DbHandler.php

class DbHandler
{
    private $conn;
    private $pdo;

    /**
     * DbHandler constructor.
     * Pass in connections to prevent race conditions being cause by multiple connections being created
     * @param {mysqli} $dbConnection - optional mysqli connection
     * @param {PDO} $pdoConnection - optional pdo connection
     */
    function __construct($dbConnection = null, $pdoConnection = null)
    {
        /**
         * @var DbConnect
         */
        $db = new DbConnect();

        /**
         * @var mysqli
         */
        $this->conn = $dbConnection ? $dbConnection : $db->connect();

        /**
         * @var PDO
         */
        $this->pdo = $pdoConnection ? $pdoConnection : $db->getPdoConnection();
    }
}