fix: DELETE/timetable 동시성 에러

src/main/java/in/koreatech/koin/domain/timetable/service/TimetableService.java

@@ -5,6 +5,9 @@
 import java.util.Objects;
 import java.util.Optional;
 
+import in.koreatech.koin.global.exception.RequestTooFastException;
+import jakarta.persistence.EntityManager;
+import jakarta.persistence.OptimisticLockException;
 import org.springframework.stereotype.Service;
 import org.springframework.transaction.annotation.Transactional;
 
@@ -36,6 +39,7 @@ public class TimetableService {
     private final TimetableFrameRepositoryV2 timetableFrameRepositoryV2;
     private final SemesterRepositoryV2 semesterRepositoryV2;
     private final UserRepository userRepository;
+    private final EntityManager entityManager;
 
     public List<LectureResponse> getLecturesBySemester(String semester) {
         List<Lecture> lectures = lectureRepositoryV2.findBySemester(semester);
@@ -111,13 +115,17 @@ public TimetableResponse getTimetables(Integer userId, String semesterRequest) {
 
     @Transactional
     public void deleteTimetableLecture(Integer userId, Integer timetableLectureId) {
-        TimetableLecture timetableLecture = timetableLectureRepositoryV2.getById(timetableLectureId);
-        TimetableFrame frame = timetableFrameRepositoryV2.getById(timetableLecture.getTimetableFrame().getId());
-        if (!Objects.equals(frame.getUser().getId(), userId)) {
-            throw AuthorizationException.withDetail("userId: " + userId);
+        try {
+            TimetableLecture timetableLecture = timetableLectureRepositoryV2.getById(timetableLectureId);
+            TimetableFrame frame = timetableFrameRepositoryV2.getById(timetableLecture.getTimetableFrame().getId());
+            if (!Objects.equals(frame.getUser().getId(), userId)) {
+                throw AuthorizationException.withDetail("userId: " + userId);
+            }
+            timetableLectureRepositoryV2.deleteById(timetableLectureId);
+            entityManager.flush();
+        } catch (OptimisticLockException e) {
+            throw new RequestTooFastException("요청이 너무 빠릅니다. 다시 시도해주세요.");
         }
-
-        timetableLectureRepositoryV2.deleteById(timetableLectureId);
     }
 
     private TimetableResponse getTimetableResponse(Integer userId, TimetableFrame timetableFrame) {

src/test/java/in/koreatech/koin/acceptance/TimetableApiTest.java

@@ -2,6 +2,7 @@
 
 import static org.assertj.core.api.Assertions.assertThat;
 
+import io.restassured.response.Response;
 import org.junit.jupiter.api.DisplayName;
 import org.junit.jupiter.api.Test;
 import org.springframework.beans.factory.annotation.Autowired;
@@ -20,6 +21,12 @@
 import io.restassured.RestAssured;
 import io.restassured.http.ContentType;
 
+import java.util.ArrayList;
+import java.util.List;
+import java.util.concurrent.CountDownLatch;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+
 @SuppressWarnings("NonAsciiCharacters")
 class TimetableApiTest extends AcceptanceTest {
 
@@ -584,4 +591,45 @@ void deleteTimetable() {
 
         assertThat(timetableRepository.findById(2)).isNotPresent();
     }
+
+    @Test
+    @DisplayName("시간표 삭제 동시성 예외 적절하게 처리하는지 테스트한다.")
+    void deleteTimetableConcurrency() throws InterruptedException {
+        User user = userFixture.준호_학생().getUser();
+        String token = userFixture.getToken(user);
+        Semester semester = semesterFixture.semester("20192");
+
+        Lecture 건축구조의_이해_및_실습 = lectureFixture.건축구조의_이해_및_실습(semester.getSemester());
+        Lecture HRD_개론 = lectureFixture.HRD_개론(semester.getSemester());
+
+        timetableV2Fixture.시간표6(user, semester, 건축구조의_이해_및_실습, HRD_개론);
+
+        ExecutorService executor = Executors.newFixedThreadPool(2);
+        CountDownLatch latch = new CountDownLatch(2);
+
+        List<Response> responseList = new ArrayList<>();
+        Runnable deleteTask = () -> {
+            Response response = RestAssured
+                    .given()
+                    .header("Authorization", "Bearer " + token)
+                    .when()
+                    .param("id", 2)
+                    .delete("/timetable");
+            responseList.add(response);
+            latch.countDown();
+        };
+
+        executor.submit(deleteTask);
+        executor.submit(deleteTask);
+
+        latch.await();
+
+        boolean hasConflict = responseList.stream()
+                .anyMatch(response -> response.getStatusCode() == 409);
+
+        assertThat(hasConflict).isTrue();
+        assertThat(timetableRepository.findById(2)).isNotPresent();
+
+        executor.shutdown();
+    }
 }