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


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
26 import org.jboss.invocation.Invocation;
27
28 /**
29  * LoadBalancingPolicy implementation that always favor the first available target i.e.
30  * no load balancing occurs. Nevertheless, the first target is randomly selected.
31  * This does not mean that fail-over will not occur if the
32  * first member in the list dies. In this case, fail-over will occur, and a new target
33  * will become the first member and invocation will continously be invoked on the same
34  * new target until its death. Each proxy using this policy will *not* elect its own
35  * prefered target: the target *is* shared with all proxies that belong to the same family
36  * (for a different behaviour please take a look at FirstAvailable)
37  *
38  * @see org.jboss.ha.framework.interfaces.LoadBalancePolicy
39  *
40  * @author <a HREF="mailto:sacha.labourey@cogito-info.ch">Sacha Labourey</a>.
41  * @version $Revision: 56192 $
42  */
43 public class FirstAvailableIdenticalAllProxies implements LoadBalancePolicy
44 {
45    // Constants -----------------------------------------------------
46 private static final long serialVersionUID = 2910756623413400467L;
47
48    // Attributes ----------------------------------------------------
49
50    // Static --------------------------------------------------------
51
52    // Constructors --------------------------------------------------
53
54     // Public --------------------------------------------------------
55
56    public void init (HARMIClient father)
57    {
58       // do not use the HARMIClient in this policy
59 }
60
61    public Object JavaDoc chooseTarget (FamilyClusterInfo clusterFamily)
62    {
63       return chooseTarget(clusterFamily, null);
64    }
65    public Object JavaDoc chooseTarget (FamilyClusterInfo clusterFamily, Invocation routingDecision)
66    {
67       Object JavaDoc target = clusterFamily.getObject ();
68       List JavaDoc targets = clusterFamily.getTargets ();
69
70       if (targets.size () == 0)
71          return null;
72       
73       if (target != null && targets.contains (target) )
74       {
75          return target;
76       }
77       else
78       {
79          int cursor = RandomRobin.localRandomizer.nextInt (targets.size());
80          target = targets.get(cursor);
81          clusterFamily.setObject (target);
82          return target;
83       }
84    }
85
86 }
87
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