Address a few small nits noticed while browsing

src/StreamJsonRpc/CommonMethodNameTransforms.cs

@@ -1,6 +1,8 @@
 // Copyright (c) Microsoft Corporation. All rights reserved.
 // Licensed under the MIT license. See LICENSE file in the project root for full license information.
 
+using System.Text.Json;
+
 namespace StreamJsonRpc;
 
 /// <summary>
@@ -45,7 +47,12 @@ public static Func<string, string> Prepend(string prefix)
         {
             return name => name;
         }
-
-        return name => prefix + name;
+        else
+        {
+            // Using a local variable for the closure avoids C# from allocating the closure
+            // earlier in the method, which would impact even the fast path.
+            string localPrefix = prefix;
+            return name => localPrefix + name;
+        }
     }
 }

src/StreamJsonRpc/HeaderDelimitedMessageHandler.cs

@@ -314,7 +314,7 @@ unsafe int WriteHeaderText(string value, Span<byte> memory)
             var mediaType = MediaTypeHeaderValue.Parse(contentTypeAsText);
             if (mediaType.CharSet is not null)
             {
-                // The common language server protocol accpets 'utf8' as a valid charset due to an early bug.  To maintain backwards compatibility, 'utf8' will be
+                // The common language server protocol accepts 'utf8' as a valid charset due to an early bug.  To maintain backwards compatibility, 'utf8' will be
                 // accepted here so StreamJsonRpc can be used to support remote language servers following common language protocol.
                 if (mediaType.CharSet.Equals("utf8", StringComparison.OrdinalIgnoreCase))
                 {
@@ -338,17 +338,6 @@ unsafe int WriteHeaderText(string value, Span<byte> memory)
         }
     }
 
-    private static bool IsLastFourBytesCrlfCrlf(byte[] buffer, int lastIndex)
-    {
-        const byte cr = (byte)'\r';
-        const byte lf = (byte)'\n';
-        return lastIndex >= 4
-            && buffer[lastIndex - 4] == cr
-            && buffer[lastIndex - 3] == lf
-            && buffer[lastIndex - 2] == cr
-            && buffer[lastIndex - 1] == lf;
-    }
-
     private static int GetContentLength(ReadOnlySequence<byte> contentLengthValue)
     {
         // Ensure the length is reasonable so we don't blow the stack if we execute the stackalloc path.

src/StreamJsonRpc/Hex.cs

@@ -7,7 +7,7 @@ namespace StreamJsonRpc;
 
 internal static class Hex
 {
-    private static readonly byte[] HexBytes = new byte[] { (byte)'0', (byte)'1', (byte)'2', (byte)'3', (byte)'4', (byte)'5', (byte)'6', (byte)'7', (byte)'8', (byte)'9', (byte)'a', (byte)'b', (byte)'c', (byte)'d', (byte)'e', (byte)'f' };
+    private static readonly byte[] HexBytes = "0123456789abcdef"u8.ToArray();
     private static readonly byte[] ReverseHexDigits = BuildReverseHexDigits();
 
     internal static void Encode(ReadOnlySpan<byte> src, ref Span<char> dest)

src/StreamJsonRpc/JsonRpc.cs

@@ -2601,10 +2601,14 @@ private async Task HandleRpcAsync(JsonRpcMessage rpc)
 
                     lock (this.dispatcherMapLock)
                     {
+#if NET
+                        this.resultDispatcherMap.Remove(resultOrError.RequestId, out data);
+#else
                         if (this.resultDispatcherMap.TryGetValue(resultOrError.RequestId, out data))
                         {
                             this.resultDispatcherMap.Remove(resultOrError.RequestId);
                         }
+#endif
                     }
 
                     if (this.TraceSource.Switch.ShouldTrace(TraceEventType.Information))

src/StreamJsonRpc/LengthHeaderMessageHandler.cs

@@ -2,6 +2,7 @@
 // Licensed under the MIT license. See LICENSE file in the project root for full license information.
 
 using System.Buffers;
+using System.Buffers.Binary;
 using System.IO.Pipelines;
 using Nerdbank.Streams;
 using StreamJsonRpc.Protocol;
@@ -109,7 +110,7 @@ protected override void Write(JsonRpcMessage content, CancellationToken cancella
             }
 
             // Now go back and fill in the header with the actual content length.
-            Utilities.Write(this.Writer.GetSpan(sizeof(int)), checked((int)contentSequence.Length));
+            BinaryPrimitives.WriteInt32BigEndian(this.Writer.GetSpan(sizeof(int)), checked((int)contentSequence.Length));
             this.Writer.Advance(sizeof(int));
             contentSequence.CopyTo(this.Writer);
 

src/StreamJsonRpc/MessagePackFormatter.cs

@@ -402,13 +402,17 @@ private static void WriteProtocolVersionPropertyAndValue(ref MessagePackWriter w
         }
     }
 
-    private static void ReadUnknownProperty(ref MessagePackReader reader, ref Dictionary<string, ReadOnlySequence<byte>>? topLevelProperties, ReadOnlySpan<byte> stringKey)
+    private static unsafe void ReadUnknownProperty(ref MessagePackReader reader, ref Dictionary<string, ReadOnlySequence<byte>>? topLevelProperties, ReadOnlySpan<byte> stringKey)
     {
         topLevelProperties ??= new Dictionary<string, ReadOnlySequence<byte>>(StringComparer.Ordinal);
 #if NETSTANDARD2_1_OR_GREATER || NET6_0_OR_GREATER
         string name = Encoding.UTF8.GetString(stringKey);
 #else
-        string name = Encoding.UTF8.GetString(stringKey.ToArray());
+        string name;
+        fixed (byte* stringKeyPtr = stringKey)
+        {
+            name = Encoding.UTF8.GetString(stringKeyPtr, stringKey.Length);
+        }
 #endif
         topLevelProperties.Add(name, GetSliceForNextToken(ref reader));
     }

src/StreamJsonRpc/Protocol/TraceParent.cs

@@ -142,10 +142,7 @@ public override string ToString()
 
         Debug.Assert(traceParentRemaining.Length == 0, "Characters were not initialized.");
 
-        fixed (char* pValue = traceparent)
-        {
-            return new string(pValue, 0, traceparent.Length);
-        }
+        return traceparent.ToString();
 
         static void AddHyphen(ref Span<char> value)
         {

src/StreamJsonRpc/ProxyGeneration.cs

@@ -294,8 +294,8 @@ internal static TypeInfo Get(Type contractInterface, ReadOnlySpan<Type> addition
                     string rpcMethodName = methodNameMap.GetRpcMethodName(method);
                     if (rpcInterfaceCode.HasValue)
                     {
-                        methodName = rpcInterfaceCode + "." + method.Name;
-                        rpcMethodName = rpcInterfaceCode + "." + rpcMethodName;
+                        methodName = $"{rpcInterfaceCode.GetValueOrDefault()}.{method.Name}";
+                        rpcMethodName = $"{rpcInterfaceCode.GetValueOrDefault()}.{rpcMethodName}";
                     }
 
                     ParameterInfo[] methodParameters = method.GetParameters();

src/StreamJsonRpc/StandardCancellationStrategy.cs

@@ -115,10 +115,14 @@ protected void CancelInboundRequest(RequestId id)
         CancellationTokenSource? cts;
         lock (this.inboundCancellationSources)
         {
+#if NET
+            this.inboundCancellationSources.Remove(id, out cts);
+#else
             if (this.inboundCancellationSources.TryGetValue(id, out cts))
             {
                 this.inboundCancellationSources.Remove(id);
             }
+#endif
         }
 
         if (cts is object)

src/StreamJsonRpc/Utilities.cs

@@ -2,6 +2,7 @@
 // Licensed under the MIT license. See LICENSE file in the project root for full license information.
 
 using System.Buffers;
+using System.Buffers.Binary;
 using System.Diagnostics.CodeAnalysis;
 
 namespace StreamJsonRpc;
@@ -18,39 +19,7 @@ internal static int ReadInt32BE(ReadOnlySequence<byte> sequence)
         sequence = sequence.Slice(0, 4);
         Span<byte> stackSpan = stackalloc byte[4];
         sequence.Slice(0, 4).CopyTo(stackSpan);
-        return ReadIntBE(stackSpan);
-    }
-
-    /// <summary>
-    /// Reads an <see cref="int"/> value to a buffer using big endian.
-    /// </summary>
-    /// <param name="buffer">The buffer to read from. Must be at most 4 bytes long.</param>
-    /// <returns>The read value.</returns>
-    internal static int ReadIntBE(ReadOnlySpan<byte> buffer)
-    {
-        Requires.Argument(buffer.Length <= 4, nameof(buffer), "Int32 length exceeded.");
-
-        int local = 0;
-        for (int offset = 0; offset < buffer.Length; offset++)
-        {
-            local <<= 8;
-            local |= buffer[offset];
-        }
-
-        return local;
-    }
-
-    /// <summary>
-    /// Writes an <see cref="int"/> value to a buffer using big endian.
-    /// </summary>
-    /// <param name="buffer">The buffer to write to. Must be at least 4 bytes long.</param>
-    /// <param name="value">The value to write.</param>
-    internal static void Write(Span<byte> buffer, int value)
-    {
-        buffer[0] = (byte)(value >> 24);
-        buffer[1] = (byte)(value >> 16);
-        buffer[2] = (byte)(value >> 8);
-        buffer[3] = (byte)value;
+        return BinaryPrimitives.ReadInt32BigEndian(stackSpan);
     }
 
     /// <summary>