T_LRUCache.java

/**
 * Logback: the reliable, generic, fast and flexible logging framework.
 * Copyright (C) 1999-2015, QOS.ch. All rights reserved.
 *
 * This program and the accompanying materials are dual-licensed under
 * either the terms of the Eclipse Public License v1.0 as published by
 * the Eclipse Foundation
 *
 *   or (per the licensee's choosing)
 *
 * under the terms of the GNU Lesser General Public License version 2.1
 * as published by the Free Software Foundation.
 */
package ch.qos.logback.classic.turbo.lru;

import java.util.ArrayList;
import java.util.Collections;
import java.util.LinkedList;
import java.util.List;

/**
 * This is an alternative (slower) implementation of LRUCache for testing
 * purposes.
 * 
 * @author Ceki Gulcu
 */
public class T_LRUCache<K> {

    int sequenceNumber;
    final int cacheSize;
    List<T_Entry<K>> cacheList = new LinkedList<T_Entry<K>>();

    public T_LRUCache(int size) {
        this.cacheSize = size;
    }

    @SuppressWarnings("unchecked")
    synchronized public void put(K k) {
        sequenceNumber++;
        T_Entry<K> te = getEntry(k);
        if (te != null) {
            te.sequenceNumber = sequenceNumber;
        } else {
            te = new T_Entry<K>(k, sequenceNumber);
            cacheList.add(te);
        }
        Collections.sort(cacheList);
        while (cacheList.size() > cacheSize) {
            cacheList.remove(0);
        }
    }

    @SuppressWarnings("unchecked")
    synchronized public K get(K k) {
        T_Entry<K> te = getEntry(k);
        if (te == null) {
            return null;
        } else {
            te.sequenceNumber = ++sequenceNumber;
            Collections.sort(cacheList);
            return te.k;
        }
    }

    synchronized public List<K> keyList() {
        List<K> keyList = new ArrayList<K>();
        for (T_Entry<K> e : cacheList) {
            keyList.add(e.k);
        }
        return keyList;
    }

    private T_Entry<K> getEntry(K k) {
        for (int i = 0; i < cacheList.size(); i++) {
            T_Entry<K> te = cacheList.get(i);
            if (te.k.equals(k)) {
                return te;
            }
        }
        return null;
    }

    public void dump() {
        System.out.print("T:");
        for (T_Entry<K> te : cacheList) {
            // System.out.print(te.toString()+"->");
            System.out.print(te.k + ", ");
        }
        System.out.println();
    }

}