tasteby/backend-java/src/main/java/com/tasteby/service/StatsService.java

package com.tasteby.service;

import com.tasteby.domain.SiteVisitStats;
import com.tasteby.mapper.StatsMapper;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.dao.DataIntegrityViolationException;
import org.springframework.stereotype.Service;

@Service
public class StatsService {

    private static final Logger log = LoggerFactory.getLogger(StatsService.class);

    private final StatsMapper mapper;

    public StatsService(StatsMapper mapper) {
        this.mapper = mapper;
    }

    public void recordVisit() {
        // #274 — 자정 경계 동시성: 두 트랜잭션이 동시에 'NOT MATCHED' 판정 → 둘 다 INSERT
        // → PK/UNIQUE 충돌 시 한 쪽 500. 1회 재시도(다음엔 MATCHED → UPDATE 분기).
        try {
            mapper.recordVisit();
        } catch (DataIntegrityViolationException e) {
            log.debug("recordVisit conflict (midnight race), retry once: {}", e.getMessage());
            try {
                mapper.recordVisit();
            } catch (DataIntegrityViolationException retryFail) {
                // 두 번째 시도도 실패: 카운트 1건 손실은 수용 (운영 영향 미미)
                log.warn("recordVisit double-conflict, dropping one count: {}", retryFail.getMessage());
            }
        }
    }

    public SiteVisitStats getVisits() {
        return SiteVisitStats.builder()
                .today(mapper.getTodayVisits())
                .total(mapper.getTotalVisits())
                .build();
    }
}