Up to to day PhpFilesAdapter stores compiled PHP files that OPcache reads fast. No services. Atomic writes. Good default for single-host pages and API fragments.
Install:
composer require symfony/cache
Usage Example:
<?php
use Symfony\Component\Cache\Adapter\PhpFilesAdapter;
use Symfony\Contracts\Cache\ItemInterface;
require __DIR__ . '/vendor/autoload.php';
$cacheDir = __DIR__ . '/../var/cache'; // place outside web root
$cache = new PhpFilesAdapter('myapp', 0, $cacheDir);
$key = 'page:home:v1';
$html = $cache->get($key, function (ItemInterface $item) {
$item->expiresAfter(900); // 15 minutes
return render_home();
});
echo $html;

Resume:
- Files only, very fast with OPcache.
- Atomic writes via callback; simple stampede control.
- Per-host cache. Clear by versioning keys or deleting files.