本地缓存，redis缓存综合应用

/**
 * 系统弹幕有效期（本地缓存10S，redis缓存1分钟）
 **/
private static Map<String,LocalDateTime> barrageShowValidMap = new ConcurrentHashMap<>();
private static Map<String,List<BarrageShowVO>>  barrageShowMap = new ConcurrentHashMap<>();
private static Long barragesShowCacheTimes = Constant.ONE_MINUTE;
private static Long barragesShowCacheLocalTimes = Constant.TEN_SECOND;

/**
* @desc   : 获取系统弹幕
* @author : 毛会懂
* @create: 2021/9/18 11:01:00
**/
private List<BarrageShowVO> getSysBarrages(Integer activityId){
    if (activityId == null) {
        throw new BusinessException(GameErrorCodeEnum.LOTTY_PRE_VERIFY_ERROR.getErrorCode(), "活动id为空");
    }

    List<BarrageShowVO> barrageShowList;
    // 从本地取系统弹幕
    String localKey = "ACTIVITY_SYS_BARRAGE_" + activityId.toString();
    LocalDateTime localDateTime = barrageShowValidMap.get(localKey);
    LocalDateTime now = LocalDateTime.now();
    if(localDateTime != null && localDateTime.isAfter(now)){
        log.info("读本地缓存");
        barrageShowList = barrageShowMap.get(localKey);
    }else {
        log.info("读redis缓存");
        String barragesKey = RedisKeyManagement.getKey(RedisKeyManagement.ACTIVITY_SYS_BARRAGES, Arrays.asList(activityId.toString()));
        barrageShowList = (List<BarrageShowVO>) redisService.get(barragesKey);
        if (barrageShowList == null) {
            synchronized (this) {
                log.info("同步读redis缓存");
                barrageShowList = (List<BarrageShowVO>) redisService.get(barragesKey);
                if (barrageShowList == null) {
                    // 查询系统弹幕
                    QueryWrapper<ActivitySysBarrageDO> sysBarrageQueryWrapper = new QueryWrapper<>();
                    sysBarrageQueryWrapper.eq("activity_id", activityId);
                    sysBarrageQueryWrapper.eq("status", EnableStatusEnum.ENABLE);
                    List<ActivitySysBarrageDO> sysBarrageList = sysBarrageService.list(sysBarrageQueryWrapper);
                    barrageShowList = new ArrayList<>();
                    if(!CollectionUtils.isEmpty(sysBarrageList)) {
                        for (ActivitySysBarrageDO barrageDO : sysBarrageList) {
                            BarrageShowVO showVO = new BarrageShowVO();
                            BeanUtils.copyProperties(barrageDO,showVO);
                            barrageShowList.add(showVO);
                        }
                    }
                    redisService.set(barragesKey, barrageShowList, barragesShowCacheTimes);
                }
            }
        }

        // 添加到本地缓存
        if(barrageShowList != null) {
            barrageShowValidMap.put(localKey, LocalDateTime.now().plusSeconds(barragesShowCacheLocalTimes));
            barrageShowMap.put(localKey, barrageShowList);
        }
        // 清除过期的缓存(只有map的size超过50才会清缓存，防止清缓存频率太高)
        if(barrageShowValidMap.size() > 50){
            Iterator<Map.Entry<String, LocalDateTime>> iterator = barrageShowValidMap.entrySet().iterator();
            while (iterator.hasNext()){
                Map.Entry<String, LocalDateTime> next = iterator.next();
                LocalDateTime value = next.getValue();
                if(value.isBefore(now)){
                    iterator.remove();
                    String key = next.getKey();
                    barrageShowMap.remove(key);
                }
            }
        }
    }
    return barrageShowList;
}