Fix pooling performance regression & add IPoolable support

Author: MrBlue

src/Pooling/ArrayPool.cs

@@ -1,4 +1,4 @@
-using System;
+using System;
 using System.Collections.Generic;
 
 namespace Oxide.Pooling
@@ -120,7 +120,11 @@ public void Return(T[] item)
 
             if (CleanOnReturn)
             {
+#if NETFRAMEWORK
+                for (int i = 0; i < item.Length; i++) item[i] = default;
+#else
                 Array.Clear(item, 0, item.Length);
+#endif
             }
 
             Stack<T[]> store = Pools[item.Length - 1];
@@ -144,7 +148,11 @@ protected override void OnPurge()
                     while (store.Count > 0)
                     {
                         T[] array = store.Pop();
+#if NETFRAMEWORK
+                        for (int j = 0; j < array.Length; j++) array[j] = default;
+#else
                         Array.Clear(array, 0, array.Length);
+#endif
                     }
                 }
             }

src/Pooling/IPoolable.cs

@@ -0,0 +1,13 @@
+namespace Oxide.Pooling
+{
+    /// <summary>
+    /// Implement this interface on pooled types to automatically reset state when returned to a pool.
+    /// </summary>
+    public interface IPoolable
+    {
+        /// <summary>
+        /// Resets the object to a clean state for reuse from the pool
+        /// </summary>
+        void Reset();
+    }
+}

src/Pooling/PoolFactory.cs

@@ -1,4 +1,4 @@
-using System;
+using System;
 using System.Collections.Generic;
 
 namespace Oxide.Pooling
@@ -79,8 +79,6 @@ public void Dispose()
 
         public const int DEFAULT_MAX_POOL_SIZE = 256;
 
-        public const bool DEFAULT_ITEM_DISPOSE = false;
-
         #endregion
 
         #region Properties
@@ -93,7 +91,7 @@ public void Dispose()
         /// <summary>
         /// Returns a new pool with default settings
         /// </summary>
-        public static IPool<T> Default => new PoolFactory<T>(DEFAULT_MAX_POOL_SIZE, DEFAULT_ITEM_DISPOSE);
+        public static IPool<T> Default => new PoolFactory<T>(DEFAULT_MAX_POOL_SIZE);
 
         /// <summary>
         /// Returns a pool instance that doesn't pool items
@@ -104,12 +102,14 @@ public void Dispose()
         /// Creates a new pool with custom settings
         /// </summary>
         /// <param name="maxPoolSize">Max items allowed to pool</param>
-        /// <param name="itemDispose">Calls dispose on items when they get returned to the pool</param>
         /// <returns>The pool provider</returns>
-        public static IPool<T> Custom(int maxPoolSize = DEFAULT_MAX_POOL_SIZE, bool itemDispose = DEFAULT_ITEM_DISPOSE) => new PoolFactory<T>(maxPoolSize, itemDispose);
+        public static IPool<T> Custom(int maxPoolSize = DEFAULT_MAX_POOL_SIZE) => new PoolFactory<T>(maxPoolSize);
+
+        private static bool IsPoolable { get; }
 
         static PoolFactory()
         {
+            IsPoolable = typeof(IPoolable).IsAssignableFrom(typeof(T));
             Shared = Default;
         }
 
@@ -119,12 +119,9 @@ static PoolFactory()
 
         private int MaxPoolSize { get; }
 
-        private bool CallItemDispose { get; }
-
-        private PoolFactory(int maxPooledSize = 50, bool callItemDispose = false)
+        private PoolFactory(int maxPooledSize = 50)
         {
             MaxPoolSize = maxPooledSize <= 0 ? throw new ArgumentOutOfRangeException(nameof(maxPooledSize)) : maxPooledSize;
-            CallItemDispose = callItemDispose;
             Store = new Stack<T>();
         }
 
@@ -143,9 +140,9 @@ public T Take()
 
         public void Return(T item)
         {
-            if (CallItemDispose && item is IDisposable dispose)
+            if (IsPoolable)
             {
-                dispose.Dispose();
+                ((IPoolable)item).Reset();
             }
 
             lock (Store)