mysql 防止超卖

START TRANSACTION;
SELECT stock FROM products WHERE id = 1 FOR UPDATE;
-- 检查库存并更新
UPDATE products SET stock = stock - 1 WHERE id = 1;
COMMIT;

-- 查询商品信息
SELECT stock, version FROM products WHERE id = 1;
-- 更新库存和版本号
UPDATE products SET stock = stock - 1, version = version + 1 WHERE id = 1 AND version = old_version;

# 使用 Redis 实现分布式锁
import redis
import time

r = redis.Redis()

def acquire_lock(lock_name, acquire_timeout=10):
    identifier = str(uuid.uuid4())
    end = time.time() + acquire_timeout
    while time.time() < end:
        if r.setnx(lock_name, identifier):
            return identifier
        time.sleep(0.001)
    return False

def release_lock(lock_name, identifier):
    with r.pipeline() as pipe:
        while True:
            try:
                pipe.watch(lock_name)
                if pipe.get(lock_name) == identifier:
                    pipe.multi()
                    pipe.delete(lock_name)
                    pipe.execute()
                    return True
                pipe.unwatch()
                break
            except redis.WatchError:
                pass
    return False

START TRANSACTION;
SELECT stock FROM products WHERE id = 1;
-- 检查库存并更新
UPDATE products SET stock = stock - 1 WHERE id = 1;
COMMIT;