非阻塞队列ConcurrentLinkedQueue之容器初步学习

  ConcurrentLinkedQueue是Queue的一个安全实现．Queue中元素按FIFO原则进行排序．采用 CAS操作，来保证元素的一致性。

CAS操作

CAS是单词compare and set的缩写，意思是指在set之前先比较该值有没有变化，只有在没变的情况下才对其赋值。

package com.pst.demo;

import java.util.concurrent.ConcurrentLinkedQueue;

public class DataContainer {

   private boolean ending = false;

   private int currCount = 0;
    
    private int _queueCapacity;
    
    private ConcurrentLinkedQueue<Object> _queue = new ConcurrentLinkedQueue<Object>();
    
    public DataContainer() {
        this(20);//默认大小
    }
    
    public DataContainer(int queueCapacity) {
        this._queueCapacity = queueCapacity;
    }
    
    public synchronized void insertData(Object data) throws InterruptedException{
        while (currCount > _queueCapacity) {
            wait();
        }
        currCount++;
        _queue.add(data);
        notifyAll();
    }
    
    public synchronized Object getData() throws InterruptedException{
        while (currCount <= 0) {
            if(!ending){
                wait();
            }else{
                break;
            }
        }
        currCount--;
        Object results = _queue.poll();
        notifyAll();
        if (results == null || results instanceof Integer) {
            this.ending = true;
        }
        return results;
    }
}