testlrumap.java

iBATIS似乎已远离众说纷纭的OR框架之列

/*
 * Copyright 1999-2004 The Apache Software Foundation
 *
 * 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 org.apache.commons.collections;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;

import junit.framework.Test;

/**
 * 
 * @author <a href="mailto:[e-mail]">James Strachan</a>
 * @author <a href="mailto:[e-mail]">Morgan Delagrange</a>
 * @version $Id: TestLRUMap.java,v 1.23.2.1 2004/05/22 12:14:05 scolebourne Exp $
 */
public class TestLRUMap extends TestSequencedHashMap
{
    public TestLRUMap(String testName) {
        super(testName);
    }

    public static Test suite() {
        return BulkTest.makeSuite(TestLRUMap.class);
    }

    public static void main(String args[]) {
        String[] testCaseName = { TestLRUMap.class.getName() };
        junit.textui.TestRunner.main(testCaseName);
    }

    public Map makeEmptyMap() {
        LRUMap map = new LRUMap();
        return map;
    }

    public void testRemoveLRU() {
        LRUMap map2 = new LRUMap(3);
        map2.put(new Integer(1),"foo");
        map2.put(new Integer(2),"foo");
        map2.put(new Integer(3),"foo");
        map2.put(new Integer(4),"foo"); // removes 1 since max size exceeded
        map2.removeLRU();  // should be Integer(2)

        assertTrue("Second to last value should exist",map2.get(new Integer(3)).equals("foo"));
        assertTrue("First value inserted should not exist", map2.get(new Integer(1)) == null);
    }

    public void testMultiplePuts() {
        LRUMap map2 = new LRUMap(2);
        map2.put(new Integer(1),"foo");
        map2.put(new Integer(2),"bar");
        map2.put(new Integer(3),"foo");
        map2.put(new Integer(4),"bar");

        assertTrue("last value should exist",map2.get(new Integer(4)).equals("bar"));
        assertTrue("LRU should not exist", map2.get(new Integer(1)) == null);
    }

    /**
     * Confirm that putAll(Map) does not cause the LRUMap
     * to exceed its maxiumum size.
     */
    public void testPutAll() {
        LRUMap map2 = new LRUMap(3);
        map2.put(new Integer(1),"foo");
        map2.put(new Integer(2),"foo");
        map2.put(new Integer(3),"foo");

        HashMap hashMap = new HashMap();
        hashMap.put(new Integer(4),"foo");

        map2.putAll(hashMap);

        assertTrue("max size is 3, but actual size is " + map2.size(),
                   map2.size() == 3);
        assertTrue("map should contain the Integer(4) object",
                   map2.containsKey(new Integer(4)));
    }

    /**
     * Test that the size of the map is reduced immediately
     * when setMaximumSize(int) is called
     */
    public void testSetMaximumSize() {
        LRUMap map = new LRUMap(6);
        map.put("1","1");
        map.put("2","2");
        map.put("3","3");
        map.put("4","4");
        map.put("5","5");
        map.put("6","6");
        map.setMaximumSize(3);

        assertTrue("map should have size = 3, but actually = " + map.size(), 
                   map.size() == 3);
    }

    public void testGetPromotion() {
        LRUMap map = new LRUMap(3);
        map.put("1","1");
        map.put("2","2");
        map.put("3","3");
        // LRU is now 1 (then 2 then 3)

        // promote 1 to top
        // eviction order is now 2,3,1
        map.get("1");
        
        // add another value, forcing a remove
        // 2 should be evicted (then 3,1,4)
        map.put("4","4");
        
        Iterator keyIterator = map.keySet().iterator();
        Object[] keys = new Object[3];
        for (int i = 0; keyIterator.hasNext() ; ++i) {
            keys[i] = keyIterator.next();
        }

        assertTrue("first evicted should be 3, was " + keys[0], keys[0].equals("3"));
        assertTrue("second evicted should be 1, was " + keys[1], keys[1].equals("1"));
        assertTrue("third evicted should be 4, was " + keys[2], keys[2].equals("4"));
        
    }

    /**
     * You should be able to subclass LRUMap and perform a 
     * custom action when items are removed automatically
     * by the LRU algorithm (the removeLRU() method).
     */
    public void testLRUSubclass() {
        LRUCounter counter = new LRUCounter(3);
        // oldest <--> newest
        // 1
        counter.put("1","foo");
        // 1 2
        counter.put("2","foo");
        // 1 2 3
        counter.put("3","foo");
        // 2 3 1
        counter.put("1","foo");
        // 3 1 4 (2 goes out)
        counter.put("4","foo");
        // 1 4 5 (3 goes out)
        counter.put("5","foo");
        // 4 5 2 (1 goes out)
        counter.put("2","foo");
        // 4 2
        counter.remove("5");

        assertTrue("size should be 2, but was " + counter.size(), counter.size() == 2);
        assertTrue("removedCount should be 3 but was " + counter.removedCount,
                   counter.removedCount == 3);

        assertTrue("first removed was '2'",counter.list.get(0).equals("2"));
        assertTrue("second removed was '3'",counter.list.get(1).equals("3"));
        assertTrue("third removed was '1'",counter.list.get(2).equals("1"));

        assertTrue("oldest key is '4'",counter.get(0).equals("4"));
        assertTrue("newest key is '2'",counter.get(1).equals("2"));
    }


    protected void entrySetEqualsMap(Set set, Map m) {
        // Overridden because LRUMap.get(Object) actually alters the map,
        // so there's no way to verify that the entry set and map contain
        // the same entries
    }

    private class LRUCounter extends LRUMap {
        int removedCount = 0;
        ArrayList list = new ArrayList(3); 

        LRUCounter(int i) {
            super(i);
        }

        protected void processRemovedLRU(Object key, Object value) {
            ++removedCount;
            list.add(key);
        }
    }

}