Memcached使用入门——（5）Memcached的CAS程序实例 .

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Memcached使用入门——（5）Memcached的CAS程序实例 .

1. 非CAS

首先看一个不是CAS的Memcached程序实例。实例的问题原型，见上一篇博文。

程序实例：

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1. 01.package com.sinosuperman.memcached;  
   
2. 02.  
   
3. 03.import java.io.IOException;  
   
4. 04.import java.net.InetSocketAddress;  
   
5. 05.  
   
6. 06.import net.spy.memcached.MemcachedClient;  
   
7. 07.  
   
8. 08.public class Test {  
   
9. 09.    public static void main(String[] args) throws IOException {  
   
10. 10.        MemcachedClient cache = new MemcachedClient(new InetSocketAddress("127.0.0.1", 11211));  
    
11. 11.         
    
12. 12.        cache.set("x", 1800, "Love");  
    
13. 13.  
    
14. 14.        String obj1 = (String) cache.get("x");  
    
15. 15.        String obj2 = (String) cache.get("x");  
    
16. 16.        obj2 = "Michael";  
    
17. 17.         
    
18. 18.        cache.set("x", 1800, obj2);  
    
19. 19.        System.out.println("Non-CAS 2:\t" + obj2);  
    
20. 20.        System.out.println("Non-CAS 1:\t" + obj1);  
    
21. 21.    }  
    
22. 22.}  
    
23. package com.sinosuperman.memcached;
    
24. 
    
25. import java.io.IOException;
    
26. import java.net.InetSocketAddress;
    
27. 
    
28. import net.spy.memcached.MemcachedClient;
    
29. 
    
30. public class Test {
    
31.         public static void main(String[] args) throws IOException {
    
32.                 MemcachedClient cache = new MemcachedClient(new InetSocketAddress("127.0.0.1", 11211));
    
33.                
    
34.                 cache.set("x", 1800, "Love");
    
35. 
    
36.                 String obj1 = (String) cache.get("x");
    
37.                 String obj2 = (String) cache.get("x");
    
38.                 obj2 = "Michael";
    
39.                
    
40.                 cache.set("x", 1800, obj2);
    
41.                 System.out.println("Non-CAS 2:\t" + obj2);
    
42.                 System.out.println("Non-CAS 1:\t" + obj1);
    
43.         }
    
44. }

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运行结果：

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1. 01.2011-12-18 23:12:39.836 INFO net.spy.memcached.MemcachedConnection:  Added {QA sa=/127.0.0.1:11211, #Rops=0, #Wops=0, #iq=0, topRop=null, topWop=null, toWrite=0, interested=0} to connect queue  
   
2. 02.2011-12-18 23:12:39.843 INFO net.spy.memcached.MemcachedConnection:  Connection state changed for sun.nio.ch.SelectionKeyImpl@b09e89  
   
3. 03.Non-CAS 2:  Michael  
   
4. 04.Non-CAS 1:  Love  
   
5. 2011-12-18 23:12:39.836 INFO net.spy.memcached.MemcachedConnection:  Added {QA sa=/127.0.0.1:11211, #Rops=0, #Wops=0, #iq=0, topRop=null, topWop=null, toWrite=0, interested=0} to connect queue
   
6. 2011-12-18 23:12:39.843 INFO net.spy.memcached.MemcachedConnection:  Connection state changed for sun.nio.ch.SelectionKeyImpl@b09e89
   
7. Non-CAS 2:        Michael
   
8. Non-CAS 1:        Love

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可见在多个Client操作时，一定会引起写不一致性的问题。




2. CAS

程序实例：

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1. 01.package com.sinosuperman.memcached;  
   
2. 02.  
   
3. 03.import java.io.IOException;  
   
4. 04.import java.net.InetSocketAddress;  
   
5. 05.  
   
6. 06.import net.spy.memcached.CASValue;  
   
7. 07.import net.spy.memcached.MemcachedClient;  
   
8. 08.  
   
9. 09.public class Test {  
   
10. 10.    @SuppressWarnings("unchecked")  
    
11. 11.    public static void main(String[] args) throws IOException {  
    
12. 12.        MemcachedClient cache = new MemcachedClient(new InetSocketAddress("127.0.0.1", 11211));  
    
13. 13.         
    
14. 14.        cache.set("y", 1800, "Love");  
    
15. 15.  
    
16. 16.        CASValue casValue1 = cache.gets("y");  
    
17. 17.        CASValue casValue2 = cache.gets("y");  
    
18. 18.        cache.cas("y", casValue2.getCas(), casValue2.getValue());  
    
19. 19.         
    
20. 20.        System.out.println("CAS 2:\t" + casValue2.getCas());  
    
21. 21.        System.out.println("Value 2:\t" + casValue2.getValue());  
    
22. 22.         
    
23. 23.        System.out.println("CAS 1:\t" + casValue1.getCas());  
    
24. 24.        System.out.println("Value 1:\t" + casValue1.getValue());  
    
25. 25.    }  
    
26. 26.}  
    
27. package com.sinosuperman.memcached;
    
28. 
    
29. import java.io.IOException;
    
30. import java.net.InetSocketAddress;
    
31. 
    
32. import net.spy.memcached.CASValue;
    
33. import net.spy.memcached.MemcachedClient;
    
34. 
    
35. public class Test {
    
36.         @SuppressWarnings("unchecked")
    
37.         public static void main(String[] args) throws IOException {
    
38.                 MemcachedClient cache = new MemcachedClient(new InetSocketAddress("127.0.0.1", 11211));
    
39.                
    
40.                 cache.set("y", 1800, "Love");
    
41. 
    
42.                 CASValue casValue1 = cache.gets("y");
    
43.                 CASValue casValue2 = cache.gets("y");
    
44.                 cache.cas("y", casValue2.getCas(), casValue2.getValue());
    
45.                
    
46.                 System.out.println("CAS 2:\t" + casValue2.getCas());
    
47.                 System.out.println("Value 2:\t" + casValue2.getValue());
    
48.                
    
49.                 System.out.println("CAS 1:\t" + casValue1.getCas());
    
50.                 System.out.println("Value 1:\t" + casValue1.getValue());
    
51.         }
    
52. }

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运行结果：

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1. 01.2011-12-18 23:07:14.528 INFO net.spy.memcached.MemcachedConnection:  Added {QA sa=/127.0.0.1:11211, #Rops=0, #Wops=0, #iq=0, topRop=null, topWop=null, toWrite=0, interested=0} to connect queue  
   
2. 02.2011-12-18 23:07:14.541 INFO net.spy.memcached.MemcachedConnection:  Connection state changed for sun.nio.ch.SelectionKeyImpl@1621e42  
   
3. 03.CAS 2:  11  
   
4. 04.Value 2:    Love  
   
5. 05.CAS 1:  11  
   
6. 06.Value 1:    Love  

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