Serialize NegotiateResponse with IBufferWriter (#1881)

benchmarks/Microsoft.AspNetCore.SignalR.Microbenchmarks/HubConnectionContextBenchmark.cs

@@ -11,6 +11,7 @@ using BenchmarkDotNet.Attributes;
 using Microsoft.AspNetCore.Connections;
 using Microsoft.AspNetCore.SignalR.Core;
 using Microsoft.AspNetCore.SignalR.Internal;
+using Microsoft.AspNetCore.Internal;
 using Microsoft.AspNetCore.SignalR.Internal.Protocol;
 using Microsoft.AspNetCore.SignalR.Microbenchmarks.Shared;
 using Microsoft.Extensions.Logging.Abstractions;

benchmarks/Microsoft.AspNetCore.SignalR.Microbenchmarks/HubConnectionSendBenchmark.cs

@@ -9,7 +9,7 @@ using BenchmarkDotNet.Attributes;
 using Microsoft.AspNetCore.Connections;
 using Microsoft.AspNetCore.Connections.Features;
 using Microsoft.AspNetCore.SignalR.Client;
-using Microsoft.AspNetCore.SignalR.Internal;
+using Microsoft.AspNetCore.Internal;
 using Microsoft.AspNetCore.SignalR.Internal.Protocol;
 using Microsoft.AspNetCore.SignalR.Microbenchmarks.Shared;
 using Microsoft.Extensions.DependencyInjection;

benchmarks/Microsoft.AspNetCore.SignalR.Microbenchmarks/HubConnectionStartBenchmark.cs

@@ -10,7 +10,7 @@ using Microsoft.AspNetCore.Connections;
 using Microsoft.AspNetCore.Connections.Features;
 using Microsoft.AspNetCore.Http.Features;
 using Microsoft.AspNetCore.SignalR.Client;
-using Microsoft.AspNetCore.SignalR.Internal;
+using Microsoft.AspNetCore.Internal;
 using Microsoft.AspNetCore.SignalR.Internal.Protocol;
 using Microsoft.AspNetCore.SignalR.Microbenchmarks.Shared;
 using Microsoft.Extensions.DependencyInjection;

benchmarks/Microsoft.AspNetCore.SignalR.Microbenchmarks/MessageParserBenchmark.cs

@@ -2,7 +2,7 @@ using System;
 using System.Buffers;
 using System.IO;
 using BenchmarkDotNet.Attributes;
-using Microsoft.AspNetCore.SignalR.Internal;
+using Microsoft.AspNetCore.Internal;
 using Microsoft.AspNetCore.SignalR.Internal.Formatters;
 
 namespace Microsoft.AspNetCore.SignalR.Microbenchmarks

benchmarks/Microsoft.AspNetCore.SignalR.Microbenchmarks/NegotiateProtocolBenchmark.cs

@@ -0,0 +1,55 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using System.Collections.Generic;
+using System.IO;
+using System.Threading.Tasks;
+using BenchmarkDotNet.Attributes;
+using Microsoft.AspNetCore.Http.Connections.Internal;
+using Microsoft.AspNetCore.Internal;
+
+namespace Microsoft.AspNetCore.SignalR.Microbenchmarks
+{
+    public class NegotiateProtocolBenchmark
+    {
+        private NegotiationResponse _negotiateResponse;
+        private Stream _stream;
+
+        [GlobalSetup]
+        public void GlobalSetup()
+        {
+            _negotiateResponse = new NegotiationResponse
+            {
+                ConnectionId = "d100338e-8c01-4281-92c2-9a967fdeebcb",
+                AvailableTransports = new List<AvailableTransport>
+                {
+                    new AvailableTransport
+                    {
+                        Transport = "WebSockets",
+                        TransferFormats = new List<string>
+                        {
+                            "Text",
+                            "Binary"
+                        }
+                    }
+                }
+            };
+            _stream = Stream.Null;
+        }
+
+        [Benchmark]
+        public Task WriteResponse_MemoryBufferWriter()
+        {
+            var writer = new MemoryBufferWriter();
+            try
+            {
+                NegotiateProtocol.WriteResponse(_negotiateResponse, writer);
+                return writer.CopyToAsync(_stream);
+            }
+            finally
+            {
+                writer.Reset();
+            }
+        }
+    }
+}

src/Common/MemoryBufferWriter.cs

@@ -0,0 +1,174 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using System;
+using System.Buffers;
+using System.Collections.Generic;
+using System.IO;
+using System.Threading.Tasks;
+
+namespace Microsoft.AspNetCore.Internal
+{
+    internal sealed class MemoryBufferWriter : IBufferWriter<byte>
+    {
+        [ThreadStatic]
+        private static MemoryBufferWriter _cachedInstance;
+
+#if DEBUG
+        private bool _inUse;
+#endif
+
+        private readonly int _segmentSize;
+        private int _bytesWritten;
+
+        private List<byte[]> _fullSegments;
+        private byte[] _currentSegment;
+        private int _position;
+
+        public MemoryBufferWriter(int segmentSize = 2048)
+        {
+            _segmentSize = segmentSize;
+        }
+
+        public int Length => _bytesWritten;
+
+        public static MemoryBufferWriter Get()
+        {
+            var writer = _cachedInstance;
+            if (writer == null)
+            {
+                writer = new MemoryBufferWriter();
+            }
+
+            // Taken off the thread static
+            _cachedInstance = null;
+#if DEBUG
+            if (writer._inUse)
+            {
+                throw new InvalidOperationException("The reader wasn't returned!");
+            }
+
+            writer._inUse = true;
+#endif
+
+            return writer;
+        }
+
+        public static void Return(MemoryBufferWriter writer)
+        {
+            _cachedInstance = writer;
+#if DEBUG
+            writer._inUse = false;
+#endif
+            writer.Reset();
+        }
+
+        public void Reset()
+        {
+            if (_fullSegments != null)
+            {
+                for (var i = 0; i < _fullSegments.Count; i++)
+                {
+                    ArrayPool<byte>.Shared.Return(_fullSegments[i]);
+                }
+
+                _fullSegments.Clear();
+            }
+
+            if (_currentSegment != null)
+            {
+                ArrayPool<byte>.Shared.Return(_currentSegment);
+                _currentSegment = null;
+            }
+
+            _bytesWritten = 0;
+            _position = 0;
+        }
+
+        public void Advance(int count)
+        {
+            _bytesWritten += count;
+            _position += count;
+        }
+
+        public Memory<byte> GetMemory(int sizeHint = 0)
+        {
+            // TODO: Use sizeHint
+            if (_currentSegment == null)
+            {
+                _currentSegment = ArrayPool<byte>.Shared.Rent(_segmentSize);
+                _position = 0;
+            }
+            else if (_position == _segmentSize)
+            {
+                if (_fullSegments == null)
+                {
+                    _fullSegments = new List<byte[]>();
+                }
+                _fullSegments.Add(_currentSegment);
+                _currentSegment = ArrayPool<byte>.Shared.Rent(_segmentSize);
+                _position = 0;
+            }
+
+            return _currentSegment.AsMemory(_position, _currentSegment.Length - _position);
+        }
+
+        public Span<byte> GetSpan(int sizeHint = 0)
+        {
+            return GetMemory(sizeHint).Span;
+        }
+
+        public Task CopyToAsync(Stream stream)
+        {
+            if (_fullSegments == null)
+            {
+                // There is only one segment so write without async
+                return stream.WriteAsync(_currentSegment, 0, _position);
+            }
+
+            return CopyToSlowAsync(stream);
+        }
+
+        private async Task CopyToSlowAsync(Stream stream)
+        {
+            if (_fullSegments != null)
+            {
+                // Copy full segments
+                for (var i = 0; i < _fullSegments.Count - 1; i++)
+                {
+                    await stream.WriteAsync(_fullSegments[i], 0, _segmentSize);
+                }
+            }
+
+            await stream.WriteAsync(_currentSegment, 0, _position);
+        }
+
+        public byte[] ToArray()
+        {
+            if (_currentSegment == null)
+            {
+                return Array.Empty<byte>();
+            }
+
+            var result = new byte[_bytesWritten];
+
+            var totalWritten = 0;
+
+            if (_fullSegments != null)
+            {
+                // Copy full segments
+                for (var i = 0; i < _fullSegments.Count; i++)
+                {
+                    _fullSegments[i].CopyTo(result, totalWritten);
+
+                    totalWritten += _segmentSize;
+                }
+            }
+
+            // Copy current incomplete segment
+            _currentSegment.AsSpan(0, _position).CopyTo(result.AsSpan(totalWritten));
+
+            return result;
+        }
+    }
+}

src/Common/Utf8BufferTextReader.cs

@@ -9,7 +9,7 @@ using System.Text;
 
 namespace Microsoft.AspNetCore.SignalR.Internal
 {
-    public class Utf8BufferTextReader : TextReader
+    internal sealed class Utf8BufferTextReader : TextReader
     {
         private readonly Decoder _decoder;
         private ReadOnlySequence<byte> _utf8Buffer;

src/Common/Utf8BufferTextWriter.cs

@@ -9,9 +9,9 @@ using System.Runtime.CompilerServices;
 using System.Runtime.InteropServices;
 using System.Text;
 
-namespace Microsoft.AspNetCore.SignalR.Internal
+namespace Microsoft.AspNetCore.Internal
 {
-    public sealed class Utf8BufferTextWriter : TextWriter
+    internal sealed class Utf8BufferTextWriter : TextWriter
     {
         private static readonly UTF8Encoding _utf8NoBom = new UTF8Encoding(encoderShouldEmitUTF8Identifier: false);
 

src/Microsoft.AspNetCore.Http.Connections.Common/Internal/NegotiateProtocol.cs

@@ -2,6 +2,7 @@
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
 using System;
+using System.Buffers;
 using System.Collections.Generic;
 using System.IO;
 using System.Text;
@@ -12,44 +13,50 @@ namespace Microsoft.AspNetCore.Http.Connections.Internal
 {
     public static class NegotiateProtocol
     {
-        private static readonly UTF8Encoding _utf8NoBom = new UTF8Encoding(encoderShouldEmitUTF8Identifier: false);
-
         private const string ConnectionIdPropertyName = "connectionId";
         private const string AvailableTransportsPropertyName = "availableTransports";
         private const string TransportPropertyName = "transport";
         private const string TransferFormatsPropertyName = "transferFormats";
 
-        public static void WriteResponse(NegotiationResponse response, Stream output)
+        public static void WriteResponse(NegotiationResponse response, IBufferWriter<byte> output)
         {
-            using (var jsonWriter = JsonUtils.CreateJsonTextWriter(new StreamWriter(output, _utf8NoBom, 1024, leaveOpen: true)))
+            var textWriter = Utf8BufferTextWriter.Get(output);
+            try
             {
-                jsonWriter.WriteStartObject();
-                jsonWriter.WritePropertyName(ConnectionIdPropertyName);
-                jsonWriter.WriteValue(response.ConnectionId);
-                jsonWriter.WritePropertyName(AvailableTransportsPropertyName);
-                jsonWriter.WriteStartArray();
-
-                foreach (var availableTransport in response.AvailableTransports)
+                using (var jsonWriter = JsonUtils.CreateJsonTextWriter(textWriter))
                 {
                     jsonWriter.WriteStartObject();
-                    jsonWriter.WritePropertyName(TransportPropertyName);
-                    jsonWriter.WriteValue(availableTransport.Transport);
-                    jsonWriter.WritePropertyName(TransferFormatsPropertyName);
+                    jsonWriter.WritePropertyName(ConnectionIdPropertyName);
+                    jsonWriter.WriteValue(response.ConnectionId);
+                    jsonWriter.WritePropertyName(AvailableTransportsPropertyName);
                     jsonWriter.WriteStartArray();
 
-                    foreach (var transferFormat in availableTransport.TransferFormats)
+                    foreach (var availableTransport in response.AvailableTransports)
                     {
-                        jsonWriter.WriteValue(transferFormat);
+                        jsonWriter.WriteStartObject();
+                        jsonWriter.WritePropertyName(TransportPropertyName);
+                        jsonWriter.WriteValue(availableTransport.Transport);
+                        jsonWriter.WritePropertyName(TransferFormatsPropertyName);
+                        jsonWriter.WriteStartArray();
+
+                        foreach (var transferFormat in availableTransport.TransferFormats)
+                        {
+                            jsonWriter.WriteValue(transferFormat);
+                        }
+
+                        jsonWriter.WriteEndArray();
+                        jsonWriter.WriteEndObject();
                     }
 
                     jsonWriter.WriteEndArray();
                     jsonWriter.WriteEndObject();
+
+                    jsonWriter.Flush();
                 }
-
-                jsonWriter.WriteEndArray();
-                jsonWriter.WriteEndObject();
-
-                jsonWriter.Flush();
+            }
+            finally
+            {
+                Utf8BufferTextWriter.Return(textWriter);
             }
         }
 

src/Microsoft.AspNetCore.Http.Connections.Common/Microsoft.AspNetCore.Http.Connections.Common.csproj

@@ -4,10 +4,12 @@
     <Description>Common primitives for ASP.NET Connection Handlers and clients</Description>
     <TargetFramework>netstandard2.0</TargetFramework>
     <RootNamespace>Microsoft.AspNetCore.Http.Connections</RootNamespace>
+    <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
   </PropertyGroup>
 
   <ItemGroup>
     <Compile Include="..\Common\JsonUtils.cs" Link="Internal\JsonUtils.cs" />
+    <Compile Include="..\Common\Utf8BufferTextWriter.cs" Link="Internal\Utf8BufferTextWriter.cs" />
   </ItemGroup>
   <ItemGroup>
     <PackageReference Include="Microsoft.AspNetCore.Connections.Abstractions" Version="$(MicrosoftAspNetCoreConnectionsAbstractionsPackageVersion)" />

src/Microsoft.AspNetCore.Http.Connections/HttpConnectionDispatcher.cs

@@ -2,6 +2,7 @@
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
 using System;
+using System.Buffers;
 using System.Collections.Generic;
 using System.Diagnostics;
 using System.IO;
@@ -14,6 +15,7 @@ using Microsoft.AspNetCore.Http.Connections.Features;
 using Microsoft.AspNetCore.Http.Connections.Internal;
 using Microsoft.AspNetCore.Http.Connections.Internal.Transports;
 using Microsoft.AspNetCore.Http.Features;
+using Microsoft.AspNetCore.Internal;
 using Microsoft.Extensions.Logging;
 using Microsoft.Extensions.Primitives;
 
@@ -373,7 +375,7 @@ namespace Microsoft.AspNetCore.Http.Connections
             await connectionDelegate(connection);
         }
 
-        private Task ProcessNegotiate(HttpContext context, HttpConnectionOptions options, ConnectionLogScope logScope)
+        private async Task ProcessNegotiate(HttpContext context, HttpConnectionOptions options, ConnectionLogScope logScope)
         {
             context.Response.ContentType = "application/json";
 
@@ -384,17 +386,27 @@ namespace Microsoft.AspNetCore.Http.Connections
             // Connection ID metadata set.
             logScope.ConnectionId = connection.ConnectionId;
 
-            // Get the bytes for the connection id
-            var negotiateResponseBuffer = GetNegotiatePayload(connection.ConnectionId, context, options);
+            // Don't use thread static instance here because writer is used with async
+            var writer = new MemoryBufferWriter();
 
-            Log.NegotiationRequest(_logger);
+            try
+            {
+                // Get the bytes for the connection id
+                WriteNegotiatePayload(writer, connection.ConnectionId, context, options);
 
-            // Write it out to the response with the right content length
-            context.Response.ContentLength = negotiateResponseBuffer.Length;
-            return context.Response.Body.WriteAsync(negotiateResponseBuffer, 0, negotiateResponseBuffer.Length);
+                Log.NegotiationRequest(_logger);
+
+                // Write it out to the response with the right content length
+                context.Response.ContentLength = writer.Length;
+                await writer.CopyToAsync(context.Response.Body);
+            }
+            finally
+            {
+                writer.Reset();
+            }
         }
 
-        private static byte[] GetNegotiatePayload(string connectionId, HttpContext context, HttpConnectionOptions options)
+        private static void WriteNegotiatePayload(IBufferWriter<byte> writer, string connectionId, HttpContext context, HttpConnectionOptions options)
         {
             var response = new NegotiationResponse();
             response.ConnectionId = connectionId;
@@ -415,10 +427,7 @@ namespace Microsoft.AspNetCore.Http.Connections
                 response.AvailableTransports.Add(_longPollingAvailableTransport);
             }
 
-            var ms = new MemoryStream();
-            NegotiateProtocol.WriteResponse(response, ms);
-
-            return ms.ToArray();
+            NegotiateProtocol.WriteResponse(response, writer);
         }
 
         private static bool ServerHasWebSockets(IFeatureCollection features)

src/Microsoft.AspNetCore.Http.Connections/Microsoft.AspNetCore.Http.Connections.csproj

@@ -6,6 +6,7 @@
   </PropertyGroup>
 
   <ItemGroup>
+    <Compile Include="..\Common\MemoryBufferWriter.cs" Link="MemoryBufferWriter.cs" />
     <Compile Include="..\Common\PipeWriterStream.cs" Link="PipeWriterStream.cs" />
     <Compile Include="..\Common\WebSocketExtensions.cs" Link="WebSocketExtensions.cs" />
     <Compile Include="..\Common\StreamExtensions.cs" Link="StreamExtensions.cs" />

src/Microsoft.AspNetCore.SignalR.Common/Internal/MemoryBufferWriter.cs

@@ -1,122 +0,0 @@
-// Copyright (c) .NET Foundation. All rights reserved.
-// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
-
-using System;
-using System.Buffers;
-using System.Collections.Generic;
-
-namespace Microsoft.AspNetCore.SignalR.Internal
-{
-    public sealed class MemoryBufferWriter : IBufferWriter<byte>
-    {
-        [ThreadStatic]
-        private static MemoryBufferWriter _cachedInstance;
-
-#if DEBUG
-        private bool _inUse;
-#endif
-
-        private readonly int _segmentSize;
-        private int _bytesWritten;
-
-        private List<byte[]> _segments;
-        private int _position;
-
-        private MemoryBufferWriter(int segmentSize = 2048)
-        {
-            _segmentSize = segmentSize;
-
-            _segments = new List<byte[]>();
-        }
-
-        public static MemoryBufferWriter Get()
-        {
-            var writer = _cachedInstance;
-            if (writer == null)
-            {
-                writer = new MemoryBufferWriter();
-            }
-
-            // Taken off the thread static
-            _cachedInstance = null;
-#if DEBUG
-            if (writer._inUse)
-            {
-                throw new InvalidOperationException("The reader wasn't returned!");
-            }
-
-            writer._inUse = true;
-#endif
-
-            return writer;
-        }
-
-        public static void Return(MemoryBufferWriter writer)
-        {
-            _cachedInstance = writer;
-#if DEBUG
-            writer._inUse = false;
-#endif
-            for (var i = 0; i < writer._segments.Count; i++)
-            {
-                ArrayPool<byte>.Shared.Return(writer._segments[i]);
-            }
-            writer._segments.Clear();
-            writer._bytesWritten = 0;
-            writer._position = 0;
-        }
-
-        public Memory<byte> CurrentSegment => _segments[_segments.Count - 1];
-
-        public void Advance(int count)
-        {
-            _bytesWritten += count;
-            _position += count;
-        }
-
-        public Memory<byte> GetMemory(int sizeHint = 0)
-        {
-            // TODO: Use sizeHint
-
-            if (_segments.Count == 0 || _position == _segmentSize)
-            {
-                _segments.Add(ArrayPool<byte>.Shared.Rent(_segmentSize));
-                _position = 0;
-            }
-
-            // Cache property access
-            var currentSegment = CurrentSegment;
-            return currentSegment.Slice(_position, currentSegment.Length - _position);
-        }
-
-        public Span<byte> GetSpan(int sizeHint = 0)
-        {
-            return GetMemory(sizeHint).Span;
-        }
-
-        public byte[] ToArray()
-        {
-            if (_segments.Count == 0)
-            {
-                return Array.Empty<byte>();
-            }
-
-            var result = new byte[_bytesWritten];
-
-            var totalWritten = 0;
-
-            // Copy full segments
-            for (var i = 0; i < _segments.Count - 1; i++)
-            {
-                _segments[i].AsMemory().CopyTo(result.AsMemory(totalWritten, _segmentSize));
-
-                totalWritten += _segmentSize;
-            }
-
-            // Copy current incomplete segment
-            CurrentSegment.Slice(0, _position).CopyTo(result.AsMemory(totalWritten, _position));
-
-            return result;
-        }
-    }
-}

src/Microsoft.AspNetCore.SignalR.Common/Internal/Protocol/HandshakeProtocol.cs

@@ -1,6 +1,7 @@
 // Copyright (c) .NET Foundation. All rights reserved.
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
+using System;
 using System.Buffers;
 using System.IO;
 using Microsoft.AspNetCore.Internal;
@@ -16,6 +17,22 @@ namespace Microsoft.AspNetCore.SignalR.Internal.Protocol
         private const string ErrorPropertyName = "error";
         private const string TypePropertyName = "type";
 
+        public static ReadOnlyMemory<byte> SuccessHandshakeData { get; }
+
+        static HandshakeProtocol()
+        {
+            var memoryBufferWriter = MemoryBufferWriter.Get();
+            try
+            {
+                WriteResponseMessage(HandshakeResponseMessage.Empty, memoryBufferWriter);
+                SuccessHandshakeData = memoryBufferWriter.ToArray();
+            }
+            finally
+            {
+                MemoryBufferWriter.Return(memoryBufferWriter);
+            }
+        }
+
         public static void WriteRequestMessage(HandshakeRequestMessage requestMessage, IBufferWriter<byte> output)
         {
             var textWriter = Utf8BufferTextWriter.Get(output);

src/Microsoft.AspNetCore.SignalR.Common/Internal/Protocol/HubProtocolExtensions.cs

@@ -1,6 +1,8 @@
 // Copyright (c) .NET Foundation. All rights reserved.
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
+using Microsoft.AspNetCore.Internal;
+
 namespace Microsoft.AspNetCore.SignalR.Internal.Protocol
 {
     public static class HubProtocolExtensions

src/Microsoft.AspNetCore.SignalR.Common/Microsoft.AspNetCore.SignalR.Common.csproj

@@ -9,6 +9,9 @@
 
   <ItemGroup>
     <Compile Include="..\Common\JsonUtils.cs" Link="Internal\JsonUtils.cs" />
+    <Compile Include="..\Common\MemoryBufferWriter.cs" Link="Internal\MemoryBufferWriter.cs" />
+    <Compile Include="..\Common\Utf8BufferTextReader.cs" Link="Internal\Utf8BufferTextReader.cs" />
+    <Compile Include="..\Common\Utf8BufferTextWriter.cs" Link="Internal\Utf8BufferTextWriter.cs" />
   </ItemGroup>
 
   <ItemGroup>

src/Microsoft.AspNetCore.SignalR.Core/HubConnectionContext.cs

@@ -14,6 +14,7 @@ using System.Threading.Tasks;
 using Microsoft.AspNetCore.Connections;
 using Microsoft.AspNetCore.Connections.Features;
 using Microsoft.AspNetCore.Http.Features;
+using Microsoft.AspNetCore.Internal;
 using Microsoft.AspNetCore.SignalR.Core;
 using Microsoft.AspNetCore.SignalR.Internal;
 using Microsoft.AspNetCore.SignalR.Internal.Protocol;
@@ -24,7 +25,6 @@ namespace Microsoft.AspNetCore.SignalR
     public class HubConnectionContext
     {
         private static readonly Action<object> _abortedCallback = AbortConnection;
-        private static readonly byte[] _successHandshakeResponseData;
 
         private readonly ConnectionContext _connectionContext;
         private readonly ILogger _logger;
@@ -36,20 +36,6 @@ namespace Microsoft.AspNetCore.SignalR
         private long _lastSendTimestamp = Stopwatch.GetTimestamp();
         private byte[] _cachedPingMessage;
 
-        static HubConnectionContext()
-        {
-            var memoryBufferWriter = MemoryBufferWriter.Get();
-            try
-            {
-                HandshakeProtocol.WriteResponseMessage(HandshakeResponseMessage.Empty, memoryBufferWriter);
-                _successHandshakeResponseData = memoryBufferWriter.ToArray();
-            }
-            finally
-            {
-                MemoryBufferWriter.Return(memoryBufferWriter);
-            }
-        }
-
         public HubConnectionContext(ConnectionContext connectionContext, TimeSpan keepAliveInterval, ILoggerFactory loggerFactory)
         {
             _connectionContext = connectionContext;
@@ -264,7 +250,7 @@ namespace Microsoft.AspNetCore.SignalR
                 if (message == HandshakeResponseMessage.Empty)
                 {
                     // success response is always an empty object so send cached data
-                    _connectionContext.Transport.Output.Write(_successHandshakeResponseData);
+                    _connectionContext.Transport.Output.Write(HandshakeProtocol.SuccessHandshakeData.Span);
                 }
                 else
                 {

src/Microsoft.AspNetCore.SignalR.Protocols.Json/Microsoft.AspNetCore.SignalR.Protocols.Json.csproj

@@ -4,10 +4,13 @@
     <Description>Implements the SignalR Hub Protocol over JSON.</Description>
     <TargetFramework>netstandard2.0</TargetFramework>
     <RootNamespace>Microsoft.AspNetCore.SignalR</RootNamespace>
+    <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
   </PropertyGroup>
 
   <ItemGroup>
     <Compile Include="..\Common\JsonUtils.cs" Link="Internal\JsonUtils.cs" />
+    <Compile Include="..\Common\Utf8BufferTextReader.cs" Link="Utf8BufferTextReader.cs" />
+    <Compile Include="..\Common\Utf8BufferTextWriter.cs" Link="Utf8BufferTextWriter.cs" />
   </ItemGroup>
 
   <ItemGroup>

test/Microsoft.AspNetCore.SignalR.Client.Tests/Microsoft.AspNetCore.SignalR.Client.Tests.csproj

@@ -4,6 +4,10 @@
     <TargetFrameworks>$(StandardTestTfms)</TargetFrameworks>
   </PropertyGroup>
 
+  <ItemGroup>
+    <Compile Include="..\..\src\Common\MemoryBufferWriter.cs" Link="MemoryBufferWriter.cs" />
+  </ItemGroup>
+
   <ItemGroup>
     <Content Include="..\xunit.runner.json" Link="xunit.runner.json">
       <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>

test/Microsoft.AspNetCore.SignalR.Client.Tests/TestConnection.cs

@@ -10,7 +10,7 @@ using System.Threading;
 using System.Threading.Tasks;
 using Microsoft.AspNetCore.Connections;
 using Microsoft.AspNetCore.Http.Features;
-using Microsoft.AspNetCore.SignalR.Internal;
+using Microsoft.AspNetCore.Internal;
 using Microsoft.AspNetCore.SignalR.Internal.Formatters;
 using Microsoft.AspNetCore.SignalR.Internal.Protocol;
 using Newtonsoft.Json;
@@ -75,17 +75,21 @@ namespace Microsoft.AspNetCore.SignalR.Client.Tests
         {
             var s = await ReadSentTextMessageAsync();
 
+            byte[] response;
+
             var output = MemoryBufferWriter.Get();
             try
             {
                 HandshakeProtocol.WriteResponseMessage(HandshakeResponseMessage.Empty, output);
-                await Application.Output.WriteAsync(output.ToArray());
+                response = output.ToArray();
             }
             finally
             {
                 MemoryBufferWriter.Return(output);
             }
 
+            await Application.Output.WriteAsync(response);
+
             return s;
         }
 

test/Microsoft.AspNetCore.SignalR.Common.Tests/Internal/Formatters/BinaryMessageFormatterTests.cs

@@ -7,6 +7,7 @@ using System.Collections.Generic;
 using System.IO;
 using System.Linq;
 using System.Text;
+using Microsoft.AspNetCore.Internal;
 using Microsoft.AspNetCore.SignalR.Internal;
 using Microsoft.AspNetCore.SignalR.Internal.Formatters;
 using Xunit;

test/Microsoft.AspNetCore.SignalR.Common.Tests/Internal/Protocol/JsonHubProtocolTests.cs

@@ -7,6 +7,7 @@ using System.Collections.Generic;
 using System.IO;
 using System.Linq;
 using System.Text;
+using Microsoft.AspNetCore.Internal;
 using Microsoft.AspNetCore.SignalR.Internal.Formatters;
 using Microsoft.AspNetCore.SignalR.Internal.Protocol;
 using Microsoft.Extensions.Options;
@@ -16,7 +17,6 @@ using Xunit;
 
 namespace Microsoft.AspNetCore.SignalR.Common.Tests.Internal.Protocol
 {
-    using Microsoft.AspNetCore.SignalR.Internal;
     using static HubMessageHelpers;
 
     public class JsonHubProtocolTests

test/Microsoft.AspNetCore.SignalR.Common.Tests/Internal/Protocol/MessagePackHubProtocolTests.cs

@@ -7,7 +7,7 @@ using System.Collections.Generic;
 using System.IO;
 using System.Linq;
 using System.Text;
-using Microsoft.AspNetCore.SignalR.Internal;
+using Microsoft.AspNetCore.Internal;
 using Microsoft.AspNetCore.SignalR.Internal.Formatters;
 using Microsoft.AspNetCore.SignalR.Internal.Protocol;
 using MsgPack;

test/Microsoft.AspNetCore.SignalR.Common.Tests/Internal/Protocol/Utf8BufferTextWriterTests.cs

@@ -5,6 +5,7 @@ using System;
 using System.Buffers;
 using System.Collections.Generic;
 using System.Text;
+using Microsoft.AspNetCore.Internal;
 using Microsoft.AspNetCore.SignalR.Internal;
 using Xunit;
 

test/Microsoft.AspNetCore.SignalR.Tests.Utils/TestClient.cs

@@ -9,6 +9,7 @@ using System.Threading;
 using System.Threading.Tasks;
 using Microsoft.AspNetCore.Connections;
 using Microsoft.AspNetCore.Connections.Features;
+using Microsoft.AspNetCore.Internal;
 using Microsoft.AspNetCore.SignalR.Internal;
 using Microsoft.AspNetCore.SignalR.Internal.Protocol;
 
@@ -16,7 +17,7 @@ namespace Microsoft.AspNetCore.SignalR.Tests
 {
     public class TestClient : ITransferFormatFeature, IConnectionHeartbeatFeature, IDisposable
     {
-        private object _heartbeatLock = new object();
+        private readonly object _heartbeatLock = new object();
         private List<(Action<object> handler, object state)> _heartbeatHandlers;
 
         private static int _id;