应用PaaS平台秒杀

const express = require('express');
const app = express();
const bodyParser = require('body-parser');
const { Pool } = require('pg');

const pool = new Pool({
  connectionString: 'your_database_url'
});

app.use(bodyParser.json());

app.post('/seckill', async (req, res) => {
  const { productId, userId } = req.body;
  const client = await pool.connect();
  try {
    await client.query('BEGIN');
    const { rows } = await client.query('SELECT stock FROM products WHERE id = $1 FOR UPDATE', [productId]);
    if (rows[0].stock <= 0) {
      return res.status(400).send('Out of stock');
    }
    await client.query('UPDATE products SET stock = stock - 1 WHERE id = $1', [productId]);
    await client.query('INSERT INTO orders (product_id, user_id) VALUES ($1, $2)', [productId, userId]);
    await client.query('COMMIT');
    res.send('Seckill successful');
  } catch (e) {
    await client.query('ROLLBACK');
    res.status(500).send('Internal Server Error');
  } finally {
    client.release();
  }
});

app.listen(3000, () => console.log('Server running on port 3000'));