LRUCache.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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.flink.runtime.util;

import java.util.ArrayDeque;
import java.util.Deque;

public class LRUCache<V> {

	private final Deque<V> lruCache = new ArrayDeque<V>();

	public static <V> LRUCache<V> create() {
		return new LRUCache<V>();
	}

	public void add(V value) {
		lruCache.addLast(value);
	}

	public V getLRU() {
		V lru = lruCache.pollFirst();
		if (lru != null) {
			add(lru);
		}
		return lru;
	}

	public V removeLRU() {
		return lruCache.pollFirst();
	}

	public boolean isEmpty() {
		return lruCache.isEmpty();
	}

	public int size() {
		return lruCache.size();
	}
}