RecyclableArrayList.AddRange(IEnumerable<T>) performance improvements. ...WhenSourceIsIEnumerable benchmarks reworked to use real IEnumerable, which can't be typecasted to anything.

Recyclable.Collections.Benchmarks/ListVsLinkedListBenchmarks.cs

@@ -19,6 +19,7 @@
 
 		private RecyclableArrayList<object>? _testObjectsAsRecyclableArrayList;
 		protected RecyclableArrayList<object> TestObjectsAsRecyclableArrayList => _testObjectsAsRecyclableArrayList ??= TestObjects.ToRecyclableArrayList();
+		protected IEnumerable<object> TestObjectsAsIEnumerable = Enumerable.Range(1, TestObjectCount).Select(static x => new object());
 
 		protected static void DoNothing<T>(T obj)
 		{

Recyclable.Collections.Benchmarks/RecyclableCollectionsBenchmarks.Array.cs

@@ -25,7 +25,7 @@ namespace Recyclable.Collections.Benchmarks
 			}
 		}
 
-		[Benchmark]
+		//[Benchmark]
 		public void Array_GetItem()
 		{
 			var data = TestObjects;
@@ -36,14 +36,14 @@ namespace Recyclable.Collections.Benchmarks
 			}
 		}
 
-		[Benchmark]
+		//[Benchmark]
 		public void Array_Count()
 		{
 			var data = _testArray;
 			DoNothing(data.Length);
 		}
 
-		[Benchmark]
+		//[Benchmark]
 		public void Array_LongCount()
 		{
 			var data = _testArray;

Recyclable.Collections.Benchmarks/RecyclableCollectionsBenchmarks.List.cs

@@ -27,7 +27,7 @@ namespace Recyclable.Collections.Benchmarks
 			DoNothing(list);
 		}
 
-		[Benchmark]
+		//[Benchmark]
 		public void List_Add()
 		{
 			var data = TestObjects;
@@ -39,7 +39,7 @@ namespace Recyclable.Collections.Benchmarks
 			}
 		}
 
-		[Benchmark(Baseline = false)]
+		//[Benchmark(Baseline = false)]
 		public void List_Add_WithCapacity()
 		{
 			var data = TestObjects;
@@ -51,7 +51,7 @@ namespace Recyclable.Collections.Benchmarks
 			}
 		}
 
-		[Benchmark]
+		//[Benchmark]
 		public void List_AddRangeWhenSourceIsArray()
 		{
 			var data = TestObjects;
@@ -59,7 +59,7 @@ namespace Recyclable.Collections.Benchmarks
 			list.AddRange(data);
 		}
 
-		[Benchmark]
+		//[Benchmark]
 		public void List_AddRangeWhenSourceIsList()
 		{
 			var data = TestObjectsAsList;
@@ -67,7 +67,7 @@ namespace Recyclable.Collections.Benchmarks
 			list.AddRange(data);
 		}
 
-		[Benchmark]
+		//[Benchmark]
 		public void List_AddRangeWhenSourceIsIList()
 		{
 			var data = (IList<object>)TestObjectsAsList;
@@ -78,12 +78,12 @@ namespace Recyclable.Collections.Benchmarks
 		[Benchmark]
 		public void List_AddRangeWhenSourceIsIEnumerable()
 		{
-			var data = (IEnumerable<object>)TestObjects;
+			var data = TestObjectsAsIEnumerable;
 			var list = new List<object>();
 			list.AddRange(data);
 		}
 
-		[Benchmark(Baseline = false)]
+		//[Benchmark(Baseline = false)]
 		public void List_AddRange_WithCapacity()
 		{
 			var data = TestObjects;
@@ -92,7 +92,7 @@ namespace Recyclable.Collections.Benchmarks
 			list.AddRange(data);
 		}
 
-		[Benchmark]
+		//[Benchmark]
 		public void List_SetItem()
 		{
 			var data = TestObjectsAsList;
@@ -103,7 +103,7 @@ namespace Recyclable.Collections.Benchmarks
 			}
 		}
 
-		[Benchmark]
+		//[Benchmark]
 		public void List_GetItem()
 		{
 			var data = TestObjectsAsList;
@@ -114,7 +114,7 @@ namespace Recyclable.Collections.Benchmarks
 			}
 		}
 
-		[Benchmark]
+		//[Benchmark]
 		public void List_Count()
 		{
 			var data = _testList;

Recyclable.Collections.Benchmarks/RecyclableCollectionsBenchmarks.RecyclableArrayList.cs

@@ -44,7 +44,7 @@ namespace Recyclable.Collections.Benchmarks
 			DoNothing(list);
 		}
 
-		[Benchmark]
+		//[Benchmark]
 		public void RecyclableArrayList_Add()
 		{
 			var data = TestObjects;
@@ -56,7 +56,7 @@ namespace Recyclable.Collections.Benchmarks
 			}
 		}
 
-		[Benchmark]
+		//[Benchmark]
 		public void RecyclableArrayList_Add_WithCapacity()
 		{
 			var data = TestObjects;
@@ -68,7 +68,7 @@ namespace Recyclable.Collections.Benchmarks
 			}
 		}
 
-		[Benchmark]
+		//[Benchmark]
 		public void RecyclableArrayList_AddRangeWhenSourceIsArray()
 		{
 			var data = TestObjects;
@@ -76,7 +76,7 @@ namespace Recyclable.Collections.Benchmarks
 			list.AddRange(data);
 		}
 
-		[Benchmark]
+		//[Benchmark]
 		public void RecyclableArrayList_AddRangeWhenSourceIsList()
 		{
 			var data = TestObjectsAsList;
@@ -84,7 +84,7 @@ namespace Recyclable.Collections.Benchmarks
 			list.AddRange(data);
 		}
 
-		[Benchmark]
+		//[Benchmark]
 		public void RecyclableArrayList_AddRangeWhenSourceIsIList()
 		{
 			var data = (IList<object>)TestObjectsAsList;
@@ -95,12 +95,12 @@ namespace Recyclable.Collections.Benchmarks
 		[Benchmark]
 		public void RecyclableArrayList_AddRangeWhenSourceIsIEnumerable()
 		{
-			var data = (IEnumerable<object>)TestObjects;
+			var data = TestObjectsAsIEnumerable;
 			using var list = new RecyclableArrayList<object>();
 			list.AddRange(data);
 		}
 
-		[Benchmark]
+		//[Benchmark]
 		public void RecyclableArrayList_AddRangeWhenSourceIsRecyclableArrayList()
 		{
 			var data = TestObjectsAsRecyclableArrayList;
@@ -108,7 +108,7 @@ namespace Recyclable.Collections.Benchmarks
 			list.AddRange(data);
 		}
 
-		[Benchmark]
+		//[Benchmark]
 		public void RecyclableArrayList_AddRange_WithCapacity()
 		{
 			var data = TestObjects;
@@ -117,7 +117,7 @@ namespace Recyclable.Collections.Benchmarks
 			list.AddRange(data);
 		}
 
-		[Benchmark]
+		//[Benchmark]
 		public void RecyclableArrayList_SetItem()
 		{
 			var data = TestObjectsAsRecyclableArrayList;
@@ -128,7 +128,7 @@ namespace Recyclable.Collections.Benchmarks
 			}
 		}
 
-		[Benchmark]
+		//[Benchmark]
 		public void RecyclableArrayList_GetItem()
 		{
 			var data = TestObjectsAsRecyclableArrayList;
@@ -139,7 +139,7 @@ namespace Recyclable.Collections.Benchmarks
 			}
 		}
 
-		[Benchmark]
+		//[Benchmark]
 		public void RecyclableArrayList_Count()
 		{
 			var data = _testRecyclableArrayList;

Recyclable.Collections/RecyclableArrayList.cs

@@ -153,7 +153,7 @@ namespace Recyclable.Collections
 
 		public bool IsReadOnly { get; } = false;
 
-		[MethodImpl(MethodImplOptions.AggressiveInlining)]
+		//[MethodImpl(MethodImplOptions.AggressiveInlining)]
 		public void Add(T item)
 		{
 			int requestedCapacity = _count + 1;
@@ -221,19 +221,90 @@ namespace Recyclable.Collections
 			_count = targetCapacity;
 		}
 
-		public void AddRange(IEnumerable<T> source, int growByCount = 100)
+		public void AddRange(IEnumerable<T> source, int growByCount = RecyclableDefaults.MinPooledArrayLength)
 		{
-			ref int capacity = ref _capacity;
-			ref int count = ref _count;
-			foreach (var item in source)
+			if (source is T[] sourceArray)
 			{
-				if (capacity == count)
+				AddRange(sourceArray);
+				return;
+			}
+
+			if (source is List<T> sourceList)
+			{
+				AddRange(sourceList);
+				return;
+			}
+
+			if (source is RecyclableArrayList<T> sourceRecyclableArrayList)
+			{
+				AddRange(sourceRecyclableArrayList);
+				return;
+			}
+
+			if (source is IList<T> sourceIList)
+			{
+				AddRange(sourceIList);
+				return;
+			}
+
+			int capacity = _capacity;
+			int targetIndex = _count;
+			Span<T> memorySpan;
+			if (source.TryGetNonEnumeratedCount(out var requiredAdditionalCapacity))
+			{
+				_ = EnsureCapacity(targetIndex + requiredAdditionalCapacity);
+				memorySpan = new(_memory);
+				foreach (var item in source)
 				{
-					_ = EnsureCapacity(capacity * growByCount);
+					memorySpan[targetIndex++] = item;
 				}
 
-				Add(item);
+				_count = targetIndex;
+				return;
 			}
+
+			int i;
+			using var enumerator = source.GetEnumerator();
+
+			memorySpan = new(_memory);
+			if (enumerator.MoveNext())
+			{
+				int available = capacity - targetIndex;
+				while (true)
+				{
+					if (targetIndex + growByCount > capacity)
+					{
+						capacity = EnsureCapacity(capacity + growByCount);
+						memorySpan = new(_memory);
+						available = capacity - targetIndex;
+					}
+
+					for (i = 0; i < available; i++)
+					{
+						memorySpan[targetIndex++] = enumerator.Current;
+						if (!enumerator.MoveNext())
+						{
+							break;
+						}
+					}
+
+					if (i < available)
+					{
+						break;
+					}
+				}
+			}
+
+			_count = targetIndex;
+
+			//foreach (var item in source)
+			//{
+			//	if (capacity == count)
+			//	{
+			//	}
+
+			//	Add(item);
+			//}
 		}
 
 		public void Clear()

Recyclable.Collections/RecyclableListExtensions.cs

@@ -5,7 +5,7 @@ namespace Recyclable.Collections
 {
 	public static class RecyclableListExtensions
 	{
-		private const int _minPooledArraySize = 100;
+		private const int _minPooledArraySize = RecyclableDefaults.MinPooledArrayLength;
 
 		public static void CopyItems<T>(this T[] memory, long startingIndex, long count, ref T[] destArray, long offset = 1)
 		{

Recyclable.CollectionsTests/RecyclableArrayListTests.cs

@@ -62,6 +62,22 @@ namespace Recyclable.CollectionsTests
 				.And.BeEquivalentTo(testData);
 		}
 
+		[Fact]
+		public void ConstructorShouldAddItemsInCorrectOrderWhenSourceIsIEnumerable()
+		{
+			// Prepare
+			var testData = _testData;
+
+			// Act
+			var list = new RecyclableArrayList<int>(testData);
+
+			// Validate
+			_ = list.Capacity.Should().Be(32, "when we succeed in taking count without enumerating, then we allocate as much memory as needed, only");
+			_ = list.Should().HaveCount(testData.Count())
+				.And.ContainInConsecutiveOrder(testData)
+				.And.BeEquivalentTo(testData);
+		}
+
 		[Fact]
 		public void InsertAtTheBeginningShouldMoveItems()
 		{