perf: Add a fast path for GetValue

unoplatform · Sep 27, 2023 · 0112ea9 · 0112ea9
1 parent 236445f
commit 0112ea9
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Showing 2 changed files with 44 additions and 7 deletions.
diff --git a/src/Uno.UI/UI/Xaml/DependencyObjectStore.cs b/src/Uno.UI/UI/Xaml/DependencyObjectStore.cs
@@ -265,6 +265,37 @@ private void Dispose(bool disposing)
 
 			ValidatePropertyOwner(property);
 
+			// As a performance optimization, avoid creating the property details and try get the value in this fast path.
+			if ((propertyDetails ??= _properties.FindPropertyDetails(property)) is null)
+			{
+				// Since property details wasn't created, the only possibilities are returning UnsetValue or the default value.
+				// UnsetValue is returned when we are asked for a non-DefaultValue precedence specific value.
+				// Otherwise, we calculate the default value, first by calling `GetDefaultValue2`, then from property metadata.
+				if (isPrecedenceSpecific)
+				{
+					Debug.Assert(precedence is not null);
+					if (precedence != DependencyPropertyValuePrecedences.DefaultValue)
+					{
+						return UnsetValue.Instance;
+					}
+				}
+
+				if (ActualInstance is UIElement uiElement && uiElement.GetDefaultValue2(property, out var defaultValue))
+				{
+					return defaultValue;
+				}
+
+				defaultValue = property.GetMetadata(_originalObjectType).DefaultValue;
+
+				// Ensures that the default value of non-nullable properties is not null
+				if (defaultValue == null && !property.IsTypeNullable)
+				{
+					defaultValue = property.GetFallbackDefaultValue();
+				}
+
+				return defaultValue;
+			}
+
 			propertyDetails ??= _properties.GetPropertyDetails(property);
 
 			return GetValue(propertyDetails, precedence, isPrecedenceSpecific);

diff --git a/src/Uno.UI/UI/Xaml/DependencyPropertyDetailsCollection.cs b/src/Uno.UI/UI/Xaml/DependencyPropertyDetailsCollection.cs
@@ -131,19 +131,19 @@ public DependencyPropertyDetails FindPropertyDetails(DependencyProperty property
 			// https://stackoverflow.com/a/17095534/26346
 			var isInRange = (uint)entryIndex <= (_maxId - _minId);
 
-			GetPropertyInheritanceConfiguration(
-				property: property,
-				hasInherits: out var hasInherits,
-				hasValueInherits: out var hasValueInherits,
-				hasValueDoesNotInherit: out var hasValueDoesNotInherits
-			);
-
 			if (isInRange)
 			{
 				ref var propertyEntry = ref Entries![entryIndex];
 
 				if (forceCreate && propertyEntry == null)
 				{
+					GetPropertyInheritanceConfiguration(
+						property: property,
+						hasInherits: out var hasInherits,
+						hasValueInherits: out var hasValueInherits,
+						hasValueDoesNotInherit: out var hasValueDoesNotInherits
+					);
+
 					propertyEntry = new DependencyPropertyDetails(property, _ownerType, hasInherits, hasValueInherits, hasValueDoesNotInherits);
 
 					if (TryResolveDefaultValueFromProviders(property, out var value))
@@ -182,6 +182,12 @@ public DependencyPropertyDetails FindPropertyDetails(DependencyProperty property
 					}
 
 					ref var propertyEntry = ref Entries![property.UniqueId - _minId];
+					GetPropertyInheritanceConfiguration(
+						property: property,
+						hasInherits: out var hasInherits,
+						hasValueInherits: out var hasValueInherits,
+						hasValueDoesNotInherit: out var hasValueDoesNotInherits
+					);
 					propertyEntry = new DependencyPropertyDetails(property, _ownerType, hasInherits, hasValueInherits, hasValueDoesNotInherits);
 					if (TryResolveDefaultValueFromProviders(property, out var value))
 					{