Cache query result per request

ModelManager.php

<?php

// ...

private $repository;

private $cachedResults = [];

public function findAll()
{
    if (!$this->isCached['findAll']) {
        $this->cachedResults['findAll'] = $this->repository->findAll();
    }

    return $this->cachedResults['findAll'];
}

private function isCached($method)
{
    return isset($this->cachedResults[$method]);
}