PrimeOrderCalculator.PartialFactorCpu simplified to work only with spans and throw exception if the number of factors is exceeded. PrimeOrderMode removed in favor of bool flag.

PerfectNumbers.Core/ArrayPools.cs

@@ -0,0 +1,104 @@
+using System.Runtime.CompilerServices;
+
+namespace PerfectNumbers.Core
+{
+	public static class Pools
+	{
+		private const int PoolCapacity = 10240; //PerfectNumberConstants.DefaultSmallPrimeFactorSlotCount << 8;
+
+		[ThreadStatic]
+		private static IntArrayPool? _intArrayPool;
+		internal static IntArrayPool ExclusiveIntArray
+		{
+			[MethodImpl(MethodImplOptions.AggressiveInlining)]
+			get
+			{
+				return _intArrayPool ??= new(PoolCapacity);
+			}
+		}
+
+
+		[ThreadStatic]
+		private static UlongArrayPool? _ulongArrayPool;
+		internal static UlongArrayPool ExclusiveUlongArray
+		{
+			[MethodImpl(MethodImplOptions.AggressiveInlining)]
+			get
+			{
+				return _ulongArrayPool ??= new(PoolCapacity);
+			}
+		}
+	}
+
+    public struct IntArrayPool(int poolCapacity)
+	{
+        private readonly int[][] _arrays = new int[poolCapacity][];
+        private int _count = 0;
+
+		[MethodImpl(MethodImplOptions.AggressiveInlining)]
+        public int[] Rent(int length)
+        {
+            int available = _count;
+            if (available == 0)
+            {
+                return new int[length];
+            }
+
+            int[][] arrays = _arrays;
+            available--;
+            _count = available;
+
+            int[] candidate = arrays[available];
+			return candidate.Length >= length ? candidate : new int[length];
+		}
+
+		[MethodImpl(MethodImplOptions.AggressiveInlining)]
+        public void Return(int[] array)
+        {
+            int[][] arrays = _arrays;
+            int available = _count;
+
+            if (available < arrays.Length)
+            {
+				arrays[available] = array;
+				_count = available + 1;
+            }
+        }
+    }
+
+    public struct UlongArrayPool(int poolCapacity)
+	{
+        private readonly ulong[][] _arrays = new ulong[poolCapacity][];
+        private int _count = 0;
+
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        public ulong[] Rent(int length)
+        {
+            int available = _count;
+            if (available == 0)
+            {
+                return new ulong[length];
+            }
+
+            ulong[][] arrays = _arrays;
+            available--;
+            _count = available;
+
+            ulong[] candidate = arrays[available];
+			return candidate.Length >= length ? candidate : new ulong[length];
+		}
+
+		[MethodImpl(MethodImplOptions.AggressiveInlining)]
+        public void Return(ulong[] array)
+        {
+            ulong[][] arrays = _arrays;
+            int available = _count;
+
+            if (available < arrays.Length)
+            {
+				arrays[available] = array;
+				_count = available + 1;
+            }
+        }
+    }
+}