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解决可能存在少买问题 #44

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解决可能存在少买问题 #44

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6a6a1d8
解决可能存在少买问题
May 22, 2023
3a563ac
注释代码
May 22, 2023
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13 changes: 13 additions & 0 deletions src/main/java/ltd/newbee/mall/redis/RedisCache.java
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Original file line number Diff line number Diff line change
Expand Up @@ -55,6 +55,19 @@ public Long luaDecrement(final String key) {
return execute.longValue();
}

public void luaIncrement(final String key) {
RedisScript<Long> redisScript = new DefaultRedisScript<>(buildLuaIncrScript(), Long.class);
Number execute = (Number) redisTemplate.execute(redisScript, Collections.singletonList(key));
}

private String buildLuaIncrScript() {
return """
local c
c = redis.call('incr',KEYS[1])
return c;""";
}


/**
* lua原子自减脚本
*/
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15 changes: 9 additions & 6 deletions src/main/java/ltd/newbee/mall/service/impl/NewBeeMallSeckillServiceImpl.java
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Expand Up @@ -119,11 +119,6 @@ public SeckillSuccessVO executeSeckill(Long seckillId, Long userId) {
if (redisCache.containsCacheSet(Constants.SECKILL_SUCCESS_USER_ID + seckillId, userId)) {
throw new NewBeeMallException("您已经购买过秒杀商品，请勿重复购买");
}
// 更新秒杀商品虚拟库存
Long stock = redisCache.luaDecrement(Constants.SECKILL_GOODS_STOCK_KEY + seckillId);
if (stock < 0) {
throw new NewBeeMallException("秒杀商品已售空");
}
NewBeeMallSeckill newBeeMallSeckill = redisCache.getCacheObject(Constants.SECKILL_KEY + seckillId);
if (newBeeMallSeckill == null) {
newBeeMallSeckill = newBeeMallSeckillMapper.selectByPrimaryKey(seckillId);
Expand All @@ -139,7 +134,11 @@ public SeckillSuccessVO executeSeckill(Long seckillId, Long userId) {
} else if (nowTime > endTime) {
throw new NewBeeMallException("秒杀已结束");
}

// 更新秒杀商品虚拟库存
Long stock = redisCache.luaDecrement(Constants.SECKILL_GOODS_STOCK_KEY + seckillId);
if (stock < 0) {
throw new NewBeeMallException("秒杀商品已售空");
}
Date killTime = new Date();
Map<String, Object> map = new HashMap<>(8);
map.put("seckillId", seckillId);
Expand All @@ -150,12 +149,16 @@ public SeckillSuccessVO executeSeckill(Long seckillId, Long userId) {
try {
newBeeMallSeckillMapper.killByProcedure(map);
} catch (Exception e) {
//恢复redis扣减
redisCache.luaIncrement(Constants.SECKILL_GOODS_STOCK_KEY + seckillId);
throw new NewBeeMallException(e.getMessage());
}
// 获取result -2sql执行失败 -1未插入数据 0未更新数据 1sql执行成功
map.get("result");
int result = MapUtils.getInteger(map, "result", -2);
if (result != 1) {
//恢复redis扣减
redisCache.luaIncrement(Constants.SECKILL_GOODS_STOCK_KEY + seckillId);
throw new NewBeeMallException("很遗憾！未抢购到秒杀商品");
}
// 记录购买过的用户
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