package com.gxx.record.utils;

import java.util.LinkedList;
import java.util.List;
import java.util.concurrent.locks.Condition;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;

/** 
 * 阻塞队列
 * 0.size 上限大小
 * 1.add 添加，达到上限大小，hold住
 * 2.remove 获取，大小为0，hold住
 * @author Gxx
 */
public class BlockingQueue {
	/**
	 * 上限大小
	 */
	private int size = 5;
	/**
	 * 内容
	 */
	private List<Object> list = new LinkedList<Object>();
	/**
	 * 锁
	 */
	private Lock lock = new ReentrantLock();
	/**
	 * 非满条件
	 */
	private Condition notFull = lock.newCondition();
	/**
	 * 非空条件
	 */
	private Condition notEmpty = lock.newCondition();
	
	/**
	 * 构造函数
	 */
	public BlockingQueue () {
	}
	
	/**
	 * 构造函数
	 * @param size
	 */
	public BlockingQueue (int size) {
		this.size = size;
	}
	
	/**
	 * 添加，达到上限大小，hold住
	 * @param object
	 */
	public void add(Object object) {
		lock.lock();
		try {
			if(size == list.size()) {
				System.out.println("    [->添加]挂起，满了:共" + list.size() + "个");
				notFull.await();
				System.out.println("    [->添加]唤醒，不满了:共" + list.size() + "个");
			}
			list.add(object);
			System.out.println("    [->添加]了1个，尝试唤醒:共" + list.size() + "个");
			notEmpty.signal();
		} catch (Exception e) {
			e.printStackTrace();
		} finally {
			lock.unlock();
		}
	}
	
	/**
	 * 获取，大小为0，hold住
	 */
	public Object remove() {
		Object object = null;
		lock.lock();
		try {
			if(0 == list.size()) {
				System.out.println("[<-获取]挂起，空了:共" + list.size() + "个");
				notEmpty.await();
				System.out.println("[<-获取]唤醒，不空了:共" + list.size() + "个");
			}
			object = list.remove(0);
			System.out.println("[<-获取]删除了1个，尝试唤醒:共" + list.size() + "个");
			notFull.signal();
		} catch (Exception e) {
			e.printStackTrace();
		} finally {
			lock.unlock();
		}
		return object;
	}
}