--- /dev/null
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Symfony\Contracts\Cache;
+
+use Psr\Cache\CacheItemPoolInterface;
+use Psr\Cache\InvalidArgumentException;
+use Psr\Log\LoggerInterface;
+
+// Help opcache.preload discover always-needed symbols
+class_exists(InvalidArgumentException::class);
+
+/**
+ * An implementation of CacheInterface for PSR-6 CacheItemPoolInterface classes.
+ *
+ * @author Nicolas Grekas <p@tchwork.com>
+ */
+trait CacheTrait
+{
+ /**
+ * {@inheritdoc}
+ *
+ * @return mixed
+ */
+ public function get(string $key, callable $callback, float $beta = null, array &$metadata = null)
+ {
+ return $this->doGet($this, $key, $callback, $beta, $metadata);
+ }
+
+ /**
+ * {@inheritdoc}
+ */
+ public function delete(string $key): bool
+ {
+ return $this->deleteItem($key);
+ }
+
+ private function doGet(CacheItemPoolInterface $pool, string $key, callable $callback, ?float $beta, array &$metadata = null, LoggerInterface $logger = null)
+ {
+ if (0 > $beta = $beta ?? 1.0) {
+ throw new class(sprintf('Argument "$beta" provided to "%s::get()" must be a positive number, %f given.', static::class, $beta)) extends \InvalidArgumentException implements InvalidArgumentException { };
+ }
+
+ $item = $pool->getItem($key);
+ $recompute = !$item->isHit() || \INF === $beta;
+ $metadata = $item instanceof ItemInterface ? $item->getMetadata() : [];
+
+ if (!$recompute && $metadata) {
+ $expiry = $metadata[ItemInterface::METADATA_EXPIRY] ?? false;
+ $ctime = $metadata[ItemInterface::METADATA_CTIME] ?? false;
+
+ if ($recompute = $ctime && $expiry && $expiry <= ($now = microtime(true)) - $ctime / 1000 * $beta * log(random_int(1, \PHP_INT_MAX) / \PHP_INT_MAX)) {
+ // force applying defaultLifetime to expiry
+ $item->expiresAt(null);
+ $logger && $logger->info('Item "{key}" elected for early recomputation {delta}s before its expiration', [
+ 'key' => $key,
+ 'delta' => sprintf('%.1f', $expiry - $now),
+ ]);
+ }
+ }
+
+ if ($recompute) {
+ $save = true;
+ $item->set($callback($item, $save));
+ if ($save) {
+ $pool->save($item);
+ }
+ }
+
+ return $item->get();
+ }
+}