项目中多级缓存设计实践总结 - qidao123.com ToB IT社区-企服评测·应用市场

/**
* 本地一级缓存使用Map
*
* @author valarchie
*/
public class MapCache {
private static final Map<String, List<DictionaryData>> DICTIONARY_CACHE = MapUtil.newHashMap(128);
static {
initDictionaryCache();
}
private static void initDictionaryCache() {
loadInCache(BusinessTypeEnum.values());
loadInCache(YesOrNoEnum.values());
loadInCache(StatusEnum.values());
loadInCache(GenderEnum.values());
loadInCache(NoticeStatusEnum.values());
loadInCache(NoticeTypeEnum.values());
loadInCache(OperationStatusEnum.values());
loadInCache(VisibleStatusEnum.values());
}
public static Map<String, List<DictionaryData>> dictionaryCache() {
return DICTIONARY_CACHE;
}
private static void loadInCache(DictionaryEnum[] dictionaryEnums) {
DICTIONARY_CACHE.put(getDictionaryName(dictionaryEnums[0].getClass()), arrayToList(dictionaryEnums));
}
private static String getDictionaryName(Class<?> clazz) {
Objects.requireNonNull(clazz);
Dictionary annotation = clazz.getAnnotation(Dictionary.class);
Objects.requireNonNull(annotation);
return annotation.name();
}
@SuppressWarnings("rawtypes")
private static List<DictionaryData> arrayToList(DictionaryEnum[] dictionaryEnums) {
if(ArrayUtil.isEmpty(dictionaryEnums)) {
return ListUtil.empty();
}
return Arrays.stream(dictionaryEnums).map(DictionaryData::new).collect(Collectors.toList());
}
}

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/**
* 缓存接口实现类二级缓存
* @author valarchie
*/
@Slf4j
public abstract class AbstractGuavaCacheTemplate<T> {
private final LoadingCache<String, Optional<T>> guavaCache = CacheBuilder.newBuilder()
// 基于容量回收。缓存的最大数量。超过就取MAXIMUM_CAPACITY = 1 << 30。依靠LRU队列recencyQueue来进行容量淘汰
.maximumSize(1024)
// 基于容量回收。但这是统计占用内存大小，maximumWeight与maximumSize不能同时使用。设置最大总权重
// 没写访问下，超过5秒会失效(非自动失效，需有任意put get方法才会扫描过期失效数据。但区别是会开一个异步线程进行刷新，刷新过程中访问返回旧数据)
.refreshAfterWrite(5L, TimeUnit.MINUTES)
// 移除监听事件
.removalListener(removal -> {
// 可做一些删除后动作，比如上报删除数据用于统计
log.info("触发删除动作，删除的key={}, value={}", removal.getKey(), removal.getValue());
})
// 并行等级。决定segment数量的参数，concurrencyLevel与maxWeight共同决定
.concurrencyLevel(16)
// 开启缓存统计。比如命中次数、未命中次数等
.recordStats()
// 所有segment的初始总容量大小
.initialCapacity(128)
// 用于测试，可任意改变当前时间。参考：https://www.geek-share.com/detail/2689756248.html
.ticker(new Ticker() {
@Override
public long read() {
return 0;
}
})
.build(new CacheLoader<String, Optional<T>>() {
@Override
public Optional<T> load(String key) {
T cacheObject = getObjectFromDb(key);
log.debug("find the local guava cache of key: {} is {}", key, cacheObject);
return Optional.ofNullable(cacheObject);
}
});
public T get(String key) {
try {
if (StrUtil.isEmpty(key)) {
return null;
}
Optional<T> optional = guavaCache.get(key);
return optional.orElse(null);
} catch (ExecutionException e) {
log.error("get cache object from guava cache failed.");
e.printStackTrace();
return null;
}
}
public void invalidate(String key) {
if (StrUtil.isEmpty(key)) {
return;
}
guavaCache.invalidate(key);
}
public void invalidateAll() {
guavaCache.invalidateAll();
}
/**
* 从数据库加载数据
* @param id
* @return
*/
public abstract T getObjectFromDb(Object id);
}

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/**
* @author valarchie
*/
@Component
@Slf4j
@RequiredArgsConstructor
public class GuavaCacheService {
@NonNull
private ISysDeptService deptService;
public final AbstractGuavaCacheTemplate<SysDeptEntity> deptCache = new AbstractGuavaCacheTemplate<SysDeptEntity>() {
@Override
public SysDeptEntity getObjectFromDb(Object id) {
return deptService.getById(id.toString());
}
};
}

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