并发编程__模拟CAS算法

Posted 2020-10-26 知行合一

 1 /*
 2  * 模拟 CAS 算法
 3  */
 4 public class TestCompareAndSwap {
 5 
 6     public static void main(String[] args) {
 7         final CompareAndSwap cas = new CompareAndSwap();
 8         
 9         for (int i = 0; i < 10; i++) {
10             new Thread(new Runnable() {
11                 
12                 @Override
13                 public void run() {
14                     int expectedValue = cas.get();
15                     boolean b = cas.compareAndSet(expectedValue, (int)(Math.random() * 101));
16                     System.out.println(b);
17                 }
18             }).start();
19         }
20         
21     }
22     
23 }
24 
25 class CompareAndSwap{
26     private int value;
27     
28     //获取内存值
29     public synchronized int get(){
30         return value;
31     }
32     
33     //比较
34     public synchronized int compareAndSwap(int expectedValue, int newValue){
35         int oldValue = value;
36         
37         if(oldValue == expectedValue){
38             this.value = newValue;
39         }
40         
41         return oldValue;
42     }
43     
44     //设置
45     public synchronized boolean compareAndSet(int expectedValue, int newValue){
46         return expectedValue == compareAndSwap(expectedValue, newValue);
47     }
48 }