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Java > Open Source Codes > demo > coordination > CounterService


1 /*
2 @COPYRIGHT@
3 */
4 package demo.coordination;
5
6 import java.text.MessageFormat JavaDoc;
7 import java.util.logging.Logger JavaDoc;
8
9 import org.springframework.beans.factory.DisposableBean;
10 import org.springframework.beans.factory.InitializingBean;
11
12 /**
13  * Simple service using process coordination via synchronization.
14  */
15 public class CounterService
16 implements InitializingBean, DisposableBean, Runnable JavaDoc
17 {
18    private static final Logger JavaDoc logger = Logger.getLogger(CounterService.class.getName());
19
20    private static final String JavaDoc LOG_PREFIX = System.getProperty("counter.log.prefix", "Counter service [INFO]:") + " ";
21    private static final int MAX_COUNTER = 999;
22    private static final String JavaDoc STATUS_FORMAT = "This node is currently <font color=\"green\"><b><i>{0}</i></b></font>.<br>The current distributed counter value is: {1}";
23
24    // By making this variables transient, Terracotta for Spring will *not* cluster it
25 private transient boolean running;
26
27    // These objects are distributed by Terracotta for Spring
28 private int counter = 0;
29    private final Object JavaDoc lock = new Object JavaDoc();
30
31    public void afterPropertiesSet()
32    throws Exception JavaDoc
33    {
34       log("Creating background thread to try to increment counter");
35       Thread JavaDoc t = new Thread JavaDoc(this, "MessageService");
36       t.start();
37    }
38
39    public void destroy()
40    throws Exception JavaDoc
41    {
42       running = false;
43    }
44
45    public void run()
46    {
47       log("[background thread] Waiting to synchronize on the counter lock...");
48       synchronized (lock)
49       {
50          log("[background thread] Got the counter lock, I will start incrementing the counter");
51          running = true;
52          boolean logFirstIncrement = true;
53          while (running)
54          {
55             synchronized (this)
56             {
57                counter++;
58                if (counter > MAX_COUNTER) counter = 0;
59                if (logFirstIncrement)
60                {
61                   log("[background thread] Incremented the counter to " + counter + " -- will increment every second");
62                   logFirstIncrement = false;
63                }
64             }
65             try
66             {
67                Thread.sleep(1000L);
68             }
69             catch (InterruptedException JavaDoc ex)
70             {
71                // Ignore and keep processing
72 }
73          }
74       }
75    }
76
77    public String JavaDoc getStatus()
78    {
79       synchronized (this)
80       {
81          return MessageFormat.format(STATUS_FORMAT, new Object JavaDoc[] { running ? "active" : "passive", new Integer JavaDoc(counter) });
82       }
83    }
84
85    private static void log(String JavaDoc message)
86    {
87       logger.info(LOG_PREFIX + message);
88    }
89
90 }
91
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