feat : 추천 동시성 문제 해결 및 테스트 완료

src/main/java/org/ezcode/codetest/domain/community/repository/BaseVoteRepository.java

@@ -9,8 +9,6 @@ public interface BaseVoteRepository<T extends BaseVote> {
 
 	T save(T voteEntity);
 
-	// existBy~가 더 효율적이긴 하지만
-	// 나중에 비추천 기능까지 생기면 재사용 가능
 	Optional<T> findByVoterIdAndTargetId(Long voterId, Long targetId);
 
 	boolean existsByVoterIdAndTargetId(Long voterId, Long targetId);

src/main/java/org/ezcode/codetest/domain/community/service/BaseVoteDomainService.java

@@ -7,9 +7,12 @@
 import org.ezcode.codetest.domain.community.model.enums.VoteType;
 import org.ezcode.codetest.domain.community.repository.BaseVoteRepository;
 import org.ezcode.codetest.domain.user.model.entity.User;
+import org.springframework.dao.DataIntegrityViolationException;
 
 import lombok.RequiredArgsConstructor;
+import lombok.extern.slf4j.Slf4j;
 
+@Slf4j
 @RequiredArgsConstructor
 public abstract class BaseVoteDomainService<T extends BaseVote, R extends BaseVoteRepository<T>> {
 
@@ -31,7 +34,15 @@ public VoteResult manageVote(User voter, Long targetId, VoteType voteType) {
 			} else {
 				T vote = buildVote(voter, targetId, voteType);
 
-				voteRepository.save(vote);
+				try {
+					voteRepository.save(vote);
+				} catch (DataIntegrityViolationException ex) {
+					// 중복 삽입 예외는 “이미 UP 상태”로 간주하고 흐름을 계속
+					// 만약 이 로그가 빈번하게 발생한다면 어떤 이유로 연속 요청(따닥 문제)가 발생하는지 확인해봐야 함
+					log.info("중복 추천 시도 감지 (따닥 문제): voter={} target={}", voter.getId(), targetId);
+
+					prevVoteType = VoteType.UP;
+				}
 			}
 		}
 

src/test/java/org/ezcode/codetest/application/community/service/DiscussionVoteServiceConcurrencyTest.java

@@ -0,0 +1,101 @@
+package org.ezcode.codetest.application.community.service;
+
+import static org.assertj.core.api.Assertions.*;
+
+import java.util.concurrent.CountDownLatch;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+import java.util.concurrent.atomic.AtomicReference;
+
+import org.ezcode.codetest.application.community.dto.request.VoteRequest;
+import org.ezcode.codetest.domain.community.model.enums.VoteType;
+import org.ezcode.codetest.domain.community.repository.DiscussionRepository;
+import org.ezcode.codetest.domain.community.repository.DiscussionVoteRepository;
+import org.ezcode.codetest.infrastructure.persistence.repository.user.UserJpaRepository;
+import org.junit.jupiter.api.Disabled;
+import org.junit.jupiter.api.DisplayName;
+import org.junit.jupiter.api.Test;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.test.autoconfigure.jdbc.AutoConfigureTestDatabase;
+import org.springframework.boot.test.context.SpringBootTest;
+import org.springframework.dao.DataIntegrityViolationException;
+import org.springframework.orm.ObjectOptimisticLockingFailureException;
+import org.springframework.test.context.ActiveProfiles;
+import org.springframework.transaction.annotation.Transactional;
+
+@Disabled
+@SpringBootTest
+@ActiveProfiles("test")
+@AutoConfigureTestDatabase(replace = AutoConfigureTestDatabase.Replace.NONE)
+class DiscussionVoteServiceConcurrencyTest {
+
+	@Autowired
+	private DiscussionVoteService discussionVoteService;
+
+	@Autowired
+	private DiscussionVoteRepository discussionVoteRepository;
+
+	@Autowired
+	private UserJpaRepository userRepository;
+
+	@Autowired
+	private DiscussionRepository discussionRepository;
+
+	@Transactional
+	@DisplayName("한 명의 유저가 동시에 추천을 요청할 경우 Race Condition이 발생하여 데이터 정합성이 깨진다")
+	@Test
+	void manageVote_concurrency_issue_test() throws InterruptedException {
+		// given (준비)
+		// 1. 테스트용 유저와 게시글 생성 및 저장
+		// User voter = userRepository.save(CommunityFixture.createUser("[email protected]"));
+		// Discussion targetDiscussion = discussionRepository.save(Discussion.builder().build());
+
+		AtomicReference<Long> exceptionCnt = new AtomicReference<>(0L);
+
+		// 2. 동시에 실행할 스레드 수 설정 (예: 100개)
+		int threadCount = 100;
+		ExecutorService executorService = Executors.newFixedThreadPool(threadCount);
+		CountDownLatch startLatch = new CountDownLatch(1); // 모든 스레드가 준비될 때까지 대기
+		CountDownLatch doneLatch = new CountDownLatch(threadCount); // 모든 스레드가 끝날 때까지 대기
+
+		// when (실행)
+		for (int i = 0; i < threadCount; i++) {
+			executorService.submit(() -> {
+				try {
+					startLatch.await(); // 모든 스레드가 여기서 대기
+					// 모든 스레드가 동일한 유저, 동일한 게시글에 UP 추천을 요청
+					discussionVoteService.manageVoteOnDiscussion(1L, 1L, new VoteRequest(VoteType.UP), 1L);
+				} catch (InterruptedException e) {
+					Thread.currentThread().interrupt();
+				} catch (DataIntegrityViolationException | ObjectOptimisticLockingFailureException e) {
+					// DB 유니크 제약조건이 있거나, JPA의 낙관적 락이 있다면 예외가 발생할 수 있음
+					// 테스트에서는 이 예외를 정상적인 실패 시나리오 중 하나로 간주
+					exceptionCnt.getAndSet(exceptionCnt.get() + 1);
+					System.out.println("예상된 동시성 예외 발생: " + e.getMessage());
+				} finally {
+					doneLatch.countDown();
+				}
+			});
+		}
+
+		// 모든 스레드를 동시에 시작
+		startLatch.countDown();
+		// 모든 스레드가 끝날 때까지 대기
+		doneLatch.await();
+		executorService.shutdown();
+
+		Thread.sleep(500);
+
+		// then (검증)
+		// 최종적으로 vote 테이블에는 단 하나의 레코드만 있어야 한다.
+		long upvoteCount = discussionVoteRepository.countUpvotesByTargetId(1L);
+
+		System.out.println("예외 발생 수 : " + exceptionCnt);
+		System.out.println("최종 투표 레코드 수: " + upvoteCount);
+
+		// 결과적으로 데이터는 하나만 저장됨
+		// voter_id, discussion_id에 유니크 제약조건을 걸었기 때문
+		// 대신에 DataIntegrityViolationException 예외 발생
+		assertThat(upvoteCount).isEqualTo(1L);
+	}
+}

src/test/resources/application-test.properties

@@ -0,0 +1,107 @@
+# ========================
+# Spring Config
+# ========================
+spring.application.name=min
+spring.config.import=optional:file:.env[.properties]
+
+# ========================
+# MySQL
+# ========================
+spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver
+spring.datasource.url=${SPRING_DATASOURCE_URL}
+spring.datasource.username=${SPRING_DATASOURCE_USERNAME}
+spring.datasource.password=${SPRING_DATASOURCE_PASSWORD}
+
+# ========================
+# JPA
+# ========================
+spring.jpa.hibernate.ddl-auto=update
+spring.jpa.show-sql=true
+spring.jpa.properties.hibernate.format_sql=true
+
+# ========================
+# Redis
+# ========================
+spring.data.redis.host=${SPRING_REDIS_HOST}
+spring.data.redis.port=${SPRING_REDIS_PORT}
+spring.data.redis.password=${SPRING_REDIS_PASSWORD}
+
+# ========================
+# JWT
+# ========================
+jwt.secret=${JWT_SECRET}
+
+# ========================
+# Swagger
+# ========================
+springdoc.api-docs.path=/v3/api-docs
+springdoc.swagger-ui.path=/swagger-ui
+
+# ========================
+# ActiveMQ
+# ========================
+spring.message.activemq.address=${ACTIVEMQ_ADDRESS}
+spring.message.activemq.username=${ACTIVEMQ_USERNAME}
+spring.message.activemq.password=${ACTIVEMQ_PASSWORD}
+spring.message.activemq.port=${ACTIVEMQ_PORT}
+
+# ========================
+# Actuator
+# ========================
+management.endpoints.web.exposure.include=health,info
+management.endpoint.health.show-details=always
+
+# ========================
+# Judge0Client
+# ========================
+external.judge0.url=${JUDGE0_URL}
+
+# ========================
+# ElasticSearch
+# ========================
+spring.datasource.elasticsearch.address=${ELASTICSEARCH_ADDRESS}
+spring.datasource.elasticsearch.username=${ELASTICSEARCH_USERNAME}
+spring.datasource.elasticsearch.password=${ELASTICSEARCH_PASSWORD}
+spring.datasource.elasticsearch.port=${ELASTICSEARCH_PORT}
+
+# ========================
+# OpenAI
+# ========================
+openai.api.url=${OPEN_API_URL}
+openai.api.key=${OPEN_API_KEY}
+
+# ========================
+# OAuth GOOGLE
+# ========================
+spring.security.oauth2.client.registration.google.client-name=google
+spring.security.oauth2.client.registration.google.client-id=${CLIENT_ID}
+spring.security.oauth2.client.registration.google.client-secret=${CLIENT_SECRET}
+spring.security.oauth2.client.registration.google.redirect-uri=${REDIRECT_URI}
+spring.security.oauth2.client.registration.google.authorization-grant-type=authorization_code
+spring.security.oauth2.client.registration.google.scope=profile,email
+
+# ========================
+# mongo
+# ========================
+spring.data.mongodb.uri=${SPRING_MONGODB_URI}
+spring.data.mongodb.auto-index-creation=true
+logging.level.org.mongodb.driver.protocol.command=DEBUG
+logging.level.org.springframework.data.mongodb.core.MongoTemplate=DEBUG
+
+# ========================
+# Spring Cache Caffeine
+# ========================
+# spring.cache.caffeine.spec=maximumSize=500,expireAfterWrite=10m
+
+spring.cache.type=caffeine
+logging.level.org.springframework.cache.interceptor.CacheInterceptor=TRACE
+
+# ========================
+# discord
+# ========================
+discord.webhook.url=${DISCORD_WEBHOOK_URL}
+
+#logging.level.org.springframework.security=DEBUG
+#logging.level.org.springframework.security.oauth2=DEBUG
+#logging.level.org.springframework.security.oauth2.client=TRACE
+#logging.level.org.springframework.web.client.RestTemplate=TRACE