Symfony write cache and logs to memory

AppKernel.php

<?php

    public function getCacheDir()
    {
        if (in_array($this->environment, array('dev', 'test'))) {
            return '/dev/shm/appname/cache/' .  $this->environment;
        }

        return parent::getCacheDir();
    }

    public function getLogDir()
    {
        if (in_array($this->environment, array('dev', 'test'))) {
            return '/dev/shm/appname/logs';
        }

        return parent::getLogDir();
    }