)
             }
         }
 
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
         private void Schedule(Work work)
         {
             _workService.Schedule(_model, work);

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

@@ -31,6 +31,7 @@
 
 using System;
 using System.Buffers;
+
 using RabbitMQ.Client.Exceptions;
 using RabbitMQ.Client.Framing.Impl;
 using RabbitMQ.Util;
@@ -126,7 +127,7 @@ private void ParseHeaderFrame(in InboundFrame frame)
                 _bodyBytes = Array.Empty<byte>();
             }
 
-            _remainingBodyBytes = (int) totalBodyBytes;
+            _remainingBodyBytes = (int)totalBodyBytes;
             UpdateContentBodyState();
         }
 

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

@@ -38,6 +38,7 @@
 using System.Text;
 using System.Threading;
 using System.Threading.Tasks;
+
 using RabbitMQ.Client.Events;
 using RabbitMQ.Client.Exceptions;
 using RabbitMQ.Client.Impl;
@@ -137,7 +138,7 @@ public event EventHandler<ShutdownEventArgs> ConnectionShutdown
             add
             {
                 ThrowIfDisposed();
-                if (CloseReason is null)
+                if (IsOpen)
                 {
                     _connectionShutdownWrapper.AddHandler(value);
                 }
@@ -157,31 +158,35 @@ public event EventHandler<ShutdownEventArgs> ConnectionShutdown
         /// <summary>
         /// This event is never fired by non-recovering connections but it is a part of the <see cref="IConnection"/> interface.
         /// </summary>
-        public event EventHandler<EventArgs> RecoverySucceeded {
+        public event EventHandler<EventArgs> RecoverySucceeded
+        {
             add { }
             remove { }
         }
 
         /// <summary>
         /// This event is never fired by non-recovering connections but it is a part of the <see cref="IConnection"/> interface.
         /// </summary>
-        public event EventHandler<ConnectionRecoveryErrorEventArgs> ConnectionRecoveryError {
+        public event EventHandler<ConnectionRecoveryErrorEventArgs> ConnectionRecoveryError
+        {
             add { }
             remove { }
         }
 
         /// <summary>
         /// This event is never fired by non-recovering connections but it is a part of the <see cref="IConnection"/> interface.
         /// </summary>
-        public event EventHandler<ConsumerTagChangedAfterRecoveryEventArgs> ConsumerTagChangeAfterRecovery {
+        public event EventHandler<ConsumerTagChangedAfterRecoveryEventArgs> ConsumerTagChangeAfterRecovery
+        {
             add { }
             remove { }
         }
 
         /// <summary>
         /// This event is never fired by non-recovering connections but it is a part of the <see cref="IConnection"/> interface.
         /// </summary>
-        public event EventHandler<QueueNameChangedAfterRecoveryEventArgs> QueueNameChangeAfterRecovery {
+        public event EventHandler<QueueNameChangedAfterRecoveryEventArgs> QueueNameChangeAfterRecovery
+        {
             add { }
             remove { }
         }
@@ -273,7 +278,7 @@ internal void Close(ShutdownEventArgs reason, bool abort, TimeSpan timeout)
                 {
                     // Try to send connection.close
                     // Wait for CloseOk in the MainLoop
-                    _session0.Transmit(ConnectionCloseWrapper(reason.ReplyCode, reason.ReplyText));
+                    _session0.Transmit(new OutgoingCommand(new Impl.ConnectionClose(reason.ReplyCode, reason.ReplyText, 0, 0)));
                 }
                 catch (AlreadyClosedException)
                 {
@@ -357,12 +362,6 @@ private void ClosingLoop()
             }
         }
 
-        private OutgoingCommand ConnectionCloseWrapper(ushort reasonCode, string reasonText)
-        {
-            Protocol.CreateConnectionClose(reasonCode, reasonText, out OutgoingCommand request, out _);
-            return request;
-        }
-
         internal ISession CreateSession()
         {
             return _sessionManager.Create();
@@ -407,9 +406,7 @@ private bool HardProtocolExceptionHandler(HardProtocolException hpe)
                 _session0.SetSessionClosing(false);
                 try
                 {
-                    _session0.Transmit(ConnectionCloseWrapper(
-                        hpe.ShutdownReason.ReplyCode,
-                        hpe.ShutdownReason.ReplyText));
+                    _session0.Transmit(new OutgoingCommand(new ConnectionClose(hpe.ShutdownReason.ReplyCode, hpe.ShutdownReason.ReplyText, 0, 0)));
                     return true;
                 }
                 catch (IOException ioe)
@@ -646,12 +643,12 @@ private void QuiesceChannel(SoftProtocolException pe)
             // our peer. The peer will respond through the lower
             // layers - specifically, through the QuiescingSession we
             // installed above.
-            newSession.Transmit(ChannelCloseWrapper(pe.ReplyCode, pe.Message));
+            newSession.Transmit(new OutgoingCommand(new Impl.ChannelClose(pe.ReplyCode, pe.Message, 0, 0)));
         }
 
         private bool SetCloseReason(ShutdownEventArgs reason)
         {
-            return System.Threading.Interlocked.CompareExchange(ref _closeReason, reason, null) is null;
+            return Interlocked.CompareExchange(ref _closeReason, reason, null) is null;
         }
 
         private void MaybeStartHeartbeatTimers()
@@ -838,12 +835,6 @@ public void Dispose()
             }
         }
 
-        private OutgoingCommand ChannelCloseWrapper(ushort reasonCode, string reasonText)
-        {
-            Protocol.CreateChannelClose(reasonCode, reasonText, out OutgoingCommand request);
-            return request;
-        }
-
         private void StartAndTune()
         {
             var connectionStartCell = new BlockingCell<ConnectionStartDetails>();

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

@@ -165,23 +165,22 @@ private InboundFrame(FrameType type, int channel, ReadOnlyMemory<byte> payload,
             _rentedArray = rentedArray;
         }
 
-        private static void ProcessProtocolHeader(Stream reader)
+        private static void ProcessProtocolHeader(Stream reader, ReadOnlySpan<byte> frameHeader)
         {
             try
             {
-                byte b1 = (byte)reader.ReadByte();
-                byte b2 = (byte)reader.ReadByte();
-                byte b3 = (byte)reader.ReadByte();
-                if (b1 != 'M' || b2 != 'Q' || b3 != 'P')
+                if (frameHeader[0] != 'M' || frameHeader[1] != 'Q' || frameHeader[2] != 'P')
                 {
                     throw new MalformedFrameException("Invalid AMQP protocol header from server");
                 }
 
-                int transportHigh = reader.ReadByte();
-                int transportLow = reader.ReadByte();
-                int serverMajor = reader.ReadByte();
                 int serverMinor = reader.ReadByte();
-                throw new PacketNotRecognizedException(transportHigh, transportLow, serverMajor, serverMinor);
+                if (serverMinor == -1)
+                {
+                    throw new EndOfStreamException();
+                }
+
+                throw new PacketNotRecognizedException(frameHeader[3], frameHeader[4], frameHeader[5], serverMinor);
             }
             catch (EndOfStreamException)
             {
@@ -198,39 +197,38 @@ private static void ProcessProtocolHeader(Stream reader)
 
         internal static InboundFrame ReadFrom(Stream reader, byte[] frameHeaderBuffer)
         {
-            int type = default;
             try
             {
-                type = reader.ReadByte();
+                if (reader.Read(frameHeaderBuffer, 0, frameHeaderBuffer.Length) == 0)
+                {
+                    throw new EndOfStreamException("Reached the end of the stream. Possible authentication failure.");
+                }
             }
             catch (IOException ioe)
             {
                 // If it's a WSAETIMEDOUT SocketException, unwrap it.
                 // This might happen when the limit of half-open connections is
                 // reached.
-                if (ioe.InnerException is null ||
-                    !(ioe.InnerException is SocketException exception) ||
-                    exception.SocketErrorCode != SocketError.TimedOut)
+                if (ioe?.InnerException is SocketException exception && exception.SocketErrorCode == SocketError.TimedOut)
+                {
+                    ExceptionDispatchInfo.Capture(exception).Throw();
+                }
+                else
                 {
                     throw;
                 }
-
-                ExceptionDispatchInfo.Capture(ioe.InnerException).Throw();
             }
 
-            switch (type)
+            byte firstByte = frameHeaderBuffer[0];
+            if (firstByte == 'A')
             {
-                case -1:
-                    throw new EndOfStreamException("Reached the end of the stream. Possible authentication failure.");
-                case 'A':
-                    // Probably an AMQP protocol header, otherwise meaningless
-                    ProcessProtocolHeader(reader);
-                    break;
+                // Probably an AMQP protocol header, otherwise meaningless
+                ProcessProtocolHeader(reader, frameHeaderBuffer.AsSpan(1, 6));
             }
 
-            reader.Read(frameHeaderBuffer, 0, frameHeaderBuffer.Length);
-            int channel = NetworkOrderDeserializer.ReadUInt16(new ReadOnlySpan<byte>(frameHeaderBuffer));
-            int payloadSize = NetworkOrderDeserializer.ReadInt32(new ReadOnlySpan<byte>(frameHeaderBuffer, 2, 4)); // FIXME - throw exn on unreasonable value
+            FrameType type = (FrameType)firstByte;
+            int channel = NetworkOrderDeserializer.ReadUInt16(new ReadOnlySpan<byte>(frameHeaderBuffer, 1, 2));
+            int payloadSize = NetworkOrderDeserializer.ReadInt32(new ReadOnlySpan<byte>(frameHeaderBuffer, 3, 4)); // FIXME - throw exn on unreasonable value
 
             const int EndMarkerLength = 1;
             // Is returned by InboundFrame.ReturnPayload in Connection.MainLoopIteration
@@ -257,7 +255,7 @@ internal static InboundFrame ReadFrom(Stream reader, byte[] frameHeaderBuffer)
                 throw new MalformedFrameException($"Bad frame end marker: {payloadBytes[payloadSize]}");
             }
 
-            return new InboundFrame((FrameType)type, channel, new Memory<byte>(payloadBytes, 0, payloadSize), payloadBytes);
+            return new InboundFrame(type, channel, new Memory<byte>(payloadBytes, 0, payloadSize), payloadBytes);
         }
 
         public byte[] TakeoverPayload()