refactor: 캐싱 전략 적용을 위해 지도 API 서비스 로직 수정

- Look-Aside + Write-Around 캐싱 전략 적용

Author: dnzp75

src/main/java/com/example/log4u/domain/diary/service/DiaryService.java

@@ -278,4 +278,8 @@ public void checkDiaryExists(Long diaryId) {
 	public List<Diary> getTop10Diaries() {
 		return diaryRepository.findTop10ByVisibilityOrderByLikeCountDesc(VisibilityType.PUBLIC);
 	}
+
+	public List<Diary> getDiaries(List<Long> ids) {
+		return diaryRepository.findAllById(ids);
+	}
 }

src/main/java/com/example/log4u/domain/map/dto/response/DiaryMarkerResponseDto.java

@@ -2,6 +2,8 @@
 
 import java.time.LocalDateTime;
 
+import com.example.log4u.domain.diary.entity.Diary;
+
 public record DiaryMarkerResponseDto(
 	Long diaryId,
 	String title,
@@ -10,6 +12,16 @@ public record DiaryMarkerResponseDto(
 	Double lat,
 	Double lon,
 	LocalDateTime createdAt
-
 ) {
+	public static DiaryMarkerResponseDto of(Diary diary) {
+		return new DiaryMarkerResponseDto(
+			diary.getDiaryId(),
+			diary.getTitle(),
+			diary.getThumbnailUrl(),
+			diary.getLikeCount(),
+			diary.getLocation().getLatitude(),
+			diary.getLocation().getLongitude(),
+			diary.getCreatedAt()
+		);
+	}
 }

src/main/java/com/example/log4u/domain/map/exception/InvalidGeohashException.java

@@ -0,0 +1,7 @@
+package com.example.log4u.domain.map.exception;
+
+public class InvalidGeohashException extends MapException {
+	public InvalidGeohashException() {
+		super(MapErrorCode.INVALID_GEOHASH);
+	}
+}

src/main/java/com/example/log4u/domain/map/exception/InvalidMapLevelException.java

@@ -0,0 +1,7 @@
+package com.example.log4u.domain.map.exception;
+
+public class InvalidMapLevelException extends MapException {
+	public InvalidMapLevelException() {
+		super(MapErrorCode.INVALID_MAP_LEVEL);
+	}
+}

src/main/java/com/example/log4u/domain/map/exception/MapErrorCode.java

@@ -12,7 +12,9 @@
 public enum MapErrorCode implements ErrorCode {
 
 	NOT_FOUND_REGION(HttpStatus.NOT_FOUND, "해당 지역(시/군/구)을 찾을 수 없습니다."),
-	UNAUTHORIZED_MAP_ACCESS(HttpStatus.FORBIDDEN, "지도 리소스에 대한 권한이 없습니다.");
+	UNAUTHORIZED_MAP_ACCESS(HttpStatus.FORBIDDEN, "지도 리소스에 대한 권한이 없습니다."),
+	INVALID_MAP_LEVEL(HttpStatus.BAD_REQUEST, "유효하지 않은 지도 level 값입니다."),
+	INVALID_GEOHASH(HttpStatus.BAD_REQUEST,"geohash 길이가 유효하지 않습니다");
 
 	private final HttpStatus httpStatus;
 	private final String message;

src/main/java/com/example/log4u/domain/map/repository/sido/query/SidoAreasRepositoryCustom.java

@@ -5,8 +5,6 @@
 import com.example.log4u.domain.map.dto.response.DiaryClusterResponseDto;
 
 public interface SidoAreasRepositoryCustom {
-	List<DiaryClusterResponseDto> findSidoAreaClusters(double south, double north, double west, double east);
-
-	List<DiaryClusterResponseDto> findAllWithDiaryCount();
 
+	List<DiaryClusterResponseDto> findByGeohashPrefix(String geohashPrefix);
 }

src/main/java/com/example/log4u/domain/map/repository/sido/query/SidoAreasRepositoryImpl.java

@@ -21,29 +21,7 @@ public SidoAreasRepositoryImpl(@Qualifier("postgresJPAQueryFactory") JPAQueryFac
 	}
 
 	@Override
-	public List<DiaryClusterResponseDto> findSidoAreaClusters(double south, double north, double west, double east) {
-		QSidoAreas s = QSidoAreas.sidoAreas;
-		QSidoAreasDiaryCount c = QSidoAreasDiaryCount.sidoAreasDiaryCount;
-
-		return queryFactory
-			.select(new QDiaryClusterResponseDto(
-				s.name,
-				s.id,
-				s.lat,
-				s.lon,
-				c.diaryCount.coalesce(0L)
-			))
-			.from(s)
-			.leftJoin(c).on(s.id.eq(c.id))
-			.where(
-				s.lat.between(south, north),
-				s.lon.between(west, east)
-			)
-			.fetch();
-	}
-
-	@Override
-	public List<DiaryClusterResponseDto> findAllWithDiaryCount() {
+	public List<DiaryClusterResponseDto> findByGeohashPrefix(String geohashPrefix) {
 		QSidoAreas s = QSidoAreas.sidoAreas;
 		QSidoAreasDiaryCount c = QSidoAreasDiaryCount.sidoAreasDiaryCount;
 
@@ -57,6 +35,7 @@ public List<DiaryClusterResponseDto> findAllWithDiaryCount() {
 			))
 			.from(s)
 			.leftJoin(c).on(s.id.eq(c.id))
+			.where(s.geohash.startsWith(geohashPrefix))
 			.fetch();
 	}
 }

src/main/java/com/example/log4u/domain/map/repository/sigg/query/SiggAreasRepositoryCustom.java

@@ -5,8 +5,6 @@
 import com.example.log4u.domain.map.dto.response.DiaryClusterResponseDto;
 
 public interface SiggAreasRepositoryCustom {
-	List<DiaryClusterResponseDto> findSiggAreaClusters(double south, double north, double west, double east);
-
-	List<DiaryClusterResponseDto> findAllWithDiaryCount();
 
+	List<DiaryClusterResponseDto> findByGeohashPrefix(String geohashPrefix);
 }

src/main/java/com/example/log4u/domain/map/repository/sigg/query/SiggAreasRepositoryImpl.java

@@ -21,30 +21,7 @@ public SiggAreasRepositoryImpl(@Qualifier("postgresJPAQueryFactory") JPAQueryFac
 	}
 
 	@Override
-	public List<DiaryClusterResponseDto> findSiggAreaClusters(double south, double north, double west, double east) {
-		QSiggAreas s = QSiggAreas.siggAreas;
-		QSiggAreasDiaryCount c = QSiggAreasDiaryCount.siggAreasDiaryCount;
-
-		return queryFactory
-			.select(new QDiaryClusterResponseDto(
-				s.sggName,
-				s.gid,
-				s.lat,
-				s.lon,
-				c.diaryCount.coalesce(0L)
-			))
-			.from(s)
-			.leftJoin(c).on(s.gid.eq(c.id))
-			.where(
-				s.lat.between(south, north),
-				s.lon.between(west, east)
-			)
-			.fetch();
-	}
-
-
-	@Override
-	public List<DiaryClusterResponseDto> findAllWithDiaryCount() {
+	public List<DiaryClusterResponseDto> findByGeohashPrefix(String geohashPrefix) {
 		QSiggAreas s = QSiggAreas.siggAreas;
 		QSiggAreasDiaryCount c = QSiggAreasDiaryCount.siggAreasDiaryCount;
 
@@ -58,6 +35,7 @@ public List<DiaryClusterResponseDto> findAllWithDiaryCount() {
 			))
 			.from(s)
 			.leftJoin(c).on(s.gid.eq(c.id))
+			.where(s.geohash.startsWith(geohashPrefix))
 			.fetch();
 	}
 }

src/main/java/com/example/log4u/domain/map/service/MapService.java

@@ -1,15 +1,26 @@
 package com.example.log4u.domain.map.service;
 
-import java.time.Duration;
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.HashSet;
 import java.util.List;
+import java.util.Set;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
 
 import org.springframework.stereotype.Service;
 import org.springframework.transaction.annotation.Transactional;
 
-import com.example.log4u.common.redis.RedisDao;
-import com.example.log4u.domain.diary.repository.DiaryRepository;
+import com.example.log4u.domain.diary.entity.Diary;
+import com.example.log4u.domain.diary.service.DiaryService;
+import com.example.log4u.domain.diary.service.DiaryGeohashService;
 import com.example.log4u.domain.map.dto.response.DiaryClusterResponseDto;
 import com.example.log4u.domain.map.dto.response.DiaryMarkerResponseDto;
+import com.example.log4u.domain.map.cache.dao.ClusterCacheDao;
+import com.example.log4u.domain.map.cache.dao.DiaryCacheDao;
+import com.example.log4u.domain.map.cache.RedisTTLPolicy;
+import com.example.log4u.domain.map.exception.InvalidGeohashException;
+import com.example.log4u.domain.map.exception.InvalidMapLevelException;
 import com.example.log4u.domain.map.repository.sido.SidoAreasDiaryCountRepository;
 import com.example.log4u.domain.map.repository.sido.SidoAreasRepository;
 import com.example.log4u.domain.map.repository.sigg.SiggAreasDiaryCountRepository;
@@ -27,28 +38,118 @@ public class MapService {
 	private final SidoAreasDiaryCountRepository sidoAreasDiaryCountRepository;
 	private final SiggAreasRepository siggAreasRepository;
 	private final SiggAreasDiaryCountRepository siggAreasDiaryCountRepository;
-	private final DiaryRepository diaryRepository;
-	private final RedisDao redisDao;
-
-	public List<DiaryClusterResponseDto> getDiaryClusters(
-		double south, double north, double west, double east, int zoom) {
-		if (zoom <= 10) {
-			return getSidoAreasClusters(south, north, west, east);
-		} else {
-			return getSiggAreasClusters(south, north, west, east);
+	private final DiaryCacheDao diaryCacheDao;
+	private final ClusterCacheDao clusterCacheDao;
+	private final DiaryService diaryService;
+	private final DiaryGeohashService diaryGeohashService;
+
+	/**
+	 * 캐싱 전략: Look-Aside + Write-Around
+	 * 	- Redis에서 클러스터 데이터를 먼저 조회 (캐시 HIT 시 바로 응답)
+	 * 	- 캐시 MISS 시 DB에서 조회 후 Redis에 저장하고 응답
+	 *
+	 * level 기준:
+	 *   - level 1: 시/도 단위 클러스터 (sido)
+	 *   - level 2: 시/군/구 단위 클러스터 (sigg)
+	 */
+	@Transactional(readOnly = true)
+	public List<DiaryClusterResponseDto> getDiaryClusters(String geohash, int level) {
+		validateGeohashLength(geohash, 3);
+		return clusterCacheDao.getDiaryCluster(geohash, level)
+			.orElseGet(() -> {
+				List<DiaryClusterResponseDto> dbResult = loadClustersFromDb(geohash, level);
+				clusterCacheDao.setDiaryCluster(geohash, level, dbResult, RedisTTLPolicy.CLUSTER_TTL);
+				return dbResult;
+			});
+	}
+
+	private List<DiaryClusterResponseDto> loadClustersFromDb(String geohash, int level) {
+		return switch (level) {
+			case 1 -> sidoAreasRepository.findByGeohashPrefix(geohash);
+			case 2 -> siggAreasRepository.findByGeohashPrefix(geohash);
+			default -> throw new InvalidMapLevelException();
+		};
+	}
+
+	/**
+	 * 캐싱 전략: Look-Aside + Write-Around
+	 *
+	 * [1단계] geohash → diaryIds 조회
+	 *   - Redis(Set)에서 diaryIds 조회 (캐시 HIT 시 바로 사용)
+	 *   - 캐시 MISS 시 DB 조회 후 Redis에 저장 (Write-Around)
+	 *
+	 * [2단계] diaryId → DiaryMarkerDto 조회
+	 *   - Redis(String)에서 Diary DTO 조회 (캐시 HIT 시 바로 사용)
+	 *   - 캐시 MISS 시 DB에서 조회 후 Redis에 저장 (Write-Around)
+	 */
+	@Transactional(readOnly = true)
+	public List<DiaryMarkerResponseDto> getDiariesByGeohash(String geohash) {
+		validateGeohashLength(geohash, 5);
+		Set<Long> diaryIds = loadDiaryIdsFromGeoCache(geohash);
+		return loadDiaryDtosFromCache(diaryIds);
+	}
+
+	private Set<Long> loadDiaryIdsFromGeoCache(String geohash) {
+		Set<Long> cachedIds = diaryCacheDao.getDiaryIdSetFromCache(geohash);
+		if (!cachedIds.isEmpty())
+			return cachedIds;
+
+		List<Long> diaryIds = diaryGeohashService.getDiaryIdsByGeohash(geohash);
+		diaryCacheDao.cacheDiaryIdSetByGeohash(geohash, diaryIds);
+		return new HashSet<>(diaryIds);
+	}
+
+	private List<DiaryMarkerResponseDto> loadDiaryDtosFromCache(Set<Long> diaryIds) {
+		List<DiaryMarkerResponseDto> cached = getCachedDiaryDtos(diaryIds);
+		List<Long> missedIds = getCacheMissedIds(diaryIds, cached);
+		List<DiaryMarkerResponseDto> loaded = loadDiariesAndCache(missedIds);
+
+		return Stream.concat(cached.stream(), loaded.stream())
+			.toList();
+	}
+
+	private List<DiaryMarkerResponseDto> getCachedDiaryDtos(Set<Long> ids) {
+		List<DiaryMarkerResponseDto> cached = new ArrayList<>();
+		for (Long id : ids) {
+			DiaryMarkerResponseDto dto = diaryCacheDao.getDiaryFromCache(id);
+			if (dto != null) cached.add(dto);
 		}
+		return cached;
 	}
 
-	private List<DiaryClusterResponseDto> getSidoAreasClusters(double south, double north, double west, double east) {
-		return sidoAreasRepository.findSidoAreaClusters(south, north, west, east);
+	private List<Long> getCacheMissedIds(Set<Long> allIds, List<DiaryMarkerResponseDto> cachedDtos) {
+		Set<Long> cachedIds = cachedDtos.stream()
+			.map(DiaryMarkerResponseDto::diaryId)
+			.collect(Collectors.toSet());
+
+		return allIds.stream()
+			.filter(id -> !cachedIds.contains(id))
+			.collect(Collectors.toList());
 	}
 
-	private List<DiaryClusterResponseDto> getSiggAreasClusters(double south, double north, double west, double east) {
-		return siggAreasRepository.findSiggAreaClusters(south, north, west, east);
+	private List<DiaryMarkerResponseDto> loadDiariesAndCache(List<Long> missedIds) {
+		if (missedIds.isEmpty())
+			return Collections.emptyList();
+
+		List<Diary> diaries = diaryService.getDiaries(missedIds);
+		List<DiaryMarkerResponseDto> result = new ArrayList<>();
+
+		for (Diary diary : diaries) {
+			DiaryMarkerResponseDto dto = DiaryMarkerResponseDto.of(diary);
+			diaryCacheDao.cacheDiary(diary.getDiaryId(), dto);
+			result.add(dto);
+		}
+
+		return result;
 	}
 
+	private void validateGeohashLength(String geohash, int expectedLength) {
+		if (geohash == null || geohash.length() != expectedLength) {
+			throw new InvalidGeohashException();
+		}
+	}
 
-		@Transactional
+	@Transactional
 	public void increaseRegionDiaryCount(Double lat, Double lon) {
 		sidoAreasRepository.findRegionByLatLon(lat, lon)
 			.flatMap(sido -> sidoAreasDiaryCountRepository.findById(sido.getId()))
@@ -81,10 +182,4 @@ public void decreaseRegionDiaryCount(Double lat, Double lon) {
 				siggAreasDiaryCountRepository.save(count);
 			});
 	}
-
-	@Transactional(readOnly = true)
-	public List<DiaryMarkerResponseDto> getDiariesInBounds(double south, double north, double west, double east) {
-		return diaryRepository.findDiariesInBounds(south, north, west, east);
-	}
-
 }