Use span chars for hash instead of bytes

BepInExFasterLoadAssetBundles/Helpers/HashingHelper.cs

@@ -11,13 +11,13 @@ internal class HashingHelper
 {
     private const int c_BufferSize = 16 * (int)FileHelper.c_MBToBytes;
 
-    public static byte[] HashFile(string path)
+    public static int HashFile(Span<char> destination, string path)
     {
         using var fileStream = new FileStream(path, FileMode.Open, FileAccess.Read, FileShare.None, c_BufferSize, FileOptions.SequentialScan);
-        return HashStream(fileStream);
+        return WriteHash(destination, fileStream);
     }
 
-    public static unsafe byte[] HashStream(Stream stream)
+    public static unsafe int WriteHash(Span<char> destination, Stream stream)
     {
         stream.Seek(0, SeekOrigin.Begin);
 
@@ -34,39 +34,26 @@ public static unsafe byte[] HashStream(Stream stream)
 
         UnsafeUtility.Free(buffer, Allocator.Temp);
 
-        var hashArray = new byte[16];
-        BinaryPrimitives.WriteUInt64LittleEndian(hashArray, hash.u64_0);
-        BinaryPrimitives.WriteUInt64LittleEndian(hashArray.AsSpan(8), hash.u64_1);
+        Span<byte> hashSpan = stackalloc byte[16];
+        BinaryPrimitives.WriteUInt64LittleEndian(hashSpan, hash.u64_0);
+        BinaryPrimitives.WriteUInt64LittleEndian(hashSpan.Slice(8), hash.u64_1);
 
-        return hashArray;
+        return HashToString(destination, hashSpan);
     }
 
-    public static string HashToString(Span<byte> hash)
+    /// <summary>
+    /// Writes user readable hash from bytes
+    /// </summary>
+    /// <param name="destination"></param>
+    /// <param name="hash"></param>
+    /// <returns>Written <see langword="char"/> count</returns>
+    private static int HashToString(Span<char> destination, ReadOnlySpan<byte> hash)
     {
-        Span<char> chars = stackalloc char[hash.Length * 2];
-
         for (var i = 0; i < hash.Length; i++)
         {
-            var b = hash[i];
-            b.TryFormat(chars[(i * 2)..], out _, "X2", CultureInfo.InvariantCulture);
-        }
-
-        return chars.ToString();
-    }
-
-    public static int WriteHash(Span<byte> destination, string hash)
-    {
-        if ((hash.Length / 2) > destination.Length)
-        {
-            throw new ArgumentOutOfRangeException("Destination is small to write hash", nameof(destination));
-        }
-
-        for (var i = 0; i < hash.Length; i += 2)
-        {
-            var s = hash.AsSpan(i, 2);
-            destination[i / 2] = byte.Parse(s, NumberStyles.HexNumber, CultureInfo.InvariantCulture);
+            hash[i].TryFormat(destination.Slice(i * 2), out _, "X2", CultureInfo.InvariantCulture);
         }
 
-        return hash.Length / 2;
+        return hash.Length * 2;
     }
 }

BepInExFasterLoadAssetBundles/Managers/AssetBundleManager.cs

@@ -80,9 +80,10 @@ public unsafe bool TryRecompressAssetBundle(Stream stream, [NotNullWhen(true)] o
             return false;
         }
 
-        var hash = HashingHelper.HashStream(stream);
-
-        path = null!;
+        Span<char> hash = stackalloc char[32];
+        HashingHelper.WriteHash(hash, stream);
+
+        path = null;
         if (FindCachedBundleByHash(hash, out var newPath))
         {
             if (newPath != null)
@@ -102,7 +103,7 @@ public unsafe bool TryRecompressAssetBundle(Stream stream, [NotNullWhen(true)] o
         if (stream is FileStream fileStream)
         {
             path = string.Copy(fileStream.Name);
-            RecompressAssetBundleInternal(new(path, hash, false, compressionType));
+            RecompressAssetBundleInternal(new(path, hash.ToString(), false, compressionType));
             return false;
         }
 
@@ -124,7 +125,7 @@ public unsafe bool TryRecompressAssetBundle(Stream stream, [NotNullWhen(true)] o
             }
         }
 
-        RecompressAssetBundleInternal(new(tempFile, hash, true, compressionType));
+        RecompressAssetBundleInternal(new(tempFile, hash.ToString(), true, compressionType));
         return false;
     }
 
@@ -137,7 +138,7 @@ public void DeleteCachedAssetBundle(string path)
         }
     }
 
-    private bool FindCachedBundleByHash(byte[] hash, out string? path)
+    private bool FindCachedBundleByHash(ReadOnlySpan<char> hash, out string? path)
     {
         path = null!;
 
@@ -184,22 +185,16 @@ static void ModifyAccessTimeAndSave(Metadata metadata)
 
     private void RecompressAssetBundleInternal(WorkAsset workAsset)
     {
-        if (!File.Exists(workAsset.Path))
+        if (!DriveHelper.HasDriveSpaceOnPath(CachePath, 10))
         {
+            Patcher.Logger.LogWarning($"Ignoring request of decompressing, because the free drive space is less than 10GB");
             return;
         }
 
-        if (DriveHelper.HasDriveSpaceOnPath(CachePath, 10))
-        {
-            Patcher.Logger.LogDebug($"Queued recompress of \"{Path.GetFileName(workAsset.Path)}\" assetbundle");
-
-            m_WorkAssets.Enqueue(workAsset);
-            StartRunner();
-            return;
-        }
+        Patcher.Logger.LogDebug($"Queued recompress of \"{Path.GetFileName(workAsset.Path)}\" assetbundle");
 
-        Patcher.Logger.LogWarning($"Ignoring request of decompressing, because the free drive space is less than 10GB");
-        return;
+        m_WorkAssets.Enqueue(workAsset);
+        StartRunner();
     }
 
     private void StartRunner()
@@ -247,7 +242,7 @@ private async Task DecompressAssetBundleAsync(WorkAsset workAsset)
     {
         var metadata = new Metadata()
         {
-            OriginalAssetBundleHash = HashingHelper.HashToString(workAsset.Hash),
+            OriginalAssetBundleHash = workAsset.Hash,
             LastAccessTime = DateTime.Now,
         };
         var originalFileName = Path.GetFileNameWithoutExtension(workAsset.Path);
@@ -274,7 +269,8 @@ private async Task DecompressAssetBundleAsync(WorkAsset workAsset)
         var result = op.result;
         var humanReadableResult = op.humanReadableResult;
         var success = op.success;
-        var newHash = HashingHelper.HashFile(outputPath);
+
+        var newHash = GetHashOfFile(outputPath);
 
         await AsyncHelper.SwitchToThreadPool();
 
@@ -292,7 +288,7 @@ private async Task DecompressAssetBundleAsync(WorkAsset workAsset)
         }
 
         // check if unity returned the same assetbundle (means that assetbundle is already decompressed)
-        if (workAsset.Hash.AsSpan().SequenceEqual(newHash))
+        if (newHash.Equals(workAsset.Hash, StringComparison.InvariantCultureIgnoreCase))
         {
             Patcher.Logger.LogDebug($"Assetbundle \"{originalFileName}\" is already uncompressed, adding to ignore list");
 
@@ -307,11 +303,19 @@ private async Task DecompressAssetBundleAsync(WorkAsset workAsset)
 
         metadata.UncompressedAssetBundleName = outputName;
         Patcher.MetadataManager.SaveMetadata(metadata);
+
+        static string GetHashOfFile(string filePath)
+        {
+            Span<char> hash = stackalloc char[32];
+            HashingHelper.HashFile(hash, filePath);
+
+            return hash.ToString();
+        }
     }
 
     private readonly struct WorkAsset
     {
-        public WorkAsset(string path, byte[] hash, bool deleteBundleAfterOperation, CompressionType compressionType)
+        public WorkAsset(string path, string hash, bool deleteBundleAfterOperation, CompressionType compressionType)
         {
             Path = path;
             Hash = hash;
@@ -320,7 +324,7 @@ public WorkAsset(string path, byte[] hash, bool deleteBundleAfterOperation, Comp
         }
 
         public string Path { get; }
-        public byte[] Hash { get; }
+        public string Hash { get; }
         public bool DeleteBundleAfterOperation { get; }
         public CompressionType CompressionType { get; }
     }

BepInExFasterLoadAssetBundles/Managers/MetadataManager.cs

@@ -19,16 +19,13 @@ public MetadataManager(string metadataFile)
         LoadFile();
     }
 
-    public Metadata? FindMetadataByHash(byte[] hash)
+    public Metadata? FindMetadataByHash(ReadOnlySpan<char> hash)
     {
-        Span<byte> tempHash = stackalloc byte[20];
-
         lock (m_Lock)
         {
             foreach (var metadata in m_Metadata)
             {
-                var writtenBytes = HashingHelper.WriteHash(tempHash, metadata.OriginalAssetBundleHash);
-                if (tempHash[..writtenBytes].SequenceEqual(hash))
+                if (hash.SequenceEqual(metadata.OriginalAssetBundleHash))
                 {
                     return metadata;
                 }

BepInExFasterLoadAssetBundles/Patcher.cs

@@ -78,7 +78,7 @@ private static void LoadAssetBundleFromFileFast(ref string path)
 
         try
         {
-            using var bundleFileStream = new FileStream(path, FileMode.Open, FileAccess.ReadWrite);
+            using var bundleFileStream = new FileStream(path, FileMode.Open, FileAccess.Read, FileShare.None, 16 * 1024 * 1024, FileOptions.SequentialScan);
 
             if (HandleStreamBundle(bundleFileStream, out var newPath))
             {