feat: Redis 캐시 연동을 위한 DAO 및 TTL 정책 클래스 추가

- 각 API 역할에 따라 캐시 DAO를 기능별로 분리 (ClusterCacheDao, DiaryCacheDao)
- Redis 장애 시 fallback을 위한 DB 조회 및 예외 처리 적용

Author: dnzp75

src/main/java/com/example/log4u/domain/map/cache/CacheKeyGenerator.java

@@ -0,0 +1,21 @@
+package com.example.log4u.domain.map.cache;
+
+public class CacheKeyGenerator {
+
+	private static final String CLUSTER_CACHE_KEY_FORMAT = "cluster:geohash:%s:level:%d";
+	private static final String DIARY_KEY_PREFIX = "marker:diary:";
+	private static final String GEOHASH_ID_SET_PREFIX = "marker:ids:geohash:";
+
+	public static String clusterCacheKey(String geohash, int level) {
+		return String.format(CLUSTER_CACHE_KEY_FORMAT, geohash, level);
+	}
+
+	public static String diaryKey(Long diaryId) {
+		return DIARY_KEY_PREFIX + diaryId;
+	}
+
+	public static String diaryIdSetKey(String geohash) {
+		return GEOHASH_ID_SET_PREFIX + geohash;
+	}
+}
+

src/main/java/com/example/log4u/domain/map/cache/RedisTTLPolicy.java

@@ -0,0 +1,9 @@
+package com.example.log4u.domain.map.cache;
+
+import java.time.Duration;
+
+public class RedisTTLPolicy {
+	public static final Duration DIARY_ID_SET_TTL = Duration.ofMinutes(60);
+	public static final Duration DIARY_TTL = Duration.ofMinutes(60);
+	public static final Duration CLUSTER_TTL = Duration.ofMinutes(60);
+}

src/main/java/com/example/log4u/domain/map/cache/dao/ClusterCacheDao.java

@@ -0,0 +1,42 @@
+package com.example.log4u.domain.map.cache.dao;
+
+import java.time.Duration;
+import java.util.List;
+import java.util.Optional;
+
+import org.springframework.data.redis.core.RedisTemplate;
+import org.springframework.stereotype.Component;
+
+import com.example.log4u.domain.map.cache.CacheKeyGenerator;
+import com.example.log4u.domain.map.dto.response.DiaryClusterResponseDto;
+
+import lombok.RequiredArgsConstructor;
+import lombok.extern.slf4j.Slf4j;
+
+@Component
+@RequiredArgsConstructor
+@Slf4j
+public class ClusterCacheDao {
+
+	private final RedisTemplate<String, List<DiaryClusterResponseDto>> diaryClusterRedisTemplate;
+
+	public Optional<List<DiaryClusterResponseDto>> getDiaryCluster(String geohash, int level) {
+		try {
+			String key = CacheKeyGenerator.clusterCacheKey(geohash, level);
+			List<DiaryClusterResponseDto> cached = diaryClusterRedisTemplate.opsForValue().get(key);
+			return Optional.ofNullable(cached);
+		} catch (Exception e) {
+			log.warn("클러스터 캐시 조회 실패 (geo={}, level={})", geohash, level, e);
+			return Optional.empty();
+		}
+	}
+
+	public void setDiaryCluster(String geohash, int level, List<DiaryClusterResponseDto> data, Duration ttl) {
+		try {
+			String key = CacheKeyGenerator.clusterCacheKey(geohash, level);
+			diaryClusterRedisTemplate.opsForValue().set(key, data, ttl);
+		} catch (Exception e) {
+			log.warn("클러스터 캐시 저장 실패 (geo={}, level={})", geohash, level, e);
+		}
+	}
+}

src/main/java/com/example/log4u/domain/map/cache/dao/DiaryCacheDao.java

@@ -0,0 +1,97 @@
+package com.example.log4u.domain.map.cache.dao;
+
+import java.util.Collections;
+import java.util.List;
+import java.util.Set;
+import java.util.stream.Collectors;
+
+import org.springframework.data.redis.core.RedisTemplate;
+import org.springframework.stereotype.Component;
+
+import com.example.log4u.domain.map.cache.CacheKeyGenerator;
+import com.example.log4u.domain.map.cache.RedisTTLPolicy;
+import com.example.log4u.domain.map.dto.response.DiaryMarkerResponseDto;
+import com.fasterxml.jackson.databind.ObjectMapper;
+
+import lombok.RequiredArgsConstructor;
+import lombok.extern.slf4j.Slf4j;
+
+@Component
+@RequiredArgsConstructor
+@Slf4j
+public class DiaryCacheDao {
+
+	private final RedisTemplate<String, Object> redisTemplate;
+	private final ObjectMapper objectMapper;
+
+	public Set<Long> getDiaryIdSetFromCache(String geohash) {
+		String key = CacheKeyGenerator.diaryIdSetKey(geohash);
+		try {
+			Set<Object> raw = redisTemplate.opsForSet().members(key);
+			if (raw == null)
+				return Collections.emptySet();
+
+			return raw.stream()
+				.map(obj -> Long.parseLong(obj.toString()))
+				.collect(Collectors.toSet());
+		} catch (Exception e) {
+			log.error("diaryId Set 조회 실패 (key: {})", key, e);
+			return Collections.emptySet();
+		}
+	}
+
+	public void cacheDiaryIdSetByGeohash(String geohash, List<Long> diaryIds) {
+		if (diaryIds == null || diaryIds.isEmpty())
+			return;
+
+		String key = CacheKeyGenerator.diaryIdSetKey(geohash);
+		try {
+			redisTemplate.opsForSet().add(key, diaryIds.toArray());
+			redisTemplate.expire(key, RedisTTLPolicy.DIARY_ID_SET_TTL);
+		} catch (Exception e) {
+			log.error("diaryId Set 저장 실패 (key: {})", key, e);
+		}
+	}
+
+	public DiaryMarkerResponseDto getDiaryFromCache(Long diaryId) {
+		String key = CacheKeyGenerator.diaryKey(diaryId);
+		try {
+			Object raw = redisTemplate.opsForValue().get(key);
+			if (raw == null) return null;
+
+			return objectMapper.readValue(raw.toString(), DiaryMarkerResponseDto.class);
+		} catch (Exception e) {
+			log.error("단건 diary 조회 실패 (key: {})", key, e);
+			return null;
+		}
+	}
+
+	public void cacheDiary(Long diaryId, DiaryMarkerResponseDto dto) {
+		String key = CacheKeyGenerator.diaryKey(diaryId);
+		try {
+			String json = objectMapper.writeValueAsString(dto);
+			redisTemplate.opsForValue().set(key, json, RedisTTLPolicy.DIARY_TTL);
+		} catch (Exception e) {
+			log.error("단건 diary 캐시 저장 실패 (key: {})", key, e);
+		}
+	}
+
+	public void evictDiaryIdFromCache(String geohash, Long diaryId) {
+		String key = CacheKeyGenerator.diaryIdSetKey(geohash);
+		try {
+			redisTemplate.opsForSet().remove(key, diaryId);
+		} catch (Exception e) {
+			log.error("diaryId 제거 실패 (key: {}, diaryId: {})", key, diaryId, e);
+		}
+	}
+
+	public void evictDiaryFromCache(Long diaryId) {
+		String key = CacheKeyGenerator.diaryKey(diaryId);
+		try {
+			redisTemplate.delete(key);
+		} catch (Exception e) {
+			log.error("diary 캐시 삭제 실패 (key: {})", key, diaryId, e);
+		}
+	}
+
+}