AutoReturnArrayPool

AutoReturnArrayPool.cs

using System;
using System.Buffers;
using System.Runtime.CompilerServices;
using System.Collections.Generic;
using System.Threading;

var allocatedArrays = new HashSet<int>(); // To track allocated arrays
int i = 0;
while (true)
{
    i++;
    var array = AutoReturnArrayPool.Rent<int>(1000000);
    int arrayId = RuntimeHelpers.GetHashCode(array); // Use RuntimeHelpers.GetHashCode() to get a stable hash code

    // Log whether the array is new or reused
    if (!allocatedArrays.Contains(arrayId))
    {
        Console.WriteLine($"New array allocated: {arrayId}");
        allocatedArrays.Add(arrayId);
    }
    else
    {
        Console.WriteLine($"Reused array: {arrayId}");
    }

    Console.WriteLine($"Total memory: {GC.GetTotalMemory(false)}");

    if (i % 30 == 0)
    {
        // Force garbage collection to observe memory usage
        GC.Collect();
        GC.WaitForPendingFinalizers();
    }

    Thread.Sleep(1000);
}

public static class AutoReturnArrayPool
{


    // A table that attaches finalizers to rented arrays
    private static readonly ConditionalWeakTable<Array, object> finalizers = new();

    public static T[] Rent<T>(int length)
    {
        var pool = ArrayPool<T>.Shared;
        var array = pool.Rent(length);

        // Check if the array is already in the table, if not, add it
        if (!finalizers.TryGetValue(array, out _))
        {
            finalizers.Add(array, new Finalizer<T>(array));
        }

        return array;
    }

    public static void Return<T>(T[] array)
    {
        var pool = ArrayPool<T>.Shared;
        Console.WriteLine("Returned");
        pool.Return(array);
        finalizers.Remove(array); // Optionally, remove from the ConditionalWeakTable to avoid memory leaks
    }

    private class Finalizer<T>
    {
        private readonly T[] array;

        public Finalizer(T[] array)
        {
            this.array = array;
        }

        ~Finalizer()
        {
            // This will be called when the array is collected
            AutoReturnArrayPool.Return(array);
        }
    }
}