Revert "Merge pull request #251 from mlemanczyk/codex/refactor-prime-checking-on-gpu-n5t2pm"

This reverts commit 936ce239db, reversing
changes made to e14b77e504.

PerfectNumbers.Core/ThreadStaticPools.cs

@@ -260,6 +260,43 @@ namespace PerfectNumbers.Core
             pool.Add(stack);
         }
 
+        [ThreadStatic]
+        private static List<Dictionary<ulong, int>>? _ulongIntDictionaryPool;
+
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        public static Dictionary<ulong, int> RentUlongIntDictionary(int capacityHint)
+        {
+            List<Dictionary<ulong, int>>? pool = _ulongIntDictionaryPool;
+            if (pool is not null)
+            {
+                int poolCount = pool.Count;
+                if (poolCount > 0)
+                {
+                    int lastIndex = poolCount - 1;
+                    Dictionary<ulong, int> dictionary = pool[lastIndex];
+                    pool.RemoveAt(lastIndex);
+                    dictionary.EnsureCapacity(capacityHint);
+
+                    return dictionary;
+                }
+            }
+
+            return new Dictionary<ulong, int>(capacityHint);
+        }
+
+        [MethodImpl(MethodImplOptions.AggressiveInlining)]
+        public static void ReturnUlongIntDictionary(Dictionary<ulong, int> dictionary)
+        {
+            List<Dictionary<ulong, int>>? pool = _ulongIntDictionaryPool;
+            if (pool is null)
+            {
+                pool = new List<Dictionary<ulong, int>>(4);
+                _ulongIntDictionaryPool = pool;
+            }
+
+            pool.Add(dictionary);
+        }
+
         [ThreadStatic]
         private static Dictionary<ulong, int>? _factorCountDictionary;