How to invalidate a Memcached value when updating a product's price in my custom PrestaShop 1.7 module?

I'm using a Prestashop 1.7 multistore. One of the stores has VAT enabled, while the other does not. I've created a custom module that hooks into the updateproduct hook. In this module, I update the price of a product, but only for the store without VAT. This ensures that both stores have the same final prices.

To enhance performance, I utilize Memcached. But I struggle to invalidate the cache correctly. Once the value for the non-VAT store gets cached (the one I alter in my module), it's never changed after attempting to set it again in the product admin. It changes properly in database, but Memcached retrieves the old value. How can I invalidate or update the stored value in Memcached? I have also no clue how to get the correct Memcached key as it's a hash like for example ps_288e7d9f7adabca7ca488166fced130a.

Currently, the only method I've found to refresh Memcached is to invalidate the entire cache, which seems to be a suboptimal solution in terms of performance.

Cache::getInstance()->delete('*');

This is my simplified hook function to update the price:

private function updateProductPrice($params)
    {
        $id_product = $params['id_product'];
        $price = $params['product']->price;
        $id_tax_rules_group = $params['product']->id_tax_rules_group;

        $shop_ids = $this->getShopIds();

        $tax_rate = $this->getTaxRate($id_tax_rules_group);

        foreach ($shop_ids as $shop_id) {
            $is_tax = Configuration::get('PS_TAX', null, null, $shop_id);
            $sql = 'SELECT `price`
                FROM `' . _DB_PREFIX_ . 'product`
                WHERE `id_product` = ' . (int) $id_product;
            $base_price = (float)Db::getInstance()->getValue($sql);
            
            if (!$is_tax) {
                $new_price = $base_price * (100 + $tax_rate) / 100;
                Db::getInstance()->update('product_shop', ['price' => $new_price], 'id_product = '.(int)$id_product . ' AND id_shop = '.(int)$shop_id);
            }
        }
    }

Without the Memcached enabled everything works just fine.

source https://stackoverflow.com/questions/77260888/how-to-invalidate-a-memcached-value-when-updating-a-products-price-in-my-custom