Apply performance optimizations using MemoryMarshal.TryGetArray

Co-authored-by: stephentoub <2642209+stephentoub@users.noreply.github.com>

Author: Copilot

src/ModelContextProtocol.Core/Protocol/BlobResourceContents.cs

@@ -1,3 +1,4 @@
+using System.Runtime.InteropServices;
 using System.Text.Json.Serialization;
 
 namespace ModelContextProtocol.Protocol;
@@ -56,10 +57,11 @@ public ReadOnlyMemory<byte> Data
         {
             if (_decodedData is null)
             {
-#if NET6_0_OR_GREATER
+#if NET
                 _decodedData = Convert.FromBase64String(System.Text.Encoding.UTF8.GetString(Blob.Span));
 #else
-                _decodedData = Convert.FromBase64String(System.Text.Encoding.UTF8.GetString(Blob.ToArray()));
+                byte[] array = MemoryMarshal.TryGetArray(Blob, out ArraySegment<byte> segment) && segment.Offset == 0 && segment.Count == segment.Array!.Length ? segment.Array : Blob.ToArray();
+                _decodedData = Convert.FromBase64String(System.Text.Encoding.UTF8.GetString(array));
 #endif
             }
             return _decodedData;

src/ModelContextProtocol.Core/Protocol/ContentBlock.cs

@@ -2,6 +2,7 @@
 using System.ComponentModel;
 using System.Diagnostics;
 using System.Diagnostics.CodeAnalysis;
+using System.Runtime.InteropServices;
 using System.Text.Json;
 using System.Text.Json.Nodes;
 using System.Text.Json.Serialization;
@@ -419,10 +420,11 @@ public ReadOnlyMemory<byte> DecodedData
         {
             if (_decodedData is null)
             {
-#if NET6_0_OR_GREATER
+#if NET
                 _decodedData = Convert.FromBase64String(System.Text.Encoding.UTF8.GetString(Data.Span));
 #else
-                _decodedData = Convert.FromBase64String(System.Text.Encoding.UTF8.GetString(Data.ToArray()));
+                byte[] array = MemoryMarshal.TryGetArray(Data, out ArraySegment<byte> segment) && segment.Offset == 0 && segment.Count == segment.Array!.Length ? segment.Array : Data.ToArray();
+                _decodedData = Convert.FromBase64String(System.Text.Encoding.UTF8.GetString(array));
 #endif
             }
             return _decodedData;
@@ -479,10 +481,11 @@ public ReadOnlyMemory<byte> DecodedData
         {
             if (_decodedData is null)
             {
-#if NET6_0_OR_GREATER
+#if NET
                 _decodedData = Convert.FromBase64String(System.Text.Encoding.UTF8.GetString(Data.Span));
 #else
-                _decodedData = Convert.FromBase64String(System.Text.Encoding.UTF8.GetString(Data.ToArray()));
+                byte[] array = MemoryMarshal.TryGetArray(Data, out ArraySegment<byte> segment) && segment.Offset == 0 && segment.Count == segment.Array!.Length ? segment.Array : Data.ToArray();
+                _decodedData = Convert.FromBase64String(System.Text.Encoding.UTF8.GetString(array));
 #endif
             }
             return _decodedData;

src/ModelContextProtocol.Core/Server/AIFunctionMcpServerResource.cs

@@ -7,6 +7,7 @@
 using System.Globalization;
 using System.Reflection;
 using System.Runtime.CompilerServices;
+using System.Runtime.InteropServices;
 using System.Text;
 using System.Text.Json;
 using System.Text.Json.Nodes;
@@ -391,7 +392,14 @@ public override async ValueTask<ReadResourceResult> ReadAsync(
 
             DataContent dc => new()
             {
-                Contents = [new BlobResourceContents { Uri = request.Params!.Uri, MimeType = dc.MediaType, Blob = System.Text.Encoding.UTF8.GetBytes(dc.Base64Data.ToString()) }],
+                Contents = [new BlobResourceContents 
+                { 
+                    Uri = request.Params!.Uri, 
+                    MimeType = dc.MediaType, 
+                    Blob = MemoryMarshal.TryGetArray(dc.Base64Data, out ArraySegment<char> segment) && segment.Offset == 0 && segment.Count == segment.Array!.Length 
+                        ? System.Text.Encoding.UTF8.GetBytes(segment.Array) 
+                        : System.Text.Encoding.UTF8.GetBytes(dc.Base64Data.ToString()) 
+                }],
             },
 
             string text => new()
@@ -420,7 +428,9 @@ public override async ValueTask<ReadResourceResult> ReadAsync(
                         {
                             Uri = request.Params!.Uri,
                             MimeType = dc.MediaType,
-                            Blob = System.Text.Encoding.UTF8.GetBytes(dc.Base64Data.ToString())
+                            Blob = MemoryMarshal.TryGetArray(dc.Base64Data, out ArraySegment<char> segment) && segment.Offset == 0 && segment.Count == segment.Array!.Length 
+                                ? System.Text.Encoding.UTF8.GetBytes(segment.Array) 
+                                : System.Text.Encoding.UTF8.GetBytes(dc.Base64Data.ToString())
                         },
 
                         _ => throw new InvalidOperationException($"Unsupported AIContent type '{ac.GetType()}' returned from resource function."),