JsonRpcMessage.Converter.Read optimization

.gitignore

@@ -80,4 +80,8 @@ docs/api
 
 # Rider
 .idea/
-.idea_modules/
+.idea_modules/
+
+# Benchmarkdotnet
+
+benchmarks/ModelContextProtocol.Benchmarks/BenchmarkDotNet.Artifacts/

Directory.Packages.props

@@ -79,5 +79,6 @@
     <PackageVersion Include="xunit.runner.visualstudio" Version="3.1.1" />
     <PackageVersion Include="System.Net.Http" Version="4.3.4" />
     <PackageVersion Include="JsonSchema.Net" Version="7.3.4" />
+    <PackageVersion Include="BenchmarkDotNet" Version="0.13.12" />
   </ItemGroup>
 </Project>

ModelContextProtocol.slnx

@@ -40,4 +40,7 @@
     <Project Path="tests/ModelContextProtocol.TestServer/ModelContextProtocol.TestServer.csproj" />
     <Project Path="tests/ModelContextProtocol.TestSseServer/ModelContextProtocol.TestSseServer.csproj" />
   </Folder>
+  <Folder Name="/benchmarks/">
+    <Project Path="benchmarks/ModelContextProtocol.Benchmarks/ModelContextProtocol.Benchmarks.csproj" />
+  </Folder>
 </Solution>

benchmarks/ModelContextProtocol.Benchmarks/JsonRpcMessageSerializationBenchmarks.cs

@@ -0,0 +1,72 @@
+using System.Text.Json;
+using System.Text.Json.Nodes;
+using BenchmarkDotNet.Attributes;
+using ModelContextProtocol.Protocol;
+
+namespace ModelContextProtocol.Benchmarks;
+
+[MemoryDiagnoser]
+public class JsonRpcMessageSerializationBenchmarks
+{
+    private byte[] _requestJson = null!;
+    private byte[] _notificationJson = null!;
+    private byte[] _responseJson = null!;
+    private byte[] _errorJson = null!;
+
+    private JsonSerializerOptions _options = null!;
+
+    [GlobalSetup]
+    public void Setup()
+    {
+        _options = McpJsonUtilities.DefaultOptions;
+
+        _requestJson = JsonSerializer.SerializeToUtf8Bytes(
+            new JsonRpcRequest
+            {
+                Id = new RequestId("1"),
+                Method = "test",
+                Params = JsonValue.Create(1)
+            },
+            _options);
+
+        _notificationJson = JsonSerializer.SerializeToUtf8Bytes(
+            new JsonRpcNotification
+            {
+                Method = "notify",
+                Params = JsonValue.Create(2)
+            },
+            _options);
+
+        _responseJson = JsonSerializer.SerializeToUtf8Bytes(
+            new JsonRpcResponse
+            {
+                Id = new RequestId("1"),
+                Result = JsonValue.Create(3)
+            },
+            _options);
+
+        _errorJson = JsonSerializer.SerializeToUtf8Bytes(
+            new JsonRpcError
+            {
+                Id = new RequestId("1"),
+                Error = new JsonRpcErrorDetail { Code = 42, Message = "oops" }
+            },
+            _options);
+    }
+
+    [Benchmark]
+    public JsonRpcMessage DeserializeRequest() =>
+        JsonSerializer.Deserialize<JsonRpcMessage>(_requestJson, _options)!;
+
+    [Benchmark]
+    public JsonRpcMessage DeserializeNotification() =>
+        JsonSerializer.Deserialize<JsonRpcMessage>(_notificationJson, _options)!;
+
+    [Benchmark]
+    public JsonRpcMessage DeserializeResponse() =>
+        JsonSerializer.Deserialize<JsonRpcMessage>(_responseJson, _options)!;
+
+    [Benchmark]
+    public JsonRpcMessage DeserializeError() =>
+        JsonSerializer.Deserialize<JsonRpcMessage>(_errorJson, _options)!;
+}

benchmarks/ModelContextProtocol.Benchmarks/ModelContextProtocol.Benchmarks.csproj

@@ -0,0 +1,19 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <OutputType>Exe</OutputType>
+    <TargetFramework>net9.0</TargetFramework>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <Nullable>enable</Nullable>
+    <IsPackable>false</IsPackable>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <PackageReference Include="BenchmarkDotNet" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <ProjectReference Include="..\..\src\ModelContextProtocol.Core\ModelContextProtocol.Core.csproj" />
+  </ItemGroup>
+
+</Project>

benchmarks/ModelContextProtocol.Benchmarks/Program.cs

@@ -0,0 +1,3 @@
+using BenchmarkDotNet.Running;
+
+BenchmarkSwitcher.FromAssembly(typeof(Program).Assembly).Run(args);

src/ModelContextProtocol.Core/McpJsonUtilities.cs

@@ -96,6 +96,9 @@ internal static bool IsValidMcpToolSchema(JsonElement element)
     [JsonSerializable(typeof(JsonRpcNotification))]
     [JsonSerializable(typeof(JsonRpcResponse))]
     [JsonSerializable(typeof(JsonRpcError))]
+
+    // JSON-RPC union to make it faster to deserialize messages
+    [JsonSerializable(typeof(JsonRpcMessage.Converter.Union))]
 
     // MCP Notification Params
     [JsonSerializable(typeof(CancelledNotificationParams))]

src/ModelContextProtocol.Core/Protocol/JsonRpcError.cs

@@ -18,10 +18,12 @@ namespace ModelContextProtocol.Protocol;
 /// </remarks>
 public sealed class JsonRpcError : JsonRpcMessageWithId
 {
+    internal const string ErrorPropertyName = "error";
+
     /// <summary>
     /// Gets detailed error information for the failed request, containing an error code, 
     /// message, and optional additional data
     /// </summary>
-    [JsonPropertyName("error")]
+    [JsonPropertyName(ErrorPropertyName)]
     public required JsonRpcErrorDetail Error { get; init; }
 }

src/ModelContextProtocol.Core/Protocol/JsonRpcMessage.cs

@@ -1,6 +1,7 @@
 using ModelContextProtocol.Server;
 using System.ComponentModel;
 using System.Text.Json;
+using System.Text.Json.Nodes;
 using System.Text.Json.Serialization;
 
 namespace ModelContextProtocol.Protocol;
@@ -16,6 +17,8 @@ namespace ModelContextProtocol.Protocol;
 [JsonConverter(typeof(Converter))]
 public abstract class JsonRpcMessage
 {
+    private const string JsonRpcPropertyName = "jsonrpc";
+
     /// <summary>Prevent external derivations.</summary>
     private protected JsonRpcMessage()
     {
@@ -25,7 +28,7 @@ private protected JsonRpcMessage()
     /// Gets the JSON-RPC protocol version used.
     /// </summary>
     /// <inheritdoc />
-    [JsonPropertyName("jsonrpc")]
+    [JsonPropertyName(JsonRpcPropertyName)]
     public string JsonRpc { get; init; } = "2.0";
 
     /// <summary>
@@ -75,6 +78,48 @@ private protected JsonRpcMessage()
     [EditorBrowsable(EditorBrowsableState.Never)]
     public sealed class Converter : JsonConverter<JsonRpcMessage>
     {
+        /// <summary>
+        /// The union to deserialize.
+        /// </summary>
+        internal struct Union
+        {
+            /// <summary>
+            /// <see cref="JsonRpcMessage.JsonRpc"/>
+            /// </summary>
+            [JsonPropertyName(JsonRpcPropertyName)]
+            public string JsonRpc { get; set; }
+
+            /// <summary>
+            /// <see cref="JsonRpcMessageWithId.Id"/>
+            /// </summary>
+            [JsonPropertyName(JsonRpcMessageWithId.IdPropertyName)]
+            public RequestId Id { get; set; }
+
+            /// <summary>
+            /// <see cref="JsonRpcRequest.Method"/>
+            /// </summary>
+            [JsonPropertyName(JsonRpcRequest.MethodPropertyName)]
+            public string? Method { get; set; }
+
+            /// <summary>
+            /// <see cref="JsonRpcRequest.Params"/>
+            /// </summary>
+            [JsonPropertyName(JsonRpcRequest.ParamsPropertyName)]
+            public JsonNode? Params { get; set; }
+
+            /// <summary>
+            /// <see cref="JsonRpcError.Error"/>
+            /// </summary>
+            [JsonPropertyName(JsonRpcError.ErrorPropertyName)]
+            public JsonRpcErrorDetail? Error { get; set; }
+
+            /// <summary>
+            /// <see cref="JsonRpcResponse.Result"/>
+            /// </summary>
+            [JsonPropertyName(JsonRpcResponse.ResultPropertyName)]
+            public JsonNode? Result { get; set; }
+        }
+
         /// <inheritdoc/>
         public override JsonRpcMessage? Read(ref Utf8JsonReader reader, Type typeToConvert, JsonSerializerOptions options)
         {
@@ -83,51 +128,63 @@ public sealed class Converter : JsonConverter<JsonRpcMessage>
                 throw new JsonException("Expected StartObject token");
             }
 
-            using var doc = JsonDocument.ParseValue(ref reader);
-            var root = doc.RootElement;
+            var union = JsonSerializer.Deserialize(ref reader, options.GetTypeInfo<Union>());
 
             // All JSON-RPC messages must have a jsonrpc property with value "2.0"
-            if (!root.TryGetProperty("jsonrpc", out var versionProperty) ||
-                versionProperty.GetString() != "2.0")
+            if (union.JsonRpc != "2.0")
             {
                 throw new JsonException("Invalid or missing jsonrpc version");
             }
 
-            // Determine the message type based on the presence of id, method, and error properties
-            bool hasId = root.TryGetProperty("id", out _);
-            bool hasMethod = root.TryGetProperty("method", out _);
-            bool hasError = root.TryGetProperty("error", out _);
-
-            var rawText = root.GetRawText();
-
             // Messages with an id but no method are responses
-            if (hasId && !hasMethod)
+            if (union.Id.HasValue && union.Method is null)
             {
                 // Messages with an error property are error responses
-                if (hasError)
+                if (union.Error != null)
                 {
-                    return JsonSerializer.Deserialize(rawText, options.GetTypeInfo<JsonRpcError>());
+                    return new JsonRpcError
+                    {
+                        Id = union.Id,
+                        Error = union.Error,
+                        JsonRpc = union.JsonRpc,
+                    };
                 }
 
                 // Messages with a result property are success responses
-                if (root.TryGetProperty("result", out _))
+                if (union.Result != null)
                 {
-                    return JsonSerializer.Deserialize(rawText, options.GetTypeInfo<JsonRpcResponse>());
+                    return new JsonRpcResponse
+                    {
+                        Id = union.Id,
+                        Result = union.Result,
+                        JsonRpc = union.JsonRpc,
+                    };
                 }
 
                 throw new JsonException("Response must have either result or error");
             }
 
             // Messages with a method but no id are notifications
-            if (hasMethod && !hasId)
+            if (union.Method != null && !union.Id.HasValue)
             {
-                return JsonSerializer.Deserialize(rawText, options.GetTypeInfo<JsonRpcNotification>());
+                return new JsonRpcNotification
+                {
+                    Method = union.Method,
+                    JsonRpc = union.JsonRpc,
+                    Params = union.Params,
+                };
             }
 
             // Messages with both method and id are requests
-            if (hasMethod && hasId)
+            if (union.Method != null && union.Id.HasValue)
             {
-                return JsonSerializer.Deserialize(rawText, options.GetTypeInfo<JsonRpcRequest>());
+                return new JsonRpcRequest
+                {
+                    Id = union.Id,
+                    Method = union.Method,
+                    JsonRpc = union.JsonRpc,
+                    Params = union.Params,
+                };
             }
 
             throw new JsonException("Invalid JSON-RPC message format");

src/ModelContextProtocol.Core/Protocol/JsonRpcMessageWithId.cs

@@ -14,6 +14,8 @@ namespace ModelContextProtocol.Protocol;
 /// </remarks>
 public abstract class JsonRpcMessageWithId : JsonRpcMessage
 {
+    internal const string IdPropertyName = "id";
+
     /// <summary>Prevent external derivations.</summary>
     private protected JsonRpcMessageWithId()
     {
@@ -25,6 +27,6 @@ private protected JsonRpcMessageWithId()
     /// <remarks>
     /// Each ID is expected to be unique within the context of a given session.
     /// </remarks>
-    [JsonPropertyName("id")]
+    [JsonPropertyName(IdPropertyName)]
     public RequestId Id { get; init; }
 }

src/ModelContextProtocol.Core/Protocol/JsonRpcRequest.cs

@@ -16,16 +16,19 @@ namespace ModelContextProtocol.Protocol;
 /// </remarks>
 public sealed class JsonRpcRequest : JsonRpcMessageWithId
 {
+    internal const string MethodPropertyName = "method";
+    internal const string ParamsPropertyName = "params";
+
     /// <summary>
     /// Name of the method to invoke.
     /// </summary>
-    [JsonPropertyName("method")]
+    [JsonPropertyName(MethodPropertyName)]
     public required string Method { get; init; }
 
     /// <summary>
     /// Optional parameters for the method.
     /// </summary>
-    [JsonPropertyName("params")]
+    [JsonPropertyName(ParamsPropertyName)]
     public JsonNode? Params { get; init; }
 
     internal JsonRpcRequest WithId(RequestId id)

src/ModelContextProtocol.Core/Protocol/JsonRpcResponse.cs

@@ -18,12 +18,14 @@ namespace ModelContextProtocol.Protocol;
 /// </remarks>
 public sealed class JsonRpcResponse : JsonRpcMessageWithId
 {
+    internal const string ResultPropertyName = "result";
+
     /// <summary>
     /// Gets the result of the method invocation.
     /// </summary>
     /// <remarks>
     /// This property contains the result data returned by the server in response to the JSON-RPC method request.
     /// </remarks>
-    [JsonPropertyName("result")]
+    [JsonPropertyName(ResultPropertyName)]
     public required JsonNode? Result { get; init; }
 }

src/ModelContextProtocol.Core/Protocol/RequestId.cs

@@ -34,6 +34,11 @@ public RequestId(long value)
     /// <remarks>This will either be a <see cref="string"/>, a boxed <see cref="long"/>, or <see langword="null"/>.</remarks>
     public object? Id => _id;
 
+    /// <summary>
+    /// Returns true if the underlying id is set.
+    /// </summary>
+    public bool HasValue => _id != null;
+
     /// <inheritdoc />
     public override string ToString() =>
         _id is string stringValue ? stringValue :