#50 오늘의 맛집 캐싱 도입

src/main/java/com/matzip/place/application/port/RankingTempStore.java

@@ -0,0 +1,17 @@
+package com.matzip.place.application.port;
+
+import com.matzip.place.api.response.PlaceRankingResponseDto;
+import com.matzip.place.domain.Campus;
+
+import java.time.LocalDate;
+import java.util.List;
+import java.util.Optional;
+
+public interface RankingTempStore {
+
+    Optional<List<PlaceRankingResponseDto>> get(LocalDate date, Campus campus);
+
+    void set(LocalDate date, Campus campus, List<PlaceRankingResponseDto> rankingResponseDtos);
+
+    void remove(LocalDate date, Campus campus);
+}

src/main/java/com/matzip/place/application/service/PlaceReadService.java

@@ -6,13 +6,13 @@
 import com.matzip.place.api.response.CategoryPlaceResponseDto;
 import com.matzip.place.api.response.MapSearchResponseDto;
 import com.matzip.place.api.response.PlaceDetailResponseDto;
+import com.matzip.place.application.port.RankingTempStore;
 import com.matzip.place.domain.entity.*;
 import com.matzip.place.api.response.PlaceRankingResponseDto;
 import com.matzip.place.domain.*;
 import com.matzip.place.infra.repository.*;
 import com.matzip.place.dto.CategoryDto;
 import com.matzip.place.dto.TagDto;
-import com.matzip.user.domain.User;
 import com.matzip.user.infra.UserRepository;
 import lombok.RequiredArgsConstructor;
 import org.springframework.data.domain.PageRequest;
@@ -39,8 +39,10 @@ public class PlaceReadService {
     private final PlaceLikeRepository placeLikeRepository;
     private final UserRepository userRepository;
     private final ViewCountService viewCountService;
+    private final RankingTempStore rankingTempStore;
 
     private static final int RANKING_SIZE = 10;
+    private static final int MINIMUM_RANKING_SIZE = 3;
 
     @Transactional
     public PlaceDetailResponseDto getPlaceDetail(Long placeId, Long userId) {
@@ -95,18 +97,17 @@ public List<MapSearchResponseDto> findPlacesInMapBounds(MapSearchRequestDto requ
 
     public List<PlaceRankingResponseDto> getRanking(Campus campus, String sort) {
         if ("views".equals(sort)) {
-            return getDailyRankingByViews(campus);
+            return getRankingByViewsWithFallback(campus);
         }
 
         // TODO: 찜 많은 맛집 기능 구현 후 추가하기
-        return getDailyRankingByViews(campus);
+        return getRankingByViewsWithFallback(campus);
     }
 
-    private List<PlaceRankingResponseDto> getDailyRankingByViews(Campus campus) {
-        LocalDate today = LocalDate.now();
+    public List<PlaceRankingResponseDto> getDailyRankingByViews(Campus campus, LocalDate date) {
         Pageable topN = PageRequest.of(0, RANKING_SIZE);
 
-        List<DailyViewCount> dailyRankings = dailyViewCountRepository.findDailyRankingByCampus(campus, today, topN);
+        List<DailyViewCount> dailyRankings = dailyViewCountRepository.findDailyRankingByCampus(campus, date, topN);
 
         return dailyRankings.stream()
                 .map(dailyViewCount -> {
@@ -117,6 +118,18 @@ private List<PlaceRankingResponseDto> getDailyRankingByViews(Campus campus) {
                 .collect(Collectors.toList());
     }
 
+    private List<PlaceRankingResponseDto> getRankingByViewsWithFallback(Campus campus) {
+        LocalDate today = LocalDate.now();
+        List<PlaceRankingResponseDto> todaysRanking = getDailyRankingByViews(campus, today);
+
+        if (todaysRanking.size() < MINIMUM_RANKING_SIZE) {
+            LocalDate yesterday = today.minusDays(1);
+            return rankingTempStore.get(yesterday, campus)
+                    .orElseGet(() -> getDailyRankingByViews(campus, yesterday));
+        }
+        return todaysRanking;
+    }
+
     /**
      * Place의 연관 데이터를 조회하는 공통 메서드
      */

src/main/java/com/matzip/place/infra/cache/PlaceRankingTempStoreMemory.java

@@ -0,0 +1,41 @@
+package com.matzip.place.infra.cache;
+
+import com.matzip.place.api.response.PlaceRankingResponseDto;
+import com.matzip.place.application.port.RankingTempStore;
+import com.matzip.place.domain.Campus;
+import org.springframework.stereotype.Component;
+
+import java.time.LocalDate;
+import java.util.List;
+import java.util.Map;
+import java.util.Optional;
+import java.util.concurrent.ConcurrentHashMap;
+
+@Component
+public class PlaceRankingTempStoreMemory implements RankingTempStore {
+
+    private final Map<String, List<PlaceRankingResponseDto>> store = new ConcurrentHashMap<>();
+
+
+    @Override
+    public Optional<List<PlaceRankingResponseDto>> get(LocalDate date, Campus campus) {
+        String key = generateKey(date, campus);
+        return Optional.ofNullable(store.get(key));
+    }
+
+    @Override
+    public void set(LocalDate date, Campus campus, List<PlaceRankingResponseDto> rankingResponseDtos) {
+        String key = generateKey(date, campus);
+        store.put(key, rankingResponseDtos);
+    }
+
+    @Override
+    public void remove(LocalDate date, Campus campus) {
+        String key = generateKey(date, campus);
+        store.remove(key);
+    }
+
+    private String generateKey(LocalDate date, Campus campus) {
+        return date.toString() + ":" + campus.name();
+    }
+}

src/main/java/com/matzip/place/infra/scheduler/PlaceRankingScheduler.java

@@ -0,0 +1,34 @@
+package com.matzip.place.infra.scheduler;
+
+import com.matzip.place.api.response.PlaceRankingResponseDto;
+import com.matzip.place.application.port.RankingTempStore;
+import com.matzip.place.application.service.PlaceReadService;
+import com.matzip.place.domain.Campus;
+import lombok.RequiredArgsConstructor;
+import org.springframework.scheduling.annotation.Scheduled;
+import org.springframework.stereotype.Component;
+
+import java.time.LocalDate;
+import java.util.Arrays;
+import java.util.List;
+
+@Component
+@RequiredArgsConstructor
+public class PlaceRankingScheduler {
+
+    private final PlaceReadService placeReadService;
+    private final RankingTempStore rankingTempStore;
+
+    @Scheduled(cron = "0 5 0 * * *")
+    public void cachePreviousDayPlaceRankings() {
+        LocalDate yesterday = LocalDate.now().minusDays(1);
+        LocalDate twoDaysAgo = LocalDate.now().minusDays(2);
+
+        Arrays.stream(Campus.values()).forEach(campus -> {
+            List<PlaceRankingResponseDto> ranking = placeReadService.getDailyRankingByViews(campus, yesterday);
+            rankingTempStore.set(yesterday, campus, ranking);
+
+            rankingTempStore.remove(twoDaysAgo, campus);
+        });
+    }
+}