Optimise XElementExtensions value conversion and hashing

uSync.Core/Extensions/XElementExtensions.cs

@@ -138,7 +138,37 @@ public static string ValueOrDefault([AllowNull] this XElement? node, string defa
     public static TObject ValueOrDefault<TObject>([AllowNull] this XElement? node, TObject defaultValue)
     {
         var value = node.ValueOrDefault(string.Empty);
-        if (value == string.Empty) return defaultValue;
+        if (value.Length == 0) return defaultValue;
+
+        return value.ConvertOrDefault(defaultValue);
+    }
+
+    /// <summary>
+    ///  Convert a non-empty string value to the requested type.
+    /// </summary>
+    /// <remarks>
+    ///  These getters are called for (almost) every attribute of every node during a
+    ///  report/import. The handful of value types actually used have direct, allocation
+    ///  free parsers that are much cheaper than routing through Umbraco's reflection based
+    ///  TryConvertTo. The typeof(TObject) == typeof(...) comparisons are folded to
+    ///  constants by the JIT per generic instantiation, so the branches have no runtime
+    ///  cost. Anything not matched falls through to TryGetValueAs.
+    /// </remarks>
+    private static TObject ConvertOrDefault<TObject>(this string value, TObject defaultValue)
+    {
+        if (typeof(TObject) == typeof(int))
+            return int.TryParse(value, out var i) ? (TObject)(object)i : defaultValue;
+
+        if (typeof(TObject) == typeof(Guid))
+            return Guid.TryParse(value, out var g) ? (TObject)(object)g : defaultValue;
+
+        if (typeof(TObject) == typeof(bool))
+            return bool.TryParse(value, out var b) ? (TObject)(object)b : defaultValue;
+
+        if (typeof(TObject).IsEnum)
+            return Enum.TryParse(typeof(TObject), value, true, out var e) && e is TObject enumValue
+                ? enumValue
+                : defaultValue;
 
         return value.TryGetValueAs<TObject>(out var result) ? result : defaultValue;
     }
@@ -284,9 +314,9 @@ public static string ValueOrDefault([AllowNull] this XAttribute? attribute, stri
     public static TObject ValueOrDefault<TObject>([AllowNull] this XAttribute attribute, TObject defaultValue)
     {
         var value = attribute.ValueOrDefault(string.Empty);
-        if (value == string.Empty) return defaultValue;
+        if (value.Length == 0) return defaultValue;
 
-        return value.TryGetValueAs<TObject>(out var result) ? result : defaultValue;
+        return value.ConvertOrDefault(defaultValue);
     }
     #endregion
 
@@ -307,17 +337,17 @@ public static TObject ValueOrDefault<TObject>([AllowNull] this XAttribute attrib
     /// </remarks>
     public static async Task<string> MakePlatformSafeHashAsync(this XElement node)
     {
-        using (MemoryStream stream = new MemoryStream())
-        {
-            await node.SaveAsync(stream, SaveOptions.None, CancellationToken.None);
-            stream.Seek(0, SeekOrigin.Begin);
+        using HashAlgorithm hashAlgorithm = CryptoConfig.AllowOnlyFipsAlgorithms ? SHA1.Create() : MD5.Create();
 
-            using (HashAlgorithm hashAlgorithm = CryptoConfig.AllowOnlyFipsAlgorithms ? SHA1.Create() : MD5.Create())
-            {
-                var hash = await hashAlgorithm.ComputeHashAsync(stream);
-                return Convert.ToHexStringLower(hash);
-            }
+        // stream the xml straight into the hash instead of buffering the whole
+        // serialized document into a MemoryStream first. CryptoStream feeds each
+        // written block to the algorithm as it arrives, so nothing is held in memory.
+        using (var cryptoStream = new CryptoStream(Stream.Null, hashAlgorithm, CryptoStreamMode.Write))
+        {
+            await node.SaveAsync(cryptoStream, SaveOptions.None, CancellationToken.None);
         }
+
+        return Convert.ToHexStringLower(hashAlgorithm.Hash!);
     }
 
 }