秒杀

@RestController
public class SeckillController {
    private static final ExecutorService executorService = new ThreadPoolExecutor(
            100,
            100,
            10,
            TimeUnit.SECONDS,
            new LinkedBlockingQueue<>(100)
            , new DefaultThreadFactory("kill-%d")
            , new ThreadPoolExecutor.CallerRunsPolicy());
    private static final String SKU_NAME = "牛奶";
    @Autowired
    private RedissonClient redissonClient;
    @Autowired
    private SeckillService seckillService;
    @GetMapping("/setStock")
    public String setStock() {
        // 将库存设置到信号量中
        // 指定默认值是 100
        boolean ok = redissonClient.getSemaphore(SKU_NAME).trySetPermits(100);
        if (ok) {
            return "库存已设置成功:100";
        } else {
            return "库存设置失败";
        }
    }
    /**
     * 秒杀小功能,利用redis作为分布式锁，使用信号量来进行库存的扣减
     */
    @GetMapping("/kill")
    public void kill() {
        for (int i = 0; i < 200; i++) {
            int num = (int) (Math.random() * 10 + 1);
            executorService.execute(() -> {
                boolean kill = seckillService.kill(SKU_NAME, num);
                if (kill) {
                    System.out.println(Thread.currentThread().getName() + ":秒杀成功，买了" + num + "个");
                    // 业务处理，用户买了 几个skuName
                    // 下单,发送消息到订单系统
                } else {
                    System.out.println(Thread.currentThread().getName() + ":想买" + num + "个，但秒杀失败");
                }
            });
        }
        // 秒杀结束，删除信号量
        redissonClient.getSemaphore(SKU_NAME).delete();
    }
}

@Service
public class SeckillService {
    @Autowired
    private RedissonClient redissonClient;
    public boolean kill(String skuName, Integer num) {
        return redissonClient.getSemaphore(skuName).tryAcquire(num);
    }
}