https://blog.sznapka.pl/injecting-repositories-to-service-in-symfony2/ - code snippet 3

class.php

<?php

namespace Example\FooBundle\Service;

use Doctrine\ORM\EntityRepository;
use Symfony\Component\HttpKernel\Log\LoggerInterface;

class FooService
{
    protected $fooRepository;
    protected $logger;

    public function __construct(
        FooRepositoryInterface $fooRepository,
        LoggerInterface $logger
    ) {
        $this->fooRepository = $fooRepository;
        $this->logger = $logger;
    }

    public function query()
    {
        $results = $this->fooRepository->fetchLatest();
        $this->logger->info(
          sprintf('Someone fetched %d foos',
            count($results)));

        return $results;
    }
}