feat: Redis 랭킹 정보를 1시간 단위로 DB에 기록하는 스케줄러 구현 (#285)

* feat: VoteRanking 엔티티 추가 (#284)

* feat: Redis 캐시된 투표 랭킹 정보를 정시마다 RDB에 저장하는 스케줄러 구현 (#284)

Author: soonge2

src/main/java/com/moa/moa_server/domain/group/repository/GroupRepository.java

@@ -5,6 +5,7 @@
 import java.util.List;
 import java.util.Optional;
 import org.springframework.data.jpa.repository.JpaRepository;
+import org.springframework.data.jpa.repository.Query;
 
 public interface GroupRepository extends JpaRepository<Group, Long> {
   Optional<Group> findByInviteCode(String inviteCode);
@@ -14,4 +15,7 @@ public interface GroupRepository extends JpaRepository<Group, Long> {
   boolean existsByName(String groupName);
 
   List<Group> findAllByUser(User user);
+
+  @Query("select g.id from Group g")
+  List<Long> findAllGroupIds();
 }

src/main/java/com/moa/moa_server/domain/ranking/entity/VoteRanking.java

@@ -0,0 +1,42 @@
+package com.moa.moa_server.domain.ranking.entity;
+
+import com.moa.moa_server.domain.global.entity.BaseTimeEntity;
+import jakarta.persistence.*;
+import java.time.LocalDateTime;
+import lombok.*;
+
+@Entity
+@Getter
+@NoArgsConstructor(access = AccessLevel.PROTECTED)
+@AllArgsConstructor
+@Builder
+@Table(
+    name = "vote_ranking",
+    uniqueConstraints = @UniqueConstraint(columnNames = {"group_id", "ranked_at", "rank"}))
+public class VoteRanking extends BaseTimeEntity {
+
+  @Id
+  @GeneratedValue(strategy = GenerationType.IDENTITY)
+  private Long id;
+
+  @Column(name = "vote_id", nullable = false)
+  private Long voteId;
+
+  @Column(name = "group_id", nullable = false)
+  private Long groupId;
+
+  @Column(nullable = false)
+  private int rank;
+
+  @Column(name = "ranked_at", nullable = false)
+  private LocalDateTime rankedAt;
+
+  public static VoteRanking of(Long voteId, Long groupId, int rank, LocalDateTime rankedAt) {
+    return VoteRanking.builder()
+        .voteId(voteId)
+        .groupId(groupId)
+        .rank(rank)
+        .rankedAt(rankedAt)
+        .build();
+  }
+}

src/main/java/com/moa/moa_server/domain/ranking/repository/VoteRankingRepository.java

@@ -0,0 +1,6 @@
+package com.moa.moa_server.domain.ranking.repository;
+
+import com.moa.moa_server.domain.ranking.entity.VoteRanking;
+import org.springframework.data.jpa.repository.JpaRepository;
+
+public interface VoteRankingRepository extends JpaRepository<VoteRanking, Long> {}

src/main/java/com/moa/moa_server/domain/ranking/scheduler/VoteRankingWriteScheduler.java

@@ -0,0 +1,94 @@
+package com.moa.moa_server.domain.ranking.scheduler;
+
+import com.moa.moa_server.domain.group.repository.GroupRepository;
+import com.moa.moa_server.domain.ranking.entity.VoteRanking;
+import com.moa.moa_server.domain.ranking.repository.VoteRankingRepository;
+import java.time.LocalDate;
+import java.time.LocalDateTime;
+import java.time.ZoneOffset;
+import java.time.format.DateTimeFormatter;
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+import java.util.Set;
+import lombok.RequiredArgsConstructor;
+import lombok.extern.slf4j.Slf4j;
+import org.springframework.data.redis.core.StringRedisTemplate;
+import org.springframework.data.redis.core.ZSetOperations;
+import org.springframework.scheduling.annotation.Scheduled;
+import org.springframework.stereotype.Component;
+import org.springframework.transaction.annotation.Transactional;
+
+@Slf4j
+@Component
+@RequiredArgsConstructor
+public class VoteRankingWriteScheduler {
+
+  private final StringRedisTemplate redisTemplate;
+  private final VoteRankingRepository voteRankingRepository;
+  private final GroupRepository groupRepository;
+
+  @Transactional
+  @Scheduled(cron = "0 0 * * * *") // 매 정시
+  public void persistVoteRankings() {
+    LocalDateTime rankedAt = LocalDateTime.now(ZoneOffset.UTC); // 저장 시각
+    String dateKey =
+        LocalDate.now(ZoneOffset.UTC).format(DateTimeFormatter.BASIC_ISO_DATE); // Redis 키 날짜
+    List<VoteRanking> rankingsToSave = collectTopRankings(rankedAt, dateKey);
+
+    try {
+      voteRankingRepository.saveAll(rankingsToSave);
+      log.info("[VoteRankingWriteScheduler] 저장 완료 - 총 {}건", rankingsToSave.size());
+    } catch (Exception e) {
+      log.error(
+          "[VoteRankingWriteScheduler] 저장 실패 - 저장 대상 {}건, reason={}",
+          rankingsToSave.size(),
+          e.getMessage(),
+          e);
+    }
+  }
+
+  /** 모든 그룹에 대해 Redis에서 Top3 랭킹을 조회하고, DB 저장용 VoteRanking 리스트를 생성. */
+  private List<VoteRanking> collectTopRankings(LocalDateTime rankedAt, String dateKey) {
+    List<Long> groupIds = groupRepository.findAllGroupIds();
+    List<VoteRanking> result = new ArrayList<>();
+
+    log.info("[VoteRankingWriteScheduler] 시작 - {}개 그룹 대상 랭킹 기록", groupIds.size());
+
+    // 각 그룹에 대해 Top3 랭킹 데이터 조회해 VoteRanking 객체로 반환
+    for (Long groupId : groupIds) {
+      result.addAll(buildRankingsFromRedis(groupId, rankedAt, dateKey));
+    }
+
+    return result;
+  }
+
+  /** Redis에서 특정 그룹의 Top3 투표를 조회하여, DB 저장용 VoteRanking 리스트로 변환. */
+  private List<VoteRanking> buildRankingsFromRedis(
+      Long groupId, LocalDateTime rankedAt, String dateKey) {
+    // Redis key 생성: ranking:{groupId}:{yyyyMMdd}
+    String key = "ranking:" + groupId + ":" + dateKey;
+
+    // 해당 그룹의 Redis Sorted Set에서 Top3 투표 ID 조회
+    Set<ZSetOperations.TypedTuple<String>> topVotes =
+        redisTemplate.opsForZSet().reverseRangeWithScores(key, 0, 2);
+
+    if (topVotes == null || topVotes.isEmpty()) return Collections.emptyList();
+
+    List<VoteRanking> rankings = new ArrayList<>();
+    int rank = 1;
+
+    for (ZSetOperations.TypedTuple<String> tuple : topVotes) {
+      String voteIdStr = tuple.getValue();
+      if (voteIdStr == null) {
+        log.warn("[VoteRankingWriteScheduler] 랭킹 키={}에 null인 voteId가 포함되어 있어 건너뜁니다.", key);
+        continue;
+      }
+
+      VoteRanking ranking = VoteRanking.of(Long.parseLong(voteIdStr), groupId, rank++, rankedAt);
+      rankings.add(ranking);
+    }
+
+    return rankings;
+  }
+}