perf(dp): Reduce property search allocations

Author: jeromelaban

src/Uno.UI/UI/Xaml/DependencyProperty.cs

@@ -31,6 +31,12 @@ public sealed partial class DependencyProperty
 		private readonly static TypeToPropertiesDictionary _getPropertiesForType = new TypeToPropertiesDictionary();
 		private readonly static NameToPropertyDictionary _getPropertyCache = new NameToPropertyDictionary();
 
+		/// <summary>
+		/// A static <see cref="PropertyCacheEntry"/> used for lookups and avoid creating new instances. This assumes that uses are non-reentrant.
+		/// </summary>
+		private readonly static PropertyCacheEntry _searchPropertyCacheEntry = new();
+
+
 		private readonly static FrameworkPropertiesForTypeDictionary _getFrameworkPropertiesForType = new FrameworkPropertiesForTypeDictionary();
 
 		private readonly PropertyMetadata _ownerTypeMetadata; // For perf consideration, we keep direct ref the metadata for the owner type
@@ -317,12 +323,11 @@ internal bool IsUnoType
 		/// <returns>A <see cref="DependencyProperty"/> instance, otherwise null it not found.</returns>
 		internal static DependencyProperty GetProperty(Type type, string name)
 		{
-			DependencyProperty result = null;
-			var key = new PropertyCacheEntry(type, name);
+			_searchPropertyCacheEntry.Update(type, name);
 
-			if (!_getPropertyCache.TryGetValue(key, out result))
+			if (!_getPropertyCache.TryGetValue(_searchPropertyCacheEntry, out var result))
 			{
-				_getPropertyCache.Add(key, result = InternalGetProperty(type, name));
+				_getPropertyCache.Add(_searchPropertyCacheEntry.Clone(), result = InternalGetProperty(type, name));
 			}
 
 			return result;
@@ -332,7 +337,9 @@ private static void ResetGetPropertyCache(Type ownerType, string name)
 		{
 			if (_getPropertyCache.Count != 0)
 			{
-				_getPropertyCache.Remove(new PropertyCacheEntry(ownerType, name));
+				_searchPropertyCacheEntry.Update(ownerType, name);
+
+				_getPropertyCache.Remove(_searchPropertyCacheEntry);
 			}
 		}
 

src/Uno.UI/UI/Xaml/DependencyPropertyCacheEntry.cs

@@ -2,6 +2,7 @@
 
 using System;
 using System.Collections;
+using System.Diagnostics.CodeAnalysis;
 using System.Text;
 using Uno.Core.Comparison;
 
@@ -12,11 +13,28 @@ namespace Windows.UI.Xaml
 	/// </summary>
 	internal class PropertyCacheEntry
 	{
-		private readonly Type Type;
-		private readonly string Name;
-		private readonly int CachedHashCode;
+		private Type Type;
+		private string Name;
+		private int CachedHashCode;
 
-		public PropertyCacheEntry(Type type, string name)
+		public PropertyCacheEntry()
+			=> Update(typeof(object), "");
+
+		private PropertyCacheEntry(PropertyCacheEntry other)
+		{
+			CachedHashCode = other.CachedHashCode;
+			Name = other.Name;
+			Type = other.Type;
+		}
+
+		public PropertyCacheEntry Clone()
+			=> new(this);
+
+		/// <summary>
+		/// Mutates the fields from this instance
+		/// </summary>
+		[MemberNotNull(nameof(Type), nameof(Name))]
+		public void Update(Type type, string name)
 		{
 			this.Type = type;
 			this.Name = name;