pool.php

См. документацию.

<?php
namespace Bitrix\Location\Common;

class Pool
{
    protected $poolSize = 0;
    protected $items = [];

    public function __construct(int $poolSize)
    {
        $this->poolSize = $poolSize;
    }

    public function getItems(): array
    {
        return $this->items;
    }
 
    public function cleanItems(): void
    {
        $this->items = [];
    }

    public function setItems(array $items): void
    {
        $this->items = $items;
    }

    public function getItem(string $index)
    {
        $result = null;
 
        if(isset($this->items[$index]))
        {
            $result = $this->items[$index];
            //come up used items
            unset($this->items[$index]);
            $this->items[$index] = $result;
        }
 
        return $result;
    }

    public function addItem(string $index, $value): void
    {
        $this->items[$index] = $value;
        $delta = count($this->items) - $this->poolSize;
 
        if($delta > 0)
        {
            $this->items = $this->decreaseSize($delta, $this->items);
        }
    }

    public function getItemsCount(): int
    {
        return count($this->items);
    }

    public function deleteItem(string $index): void
    {       
        if(isset($this->items[$index]))
        {
            unset($this->items[$index]);
        }
    }

    protected function decreaseSize(int $delta, array $items): array
    {
        if($delta <= 0 || count($items) <= 0)
        {
            return $items;
        }
 
        do
        {
            reset($items);
            unset($items[key($items)]);
            $delta--;
        }
        while($delta > 0);
 
        return $items;
    }
}