Redis增减库存避坑的实现

# 获取商品库存数量
def get_stock(product_id):
    redis_conn = Redis()
    stock = redis_conn.get(f'stock:{product_id}')
    return int(stock) if stock else 0

# 更新商品库存数量
def update_stock(product_id, quantity):
    redis_conn = Redis()
    redis_conn.incrby(f'stock:{product_id}', quantity)

# 判断商品库存是否充足
def check_stock(product_id, quantity):
    stock = get_stock(product_id)
    return stock >= quantity

# 避免超卖问题
def avoid_over_sell(product_id, quantity):
    redis_conn = Redis()
    with redis_conn.pipeline() as pipe:
        while True:
            try:
                pipe.watch(f'stock:{product_id}')
                stock = pipe.get(f'stock:{product_id}')
                stock = int(stock) if stock else 0
                if stock < quantity:
                    pipe.unwatch()
                    raise Exception('库存不足')
                pipe.multi()
                pipe.decrby(f'stock:{product_id}', quantity)
                pipe.execute()
                break
            except WatchError:
                continue

		// 库存存在则加一
        if(redisService.get(prefix, key, Integer.class) != null){
            redisService.incr(prefix, key);
        }

        // 首先获取当前访问频次
		Integer count = redisService.get(prefix, key, Integer.class);
        // 如果频次为空，则设置访问次数为1
		if (count == null) {
            redisService.set(prefix, key, 1);
        } else if (count < checkFrequencyCount) {
            // 如果频次小于限制，则设置访问次数加1
            redisService.incr(prefix, key);
        } else {
			// 如果频次超过限制，则限流
            throw new AppException("访问频次过高，请稍候再试");
        }

		long count = redisService.incr(prefix, key);
		// 判断必须放在后面，否则key没有过期时间永远无法清除
        long expire = redisService.ttl(prefix, key);
        if (expire == -1) {
            redisService.setExpire(prefix, key, accessExpireSecond);
        }
        if (count > checkFrequencyCount) {
            throw new AppException("访问频次过高，请稍候再试");
        }

--- 获取key
local key = KEYS[1]
--- 获取参数:incr、decr
local action = ARGV[1]
--- 如果key存在，再执行增加或减少的操作
if redis.call('exists', key) == 1 
then redis.call(action, key)
    return true
end 
return false

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.core.io.ClassPathResource;
import org.springframework.data.redis.core.script.DefaultRedisScript;
import org.springframework.scripting.support.ResourceScriptSource;

@Configuration
public class LuaConfiguration {
    @Bean(name = "update")
    public DefaultRedisScript<Boolean> redisScript() {
        DefaultRedisScript<Boolean> redisScript = new DefaultRedisScript<>();
        redisScript.setScriptSource(new ResourceScriptSource(new ClassPathResource("luascript/updateStore.lua")));
        redisScript.setResultType(Boolean.class);
        return redisScript;
    }
}

    @Resource(name = "update")
    private DefaultRedisScript<Boolean> redisScript;
    @Resource
    private StringRedisTemplate stringRedisTemplate;
	// 执行脚本并传参
	Boolean result = stringRedisTemplate.execute(redisScript, Arrays.asList(stockPrefix.getPrefix() + key), "incr");