@Configuration
public class OrderThreadPoolConfig {

    @Bean("orderExecutor")
    public ThreadPoolTaskExecutor orderExecutor() {
        ThreadPoolTaskExecutor executor = new ThreadPoolTaskExecutor();
        executor.setCorePoolSize(8);
        executor.setMaxPoolSize(16);
        executor.setQueueCapacity(200);
        executor.setKeepAliveSeconds(60);
        executor.setThreadNamePrefix("order-create-");
        executor.setRejectedExecutionHandler(new ThreadPoolExecutor.CallerRunsPolicy());
        executor.initialize();
        return executor;
    }
}

@Service
public class OrderCheckService {

    public boolean checkStock(Long skuId) {
        sleep(100);
        return true;
    }

    public boolean checkUser(Long userId) {
        sleep(80);
        return true;
    }

    public int calcPrice(Long skuId) {
        sleep(120);
        return 99;
    }

    private void sleep(long ms) {
        try {
            Thread.sleep(ms);
        } catch (InterruptedException e) {
            Thread.currentThread().interrupt();
        }
    }
}

@Service
public class OrderService {

    @Resource(name = "orderExecutor")
    private Executor orderExecutor;

    @Autowired
    private OrderCheckService orderCheckService;

    public String createOrder(Long userId, Long skuId) throws Exception {

        long start = System.currentTimeMillis();

        CompletableFuture<Boolean> stockFuture =
                CompletableFuture.supplyAsync(
                        () -> orderCheckService.checkStock(skuId),
                        orderExecutor);

        CompletableFuture<Boolean> userFuture =
                CompletableFuture.supplyAsync(
                        () -> orderCheckService.checkUser(userId),
                        orderExecutor);

        CompletableFuture<Integer> priceFuture =
                CompletableFuture.supplyAsync(
                        () -> orderCheckService.calcPrice(skuId),
                        orderExecutor);

        CompletableFuture.allOf(
                stockFuture, userFuture, priceFuture).join();

        if (!stockFuture.get()) {
            throw new RuntimeException("庫存不足");
        }

        int price = priceFuture.get();

        lockStock(skuId);
        saveOrder(userId, skuId, price);

        return "success, cost=" +
                (System.currentTimeMillis() - start) + "ms";
    }

    private void lockStock(Long skuId) {
        sleep(50);
    }

    private void saveOrder(Long userId, Long skuId, int price) {
        sleep(80);
    }

    private void sleep(long ms) {
        try {
            Thread.sleep(ms);
        } catch (InterruptedException e) {
            Thread.currentThread().interrupt();
        }
    }
}

@RestController
@RequestMapping("/order")
public class OrderController {

    @Autowired
    private OrderService orderService;

    @PostMapping("/create")
    public String createOrder(
            @RequestParam Long userId,
            @RequestParam Long skuId) throws Exception {
        return orderService.createOrder(userId, skuId);
    }
}