Optimize Guid.Combine and HexString generation.

src/Umbraco.Core/HexEncoder.cs

@@ -0,0 +1,84 @@
+using System.Linq;
+using System.Runtime.CompilerServices;
+
+namespace Umbraco.Core
+{
+    /// <summary>
+    /// Provides methods for encoding byte arrays into hexidecimal strings.
+    /// </summary>
+    internal static class HexEncoder
+    {
+        // LUT's that provide the hexidecimal representation of each possible byte value.
+        private static readonly char[] HexLutBase = new char[] { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F' };
+
+        // The base LUT arranged in 16x each item order. 0 * 16, 1 * 16, .... F * 16
+        private static readonly char[] HexLutHi = Enumerable.Range(0, 256).Select(x => HexLutBase[x / 0x10]).ToArray();
+
+        // The base LUT repeated 16x.
+        private static readonly char[] HexLutLo = Enumerable.Range(0, 256).Select(x => HexLutBase[x % 0x10]).ToArray();
+
+        /// <summary>
+        /// Converts a <see cref="T:byte[]"/> to a hexidecimal formatted <see cref="string"/> padded to 2 digits.
+        /// </summary>
+        /// <param name="bytes">The bytes.</param>
+        /// <returns>The <see cref="string"/>.</returns>
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        public static string Encode(byte[] bytes)
+        {
+            var length = bytes.Length;
+            var chars = new char[length * 2];
+
+            var index = 0;
+            for (var i = 0; i < length; i++)
+            {
+                var byteIndex = bytes[i];
+                chars[index++] = HexLutHi[byteIndex];
+                chars[index++] = HexLutLo[byteIndex];
+            }
+
+            return new string(chars, 0, chars.Length);
+        }
+
+        /// <summary>
+        /// Converts a <see cref="T:byte[]"/> to a hexidecimal formatted <see cref="string"/> padded to 2 digits
+        /// and split into blocks with the given char separator.
+        /// </summary>
+        /// <param name="bytes">The bytes.</param>
+        /// <param name="separator">The separator.</param>
+        /// <param name="blockSize">The block size.</param>
+        /// <param name="blockCount">The block count.</param>
+        /// <returns></returns>
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        public static string Encode(byte[] bytes, char separator, int blockSize, int blockCount)
+        {
+            var length = bytes.Length;
+            var chars = new char[(length * 2) + blockCount];
+            var count = 0;
+            var size = 0;
+            var index = 0;
+
+            for (var i = 0; i < length; i++)
+            {
+                var byteIndex = bytes[i];
+                chars[index++] = HexLutHi[byteIndex];
+                chars[index++] = HexLutLo[byteIndex];
+
+                if (count == blockCount)
+                {
+                    continue;
+                }
+
+                if (++size < blockSize)
+                {
+                    continue;
+                }
+
+                chars[index++] = separator;
+                size = 0;
+                count++;
+            }
+
+            return new string(chars, 0, chars.Length);
+        }
+    }
+}