feat: SSE 서비스 운영 상태 정의 로직 구현

src/main/java/kr/allcll/backend/admin/preseat/AdminPreSeatService.java

@@ -3,6 +3,8 @@
 import java.time.LocalDate;
 import java.util.List;
 import kr.allcll.backend.admin.preseat.dto.PreSeatResponse;
+import kr.allcll.backend.admin.seat.SeatStreamStatus;
+import kr.allcll.backend.admin.seat.SeatStreamStatusService;
 import kr.allcll.crawler.client.SeatClient;
 import kr.allcll.crawler.client.model.SeatResponse;
 import kr.allcll.crawler.client.payload.SeatPayload;
@@ -25,10 +27,11 @@ public class AdminPreSeatService {
     private final SeatClient seatClient;
     private final Credentials credentials;
     private final AllPreSeatBuffer allPreSeatBuffer;
+    private final SeatStreamStatusService seatStreamStatusService;
     private final CrawlerSubjectRepository crawlerSubjectRepository;
 
-
     public void getAllPreSeat(String userId) {
+        seatStreamStatusService.updateSeatStreamStatus(SeatStreamStatus.PRESEAT);
         Credential credential = credentials.findByUserId(userId);
         List<CrawlerSubject> crawlerSubjects = crawlerSubjectRepository.findAllBySemesterAt(CrawlerSemester.now());
         for (CrawlerSubject crawlerSubject : crawlerSubjects) {
@@ -52,6 +55,7 @@ private void sendExternalPreSeatsRequest(CrawlerSubject crawlerSubject, Credenti
         } catch (CrawlerAllcllException e) {
             log.error(
                 "[여석] 외부 API 호출에 실패했습니다. PreSeat: " + crawlerSubject.getCuriNo() + "-" + crawlerSubject.getClassName());
+            seatStreamStatusService.updateSeatStreamStatus(SeatStreamStatus.ERROR);
         }
     }
 

src/main/java/kr/allcll/backend/admin/seat/AdminSeatApi.java

@@ -2,7 +2,7 @@
 
 import jakarta.servlet.http.HttpServletRequest;
 import kr.allcll.backend.admin.AdminRequestValidator;
-import kr.allcll.backend.admin.seat.dto.SeatStatusResponse;
+import kr.allcll.backend.admin.seat.dto.SeatCrawlingStatusResponse;
 import lombok.RequiredArgsConstructor;
 import org.springframework.http.ResponseEntity;
 import org.springframework.web.bind.annotation.GetMapping;
@@ -41,12 +41,12 @@ public ResponseEntity<Void> seasonSeatStart(HttpServletRequest request,
     }
 
     @GetMapping("/api/admin/seat/check")
-    public ResponseEntity<SeatStatusResponse> getSeatStatus(HttpServletRequest request) {
+    public ResponseEntity<SeatCrawlingStatusResponse> getSeatStatus(HttpServletRequest request) {
         if (validator.isRateLimited(request) || validator.isUnauthorized(request)) {
             return ResponseEntity.status(401).build();
         }
-        SeatStatusResponse seatStatusResponse = adminSeatService.getSeatCrawlerStatus();
-        return ResponseEntity.ok(seatStatusResponse);
+        SeatCrawlingStatusResponse seatCrawlingStatusResponse = adminSeatService.getSeatCrawlingStatus();
+        return ResponseEntity.ok(seatCrawlingStatusResponse);
     }
 
     @PostMapping("/api/admin/seat/cancel")

src/main/java/kr/allcll/backend/admin/seat/AdminSeatService.java

@@ -5,7 +5,7 @@
 import java.time.LocalDateTime;
 import java.util.concurrent.atomic.AtomicLong;
 import kr.allcll.backend.admin.seat.dto.ChangeSubjectsResponse;
-import kr.allcll.backend.admin.seat.dto.SeatStatusResponse;
+import kr.allcll.backend.admin.seat.dto.SeatCrawlingStatusResponse;
 import kr.allcll.crawler.client.SeatClient;
 import kr.allcll.crawler.client.model.SeatResponse;
 import kr.allcll.crawler.client.payload.SeatPayload;
@@ -25,42 +25,47 @@
 @RequiredArgsConstructor
 public class AdminSeatService {
 
+    private final AtomicLong lastSuccessCrawlingTime = new AtomicLong(0);
     private static final long RECENT_CRAWLING_SUCCESS_THRESHOLD_MS = 3_000;
+
     private final SeatClient seatClient;
     private final Credentials credentials;
+    private final AllSeatBuffer allSeatBuffer;
+    private final ChangeDetector changeDetector;
+    private final SjptProperties sjptProperties;
     private final TargetSubjectStorage targetSubjectStorage;
     private final CrawlerScheduledTaskHandler seatScheduler;
     private final SeatPersistenceService seatPersistenceService;
-    private final SjptProperties sjptProperties;
-    private final ChangeDetector changeDetector;
-    private final AllSeatBuffer allSeatBuffer;
-    private final AtomicLong lastSuccessCrawlingTime = new AtomicLong(0);
+    private final SeatStreamStatusService seatStreamStatusService;
 
     public void getAllSeatPeriodically(String userId) {
+        seatStreamStatusService.updateSeatStreamStatus(SeatStreamStatus.LIVE);
         Credential credential = credentials.findByUserId(userId);
         fetchPinSeat(credential);
         fetchGeneralSeat(credential);
     }
 
     public void getSeasonSeatPeriodically(String userId) {
+        seatStreamStatusService.updateSeatStreamStatus(SeatStreamStatus.LIVE);
         Credential credential = credentials.findByUserId(userId);
         fetchPinSeat(credential);
         fetchGeneralSeat(credential);
     }
 
     public void cancelSeatScheduling() {
         seatScheduler.cancelAll();
+        seatStreamStatusService.updateSeatStreamStatus(SeatStreamStatus.IDLE);
     }
 
-    public SeatStatusResponse getSeatCrawlerStatus() {
+    public SeatCrawlingStatusResponse getSeatCrawlingStatus() {
         int seatSchedulerTaskCount = seatScheduler.getTaskCount();
         boolean validSeatSchedulerCount = seatSchedulerTaskCount == sjptProperties.getRequestPerSecondCount();
         boolean validRecentCrawlingSuccess =
             (System.currentTimeMillis() - lastSuccessCrawlingTime.get()) <= RECENT_CRAWLING_SUCCESS_THRESHOLD_MS;
 
         boolean isActive = validSeatSchedulerCount && validRecentCrawlingSuccess;
 
-        return SeatStatusResponse.of(isActive);
+        return SeatCrawlingStatusResponse.of(isActive);
     }
 
     private void fetchPinSeat(Credential credential) {
@@ -125,6 +130,7 @@ private void sendExternalRequestWithOutDetect(CrawlerSubject crawlerSubject, Cre
         } catch (CrawlerAllcllException e) {
             log.error(
                 "[여석] 외부 API 호출에 실패했습니다. 과목: " + crawlerSubject.getCuriNo() + "-" + crawlerSubject.getClassName());
+            seatStreamStatusService.updateSeatStreamStatus(SeatStreamStatus.ERROR);
         }
     }
 

src/main/java/kr/allcll/backend/admin/seat/SeatStreamStatus.java

@@ -0,0 +1,18 @@
+package kr.allcll.backend.admin.seat;
+
+public enum SeatStreamStatus {
+    LIVE("과목의 여석을 실시간으로 볼 수 있어요."),
+    PRESEAT("전체 학년 여석 탭을 이용해 주세요."),
+    IDLE("과목 실시간 여석 제공 전이에요. 서비스가 시작되면 알림을 드릴게요."),
+    ERROR("서비스 점검 중이에요. 조금만 기다려주세요.");
+
+    private final String message;
+
+    SeatStreamStatus(String message) {
+        this.message = message;
+    }
+
+    public String getMessage() {
+        return message;
+    }
+}

src/main/java/kr/allcll/backend/admin/seat/SeatStreamStatusService.java

@@ -0,0 +1,34 @@
+package kr.allcll.backend.admin.seat;
+
+import java.util.Objects;
+import kr.allcll.backend.admin.seat.dto.SeatStreamStatusResponse;
+import kr.allcll.backend.support.sse.SseEventBuilderFactory;
+import kr.allcll.backend.support.sse.SseService;
+import lombok.RequiredArgsConstructor;
+import org.springframework.stereotype.Service;
+
+@Service
+@RequiredArgsConstructor
+public class SeatStreamStatusService {
+
+    private final SseService sseService;
+    public final SeatStreamStatusStore seatStreamStatusStore;
+
+    public void updateSeatStreamStatus(SeatStreamStatus newStatus) {
+        SeatStreamStatus currentStatus = seatStreamStatusStore.getCurrentStatus();
+        if (Objects.equals(currentStatus, newStatus)) {
+            return;
+        }
+        seatStreamStatusStore.updateCurrentStatus(newStatus);
+
+        SeatStreamStatusResponse sseStatusResponse = getSeatStreamStatusResponse(newStatus);
+        sseService.propagate(SseEventBuilderFactory.EVENT_SEAT_STREAM_STATUS, sseStatusResponse);
+    }
+
+    private SeatStreamStatusResponse getSeatStreamStatusResponse(SeatStreamStatus newStatus) {
+        return SeatStreamStatusResponse.of(
+            newStatus.name().toLowerCase(),
+            newStatus.getMessage()
+        );
+    }
+}

src/main/java/kr/allcll/backend/admin/seat/SeatStreamStatusStore.java

@@ -0,0 +1,21 @@
+package kr.allcll.backend.admin.seat;
+
+import org.springframework.stereotype.Component;
+
+@Component
+public class SeatStreamStatusStore {
+
+    private volatile SeatStreamStatus currentStatus;
+
+    public SeatStreamStatusStore() {
+        this.currentStatus = SeatStreamStatus.IDLE;
+    }
+
+    public SeatStreamStatus getCurrentStatus() {
+        return currentStatus;
+    }
+
+    public void updateCurrentStatus(SeatStreamStatus newStatus) {
+        this.currentStatus = newStatus;
+    }
+}

src/main/java/kr/allcll/backend/admin/seat/dto/SeatCrawlingStatusResponse.java

@@ -0,0 +1,10 @@
+package kr.allcll.backend.admin.seat.dto;
+
+public record SeatCrawlingStatusResponse(
+    boolean isActive
+) {
+
+    public static SeatCrawlingStatusResponse of(boolean isActive) {
+        return new SeatCrawlingStatusResponse(isActive);
+    }
+}

src/main/java/kr/allcll/backend/admin/seat/dto/SeatStreamStatusResponse.java

@@ -0,0 +1,11 @@
+package kr.allcll.backend.admin.seat.dto;
+
+public record SeatStreamStatusResponse(
+    String status,
+    String message
+) {
+
+    public static SeatStreamStatusResponse of(String status, String message) {
+        return new SeatStreamStatusResponse(status, message);
+    }
+}

src/main/java/kr/allcll/backend/support/sse/SseEventBuilderFactory.java

@@ -4,6 +4,8 @@
 import com.fasterxml.jackson.databind.ObjectMapper;
 import com.fasterxml.jackson.databind.SerializationFeature;
 import com.fasterxml.jackson.datatype.jsr310.JavaTimeModule;
+import kr.allcll.backend.admin.seat.SeatStreamStatus;
+import kr.allcll.backend.admin.seat.dto.SeatStreamStatusResponse;
 import org.springframework.http.MediaType;
 import org.springframework.web.servlet.mvc.method.annotation.SseEmitter;
 import org.springframework.web.servlet.mvc.method.annotation.SseEmitter.SseEventBuilder;
@@ -12,6 +14,9 @@ public class SseEventBuilderFactory {
 
     private static final ObjectMapper objectMapper = new ObjectMapper();
 
+    public static final String EVENT_CONNECTION = "connection";
+    public static final String EVENT_SEAT_STREAM_STATUS = "status";
+
     private static final long RECONNECT_TIME_MILLIS = 1000L;
 
     static {
@@ -32,10 +37,26 @@ public static SseEventBuilder create(String eventName, Object value) {
 
     public static SseEventBuilder createInitialEvent() {
         return baseEvent()
-            .name("connection")
+            .name(EVENT_CONNECTION)
             .data("success", MediaType.TEXT_PLAIN);
     }
 
+    public static SseEventBuilder createInitialSeatStreamStatusEvent(SeatStreamStatus seatStreamStatus) {
+        SeatStreamStatusResponse seatStreamStatusResponse = SeatStreamStatusResponse.of(
+            seatStreamStatus.name().toLowerCase(),
+            seatStreamStatus.getMessage()
+        );
+
+        try {
+            String sseEvent = objectMapper.writeValueAsString(seatStreamStatusResponse);
+            return baseEvent()
+                .name(EVENT_SEAT_STREAM_STATUS)
+                .data(sseEvent, MediaType.APPLICATION_JSON);
+        } catch (JsonProcessingException e) {
+            throw new RuntimeException(e);
+        }
+    }
+
     private static SseEventBuilder baseEvent() {
         return SseEmitter.event()
             .reconnectTime(RECONNECT_TIME_MILLIS);

src/main/java/kr/allcll/backend/support/sse/SseService.java

@@ -2,7 +2,8 @@
 
 import java.io.IOException;
 import java.util.List;
-import kr.allcll.backend.support.sse.dto.SseStatusResponse;
+import kr.allcll.backend.admin.seat.SeatStreamStatus;
+import kr.allcll.backend.admin.seat.SeatStreamStatusStore;
 import lombok.RequiredArgsConstructor;
 import lombok.extern.slf4j.Slf4j;
 import org.springframework.stereotype.Service;
@@ -15,12 +16,20 @@
 public class SseService {
 
     private final SseEmitterStorage sseEmitterStorage;
+    private final SeatStreamStatusStore seatStreamStatusStore;
 
     public SseEmitter connect(String token) {
         SseEmitter sseEmitter = createSseEmitter();
         sseEmitterStorage.add(token, sseEmitter);
+
         SseEventBuilder initialEvent = SseEventBuilderFactory.createInitialEvent();
         sendEvent(sseEmitter, initialEvent);
+
+        SeatStreamStatus seatStreamStatus = seatStreamStatusStore.getCurrentStatus();
+        SseEventBuilder initialSeatStreamStatusEvent = SseEventBuilderFactory.createInitialSeatStreamStatusEvent(
+            seatStreamStatus);
+        sendEvent(sseEmitter, initialSeatStreamStatusEvent);
+
         return sseEmitter;
     }
 
@@ -54,9 +63,4 @@ private void sendEvent(SseEmitter sseEmitter, SseEventBuilder eventBuilder) {
     public List<String> getConnectedTokens() {
         return sseEmitterStorage.getUserTokens().stream().toList();
     }
-
-    public SseStatusResponse isConnected(String token) {
-        boolean isConnected = sseEmitterStorage.getEmitter(token).isPresent();
-        return SseStatusResponse.of(isConnected);
-    }
 }

src/test/java/kr/allcll/backend/support/sse/SseServiceTest.java

@@ -53,6 +53,7 @@ void sseConnectionTest() {
 
         // then
         SseTestHelper.assertResponseContainsMessage(response, "success");
+        SseTestHelper.assertResponseContainsMessage(response, "idle");
     }
 
     @DisplayName("동시에 여러 클라이언트와 SSE 연결을 유지하고, 모두에게 메시지를 전달한다.")
@@ -86,6 +87,10 @@ void ssePropagationTest() {
             + "data:success\n"
             + "\n"
             + "retry:1000\n"
+            + "event:status\n"
+            + "data:{\"status\":\"idle\",\"message\":\"과목 실시간 여석 제공 전이에요. 서비스가 시작되면 알림을 드릴게요.\"}\n"
+            + "\n"
+            + "retry:1000\n"
             + "event:message\n"
             + "data:\"Hello, SSE!\"\n"
             + "\n";