PendingEntry renamed to PartialFactorPendingEntry and moved to its own file. PrimeOrderCalculator.PartialFactor partially optimized to use fixed buffers factors & exponents.

PerfectNumbers.Core/PartialFactorPendingEntry.cs

@@ -0,0 +1,50 @@
+using System.Runtime.CompilerServices;
+
+namespace PerfectNumbers.Core;
+
+internal sealed class PartialFactorPendingEntry(ulong value, bool knownComposite)
+{
+	[ThreadStatic]
+	private static PartialFactorPendingEntry? _poolHead;
+	private PartialFactorPendingEntry? _next;
+
+	[MethodImpl(MethodImplOptions.AggressiveInlining | MethodImplOptions.AggressiveOptimization)]
+	public static PartialFactorPendingEntry Rent(ulong value, bool knownComposite)
+	{
+		var poolHead = _poolHead;
+		if (poolHead == null)
+		{
+			return new(value, knownComposite);
+		}
+
+		_poolHead = poolHead._next;
+		poolHead.Value = value;
+		poolHead.KnownComposite = knownComposite;
+		poolHead.HasKnownPrimality = knownComposite;
+		poolHead.IsPrime = false;
+		return poolHead;
+	}
+
+	[MethodImpl(MethodImplOptions.AggressiveInlining | MethodImplOptions.AggressiveOptimization)]
+	public static void Return(PartialFactorPendingEntry entry)
+	{
+		entry._next = _poolHead;
+		_poolHead = entry;
+	}
+
+	public ulong Value = value;
+	public bool KnownComposite = knownComposite;
+	public bool HasKnownPrimality = knownComposite;
+	public bool IsPrime = false;
+
+	[MethodImpl(MethodImplOptions.AggressiveInlining | MethodImplOptions.AggressiveOptimization)]
+	public void WithPrimality(bool isPrime)
+	{
+		KnownComposite = KnownComposite || !isPrime;
+		HasKnownPrimality = true;
+		IsPrime = isPrime;
+	}
+}
+
+
+

PerfectNumbers.Core/PartialFactorResult.cs

@@ -1,4 +1,4 @@
-using System.Numerics;
+using PerfectNumbers.Core.Gpu;
 
 namespace PerfectNumbers.Core
 {
@@ -7,8 +7,8 @@ namespace PerfectNumbers.Core
 		[ThreadStatic]
 		private static PartialFactorResult? s_poolHead;
 
-		public ulong[]? Factors;
-		public int[]? Exponents;
+		public readonly ulong[] Factors = new ulong[PrimeOrderConstants.GpuSmallPrimeFactorSlots];
+		public readonly int[] Exponents = new int[PrimeOrderConstants.GpuSmallPrimeFactorSlots];
 		private PartialFactorResult? _next;
 		public ulong Cofactor;
 		public bool FullyFactored;
@@ -19,7 +19,7 @@ namespace PerfectNumbers.Core
 		{
 		}
 
-		public static PartialFactorResult Rent(in ulong[]? factors, in int[]? exponents, ulong cofactor, bool fullyFactored, int count, bool cofactorIsPrime)
+		public static PartialFactorResult Rent()
 		{
 			PartialFactorResult? instance = s_poolHead;
 			if (instance is null)
@@ -32,34 +32,10 @@ namespace PerfectNumbers.Core
 			}
 
 			instance._next = null;
-			instance.Factors = factors;
-			instance.Exponents = exponents;
-			instance.Cofactor = cofactor;
-			instance.FullyFactored = fullyFactored;
-			instance.Count = count;
-			instance.CofactorIsPrime = cofactorIsPrime;
-			return instance;
-		}
-
-		public static PartialFactorResult Rent(ulong cofactor, bool fullyFactored, int count, bool cofactorIsPrime)
-		{
-			PartialFactorResult? instance = s_poolHead;
-			if (instance is null)
-			{
-				instance = new PartialFactorResult();
-			}
-			else
-			{
-				s_poolHead = instance._next;
-			}
-
-			instance._next = null;
-			instance.Factors = null;
-			instance.Exponents = null;
-			instance.Cofactor = cofactor;
-			instance.FullyFactored = fullyFactored;
-			instance.Count = count;
-			instance.CofactorIsPrime = cofactorIsPrime;
+			instance.Cofactor = 0UL;
+			instance.FullyFactored = false;
+			instance.Count = 0;
+			instance.CofactorIsPrime = false;
 			return instance;
 		}
 
@@ -73,59 +49,29 @@ namespace PerfectNumbers.Core
 		{
 			ulong[]? sourceFactors = Factors;
 			int sourceCount = Count;
-			if (sourceFactors is null || sourceCount == 0)
+			if (sourceCount == 0)
 			{
 				InitializeWithPrime(prime);
 				return;
 			}
 
-			int newSize = (int)BitOperations.RoundUpToPowerOf2((uint)sourceCount + 1U);
-			ulong[] extendedFactors = sourceFactors.Length >= newSize
-				? sourceFactors
-				: ResizeFactors(sourceFactors, sourceCount, newSize);
-
 			int[] sourceExponents = Exponents!;
-			int[] extendedExponents = sourceExponents.Length >= newSize
-				? sourceExponents
-				: ResizeExponents(sourceCount, newSize, sourceExponents);
 
-			newSize = sourceCount + 1;
-			extendedFactors[sourceCount] = prime;
-			extendedExponents[sourceCount] = 1;
-			Array.Sort(extendedFactors, extendedExponents, 0, newSize);
+			int newSize = sourceCount + 1;
+			sourceFactors[sourceCount] = prime;
+			sourceExponents[sourceCount] = 1;
+			Array.Sort(sourceFactors, sourceExponents, 0, newSize);
 
-			Factors = extendedFactors;
-			Exponents = extendedExponents;
 			Cofactor = 1UL;
 			FullyFactored = true;
 			Count = newSize;
 			CofactorIsPrime = false;
 		}
 
-		private static int[] ResizeExponents(int sourceCount, int newSize, in int[] sourceExponents)
-		{
-			int[] extendedExponents = FixedCapacityPools.ExclusiveIntArray.Rent(newSize);
-			Array.Copy(sourceExponents, 0, extendedExponents, 0, sourceCount);
-			FixedCapacityPools.ExclusiveIntArray.Return(sourceExponents);
-			return extendedExponents;
-		}
-
-		private static ulong[] ResizeFactors(in ulong[] sourceFactors, int sourceCount, int newSize)
-		{
-			ulong[] extendedFactors = FixedCapacityPools.ExclusiveUlongArray.Rent(newSize);
-			Array.Copy(sourceFactors, 0, extendedFactors, 0, sourceCount);
-			FixedCapacityPools.ExclusiveUlongArray.Return(sourceFactors);
-			return extendedFactors;
-		}
-
 		private void InitializeWithPrime(ulong prime)
 		{
-			ulong[] factors = FixedCapacityPools.ExclusiveUlongArray.Rent(1);
-			int[] exponents = FixedCapacityPools.ExclusiveIntArray.Rent(1);
-			factors[0] = prime;
-			exponents[0] = 1;
-			Factors = factors;
-			Exponents = exponents;
+			Factors[0] = prime;
+			Exponents[0] = 1;
 			Cofactor = 1UL;
 			FullyFactored = true;
 			Count = 1;
@@ -136,19 +82,6 @@ namespace PerfectNumbers.Core
 		{
 			if (this != Empty)
 			{
-
-				ulong[]? factors = Factors;
-
-				if (factors is not null)
-				{
-					int[] exponents = Exponents!;
-					Factors = null;
-					Exponents = null;
-
-					FixedCapacityPools.ExclusiveUlongArray.Return(factors);
-					FixedCapacityPools.ExclusiveIntArray.Return(exponents);
-				}
-
 				_next = s_poolHead;
 				s_poolHead = this;
 			}

PerfectNumbers.Core/PrimeOrderCalculator.Cpu.cs

@@ -10,50 +10,6 @@ namespace PerfectNumbers.Core;
 
 internal static partial class PrimeOrderCalculator
 {
-	internal sealed class PendingEntry(ulong value, bool knownComposite)
-	{
-		[ThreadStatic]
-		private static PendingEntry? _poolHead;
-		private PendingEntry? _next;
-
-		[MethodImpl(MethodImplOptions.AggressiveInlining | MethodImplOptions.AggressiveOptimization)]
-		public static PendingEntry Rent(ulong value, bool knownComposite)
-		{
-			var poolHead = _poolHead;
-			if (poolHead == null)
-			{
-				return new(value, knownComposite);
-			}
-
-			_poolHead = poolHead._next;
-			poolHead.Value = value;
-			poolHead.KnownComposite = knownComposite;
-			poolHead.HasKnownPrimality = knownComposite;
-			poolHead.IsPrime = false;
-			return poolHead;
-		}
-
-		[MethodImpl(MethodImplOptions.AggressiveInlining | MethodImplOptions.AggressiveOptimization)]
-		public static void Return(PendingEntry entry)
-		{
-			entry._next = _poolHead;
-			_poolHead = entry;
-		}
-
-		public ulong Value = value;
-		public bool KnownComposite = knownComposite;
-		public bool HasKnownPrimality = knownComposite;
-		public bool IsPrime = false;
-
-		[MethodImpl(MethodImplOptions.AggressiveInlining | MethodImplOptions.AggressiveOptimization)]
-		public void WithPrimality(bool isPrime)
-		{
-			KnownComposite = KnownComposite || !isPrime;
-			HasKnownPrimality = true;
-			IsPrime = isPrime;
-		}
-	}
-
 	public static ulong CalculateCpu(
 		ulong prime,
 		ulong? previousOrder,
@@ -575,10 +531,10 @@ internal static partial class PrimeOrderCalculator
 	[MethodImpl(MethodImplOptions.AggressiveInlining | MethodImplOptions.AggressiveOptimization)]
 	private static ulong ExponentLoweringCpu(ulong order, ulong prime, PartialFactorResult factors, in MontgomeryDivisorData divisorData)
 	{
-		ReadOnlySpan<ulong> factorSpan = factors.Factors;
-		ReadOnlySpan<int> exponentsSpan = factors.Exponents;
-
 		int length = factors.Count;
+		ReadOnlySpan<ulong> factorSpan = factors.Factors.AsSpan(0, length);
+		ReadOnlySpan<int> exponentsSpan = factors.Exponents.AsSpan(0, length);
+
 		int newLength = length + 1;
 		ulong[] tempFactorsArray = FixedCapacityPools.ExclusiveUlongArray.Rent(newLength);
 		int[] tempExponentsArray = FixedCapacityPools.ExclusiveIntArray.Rent(newLength);
@@ -1343,14 +1299,18 @@ internal static partial class PrimeOrderCalculator
 		}
 
 		// stackalloc is faster than pooling
-		Span<ulong> primeSlots = stackalloc ulong[PrimeOrderConstants.GpuSmallPrimeFactorSlots];
-		Span<int> exponentSlots = stackalloc int[PrimeOrderConstants.GpuSmallPrimeFactorSlots];
+
+		var result = PartialFactorResult.Rent();
+		ulong[] factors = result.Factors;
+		Span<ulong> primeSlots = new(factors);
+		int[] exponents = result.Exponents;
+		Span<int> exponentSlots = new(exponents);
 
 		// We don't need to worry about leftovers, because we always use indexes within the calculated counts
 		// primeSlots.Clear();
 		// exponentSlots.Clear();
 
-		List<PendingEntry> pending = ThreadStaticPools.RentPrimeOrderPendingEntryList(PrimeOrderConstants.GpuSmallPrimeFactorSlots);
+		List<PartialFactorPendingEntry> pending = ThreadStaticPools.RentPrimeOrderPendingEntryList(PrimeOrderConstants.GpuSmallPrimeFactorSlots);
 
 		PopulateSmallPrimeFactorsCpu(
 			value,
@@ -1360,7 +1320,6 @@ internal static partial class PrimeOrderCalculator
 			out int factorCount,
 			out ulong remaining);
 
-		bool limitReached;
 		if (remaining > 1UL)
 		{
 			if (config.PollardRhoMilliseconds > 0)
@@ -1369,13 +1328,13 @@ internal static partial class PrimeOrderCalculator
 				FixedCapacityStack<ulong> compositeStack = ThreadStaticPools.RentUlongStack(PrimeOrderConstants.GpuSmallPrimeFactorSlots);
 				compositeStack.Push(remaining);
 
-				CollectFactorsCpu(primeSlots, exponentSlots, ref factorCount, pending, compositeStack, deadlineTimestamp, out limitReached);
+				CollectFactorsCpu(primeSlots, exponentSlots, ref factorCount, pending, compositeStack, deadlineTimestamp, out bool limitReached);
 
 				if (limitReached)
 				{
 					while (compositeStack.Count > 0)
 					{
-						pending.Add(PendingEntry.Rent(compositeStack.Pop(), knownComposite: false));
+						pending.Add(PartialFactorPendingEntry.Rent(compositeStack.Pop(), knownComposite: false));
 					}
 				}
 
@@ -1384,7 +1343,7 @@ internal static partial class PrimeOrderCalculator
 			}
 			else
 			{
-				pending.Add(PendingEntry.Rent(remaining, knownComposite: false));
+				pending.Add(PartialFactorPendingEntry.Rent(remaining, knownComposite: false));
 			}
 		}
 
@@ -1399,14 +1358,14 @@ internal static partial class PrimeOrderCalculator
 
 		for (; index < pendingCount; index++)
 		{
-			PendingEntry entry = pending[index];
+			PartialFactorPendingEntry entry = pending[index];
 			ulong composite = entry.Value;
 
 			if (entry.KnownComposite)
 			{
 				cofactor = checked(cofactor * composite);
 				cofactorContainsComposite = true;
-				PendingEntry.Return(entry);
+				PartialFactorPendingEntry.Return(entry);
 				continue;
 			}
 
@@ -1429,7 +1388,7 @@ internal static partial class PrimeOrderCalculator
 				cofactorContainsComposite = true;
 			}
 
-			PendingEntry.Return(entry);
+			PartialFactorPendingEntry.Return(entry);
 		}
 
 		bool cofactorIsPrime;
@@ -1446,19 +1405,6 @@ internal static partial class PrimeOrderCalculator
 			cofactorIsPrime = PrimeTesterByLastDigit.IsPrimeCpu(cofactor);
 		}
 
-		PartialFactorResult result;
-		if (factorCount == 0)
-		{
-			if (cofactor == value)
-			{
-				result = PartialFactorResult.Rent(cofactor, false, 0, cofactorIsPrime);
-				goto ReturnResult;
-			}
-
-			result = PartialFactorResult.Rent(cofactor, cofactor == 1UL, 0, cofactorIsPrime);
-			goto ReturnResult;
-		}
-
 		// This will never happen in production code. We'll always get at least 1 factor
 		// if (factorCount == 0)
 		// {
@@ -1472,37 +1418,22 @@ internal static partial class PrimeOrderCalculator
 		// 	goto ReturnResult;
 		// }
 
-		ulong[] factorsArray = FixedCapacityPools.ExclusiveUlongArray.Rent(factorCount);
-		int[] exponentsArray = FixedCapacityPools.ExclusiveIntArray.Rent(factorCount);
-
-		for (int i = 0; i < factorCount; i++)
-		{
-			factorsArray[i] = primeSlots[i];
-			exponentsArray[i] = exponentSlots[i];
-
-			// This will never happen on the execution path from production code
-			// if (primeValue == 0UL || exponentValue == 0)
-			// {
-			// 	throw new Exception("Prime value or exponent equals zero");
-			// 	continue;
-			// }
-		}
-
-		Array.Sort(factorsArray, exponentsArray, 0, factorCount);
+		Array.Sort(factors, exponents, 0, factorCount);
 
 		// Check if it was it factored completely
-		limitReached = cofactor == 1UL;
 
-		result = PartialFactorResult.Rent(factorsArray, exponentsArray, cofactor, limitReached, factorCount, cofactorIsPrime);
+		result.Cofactor = cofactor;
+		result.FullyFactored = cofactor == 1UL;
+		result.Count = factorCount;
+		result.CofactorIsPrime = cofactorIsPrime;
 
-	ReturnResult:
 		pending.Clear();
 		ThreadStaticPools.ReturnPrimeOrderPendingEntryList(pending);
 		return result;
 	}
 
 	[MethodImpl(MethodImplOptions.AggressiveOptimization)]
-	private static void CollectFactorsCpu(Span<ulong> primeSlots, Span<int> exponentSlots, ref int factorCount, List<PendingEntry> pending, FixedCapacityStack<ulong> compositeStack, long deadlineTimestamp, out bool pollardRhoDeadlineReached)
+	private static void CollectFactorsCpu(Span<ulong> primeSlots, Span<int> exponentSlots, ref int factorCount, List<PartialFactorPendingEntry> pending, FixedCapacityStack<ulong> compositeStack, long deadlineTimestamp, out bool pollardRhoDeadlineReached)
 	{
 		while (compositeStack.Count > 0)
 		{
@@ -1518,13 +1449,13 @@ internal static partial class PrimeOrderCalculator
 			pollardRhoDeadlineReached = Stopwatch.GetTimestamp() > deadlineTimestamp;
 			if (pollardRhoDeadlineReached)
 			{
-				pending.Add(PendingEntry.Rent(composite, knownComposite: true));
+				pending.Add(PartialFactorPendingEntry.Rent(composite, knownComposite: true));
 				continue;
 			}
 
 			if (!TryPollardRhoCpu(composite, deadlineTimestamp, out ulong factor))
 			{
-				pending.Add(PendingEntry.Rent(composite, knownComposite: true));
+				pending.Add(PartialFactorPendingEntry.Rent(composite, knownComposite: true));
 				continue;
 			}
 

PerfectNumbers.Core/PrimeOrderCalculator.Gpu.cs

@@ -161,7 +161,7 @@ internal static partial class PrimeOrderCalculator
     }
 
 	[MethodImpl(MethodImplOptions.AggressiveOptimization)]
-	private static void CollectFactorsGpu(PrimeOrderCalculatorAccelerator gpu, ref Span<ulong> primeSlots, ref Span<int> exponentSlots, ref ulong[] primeSlotArray, ref int[] exponentSlotArray, ref int factorCount, List<PendingEntry> pending, Stack<ulong> compositeStack, long deadlineTimestamp, ref bool pollardRhoDeadlineReached)
+	private static void CollectFactorsGpu(PrimeOrderCalculatorAccelerator gpu, ref Span<ulong> primeSlots, ref Span<int> exponentSlots, ref ulong[] primeSlotArray, ref int[] exponentSlotArray, ref int factorCount, List<PartialFactorPendingEntry> pending, Stack<ulong> compositeStack, long deadlineTimestamp, ref bool pollardRhoDeadlineReached)
 	{
 		while (compositeStack.Count > 0)
 		{
@@ -178,14 +178,14 @@ internal static partial class PrimeOrderCalculator
 			if (currentTimestamp > deadlineTimestamp)
 			{
 				pollardRhoDeadlineReached = true;
-				pending.Add(new PendingEntry(composite, knownComposite: true));
+				pending.Add(new PartialFactorPendingEntry(composite, knownComposite: true));
 				continue;
 			}
 
 			// if (!TryPollardRhoGpu(gpu, composite, out ulong factor))
 			if (!TryPollardRhoCpu(composite, deadlineTimestamp, out ulong factor))
 			{
-				pending.Add(new PendingEntry(composite, knownComposite: true));
+				pending.Add(new PartialFactorPendingEntry(composite, knownComposite: true));
 				continue;
 			}
 
@@ -345,10 +345,11 @@ internal static partial class PrimeOrderCalculator
 		}
 
 		// stackalloc is faster than pooling
-		Span<ulong> primeSlots = stackalloc ulong[PrimeOrderConstants.GpuSmallPrimeFactorSlots];
-		Span<int> exponentSlots = stackalloc int[PrimeOrderConstants.GpuSmallPrimeFactorSlots];
-		ulong[] primeSlotArray = [];
-		int[] exponentSlotArray = [];
+		var result = PartialFactorResult.Rent();
+		ulong[] factors = result.Factors;
+		Span<ulong> primeSlots = new (factors);
+		int[] exponents = result.Exponents;
+		Span<int> exponentSlots = new (exponents);
 		// We don't need to worry about leftovers, because we always use indexes within the calculated counts
 		// primeSlots.Clear();
 		// exponentSlots.Clear();
@@ -358,7 +359,7 @@ internal static partial class PrimeOrderCalculator
 
 		bool gpuFactored = PrimeOrderGpuHeuristics.TryPartialFactor(gpu, value, limit, primeSlots, exponentSlots, out int factorCount, out remaining);
 
-		List<PendingEntry> pending = ThreadStaticPools.RentPrimeOrderPendingEntryList(2);
+		List<PartialFactorPendingEntry> pending = ThreadStaticPools.RentPrimeOrderPendingEntryList(2);
 
 		if (!gpuFactored)
 		{
@@ -386,7 +387,7 @@ internal static partial class PrimeOrderCalculator
 				{
 					while (compositeStack.Count > 0)
 					{
-						pending.Add(new PendingEntry(compositeStack.Pop(), knownComposite: false));
+						pending.Add(new PartialFactorPendingEntry(compositeStack.Pop(), knownComposite: false));
 					}
 				}
 
@@ -395,7 +396,7 @@ internal static partial class PrimeOrderCalculator
 			}
 			else
 			{
-				pending.Add(new PendingEntry(remaining, knownComposite: false));
+				pending.Add(new PartialFactorPendingEntry(remaining, knownComposite: false));
 			}
 		}
 
@@ -405,7 +406,7 @@ internal static partial class PrimeOrderCalculator
 		int index = 0;
 		for (; index < pendingCount; index++)
 		{
-			PendingEntry entry = pending[index];
+			PartialFactorPendingEntry entry = pending[index];
 			ulong composite = entry.Value;
 
 			if (entry.KnownComposite)
@@ -450,19 +451,6 @@ internal static partial class PrimeOrderCalculator
 			cofactorIsPrime = PrimeTesterByLastDigit.IsPrimeCpu(cofactor);
 		}
 
-		PartialFactorResult result;
-		if (factorCount == 0)
-		{
-			if (cofactor == value)
-			{
-				result = PartialFactorResult.Rent(cofactor, false, 0, cofactorIsPrime);
-				goto ReturnResult;
-			}
-
-			result = PartialFactorResult.Rent(cofactor, cofactor == 1UL, 0, cofactorIsPrime);
-			goto ReturnResult;
-		}
-
 		// This will never happen in production code. We'll always get at least 1 factor
 		// if (factorCount == 0)
 		// {
@@ -476,38 +464,13 @@ internal static partial class PrimeOrderCalculator
 		// 	goto ReturnResult;
 		// }
 
-		ArrayPool<ulong> ulongPool = ThreadStaticPools.UlongPool;
-		ArrayPool<int> intPool = ThreadStaticPools.IntPool;
-
-		ulong[] factorsArray = ulongPool.Rent(factorCount);
-		int[] exponentsArray = intPool.Rent(factorCount);
-
-		for (int i = 0; i < factorCount; i++)
-		{
-			factorsArray[i] = primeSlots[i];
-			exponentsArray[i] = exponentSlots[i];
-
-			// This will never happen on the execution path from production code
-			// if (primeValue == 0UL || exponentValue == 0)
-			// {
-			// 	throw new Exception("Prime value or exponent equals zero");
-			// 	continue;
-			// }
-		}
-
-		Array.Sort(factorsArray, exponentsArray, 0, factorCount);
+		Array.Sort(factors, exponents, 0, factorCount);
 
 		// Check if it was factored completely
-		limitReached = cofactor == 1UL;
-
-		result = PartialFactorResult.Rent(factorsArray, exponentsArray, cofactor, limitReached, factorCount, cofactorIsPrime);
-
-	ReturnResult:
-		if (primeSlotArray.Length > 0)
-		{
-			ThreadStaticPools.UlongPool.Return(primeSlotArray, clearArray: false);
-			ThreadStaticPools.IntPool.Return(exponentSlotArray!, clearArray: false);
-		}
+		result.Cofactor = cofactor;
+		result.FullyFactored = cofactor == 1UL;
+		result.Count = factorCount;
+		result.CofactorIsPrime = cofactorIsPrime;
 
 		pending.Clear();
 		ThreadStaticPools.ReturnPrimeOrderPendingEntryList(pending);

PerfectNumbers.Core/PrimeOrderCalculator.Hybrid.cs

@@ -83,7 +83,7 @@ internal static partial class PrimeOrderCalculator
 	}
 
 	[MethodImpl(MethodImplOptions.AggressiveOptimization)]
-	private static void CollectFactorsHybrid(PrimeOrderCalculatorAccelerator gpu, Span<ulong> primeSlots, Span<int> exponentSlots, ref int factorCount, List<PendingEntry> pending, FixedCapacityStack<ulong> compositeStack, long deadlineTimestamp, out bool pollardRhoDeadlineReached)
+	private static void CollectFactorsHybrid(PrimeOrderCalculatorAccelerator gpu, Span<ulong> primeSlots, Span<int> exponentSlots, ref int factorCount, List<PartialFactorPendingEntry> pending, FixedCapacityStack<ulong> compositeStack, long deadlineTimestamp, out bool pollardRhoDeadlineReached)
 	{
 		while (compositeStack.Count > 0)
 		{
@@ -99,13 +99,13 @@ internal static partial class PrimeOrderCalculator
 			pollardRhoDeadlineReached = Stopwatch.GetTimestamp() > deadlineTimestamp;
 			if (pollardRhoDeadlineReached)
 			{
-				pending.Add(new PendingEntry(composite, knownComposite: true));
+				pending.Add(new PartialFactorPendingEntry(composite, knownComposite: true));
 				continue;
 			}
 
 			if (!TryPollardRhoCpu(composite, deadlineTimestamp, out ulong factor))
 			{
-				pending.Add(new PendingEntry(composite, knownComposite: true));
+				pending.Add(new PartialFactorPendingEntry(composite, knownComposite: true));
 				continue;
 			}
 
@@ -142,18 +142,19 @@ internal static partial class PrimeOrderCalculator
 		}
 
 		// stackalloc is faster than pooling
-		Span<ulong> primeSlots = stackalloc ulong[PrimeOrderConstants.GpuSmallPrimeFactorSlots];
-		Span<int> exponentSlots = stackalloc int[PrimeOrderConstants.GpuSmallPrimeFactorSlots];
-		ulong[] primeSlotArray = [];
-		int[] exponentSlotArray = [];
+
+		var result = PartialFactorResult.Rent();
+		ulong[] factors = result.Factors;
+		Span<ulong> primeSlots = new(factors);
+		int[] exponents = result.Exponents;
+		Span<int> exponentSlots = new(exponents);
 		// We don't need to worry about leftovers, because we always use indexes within the calculated counts
 		// primeSlots.Clear();
 		// exponentSlots.Clear();
 
 		uint limit = config.SmallFactorLimit == 0 ? uint.MaxValue : config.SmallFactorLimit;
-		ulong remaining = value;
 
-		List<PendingEntry> pending = ThreadStaticPools.RentPrimeOrderPendingEntryList(2);
+		List<PartialFactorPendingEntry> pending = ThreadStaticPools.RentPrimeOrderPendingEntryList(2);
 
 		PopulateSmallPrimeFactorsCpu(
 			value,
@@ -161,7 +162,7 @@ internal static partial class PrimeOrderCalculator
 			primeSlots,
 			exponentSlots,
 			out int factorCount,
-			out remaining);
+			out ulong remaining);
 
 		bool limitReached;
 		if (remaining > 1UL)
@@ -178,7 +179,7 @@ internal static partial class PrimeOrderCalculator
 				{
 					while (compositeStack.Count > 0)
 					{
-						pending.Add(new PendingEntry(compositeStack.Pop(), knownComposite: false));
+						pending.Add(new PartialFactorPendingEntry(compositeStack.Pop(), knownComposite: false));
 					}
 				}
 
@@ -187,7 +188,7 @@ internal static partial class PrimeOrderCalculator
 			}
 			else
 			{
-				pending.Add(new PendingEntry(remaining, knownComposite: false));
+				pending.Add(new PartialFactorPendingEntry(remaining, knownComposite: false));
 			}
 		}
 
@@ -197,7 +198,7 @@ internal static partial class PrimeOrderCalculator
 		int index = 0;
 		for (; index < pendingCount; index++)
 		{
-			PendingEntry entry = pending[index];
+			PartialFactorPendingEntry entry = pending[index];
 			ulong composite = entry.Value;
 
 			if (entry.KnownComposite)
@@ -242,19 +243,6 @@ internal static partial class PrimeOrderCalculator
 			cofactorIsPrime = RunOnCpu() ? PrimeTesterByLastDigit.IsPrimeCpu(cofactor) : HeuristicCombinedPrimeTester.IsPrimeGpu(gpu, cofactor);
 		}
 
-		PartialFactorResult result;
-		if (factorCount == 0)
-		{
-			if (cofactor == value)
-			{
-				result = PartialFactorResult.Rent(cofactor, false, 0, cofactorIsPrime);
-				goto ReturnResult;
-			}
-
-			result = PartialFactorResult.Rent(cofactor, cofactor == 1UL, 0, cofactorIsPrime);
-			goto ReturnResult;
-		}
-
 		// This will never happen in production code. We'll always get at least 1 factor
 		// if (factorCount == 0)
 		// {
@@ -268,38 +256,12 @@ internal static partial class PrimeOrderCalculator
 		// 	goto ReturnResult;
 		// }
 
-		ArrayPool<ulong> ulongPool = ThreadStaticPools.UlongPool;
-		ArrayPool<int> intPool = ThreadStaticPools.IntPool;
+		Array.Sort(factors, exponents, 0, factorCount);
 
-		ulong[] factorsArray = ulongPool.Rent(factorCount);
-		int[] exponentsArray = intPool.Rent(factorCount);
-
-		for (int i = 0; i < factorCount; i++)
-		{
-			factorsArray[i] = primeSlots[i];
-			exponentsArray[i] = exponentSlots[i];
-
-			// This will never happen on the execution path from production code
-			// if (primeValue == 0UL || exponentValue == 0)
-			// {
-			// 	throw new Exception("Prime value or exponent equals zero");
-			// 	continue;
-			// }
-		}
-
-		Array.Sort(factorsArray, exponentsArray, 0, factorCount);
-
-		// Check if it was factored completely
-		limitReached = cofactor == 1UL;
-
-		result = PartialFactorResult.Rent(factorsArray, exponentsArray, cofactor, limitReached, factorCount, cofactorIsPrime);
-
-	ReturnResult:
-		if (primeSlotArray.Length > 0)
-		{
-			ThreadStaticPools.UlongPool.Return(primeSlotArray, clearArray: false);
-			ThreadStaticPools.IntPool.Return(exponentSlotArray!, clearArray: false);
-		}
+		result.Cofactor = cofactor;
+		result.FullyFactored = cofactor == 1UL;
+		result.Count = factorCount;
+		result.CofactorIsPrime = cofactorIsPrime;
 
 		pending.Clear();
 		ThreadStaticPools.ReturnPrimeOrderPendingEntryList(pending);

PerfectNumbers.Core/ThreadStaticPools.cs

@@ -263,12 +263,12 @@ namespace PerfectNumbers.Core
 		public static void Return((ulong, ulong)[] array) => _ulongUlongTupleArrayPool!.Return(array, clearArray: false);
 
 		[ThreadStatic]
-		private static FixedCapacityStack<List<PrimeOrderCalculator.PendingEntry>>? _primeOrderPendingEntryListPool;
+		private static FixedCapacityStack<List<PartialFactorPendingEntry>>? _primeOrderPendingEntryListPool;
 
 		[MethodImpl(MethodImplOptions.AggressiveInlining | MethodImplOptions.AggressiveOptimization)]
-		internal static List<PrimeOrderCalculator.PendingEntry> RentPrimeOrderPendingEntryList(int capacityHint)
+		internal static List<PartialFactorPendingEntry> RentPrimeOrderPendingEntryList(int capacityHint)
 		{
-			FixedCapacityStack<List<PrimeOrderCalculator.PendingEntry>>? pool = _primeOrderPendingEntryListPool;
+			FixedCapacityStack<List<PartialFactorPendingEntry>>? pool = _primeOrderPendingEntryListPool;
 			if (pool is not null)
 			{
 				if (pool.Pop() is { } list)
@@ -286,11 +286,11 @@ namespace PerfectNumbers.Core
 				_primeOrderPendingEntryListPool = new(PerfectNumberConstants.DefaultPoolCapacity);
 			}
 
-			return new List<PrimeOrderCalculator.PendingEntry>(capacityHint);
+			return new List<PartialFactorPendingEntry>(capacityHint);
 		}
 
 		[MethodImpl(MethodImplOptions.AggressiveInlining | MethodImplOptions.AggressiveOptimization)]
-		internal static void ReturnPrimeOrderPendingEntryList(List<PrimeOrderCalculator.PendingEntry> list) => _primeOrderPendingEntryListPool!.Push(list);
+		internal static void ReturnPrimeOrderPendingEntryList(List<PartialFactorPendingEntry> list) => _primeOrderPendingEntryListPool!.Push(list);
 
 		[ThreadStatic]
 		private static FixedCapacityStack<FixedCapacityStack<ulong>>? _ulongStackPool;