package com.ibeetl.code.ch03;

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

/** Condition使用示例，参考
 * https://blog.csdn.net/SEU_Calvin/article/details/70211712
 * @author 公众号 java系统优化
 * @param <T>
 */
public class MyArrayBlockingQueue<T> {
	//维护的数据
	private final T[] datas;
	//数据的个数
	private int count;
	//插入取出的索引
	private int putIndex;
	private int takeIndex;

	//锁
	private final Lock lock = new ReentrantLock();
	//定义两个条件，分别为“集合满”和“集合空”
	private Condition full = lock.newCondition();
	private Condition empty = lock.newCondition();

	//提供MyArrayBlockingQueue的构造方法，初始化T[]数据
	public MyArrayBlockingQueue() {
		this(10);
	}

	public MyArrayBlockingQueue(int maxSize) {
		this.datas = (T[]) new Object[maxSize];
	}

	public void put(T data){
		lock.lock();
		try {
			if(count == datas.length){
				//此时集合已经满了
				System.out.println("集合已满，请等待...");
				//使调用线程挂起
				full.await();
			}
			//不满则添加新元素
			datas[putIndex++] = data;
			count++;

			//此时唤醒等待取数据的线程
			empty.signalAll();

		} catch (Exception e) {
			e.printStackTrace();
		}finally{
			lock.unlock();
		}
	}


	public T take(){
		lock.lock();
		try {
			if(count == 0){
				//此时集合已经空了
				System.out.println("集合已空，请等待...");
				//使调用线程挂起
				empty.await();
			}

			//不空则取出最后一个数据
			takeIndex = count - 1;
			T result = datas[takeIndex--];
			count--;

			//此时唤醒等待写数据的线程
			full.signalAll();

			return result;

		} catch (Exception e) {
			e.printStackTrace();
		}finally{
			lock.unlock();
		}
		return null;
	}


}