刷题之动态规划

一次扣减一个商品库存
@Component
public class LuaDemo {

@Autowired
private StringRedisTemplate redisTemplate;


public void test() {

  List<String> keys = new ArrayList<>();
    keys.add("yanjie007");

    String lua = "return redis.call('set',KEYS[1],ARGV[1])";

    RedisScript<String> redisScript=  RedisScript.of(lua,String.class);

    String shuai = stringRedisTemplate.execute(redisScript, keys, "今天真帅");

    System.out.println(shuai);

}

}

//扣减库存
@Test
void test2() throws IOException {
valueOperations.set(key,15L);
StringBuilder sb = new StringBuilder();
sb.append(" local key = KEYS[1] “);
sb.append(” local qty = ARGV[1] “);
sb.append(” local redis_qty = redis.call(‘get’,key) “);
sb.append(” if tonumber(redis_qty) >= tonumber(qty) then “);
sb.append(” redis.call(‘decrby’,key,qty) “);
sb.append(” return -1 “);
sb.append(” else “);
sb.append(” return tonumber(redis_qty) “); // 0, 1,2,3 …
sb.append(” end “);
sb.append(” ");
RedisScript script = RedisScript.of(sb.toString(),Long.class);
ExecutorService executorService = Executors.newCachedThreadPool();

    for (int i = 1; i <= 10; i++) {
        int finalI = i;
        executorService.execute(()->{
            int needQty = RandomUtil.randomInt(1, 5);
            Long qty =  stringRedisTemplate.execute(script, CollUtil.newArrayList(key), needQty+"");
         if(qty.intValue() == -1 ){
             System.out.println("线程"+ finalI +"扣减成功,需求量是："+needQty);
          } else {

             System.out.println("线程"+ finalI +"扣减失败,当前库存变量是："+qty);
         }
        });
    }


    System.in.read();
}

一次扣减多个商品的库存
void test4() {

    StringBuilder sb = new StringBuilder();
    sb.append(" local table = {}  "); // 你要扣减的key ：product.1
    sb.append(" local values =  redis.call('mget',  unpack(KEYS) )"); // [product.1,product.2]   =>  product.1 product.2
    sb.append(" for i = 1, #KEYS   do  ");
    sb.append("   if  tonumber(ARGV[i]) > tonumber(values[i])   then ");
    sb.append("     table[#table + 1] =  KEYS[i] .. '=' .. values[i] "); // product.1=23
    sb.append("   end ");
    sb.append(" end ");
    sb.append(" if #table > 0 then ");
    sb.append("   return table  ");
    sb.append(" end ");
    sb.append(" for i = 1 , #KEYS do ");
    sb.append("   redis.call('decrby',KEYS[i],ARGV[i])  ");
    sb.append(" end ");
    sb.append(" return {} ");
    RedisScript<List> luaScript = RedisScript.of(sb.toString(), List.class);

      List<StockProduct> stockProducts =  new ArrayList<>();
      stockProducts.add(new StockProduct(5,1));
      stockProducts.add(new StockProduct(4,2));

    List<String> keys = stockProducts.stream().map(it -> "product." + it.getId()).collect(Collectors.toList());
    Object[] qtys = stockProducts.stream().map(it -> it.getQty() + "").toArray();
    List<String> list = stringRedisTemplate.execute(luaScript,
            keys,
            qtys);
    if(list.isEmpty()){
        System.out.println("库存冻结成功");
    } else {

        for (String key_qty : list) {
            String[] split = key_qty.split("=");
            System.out.println(split[0] + "库存不足，剩余库存量：" + split[1]);
        }

    }


    ThreadUtil.safeSleep(3000);


}