✨ feat : 채팅 정답 처리 동시성 제어 (#170)

silver-eunjoo · web-flow · commit fee0f680f80f · 2025-07-31T18:35:16.000+09:00
* 🔧 chore : dev 기준으로 rebase 후 변경사항 반영

* ✅ test : 정답 처리 동시성 제어

* chore: Java 스타일 수정

---------

Co-authored-by: github-actions &lt;&gt;
diff --git a/backend/src/main/java/io/f1/backend/domain/game/app/ChatService.java b/backend/src/main/java/io/f1/backend/domain/game/app/ChatService.java
@@ -20,7 +20,6 @@
 public class ChatService {
 
     private final RoomService roomService;
-    private final TimerService timerService;
     private final MessageSender messageSender;
     private final ApplicationEventPublisher eventPublisher;
 
@@ -41,7 +40,12 @@ public void chat(Long roomId, UserPrincipal userPrincipal, ChatMessage chatMessa
 
         String answer = currentQuestion.getAnswer();
 
-        if (answer.equals(chatMessage.message())) {
+        if (!answer.equals(chatMessage.message())) {
+            return;
+        }
+
+        // false -> true
+        if (room.compareAndSetAnsweredFlag(false, true)) {
             eventPublisher.publishEvent(
                     new GameCorrectAnswerEvent(
                             room, userPrincipal.getUserId(), chatMessage, answer));
diff --git a/backend/src/main/java/io/f1/backend/domain/game/app/GameService.java b/backend/src/main/java/io/f1/backend/domain/game/app/GameService.java
@@ -123,6 +123,7 @@ public void onCorrectAnswer(GameCorrectAnswerEvent event) {
                 ofPlayerEvent(chatMessage.nickname(), RoomEventType.CORRECT_ANSWER));
 
         timerService.cancelTimer(room);
+        room.compareAndSetAnsweredFlag(true, false);
 
         if (!timerService.validateCurrentRound(room)) {
             gameEnd(room);
@@ -142,6 +143,12 @@ public void onCorrectAnswer(GameCorrectAnswerEvent event) {
     @EventListener
     public void onTimeout(GameTimeoutEvent event) {
         Room room = event.room();
+
+        // false -> true 여야 하는데 실패했을 때 => 이미 정답 처리가 된 경우 (onCorrectAnswer 로직 실행 중)
+        if (!room.compareAndSetAnsweredFlag(false, true)) {
+            return;
+        }
+
         log.debug(room.getId() + "번 방 타임아웃! 현재 라운드 : " + room.getCurrentRound());
 
         String destination = getDestination(room.getId());
@@ -167,6 +174,8 @@ public void onTimeout(GameTimeoutEvent event) {
                 destination,
                 MessageType.QUESTION_START,
                 toQuestionStartResponse(room, CONTINUE_DELAY));
+
+        room.compareAndSetAnsweredFlag(true, false);
     }
 
     public void gameEnd(Room room) {
diff --git a/backend/src/main/java/io/f1/backend/domain/game/model/Room.java b/backend/src/main/java/io/f1/backend/domain/game/model/Room.java
@@ -16,6 +16,7 @@
 import java.util.concurrent.Executors;
 import java.util.concurrent.ScheduledExecutorService;
 import java.util.concurrent.ScheduledFuture;
+import java.util.concurrent.atomic.AtomicBoolean;
 
 @Getter
 public class Room {
@@ -42,6 +43,8 @@ public class Room {
 
     private ScheduledFuture<?> timer;
 
+    private final AtomicBoolean answered = new AtomicBoolean(false);
+
     public Room(Long id, RoomSetting roomSetting, GameSetting gameSetting, Player host) {
         this.id = id;
         this.roomSetting = roomSetting;
@@ -194,4 +197,12 @@ public boolean isPlayerInState(Long userId, ConnectionState state) {
     public boolean isPasswordIncorrect(String password) {
         return roomSetting.locked() && !roomSetting.password().equals(password);
     }
+
+    public boolean compareAndSetAnsweredFlag(boolean expected, boolean newValue) {
+        return answered.compareAndSet(expected, newValue);
+    }
+
+    public AtomicBoolean getAnsweredFlag() {
+        return this.answered;
+    }
 }
diff --git a/backend/src/test/java/io/f1/backend/domain/game/app/ChatServiceTests.java b/backend/src/test/java/io/f1/backend/domain/game/app/ChatServiceTests.java
@@ -0,0 +1,212 @@
+package io.f1.backend.domain.game.app;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.junit.jupiter.api.Assertions.*;
+import static org.mockito.ArgumentMatchers.any;
+import static org.mockito.BDDMockito.given;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.never;
+import static org.mockito.Mockito.times;
+import static org.mockito.Mockito.verify;
+
+import io.f1.backend.domain.game.dto.ChatMessage;
+import io.f1.backend.domain.game.event.GameCorrectAnswerEvent;
+import io.f1.backend.domain.game.model.GameSetting;
+import io.f1.backend.domain.game.model.Player;
+import io.f1.backend.domain.game.model.Room;
+import io.f1.backend.domain.game.model.RoomSetting;
+import io.f1.backend.domain.game.model.RoomState;
+import io.f1.backend.domain.game.websocket.MessageSender;
+import io.f1.backend.domain.question.entity.Question;
+import io.f1.backend.domain.user.dto.UserPrincipal;
+import io.f1.backend.domain.user.entity.User;
+
+import lombok.extern.slf4j.Slf4j;
+
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.DisplayName;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.extension.ExtendWith;
+import org.mockito.ArgumentCaptor;
+import org.mockito.Mock;
+import org.mockito.MockitoAnnotations;
+import org.mockito.junit.jupiter.MockitoExtension;
+import org.springframework.context.ApplicationEventPublisher;
+import org.springframework.security.core.context.SecurityContextHolder;
+
+import java.lang.reflect.Field;
+import java.time.Instant;
+import java.time.LocalDateTime;
+import java.util.Collections;
+import java.util.concurrent.CountDownLatch;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+
+@Slf4j
+@ExtendWith(MockitoExtension.class)
+class ChatServiceTests {
+
+    private ChatService chatService;
+
+    @Mock private RoomService roomService;
+    @Mock private ApplicationEventPublisher eventPublisher;
+    @Mock private MessageSender messageSender;
+
+    @BeforeEach
+    void setUp() {
+        MockitoAnnotations.openMocks(this); // @Mock 어노테이션이 붙은 필드들을 초기화합니다.
+
+        chatService = new ChatService(roomService, messageSender, eventPublisher);
+
+        SecurityContextHolder.clearContext();
+    }
+
+    @Test
+    @DisplayName("정답이 아닐 때 이벤트가 발행되지 않는다.")
+    void noEventWhenIncorrect() throws Exception {
+
+        // given
+        Long roomId = 1L;
+        ChatMessage wrongMessage = new ChatMessage("뜨거운제티", "오답", Instant.now());
+
+        Room room = mock(Room.class);
+        Question question = mock(Question.class);
+        User user = createUser(1);
+        UserPrincipal userPrincipal = new UserPrincipal(user, Collections.emptyMap());
+
+        given(roomService.findRoom(roomId)).willReturn(room);
+        given(room.isPlaying()).willReturn(true);
+        given(room.getCurrentQuestion()).willReturn(question);
+        given(question.getAnswer()).willReturn("정답");
+
+        // when
+        chatService.chat(roomId, userPrincipal, wrongMessage);
+
+        // then
+        verify(eventPublisher, never()).publishEvent(any(GameCorrectAnswerEvent.class));
+    }
+
+    @Test
+    @DisplayName("정답일 때 GameCorrectAnswerEvent가 발행된다. ")
+    void EventPublishedWhenCorrect() throws Exception {
+
+        // given
+        Long roomId = 1L;
+        ChatMessage answer = new ChatMessage("뜨거운제티", "정답", Instant.now());
+
+        Room room = mock(Room.class);
+        Question question = mock(Question.class);
+        User user = createUser(1);
+        UserPrincipal userPrincipal = new UserPrincipal(user, Collections.emptyMap());
+
+        given(roomService.findRoom(roomId)).willReturn(room);
+        given(room.isPlaying()).willReturn(true);
+        given(room.getCurrentQuestion()).willReturn(question);
+        given(question.getAnswer()).willReturn("정답");
+        given(room.compareAndSetAnsweredFlag(false, true)).willReturn(true);
+
+        // when
+        chatService.chat(roomId, userPrincipal, answer);
+
+        // then
+        verify(eventPublisher, times(1)).publishEvent(any(GameCorrectAnswerEvent.class));
+    }
+
+    @Test
+    @DisplayName("동시에 여러 명의 사용자가 채팅을 보냈을 때, 한 명만 정답인정")
+    void onlyOneCorrectPlayerWhenConcurrentCorrectAnswers() throws Exception {
+
+        // given
+        Long roomId = 1L;
+        Long quizId = 1L;
+        Long playerId = 1L;
+        int maxUserCount = 5;
+        String password = "123";
+        boolean locked = true;
+        String correctAnswer = "정답";
+
+        Room room = createRoom(roomId, playerId, quizId, password, maxUserCount, locked);
+        Question question = mock(Question.class);
+        room.updateRoomState(RoomState.PLAYING);
+        room.increaseCurrentRound();
+        room.updateQuestions(Collections.singletonList(question));
+
+        // room이 실제 객체이므로, RoomService만 mock으로 대체
+        given(roomService.findRoom(roomId)).willReturn(room);
+        given(question.getAnswer()).willReturn(correctAnswer);
+
+        int userCount = 8;
+        ExecutorService executor = Executors.newFixedThreadPool(userCount);
+
+        CountDownLatch countDownLatch = new CountDownLatch(userCount);
+
+        ChatMessage msg = new ChatMessage("닉네임", correctAnswer, Instant.now());
+
+        for (int i = 0; i < userCount; i++) {
+            final int idx = i;
+            executor.submit(
+                    () -> {
+                        try {
+                            User user = createUser(idx);
+                            UserPrincipal principal =
+                                    new UserPrincipal(user, Collections.emptyMap());
+                            chatService.chat(roomId, principal, msg);
+                        } finally {
+                            countDownLatch.countDown();
+                        }
+                    });
+        }
+
+        countDownLatch.await();
+
+        // then: 이벤트는 단 1번만 발행돼야 함
+        ArgumentCaptor<GameCorrectAnswerEvent> captor =
+                ArgumentCaptor.forClass(GameCorrectAnswerEvent.class);
+        verify(eventPublisher, times(1)).publishEvent(captor.capture());
+
+        GameCorrectAnswerEvent event = captor.getValue();
+        log.info("정답 인정된 유저 ID : {}", event.userId());
+        assertThat(event.userId()).isBetween(0L, 7L);
+
+        verify(eventPublisher, times(1)).publishEvent(any(GameCorrectAnswerEvent.class));
+        assertThat(room.getAnswered().get()).isTrue();
+    }
+
+    private Room createRoom(
+            Long roomId,
+            Long playerId,
+            Long quizId,
+            String password,
+            int maxUserCount,
+            boolean locked) {
+        RoomSetting roomSetting = new RoomSetting("방제목", maxUserCount, locked, password);
+        GameSetting gameSetting = new GameSetting(quizId, 10, 60);
+        Player host = new Player(playerId, "nickname");
+
+        return new Room(roomId, roomSetting, gameSetting, host);
+    }
+
+    private User createUser(int i) {
+        Long userId = i + 1L;
+        String provider = "provider +" + i;
+        String providerId = "providerId" + i;
+        LocalDateTime lastLogin = LocalDateTime.now();
+
+        User user =
+                User.builder()
+                        .provider(provider)
+                        .providerId(providerId)
+                        .lastLogin(lastLogin)
+                        .build();
+
+        try {
+            Field idField = User.class.getDeclaredField("id");
+            idField.setAccessible(true);
+            idField.set(user, userId);
+        } catch (Exception e) {
+            throw new RuntimeException("ID 설정 실패", e);
+        }
+
+        return user;
+    }
+}
diff --git a/backend/src/test/java/io/f1/backend/domain/game/app/GameFlowTests.java b/backend/src/test/java/io/f1/backend/domain/game/app/GameFlowTests.java
