Use more pooled Utf8BufferTextReaders (#1728)

- Use it in the HandshakeProtocol
- Move CreateJsonTextReader to JsonUtils

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

@@ -56,33 +56,32 @@ namespace Microsoft.AspNetCore.SignalR.Internal.Protocol
             return new JsonTextWriter(new StreamWriter(output, _utf8NoBom, 1024, leaveOpen: true));
         }
 
-        private static JsonTextReader CreateJsonTextReader(ReadOnlyMemory<byte> payload)
-        {
-            var textReader = new Utf8BufferTextReader();
-            textReader.SetBuffer(payload);
-            var reader = new JsonTextReader(textReader);
-            reader.ArrayPool = JsonArrayPool<char>.Shared;
-
-            return reader;
-        }
-
         public static HandshakeResponseMessage ParseResponseMessage(ReadOnlyMemory<byte> payload)
         {
-            using (var reader = CreateJsonTextReader(payload))
+            var textReader = Utf8BufferTextReader.Get(payload);
+
+            try
             {
-                var token = JToken.ReadFrom(reader);
+                using (var reader = JsonUtils.CreateJsonTextReader(textReader))
-                var handshakeJObject = JsonUtils.GetObject(token);
-
-                // a handshake response does not have a type
-                // check the incoming message was not any other type of message
-                var type = JsonUtils.GetOptionalProperty<string>(handshakeJObject, TypePropertyName);
-                if (!string.IsNullOrEmpty(type))
                 {
-                    throw new InvalidOperationException("Handshake response should not have a 'type' value.");
+                    var token = JToken.ReadFrom(reader);
-                }
+                    var handshakeJObject = JsonUtils.GetObject(token);
 
-                var error = JsonUtils.GetOptionalProperty<string>(handshakeJObject, ErrorPropertyName);
+                    // a handshake response does not have a type
-                return new HandshakeResponseMessage(error);
+                    // check the incoming message was not any other type of message
+                    var type = JsonUtils.GetOptionalProperty<string>(handshakeJObject, TypePropertyName);
+                    if (!string.IsNullOrEmpty(type))
+                    {
+                        throw new InvalidOperationException("Handshake response should not have a 'type' value.");
+                    }
+
+                    var error = JsonUtils.GetOptionalProperty<string>(handshakeJObject, ErrorPropertyName);
+                    return new HandshakeResponseMessage(error);
+                }
+            }
+            finally
+            {
+                Utf8BufferTextReader.Return(textReader);
             }
         }
 
@@ -99,13 +98,21 @@ namespace Microsoft.AspNetCore.SignalR.Internal.Protocol
                 throw new InvalidDataException("Unable to parse payload as a handshake request message.");
             }
 
-            using (var reader = CreateJsonTextReader(payload))
+            var textReader = Utf8BufferTextReader.Get(payload);
+            try
             {
-                var token = JToken.ReadFrom(reader);
+                using (var reader = JsonUtils.CreateJsonTextReader(textReader))
-                var handshakeJObject = JsonUtils.GetObject(token);
+                {
-                var protocol = JsonUtils.GetRequiredProperty<string>(handshakeJObject, ProtocolPropertyName);
+                    var token = JToken.ReadFrom(reader);
-                var protocolVersion = JsonUtils.GetRequiredProperty<int>(handshakeJObject, ProtocolVersionName, JTokenType.Integer);
+                    var handshakeJObject = JsonUtils.GetObject(token);
-                requestMessage = new HandshakeRequestMessage(protocol, protocolVersion);
+                    var protocol = JsonUtils.GetRequiredProperty<string>(handshakeJObject, ProtocolPropertyName);
+                    var protocolVersion = JsonUtils.GetRequiredProperty<int>(handshakeJObject, ProtocolVersionName, JTokenType.Integer);
+                    requestMessage = new HandshakeRequestMessage(protocol, protocolVersion);
+                }
+            }
+            finally
+            {
+                Utf8BufferTextReader.Return(textReader);
             }
 
             return true;

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

@@ -83,7 +83,7 @@ namespace Microsoft.AspNetCore.SignalR.Internal.Protocol
             TextMessageFormatter.WriteRecordSeparator(output);
         }
 
-        private HubMessage ParseMessage(TextReader textReader, IInvocationBinder binder)
+        private HubMessage ParseMessage(Utf8BufferTextReader textReader, IInvocationBinder binder)
         {
             try
             {
@@ -108,11 +108,8 @@ namespace Microsoft.AspNetCore.SignalR.Internal.Protocol
                 Dictionary<string, string> headers = null;
                 var completed = false;
 
-                using (var reader = new JsonTextReader(textReader))
+                using (var reader = JsonUtils.CreateJsonTextReader(textReader))
                 {
-                    reader.ArrayPool = JsonArrayPool<char>.Shared;
-                    reader.CloseInput = false;
-
                     JsonUtils.CheckRead(reader);
 
                     // We're always parsing a JSON object

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

@@ -10,6 +10,17 @@ namespace Microsoft.AspNetCore.SignalR.Internal.Protocol
 {
     public static class JsonUtils
     {
+        internal static JsonTextReader CreateJsonTextReader(Utf8BufferTextReader textReader)
+        {
+            var reader = new JsonTextReader(textReader);
+            reader.ArrayPool = JsonArrayPool<char>.Shared;
+
+            // Don't close the output, Utf8BufferTextReader is resettable
+            reader.CloseInput = false;
+
+            return reader;
+        }
+
         public static JObject GetObject(JToken token)
         {
             if (token == null || token.Type != JTokenType.Object)