Lua脚本的使用

一、使用lua脚本扣减单个商品的库存

@SpringBootTest
class LuaTests {@AutowiredStringRedisTemplate stringRedisTemplate;@Testvoid test3() {for (int i = 1; i <= 5; i++) {stringRedisTemplate.opsForValue().set("product."+i,String.valueOf(i));}}@Testvoid test2() {StringBuilder sb = new StringBuilder();sb.append(" local key = KEYS[1] "); // 你要扣减的key ：product.1sb.append(" local qty = ARGV[1] "); // 你要扣减的数量，需求量sb.append(" local redis_qty = redis.call('get',key) "); //获取redis库存实际数量sb.append(" if tonumber(redis_qty) >= tonumber(qty) then ");//需求量与库存量对比sb.append("     redis.call('decrby',key,qty) "); //满足sb.append("   return -1  "); //满足sb.append(" else ");sb.append("   return tonumber(redis_qty) ");  //不满足，就给剩余库存量 ，0 1 2 。。。。sb.append(" end ");RedisScript<Long> luaScript = RedisScript.of(sb.toString(), Long.class);ExecutorService executorService = Executors.newFixedThreadPool(5);for (int i = 1; i <= 5; i++) {executorService.execute(()->{int qty = RandomUtil.randomInt(1,6);Long count = stringRedisTemplate.execute(luaScript, CollUtil.newArrayList("product.5"),String.valueOf(qty));if (count == -1L) {System.out.println(Thread.currentThread().getId() + " 扣减成功,扣减了-> "+ qty);} else {System.out.println(Thread.currentThread().getId() + "扣减失败，需求量是："+qty+"，剩余库存量："+count);}});}// 线程睡眠3秒 ThreadUtil.safeSleep(3000);}
}

二、使用lua脚本扣减多个商品的库存

@Testvoid test4() {StringBuilder sb = new StringBuilder();sb.append(" local table = {}  "); // 你要扣减的key ：product.1sb.append(" local values =  redis.call('mget',  unpack(KEYS) )"); // [product.1,product.2]   =>  product.1 product.2sb.append(" for i = 1, #KEYS   do  ");sb.append("   if  tonumber(ARGV[i]) > tonumber(values[i])   then ");// ..的意思就是组合,也就是字符串相加sb.append("     table[#table + 1] =  KEYS[i] .. '=' .. values[i] "); //product.1=23sb.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);}

三、通过分布式锁，扣减商品的库存

package com.by;import cn.hutool.core.date.DateUtil;
import cn.hutool.core.thread.ThreadUtil;
import cn.hutool.core.util.RandomUtil;
import com.by.moder.Student;
import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.data.redis.core.RedisTemplate;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.data.redis.core.ValueOperations;import javax.annotation.Resource;
import java.util.concurrent.Executor;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;@SpringBootTest
class SetNXTests {@AutowiredStringRedisTemplate stringRedisTemplate;// @Autowired@Resource(name = "redisTemplate")ValueOperations<String,String> valueOperations;@Testvoid Test() {//线程池ExecutorService executorService = Executors.newFixedThreadPool(5);for (int i = 1; i <=5; i++) {executorService.execute(()->{//某一个工人String ioId = "IO"+ RandomUtil.randomInt(1,1000);while (true){// 判断是否存在Boolean b = valueOperations.setIfAbsent("lock.product.1",ioId+":"+ DateUtil.now());if(b){System.out.println(Thread.currentThread().getId()+"获取到了分布式锁");//执行业务ThreadUtil.safeSleep(3000);// 执行业务成功后stringRedisTemplate.delete("lock.product.1");System.out.println(Thread.currentThread().getId()+"释放了分布式锁");break;}else {//Thread.currentThread().getId() :当前线程的idSystem.out.println(Thread.currentThread().getId()+"没有获取到分布式锁");ThreadUtil.safeSleep(1000);}}});}//睡眠ThreadUtil.safeSleep(100000);}
}