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/*
 * 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 x7.core.util;

import java.util.Collection;
import java.util.Iterator;
import java.util.Queue;
import java.util.concurrent.ConcurrentLinkedQueue;

/**
 * Fixed Length Queue
 * @author Sim
 *
 */
public class LimitQueue implements Queue{

	private int limit;
	
	private Queue queue = new ConcurrentLinkedQueue();
	
	public LimitQueue(int limit){
		this.limit = limit;
	}
	
	/**
	 * 入队
	 * @param e
	 */
	@Override
	public boolean offer(E e){
		if(queue.size() >= limit){
			//如果超出长度,入队时,先出队
			queue.poll();
		}
		return queue.offer(e);
	}
	
	/**
	 * 出队
	 * @return
	 */
	@Override
	public E poll() {
		return queue.poll();
	}
	
	/**
	 * 获取队列
	 * @return
	 */
	public Queue getQueue(){
		return queue;
	}
	
	/**
	 * 获取限制大小
	 * @return
	 */
	public int getLimit(){
		return limit;
	}

	@Override
	public boolean add(E e) {
		return queue.add(e);
	}

	@Override
	public E element() {
		return queue.element();
	}

	@Override
	public E peek() {
		return queue.peek();
	}

	@Override
	public boolean isEmpty() {
		return queue.size() == 0 ? true : false;
	}

	@Override
	public int size() {
		return queue.size();
	}

	@Override
	public E remove() {
		return queue.remove();
	}

	@Override
	public boolean addAll(Collection c) {
		return queue.addAll(c);
	}

	@Override
	public void clear() {
		queue.clear();
	}

	@Override
	public boolean contains(Object o) {
		return queue.contains(o);
	}

	@Override
	public boolean containsAll(Collection c) {
		return queue.containsAll(c);
	}

	@Override
	public Iterator iterator() {
		return queue.iterator();
	}

	@Override
	public boolean remove(Object o) {
		return queue.remove(o);
	}

	@Override
	public boolean removeAll(Collection c) {
		return queue.removeAll(c);
	}

	@Override
	public boolean retainAll(Collection c) {
		return queue.retainAll(c);
	}

	@Override
	public Object[] toArray() {
		return queue.toArray();
	}

	@Override
	public  T[] toArray(T[] a) {
		return queue.toArray(a);
	}

}