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Java > Open Source Codes > org > jboss > ha > framework > interfaces > RandomRobin


1 /*
2   * JBoss, Home of Professional Open Source
3   * Copyright 2005, JBoss Inc., and individual contributors as indicated
4   * by the @authors tag. See the copyright.txt in the distribution for a
5   * full listing of individual contributors.
6   *
7   * This is free software; you can redistribute it and/or modify it
8   * under the terms of the GNU Lesser General Public License as
9   * published by the Free Software Foundation; either version 2.1 of
10   * the License, or (at your option) any later version.
11   *
12   * This software is distributed in the hope that it will be useful,
13   * but WITHOUT ANY WARRANTY; without even the implied warranty of
14   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15   * Lesser General Public License for more details.
16   *
17   * You should have received a copy of the GNU Lesser General Public
18   * License along with this software; if not, write to the Free
19   * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
20   * 02110-1301 USA, or see the FSF site: http://www.fsf.org.
21   */
22 package org.jboss.ha.framework.interfaces;
23
24 import java.util.List JavaDoc;
25 import java.util.Random JavaDoc;
26
27 import org.jboss.invocation.Invocation;
28
29 /**
30  * LoadBalancingPolicy implementation that always fully randomly select its target
31  * (without basing its decision on any historic).
32  *
33  * @author <a HREF="mailto:sacha.labourey@cogito-info.ch">Sacha Labourey</a>.
34  * @version $Revision: 56192 $
35  * @see org.jboss.ha.framework.interfaces.LoadBalancePolicy
36  */
37 public class RandomRobin implements LoadBalancePolicy
38 {
39    // Constants -----------------------------------------------------
40 /** @since 1.1.2.3 */
41    private static final long serialVersionUID = -3599638697906618428L;
42    /** This needs to be a class variable or else you end up with multiple
43     * Random numbers with the same seed when many clients lookup a proxy.
44     */
45    public static final Random JavaDoc localRandomizer = new Random JavaDoc (System.currentTimeMillis ());
46
47    // Static --------------------------------------------------------
48
49    // Constructors --------------------------------------------------
50
51     // Public --------------------------------------------------------
52
53    // LoadBalancePolicy implementation ----------------------------------------------
54
55    public void init (HARMIClient father)
56    {
57       // do not use the HARMIClient in this policy
58 }
59
60    public Object JavaDoc chooseTarget (FamilyClusterInfo clusterFamily)
61    {
62       return chooseTarget(clusterFamily, null);
63    }
64    public Object JavaDoc chooseTarget (FamilyClusterInfo clusterFamily, Invocation routingDecision)
65    {
66       List JavaDoc targets = clusterFamily.getTargets ();
67       int max = targets.size();
68
69       if (max == 0)
70          return null;
71
72       int cursor = localRandomizer.nextInt (max);
73       return targets.get(cursor);
74    }
75
76 }
77
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