From 1769d47ba5dc0293d27fc276cf031d6f3b697db4 Mon Sep 17 00:00:00 2001
From: Kamron Batman <3953314+kamronbatman@users.noreply.github.com>
Date: Fri, 17 Nov 2023 16:11:35 -0800
Subject: [PATCH] fix: Removes Standart XxHash in favor of the built in one
 (#1598)

---
 Projects/Server/Server.csproj            |  2 +-
 Projects/Server/Utilities/HashUtility.cs | 68 ++++++++++++++----------
 2 files changed, 42 insertions(+), 28 deletions(-)

diff --git a/Projects/Server/Server.csproj b/Projects/Server/Server.csproj
index 377ca0535..66f2cb044 100755
--- a/Projects/Server/Server.csproj
+++ b/Projects/Server/Server.csproj
@@ -34,7 +34,7 @@
     <ItemGroup>
         <PackageReference Include="CommunityToolkit.HighPerformance" Version="8.2.2" />
         <PackageReference Include="PollGroup" Version="1.4.3" />
-        <PackageReference Include="Standart.Hash.xxHash.Signed" Version="4.0.5" />
+        <PackageReference Include="System.IO.Hashing" Version="8.0.0" />
         <PackageReference Include="Zlib.Bindings" Version="1.11.0" />
 
         <PackageReference Include="ModernUO.Serialization.Annotations" Version="2.8.0" />
diff --git a/Projects/Server/Utilities/HashUtility.cs b/Projects/Server/Utilities/HashUtility.cs
index 8bab93691..559886907 100644
--- a/Projects/Server/Utilities/HashUtility.cs
+++ b/Projects/Server/Utilities/HashUtility.cs
@@ -14,22 +14,12 @@
  *************************************************************************/
 
 using System;
+using System.IO.Hashing;
 using System.Numerics;
 using System.Runtime.CompilerServices;
-using Standart.Hash.xxHash;
 
 namespace Server;
 
-/// <summary>
-/// Represents supported non-cryptographic fast hash algorithms.
-/// </summary>
-public enum FastHashAlgorithm
-{
-    None, // Used for collisions where full-data is serialized instead
-    XxHash3_64, // xxHash3 64bit
-    XxHash_32, // xxHash 32bit
-}
-
 public static class HashUtility
 {
     // *************** DO NOT CHANGE THIS NUMBER ****************
@@ -38,27 +28,51 @@ public static class HashUtility
     private const ulong xxHash3Seed = 9609125370673258709ul; // Randomly generated 64-bit prime number
     private const uint xxHash1Seed = 665738807u; // Randomly generated 32-bit prime number
 
-    [MethodImpl(MethodImplOptions.AggressiveInlining)]
-    public static ulong ComputeHash64(string? data, FastHashAlgorithm algorithm = FastHashAlgorithm.XxHash3_64) =>
-        algorithm switch
+    [ThreadStatic]
+    private static XxHash3 _xxHash3;
+
+    [ThreadStatic]
+    private static XxHash32 _xxHash32;
+
+    public static unsafe ulong ComputeHash64(string? str)
+    {
+        if (str == null)
         {
-            FastHashAlgorithm.XxHash3_64 => ComputeXXHash3_64(data),
-            _                            => throw new NotSupportedException($"Hash {algorithm} is not supported.")
-        };
+            return 0;
+        }
 
-    [MethodImpl(MethodImplOptions.AggressiveInlining)]
-    public static ulong ComputeXXHash3_64(string? data) => data == null ? 0 : xxHash3.ComputeHash(data, xxHash3Seed);
+        var hasher = _xxHash3 ??= new XxHash3(unchecked((long)xxHash3Seed));
 
-    [MethodImpl(MethodImplOptions.AggressiveInlining)]
-    public static uint ComputeHash32(string? data, FastHashAlgorithm algorithm = FastHashAlgorithm.XxHash_32) =>
-        algorithm switch
+        fixed (char* src = &str.GetPinnableReference())
         {
-            FastHashAlgorithm.XxHash_32 => ComputeXXHash_32(data),
-            _                            => throw new NotSupportedException($"Hash {algorithm} is not supported.")
-        };
+            hasher.Append(new ReadOnlySpan<byte>(src, str.Length * 2));
+        }
 
-    [MethodImpl(MethodImplOptions.AggressiveInlining)]
-    public static uint ComputeXXHash_32(string? data) => data == null ? 0 : xxHash32.ComputeHash(data, xxHash1Seed);
+        var result = hasher.GetCurrentHashAsUInt64();
+        hasher.Reset();
+
+        return result;
+    }
+
+    public static unsafe uint ComputeHash32(string? str)
+    {
+        if (str == null)
+        {
+            return 0;
+        }
+
+        var hasher = _xxHash32 ??= new XxHash32(unchecked((int)xxHash1Seed));
+
+        fixed (char* src = &str.GetPinnableReference())
+        {
+            hasher.Append(new ReadOnlySpan<byte>(src, str.Length * 2));
+        }
+
+        var result = hasher.GetCurrentHashAsUInt32();
+        hasher.Reset();
+
+        return result;
+    }
 
     public static unsafe int GetNetFrameworkHashCode(this string? str)
     {