Optimize Sha256 hasher

Common.Tests/Utils/HashingUtilsTests.cs

@@ -6,6 +6,7 @@ public class HashingUtilsTests
 {
     [Test]
     [Arguments("test", "9f86d081884c7d659a2feaa0c55ad015a3bf4f1b2b0b822cd15d6c15b0f00a08")]
+    [Arguments("Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in", "2fac5f5f1d048a84fbb75c389f4596e05023ac17da4fcf45a5954d2d9a394301")]
     public async Task HashSha256(string str, string expectedHash)
     {
         // Act

Common/Utils/HashingUtils.cs

@@ -1,4 +1,5 @@
-using System.Security.Cryptography;
+using System.Buffers;
+using System.Security.Cryptography;
 using System.Text;
 
 namespace OpenShock.Common.Utils;
@@ -12,8 +13,33 @@ public static class HashingUtils
     /// <returns></returns>
     public static string HashSha256(string str)
     {
-        Span<byte> tempSpan = stackalloc byte[32];
-        SHA256.HashData(Encoding.UTF8.GetBytes(str), tempSpan);
-        return Convert.ToHexStringLower(tempSpan);
+        Span<byte> hashDigest = stackalloc byte[SHA256.HashSizeInBytes];
+
+        const int maxStackSize = 256; // Threshold for stack allocation
+        int byteCount = Encoding.UTF8.GetByteCount(str);
+
+        if (byteCount > maxStackSize)
+        {
+            byte[] decodedBytes = ArrayPool<byte>.Shared.Rent(byteCount);
+
+            try
+            {
+                int decodedCount = Encoding.UTF8.GetBytes(str, decodedBytes);
+                SHA256.HashData(decodedBytes.AsSpan(0, decodedCount), hashDigest);
+            }
+            finally
+            {
+                ArrayPool<byte>.Shared.Return(decodedBytes, true);
+            }
+        }
+        else
+        {
+            Span<byte> decodedBytes = stackalloc byte[maxStackSize];
+            int decodedCount = Encoding.UTF8.GetBytes(str, decodedBytes);
+            SHA256.HashData(decodedBytes[..decodedCount], hashDigest);
+        }
+
+
+        return Convert.ToHexStringLower(hashDigest);
     }
 }