shlink/module/Common/src/Middleware/CloseDbConnectionMiddleware.php

<?php
declare(strict_types=1);

namespace Shlinkio\Shlink\Common\Middleware;

use Doctrine\ORM\EntityManagerInterface;
use Psr\Http\Message\ResponseInterface;
use Psr\Http\Message\ServerRequestInterface;
use Psr\Http\Server\MiddlewareInterface;
use Psr\Http\Server\RequestHandlerInterface;

class CloseDbConnectionMiddleware implements MiddlewareInterface
{
    /** @var EntityManagerInterface */
    private $em;

    public function __construct(EntityManagerInterface $em)
    {
        $this->em = $em;
    }

    /**
     * Process an incoming server request and return a response, optionally delegating
     * response creation to a handler.
     */
    public function process(ServerRequestInterface $request, RequestHandlerInterface $handler): ResponseInterface
    {
        $handledRequest =  $handler->handle($request);
        $this->em->getConnection()->close();
        $this->em->clear();

        return $handledRequest;
    }
}