Cache\Adapter\Filesystem\FilesystemCachePool::storeItemInCache PHP Method

    protected function storeItemInCache(CacheItemInterface $item, $ttl)
    {
        $tags = [];
        if ($item instanceof TaggableItemInterface) {
            $tags = $item->getTags();
        }
        $data = serialize([$ttl === null ? null : time() + $ttl, $item->get(), $tags]);
        $file = $this->getFilePath($item->getKey());
        if ($this->filesystem->has($file)) {
            // Update file if it exists
            return $this->filesystem->update($file, $data);
        }
        try {
            return $this->filesystem->write($file, $data);
        } catch (FileExistsException $e) {
            // To handle issues when/if race conditions occurs, we try to update here.
            return $this->filesystem->update($file, $data);
        }
    }