2X faster assignment for nullable types

jitbit · May 5, 2023 · 5aecb6c · 5aecb6c
1 parent ab0378c
commit 5aecb6c
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Showing 3 changed files with 45 additions and 9 deletions.
diff --git a/MapDataReader.Benchmarks/Program.cs b/MapDataReader.Benchmarks/Program.cs
@@ -19,9 +19,10 @@ public class Benchy
 	{
 		static TestClass _o = new TestClass();
 		static PropertyInfo _prop = _o.GetType().GetProperty("String1", BindingFlags.Public | BindingFlags.Instance);
+		static PropertyInfo _nullableprop = _o.GetType().GetProperty("IntNullable", BindingFlags.Public | BindingFlags.Instance);
 
 		[Benchmark]
-		public void SetPropReflection()
+		public void SetProp_Reflection()
 		{
 			PropertyInfo prop = _o.GetType().GetProperty("String1", BindingFlags.Public | BindingFlags.Instance);
 			if (null != prop && prop.CanWrite)
@@ -31,26 +32,38 @@ public void SetPropReflection()
 		}
 
 		[Benchmark]
-		public void SetPropReflectionCached()
+		public void SetProp_ReflectionCached()
 		{
 			_prop.SetValue(_o, "Value");
 		}
 
 		[Benchmark]
-		public void SetPropMapDataReader()
+		public void SetProp_MapDataReader()
 		{
 			_o.SetPropertyByName("String1", "Value");
 		}
-
+
+		[Benchmark]
+		public void SetNullableProp_ReflectionCached()
+		{
+			_nullableprop.SetValue(_o, 123);
+		}
+
 		[Benchmark]
-		public void MapDatareaderViaDapper()
+		public void SetNullableProp_MapDataReader()
+		{
+			_o.SetPropertyByName("IntNullable", 123);
+		}
+
+		[Benchmark]
+		public void MapDatareader_ViaDapper()
 		{
 			var dr = _dt.CreateDataReader();
 			var list = dr.Parse<TestClass>().ToList();
 		}
 
 		[Benchmark]
-		public void MapDataReaderViaMapaDataReader()
+		public void MapDataReader_ViaMapaDataReader()
 		{
 			var dr = _dt.CreateDataReader();
 			var list = dr.ToTestClass();
@@ -63,10 +76,19 @@ public static void Setup()
 		{
 			//create datatable with test data
 			_dt = new DataTable();
-			_dt.Columns.AddRange(new[] { new DataColumn("String1", typeof(string)), new DataColumn("String2", typeof(string)), new DataColumn("String3", typeof(string)), new DataColumn("Int", typeof(int)), new DataColumn("Int2", typeof(int)) });
+			_dt.Columns.AddRange(new[] {
+				new DataColumn("String1", typeof(string)),
+				new DataColumn("String2", typeof(string)),
+				new DataColumn("String3", typeof(string)),
+				new DataColumn("Int", typeof(int)),
+				new DataColumn("Int2", typeof(int)),
+				new DataColumn("IntNullable", typeof(int))
+			});
+
+
 			for (int i = 0; i < 1000; i++)
 			{
-				_dt.Rows.Add("xxx", "yyy", "zzz", 123, 321);
+				_dt.Rows.Add("xxx", "yyy", "zzz", 123, 321, 3211);
 			}
 		}
 	}
@@ -79,5 +101,6 @@ public class TestClass
 		public string String3 { get; set; }
 		public string Int { get; set; }
 		public string Int2 { get; set; }
+		public int? IntNullable { get; set; }
 	}
 }
diff --git a/MapDataReader.Tests/TestActualCode.cs b/MapDataReader.Tests/TestActualCode.cs
@@ -100,6 +100,12 @@ public void TestPrimitiveTypesAssign()
 			o.SetPropertyByName("NUllableBirthDay", dt);
 			Assert.IsTrue(o.NUllableBirthDay == dt);
 
+			//test nullable assign
+			DateTime? ndt = null;
+			ndt = new DateTime(2022, 10, 10);
+			o.SetPropertyByName("NUllableBirthDay", ndt);
+			Assert.IsTrue(o.NUllableBirthDay == ndt);
+
 			o.SetPropertyByName("GetOnly", 321); //should not throw any exception, even though this property is not settable
 
 			o.SetPropertyByName("ByeArray", new byte[3] { 1, 2, 3 });

diff --git a/MapDataReader/MapperGenerator.cs b/MapDataReader/MapperGenerator.cs
@@ -51,10 +51,17 @@ private static void SetPropertyByUpperName(this {typeNodeSymbol.FullName()} targ
 								{
 									var pTypeName = p.Type.FullName();
 
-									if (p.Type.IsReferenceType || (pTypeName.EndsWith("?") && !p.Type.IsNullableEnum())) //ref types and nullable type - just cast to property type (unless nullable Enum)
+									if (p.Type.IsReferenceType) //ref types - just cast to property type
 									{
 										return $@"	if (name == ""{p.Name.ToUpperInvariant()}"") {{ target.{p.Name} = value as {pTypeName}; return; }}";
 									}
+									else if (pTypeName.EndsWith("?") && !p.Type.IsNullableEnum()) //nullable type (unless nullable Enum)
+									{
+										var nonNullableTypeName = pTypeName.TrimEnd('?');
+
+										//do not use "as" operator becasue "as" is slow for nullable types. Use "is" and a null-check
+										return $@"	if (name == ""{p.Name.ToUpperInvariant()}"") {{ if(value==null) target.{p.Name}=null; else if(value is {nonNullableTypeName}) target.{p.Name}=({nonNullableTypeName})value; return; }}";
+									}
 									else if (p.Type.TypeKind == TypeKind.Enum || p.Type.IsNullableEnum()) //enum? pre-convert to underlying type then to int, you can't cast a boxed int to enum directly. Also to support assigning "smallint" database col to int32 (for example), which does not work at first (you can't cast a boxed "byte" to "int")
 									{
 										return $@"	if (value != null && name == ""{p.Name.ToUpperInvariant()}"") {{ target.{p.Name} = ({pTypeName})(value.GetType() == typeof(int) ? (int)value : (int)Convert.ChangeType(value, typeof(int))); return; }}"; //pre-convert enums to int first (after unboxing, see below)