package doumeemes.core.cache;
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import lombok.Data;
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import lombok.extern.slf4j.Slf4j;
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import org.apache.commons.lang3.SerializationUtils;
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import org.springframework.stereotype.Component;
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import java.io.Serializable;
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import java.util.*;
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import java.util.concurrent.ConcurrentHashMap;
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/**
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* 单机本地缓存，项目初始阶段使用
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* - 超过指定大小可通过日志方式报警
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* - 延长超时时间
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* @author Eva.Caesar Liu
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* @date 2019/3/23 17:57
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*/
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@Slf4j
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@Component
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public final class LocalCache<K,V> {
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// 警告大小
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private final int WARN_SIZE = 1073741824;
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// GB大小
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private final int GB_SIZE = 1073741824;
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// 缓存实例
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private static LocalCache instance;
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// 数据存储对象
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private ConcurrentHashMap<K, Value<V>> cache = new ConcurrentHashMap();
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private LocalCache(){}
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public static LocalCache getInstance() {
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if(instance == null) {
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synchronized (LocalCache.class) {
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if(instance == null)
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instance = new LocalCache();
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}
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}
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return instance;
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}
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/**
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* 添加缓存，超时时间为30分钟
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* @param key 缓存键
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* @param value 缓存值
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*/
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public void put(K key, V value) {
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Value<V> v = cache.get(key);
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if (v != null) {
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v.value = value;
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return;
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}
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put(key, value, 30 * 60 * 1000);
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}
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/**
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* 添加缓存
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* @param key 缓存键
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* @param value 缓存值
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* @param timeout 超时时间
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*/
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public void put(K key, V value, long timeout) {
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if(key == null) throw new NullPointerException("key can not be null");
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// 清理旧数据
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long now = System.currentTimeMillis();
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for(Map.Entry<K, Value<V>> entry: cache.entrySet()){
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Value v = entry.getValue();
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if(v.getValue() == null) // 值为空时清除掉
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cache.remove(entry.getKey());
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if(now - v.getBirthtime() > v.getTimeout()) // 超时时清除掉
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cache.remove(entry.getKey());
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}
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// 添加缓存
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Value<V> v = new Value<>();
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v.setBirthtime(now);
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v.setTimeout(timeout);
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v.setValue(value);
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cache.put(key, v);
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// 获取对象大小，超过一定大小打印警告
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int cacheSize = SerializationUtils.serialize(cache).length;
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if(cacheSize > WARN_SIZE) {
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log.warn("本地缓存已超过{}G，当前缓存容量为：{}G", (double) Math.round((double) WARN_SIZE / GB_SIZE * 100) / 100, (double) Math.round((double) cacheSize / GB_SIZE * 100) / 100);
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}
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}
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/**
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* 根据key获取缓存对象
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* @param key 缓存键
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*/
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public V get(K key) {
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if(key == null) return null;
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Value<V> value = cache.get(key);
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if(value == null)
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return null;
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if(value.getValue() == null)
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return null;
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if(System.currentTimeMillis() - value.getBirthtime() > value.getTimeout()) {
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remove(key);
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return null;
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}
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return value.getValue();
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}
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/**
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* 根据key获取缓存对象
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* @param key 缓存键
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*
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* @return V
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*/
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public V remove(K key) {
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if(key == null) return null;
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Value<V> value = cache.get(key);
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if (value == null) {
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return null;
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}
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cache.remove(key);
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return value.value;
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}
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/**
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* 清空缓存
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*/
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public void clear () {
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cache.clear();
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}
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/**
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* 获取缓存数
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*/
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public int size () {
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return cache.size();
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}
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/**
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* 获取缓存所有的key
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*/
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public Set<K> keys () {
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return cache.keySet();
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}
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/**
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* 获取缓存值
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*/
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public Collection<V> values () {
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Collection<Value<V>> values = cache.values();
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List<V> vs = new ArrayList(keys().size());
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for (Value<V> v : values) {
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if (v.value != null) {
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vs.add(v.value);
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}
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}
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return vs;
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}
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/**
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* 重置缓存诞生时间
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* @param key 缓存键
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*/
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public void relive(String key) {
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if (key == null) return;
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Value v = cache.get(key);
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if (v == null) {
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return;
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}
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v.setBirthtime(new Date().getTime());
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}
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@Data
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private static class Value<V> implements Serializable {
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// 缓存具体值
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private V value;
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// 存储时间
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private long birthtime;
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// 超时时间
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private long timeout;
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}
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}
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