using System;
using System.Collections.Generic;

public static class ByteArrayPool
{
    private static Queue<WeakReference> pool = new Queue<WeakReference>();
    
    public static ArraySegment<byte> Take(int count)
    {
        // if there are any items to check in the pool
        if (pool.Count > 0)
        {
            for (int i = 0; i < pool.Count; i++)
            {
                // get the weakreference to the item
                var item = pool.Dequeue();
                
                // if the item is alive, someone is using it,
                // so put it back in the pool and try the next one.
                if (item.IsAlive)
                {
                    pool.Enqueue(item);
                    continue;
                }
                
                // if the item has actually been garbage collected, then skip it and
                // keep searching.
                var bytes = item.Target as byte[];
                if (bytes == null)
                    continue;
                
                // if we get to here, the item is good, so keep it in the pool
                pool.Enqueue(item);
                
                // if it has enough capacity, return it.
                if (bytes.Length >= count)
                {
                    return new ArraySegment<byte>(bytes, 0, count);
                }
            }
        }
        
        // nothing was found, so create a new array and track it in the pool.
        var segment = new ArraySegment<byte>(new byte[count]);
        pool.Enqueue(new WeakReference(segment));
        return segment;
    }
}