인프런 커뮤니티 질문&답변

package com.example.stock.repository;

import org.springframework.data.redis.core.RedisTemplate;
import org.springframework.stereotype.Component;

import java.time.Duration;

@Component
public class RedisLockRepository {

    private RedisTemplate<String, String> redisTemplate;

    public RedisLockRepository(RedisTemplate<String, String> redisTemplate) {
        this.redisTemplate = redisTemplate;
    }

    public Boolean lock(Long key) {
        return redisTemplate
                .opsForValue()
                .setIfAbsent(generateKey(key), "lock", Duration.ofMillis(3_000));
    }

    public void unlock(Long key) {
        redisTemplate.delete(generateKey(key));
    }

    private String generateKey(Long key) {
        return key.toString();
    }
}

package com.example.stock.facade;

import com.example.stock.repository.RedisLockRepository;
import com.example.stock.service.StockService;
import org.springframework.stereotype.Component;

@Component
public class LettuceLockStockFacade {

    private final RedisLockRepository redisLockRepository;

    private final StockService stockService;

    public LettuceLockStockFacade(RedisLockRepository redisLockRepository, StockService stockService) {
        this.redisLockRepository = redisLockRepository;
        this.stockService = stockService;
    }

    public void decrease(Long key, Long quantity) throws InterruptedException {
        while(!redisLockRepository.lock(key)){
            Thread.sleep(100);
        }
        try{
            stockService.decrease(key, quantity);
        }finally {
            redisLockRepository.unlock(key);
        }
    }
}

package com.example.stock.facade;

import com.example.stock.domain.Stock;
import com.example.stock.repository.StockRepository;
import org.junit.jupiter.api.AfterEach;
import org.junit.jupiter.api.BeforeEach;
import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;

import java.util.concurrent.CountDownLatch;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

import static org.junit.jupiter.api.Assertions.*;

@SpringBootTest
class LettuceLockStockFacadeTest {
    @Autowired
    private LettuceLockStockFacade lettuceLockStockFacade;

    @Autowired
    private StockRepository stockRepository;

    @BeforeEach
    public void before(){
        stockRepository.saveAndFlush(new Stock(1L, 100L));
    }

    @AfterEach
    public void after(){
        stockRepository.deleteAll();
    }

    @Test
    public void 동시에_100개의_요청() throws InterruptedException {
        int threadCount = 100;
        ExecutorService executorService = Executors.newFixedThreadPool(32);
        CountDownLatch latch = new CountDownLatch(threadCount);

        for(int i = 0; i < threadCount; i++){
            executorService.submit(() -> {
                try{
                    lettuceLockStockFacade.decrease(1L, 1L);
                } catch (InterruptedException e) {
                    throw new RuntimeException(e);
                } finally {
                    latch.countDown();
                }
            });
        }
        latch.await();

        Stock stock = stockRepository.findById(1L).orElseThrow();
        assertEquals(0, stock.getQuantity());
    }
}

이렇게 코딩했고 dockre에 redis를 설치하고 window Shell에서 데이터가 남아 있을까봐 1번 key 값을 삭제해서 돌렸는데도 오류가 발생했습니다.

또한 레디스가 실행이 되지 않은 채 했을까봐 ping을 입력했는데 pong이라는 응답을 받았습니다.

Hibernate: drop table if exists stock
2024-11-03T22:08:40.414+09:00 DEBUG 17108 --- [    Test worker] org.hibernate.SQL                        : create table stock (id bigint not null auto_increment, product_id bigint, quantity bigint, version bigint, primary key (id)) engine=InnoDB
Hibernate: create table stock (id bigint not null auto_increment, product_id bigint, quantity bigint, version bigint, primary key (id)) engine=InnoDB
2024-11-03T22:08:40.439+09:00  INFO 17108 --- [    Test worker] j.LocalContainerEntityManagerFactoryBean : Initialized JPA EntityManagerFactory for persistence unit 'default'
2024-11-03T22:08:41.136+09:00  INFO 17108 --- [    Test worker] o.s.d.j.r.query.QueryEnhancerFactory     : Hibernate is in classpath; If applicable, HQL parser will be used.
2024-11-03T22:08:42.092+09:00  WARN 17108 --- [    Test worker] JpaBaseConfiguration$JpaWebConfiguration : spring.jpa.open-in-view is enabled by default. Therefore, database queries may be performed during view rendering. Explicitly configure spring.jpa.open-in-view to disable this warning
2024-11-03T22:08:42.990+09:00  INFO 17108 --- [    Test worker] c.e.s.facade.LettuceLockStockFacadeTest  : Started LettuceLockStockFacadeTest in 6.21 seconds (process running for 7.345)
2024-11-03T22:08:43.504+09:00 DEBUG 17108 --- [    Test worker] org.hibernate.SQL                        : insert into stock (product_id,quantity,version) values (?,?,?)
Hibernate: insert into stock (product_id,quantity,version) values (?,?,?)
2024-11-03T22:08:44.203+09:00 DEBUG 17108 --- [    Test worker] org.hibernate.SQL                        : select s1_0.id,s1_0.product_id,s1_0.quantity,s1_0.version from stock s1_0 where s1_0.id=?
Hibernate: select s1_0.id,s1_0.product_id,s1_0.quantity,s1_0.version from stock s1_0 where s1_0.id=?
2024-11-03T22:08:44.245+09:00 DEBUG 17108 --- [    Test worker] org.hibernate.SQL                        : select s1_0.id,s1_0.product_id,s1_0.quantity,s1_0.version from stock s1_0
Hibernate: select s1_0.id,s1_0.product_id,s1_0.quantity,s1_0.version from stock s1_0
2024-11-03T22:08:44.252+09:00 DEBUG 17108 --- [    Test worker] org.hibernate.SQL                        : delete from stock where id=? and version=?
Hibernate: delete from stock where id=? and version=?

Expected :0
Actual   :100
<Click to see difference>

org.opentest4j.AssertionFailedError: expected: <0> but was: <100>
	at org.junit.jupiter.api.AssertionFailureBuilder.build(AssertionFailureBuilder.java:151)
	at org.junit.jupiter.api.AssertionFailureBuilder.buildAndThrow(AssertionFailureBuilder.java:132)
	at org.junit.jupiter.api.AssertEquals.failNotEqual(AssertEquals.java:197)
	at org.junit.jupiter.api.AssertEquals.assertEquals(AssertEquals.java:182)
	at org.junit.jupiter.api.AssertEquals.assertEquals(AssertEquals.java:177)
	at org.junit.jupiter.api.Assertions.assertEquals(Assertions.java:639)
	at com.example.stock.facade.LettuceLockStockFacadeTest.동시에_100개의_요청(LettuceLockStockFacadeTest.java:55)
	at java.base/java.lang.reflect.Method.invoke(Method.java:568)
	at java.base/java.util.ArrayList.forEach(ArrayList.java:1511)
	at java.base/java.util.ArrayList.forEach(ArrayList.java:1511)


Java HotSpot(TM) 64-Bit Server VM warning: Sharing is only supported for boot loader classes because bootstrap classpath has been appended

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