在把这段生成的下单函数当作架构边界前，请审查它。
使用已认证的客户数据创建一个订单，安全预留库存，在重试期间最多扣款一次，并提供可用的运维证据。
JavaScript
async function placeOrder(request, db, payment, metrics) {
const customer = await db.query(
`SELECT * FROM customers WHERE id = '${request.customerId}'`,
);
if (!customer) throw new Error('customer not found');
const lines = [];
for (const item of request.items) {
const product = await db.query('SELECT * FROM products WHERE id = ?', [item.sku]);
if (product.stock < item.quantity) throw new Error('out of stock');
lines.push({ ...item, price: product.price });
}
const amount = lines.reduce((sum, line) => sum + line.price * line.quantity, 0);
const receipt = await payment.charge({ amount, orderId: request.orderId });
await db.query('INSERT INTO orders VALUES (?, ?, ?)', [
request.orderId, request.customerId, JSON.stringify(lines),
]);
metrics.push({ name: 'order.created', customer, amount });
return { orderId: request.orderId, receipt };
}
生成代码仅作示例，不代表任何特定模型