/*
* Copyright 2008-2009 the original author or authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package net.hasor.rsf.utils;
/**
* 令热策略的,LRU
* @version : 2014年11月4日
* @author 赵永春(zyc@hasor.net)
*/
public class ByteStringCachelUtils {
private static final LRU<Integer, String> stringCache1;
private static final LRU<String, byte[]> stringCache2;
static {
stringCache1 = new LRU<Integer, String>();
stringCache2 = new LRU<String, byte[]>();
}
public static String fromCache(byte[] stringByte) {
// if (stringByte == null) {
// return null;
// }
// int hashCode = Arrays.hashCode(stringByte);
// String oriData = stringCache1.get(hashCode);
// if (oriData == null) {
// oriData = new String(stringByte);
// stringCache1.put(hashCode, oriData);
// }
// return oriData;
if (stringByte == null)
return null;
else
return new String(stringByte);
}
public static byte[] fromCache(String string) {
if (string == null) {
return null;
}
// byte[] stringByte = stringCache2.get(string);
// if (stringByte == null) {
// stringByte = string.getBytes();
// stringCache2.put(string, stringByte);
// }
// return stringByte;
return string.getBytes();
}
}
//
//
class LRU<K, V> {
/**链表元素*/
private class LRU_Entity {
public LRU_Entity pre; //链表前一个元素
public LRU_Entity next; //链表后一个元素
public int count; //总数
public boolean isNew;
public K key; //Key
public V val; //值
}
//
private LRU_Entity root = null; //链表的起始点
private int linkSize = 0;
private int maxSize = 400;
//
//
//
private LRU_Entity entByKey(K key) {
if (this.root == null) {
return null;
}
//0.从热端开始搜索目标
LRU_Entity searchRoot = this.root;
LRU_Entity currentRoot = searchRoot;
do {
//1.判断当前节点是否为目标
if (key.equals(currentRoot.key)) {
return currentRoot;
} else {
currentRoot = currentRoot.next;
}
//2.循环了一圈
if (currentRoot == searchRoot) {
break;
}
} while (true);
//
return null;
}
//
public V get(K key) {
LRU_Entity valEnt = entByKey(key);
if (valEnt != null) {
valEnt.count++;
return valEnt.val;
}
return null;
}
//
public V put(K key, V val) {
LRU_Entity valEnt = entByKey(key);
if (valEnt != null) {
if (valEnt.key.equals(key)) {
valEnt.count++;
return valEnt.val;
} else {
valEnt.count = 0;
V oldVal = valEnt.val;
valEnt.val = val;
this.moveOrAdd(valEnt);
return oldVal;
}
} else {
valEnt = new LRU_Entity();
valEnt.count = 0;
valEnt.isNew = true;
valEnt.key = key;
valEnt.val = val;
this.moveOrAdd(valEnt);
return null;
}
}
//
/*将元素移动或添加到到冷端尾*/
private void moveOrAdd(LRU_Entity valEnt) {
weedOut();
int realSize = linkSize;
//剔除
if (!valEnt.isNew) {
valEnt.pre.next = valEnt.next;
valEnt.next.pre = valEnt.pre;
realSize--;
}
//新增
if (this.root == null) {
this.root = valEnt;
}
LRU_Entity root = this.root;
valEnt.pre = root.pre;
root.pre = valEnt;
root.next = valEnt;
valEnt.next = root;
//
this.root = valEnt;
realSize++;
linkSize = realSize;
}
//
/*执行淘汰策略*/
private void weedOut() {
if (this.linkSize > this.maxSize) {
//
System.out.println("weedOut");
//
}
}
}