feat: 제출 관련 분산락 구현 (redis)

server/build.gradle

@@ -39,8 +39,8 @@ dependencies {
     runtimeOnly 'org.postgresql:postgresql'
 
     // redis
-//    implementation 'org.springframework.boot:spring-boot-starter-data-redis'
-//    implementation 'io.lettuce.core:lettuce-core'
+    implementation 'org.springframework.boot:spring-boot-starter-data-redis'
+    implementation 'org.springframework.boot:spring-boot-starter-cache'
 
     // lombok
     compileOnly 'org.projectlombok:lombok'

server/compose.local.yml

@@ -0,0 +1,7 @@
+services:
+  redis:
+    container_name: fluffy-redis
+    image: redis:7.4.1
+    restart: always
+    ports:
+      - '6379:6379'

server/compose.yml

@@ -10,3 +10,9 @@ services:
       TZ: Asia/Seoul
       SPRING_PROFILES_ACTIVE: prod
     restart: always
+  redis:
+    container_name: fluffy-redis
+    image: redis:7.4.1
+    restart: always
+    ports:
+      - '6379:6379'

server/src/main/java/com/fluffy/global/cache/LockManager.java

@@ -0,0 +1,21 @@
+package com.fluffy.global.cache;
+
+import java.time.Duration;
+import lombok.RequiredArgsConstructor;
+import org.springframework.data.redis.core.RedisTemplate;
+import org.springframework.stereotype.Component;
+
+@Component
+@RequiredArgsConstructor
+public class LockManager {
+
+    private final RedisTemplate<String, String> redisTemplate;
+
+    public Boolean lock(String key) {
+        return redisTemplate.opsForValue().setIfAbsent(key, "lock", Duration.ofSeconds(3));
+    }
+
+    public Boolean unlock(String key) {
+        return redisTemplate.delete(key);
+    }
+}

server/src/main/java/com/fluffy/global/cache/RedisConfig.java

@@ -0,0 +1,30 @@
+package com.fluffy.global.cache;
+
+import org.springframework.beans.factory.annotation.Value;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.data.redis.connection.RedisConnectionFactory;
+import org.springframework.data.redis.connection.lettuce.LettuceConnectionFactory;
+import org.springframework.data.redis.core.RedisTemplate;
+
+@Configuration
+public class RedisConfig {
+
+    @Value("${spring.data.redis.host}")
+    private String redisHost;
+
+    @Value("${spring.data.redis.port}")
+    private int redisPort;
+
+    @Bean
+    public RedisConnectionFactory redisConnectionFactory() {
+        return new LettuceConnectionFactory(redisHost, redisPort);
+    }
+
+    @Bean
+    public RedisTemplate<String, Object> redisTemplate() {
+        RedisTemplate<String, Object> template = new RedisTemplate<>();
+        template.setConnectionFactory(redisConnectionFactory());
+        return template;
+    }
+}

server/src/main/java/com/fluffy/global/cache/RedisLockUtil.java

@@ -0,0 +1,51 @@
+package com.fluffy.global.cache;
+
+import java.util.function.Supplier;
+import lombok.RequiredArgsConstructor;
+import lombok.extern.slf4j.Slf4j;
+import org.springframework.stereotype.Component;
+
+@Slf4j
+@Component
+@RequiredArgsConstructor
+public class RedisLockUtil {
+
+    private final LockManager manager;
+
+    public <T> T acquireAndRunLock(String key, Supplier<T> block) {
+        if (key == null || key.isBlank()) {
+            throw new IllegalArgumentException("[RedisLock] Key cannot be null or empty");
+        }
+
+        if (Boolean.TRUE.equals(acquireLock(key))) {
+            return proceedWithLock(key, block);
+        }
+
+        throw new IllegalStateException("[RedisLock] Failed to acquire lock for key: " + key);
+    }
+
+    private Boolean acquireLock(String key) {
+        try {
+            return manager.lock(key);
+        } catch (Exception e) {
+            log.error("[RedisLock] Failed to acquire lock for key: {}", key, e);
+            return false;
+        }
+    }
+
+    private <T> T proceedWithLock(String key, Supplier<T> block) {
+        try {
+            return block.get();
+        } finally {
+            releaseLock(key);
+        }
+    }
+
+    private void releaseLock(String key) {
+        try {
+            manager.unlock(key);
+        } catch (Exception e) {
+            log.error("[RedisLock] Failed to release lock for key: {}", key, e);
+        }
+    }
+}

server/src/main/java/com/fluffy/submission/application/SubmissionService.java

@@ -4,6 +4,7 @@
 import com.fluffy.auth.domain.MemberRepository;
 import com.fluffy.exam.domain.Exam;
 import com.fluffy.exam.domain.ExamRepository;
+import com.fluffy.global.cache.RedisLockUtil;
 import com.fluffy.global.exception.BadRequestException;
 import com.fluffy.submission.application.dto.SubmissionAppRequest;
 import com.fluffy.submission.domain.Submission;
@@ -20,6 +21,7 @@ public class SubmissionService {
     private final SubmissionRepository submissionRepository;
     private final MemberRepository memberRepository;
     private final SubmissionMapper submissionMapper;
+    private final RedisLockUtil redisLockUtil;
 
     @Transactional
     public void submit(SubmissionAppRequest request) {
@@ -30,13 +32,15 @@ public void submit(SubmissionAppRequest request) {
             throw new BadRequestException("시험이 공개되지 않았습니다.");
         }
 
-        //TODO: 존재하지 않는 것에 대한 동시성 문제 aka 따닥 -> Redis 분산락 고려 ?
-        //TODO: unique 제약조건 examId, memberId ?
         if (submissionRepository.existsByExamIdAndMemberId(exam.getId(), member.getId())) {
             throw new BadRequestException("이미 제출한 시험입니다.");
         }
 
-        Submission submission = submissionMapper.toSubmission(exam, member.getId(), request);
-        submissionRepository.save(submission);
+        String key = "submission:%d:%d".formatted(exam.getId(), member.getId());
+        redisLockUtil.acquireAndRunLock(key, () -> {
+            Submission submission = submissionMapper.toSubmission(exam, member.getId(), request);
+            submissionRepository.save(submission);
+            return null;
+        });
     }
 }

server/src/main/resources/application-local.yml

@@ -14,6 +14,12 @@ spring:
         highlight_sql: true
     hibernate:
       ddl-auto: create-drop
+  data:
+    redis:
+      host: localhost
+      port: 6379
+  cache:
+    type: redis
   mail:
     host: ${MAIL_HOST}
     port: 587

server/src/main/resources/application-prod.yml

@@ -12,6 +12,12 @@ spring:
         highlight_sql: true
     hibernate:
       ddl-auto: validate
+  data:
+    redis:
+      host: fluffy-redis
+      port: 6379
+  cache:
+    type: redis
   mail:
     host: ${MAIL_HOST}
     port: 587

server/src/test/java/com/fluffy/integration/submission/SubmissionServiceIntegrationTest.java

@@ -61,7 +61,7 @@ void submit() throws InterruptedException {
                 try {
                     submissionService.submit(request);
                 } catch (RuntimeException e) {
-                    // ignore
+                    e.printStackTrace();
                 }
             });
         }

server/src/test/resources/application-test.yml

@@ -6,6 +6,12 @@ spring:
       hibernate:
         format_sql: true
         highlight_sql: true
+  data:
+    redis:
+      host: localhost
+      port: 6379
+  cache:
+    type: redis
   mail:
     host: smtp.gmail.com
     port: 587