guard_clauses_06.php

<?php

public function unlock($orderId, $userId)
{
    if (empty($this->type)) {
        throw new LockException("Can not unlock the order: type is mandatory.");
    }

    if (empty($orderId)) {
        throw new LockException("Can not unlock the order: no orderId was provided");
    }

    if (!in_array($this->type, $this->availableType)) {
        throw new LockException("Can not unlock the order: the provided type (".$this->type.") is none of " . implode($this->availableType));
    }

    $redis = $this->app['cache'];   // Assign the variable once all validations passed.

    $result = $redis->hGet(sprintf(self::REDIS_CACHE_TEMPORARY_LOCK, $this->type), $orderId);

    if (empty($result)) {
        throw new LockException("This order wasn't locked. Can't unlock");
    }

    // lock if it's the same user who try to unlock
    $data = json_decode($result, true);
    
    if ($userId != $data['user']['id']) {
        throw new LockException("Unlock failed. You can't unlock something that isn't yours");
    }

    $result = $redis->hDel(sprintf(self::REDIS_CACHE_TEMPORARY_LOCK, $this->type), $orderId);

    if ($result != true) {
        /* This unlock should be atomic to avoid a race condition, but it's out of the scope of this article */
        throw new LockException("Unlock failed. Please try again");
    }

    return true;
}