01: /*
02: * JBoss, Home of Professional Open Source.
03: * Copyright 2006, Red Hat Middleware LLC, and individual contributors
04: * as indicated by the @author tags. See the copyright.txt file in the
05: * distribution for a full listing of individual contributors.
06: *
07: * This is free software; you can redistribute it and/or modify it
08: * under the terms of the GNU Lesser General Public License as
09: * 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.ArrayList;
25: import org.jboss.invocation.Invocation;
26:
27: /**
28: * LoadBalancingPolicy implementation that always favor the next available
29: * target load balancing always occurs.
30: *
31: * @see org.jboss.ha.framework.interfaces.LoadBalancePolicy
32: *
33: * @author <a href="mailto:sacha.labourey@cogito-info.ch">Sacha Labourey</a>.
34: * @author <a href="mailto:bill@burkecentral.com">Bill Burke</a>.
35: * @version $Revision: 57188 $
36: */
37: public class RoundRobin implements LoadBalancePolicy {
38: // Constants -----------------------------------------------------
39: /** @since 1.3.4.2 */
40: private static final long serialVersionUID = 8660076707279597114L;
41:
42: // Attributes ----------------------------------------------------
43:
44: // Static --------------------------------------------------------
45:
46: // Constructors --------------------------------------------------
47:
48: // Public --------------------------------------------------------
49:
50: public void init(HARMIClient father) {
51: // do not use the HARMIClient in this policy
52: }
53:
54: public Object chooseTarget(FamilyClusterInfo clusterFamily) {
55: return this .chooseTarget(clusterFamily, null);
56: }
57:
58: public Object chooseTarget(FamilyClusterInfo clusterFamily,
59: Invocation routingDecision) {
60: int cursor = clusterFamily.getCursor();
61: ArrayList targets = clusterFamily.getTargets();
62:
63: if (targets.size() == 0)
64: return null;
65:
66: if (cursor == FamilyClusterInfo.UNINITIALIZED_CURSOR) {
67: // Obtain a random index into targets
68: cursor = RandomRobin.localRandomizer
69: .nextInt(targets.size());
70: } else {
71: // Choose the next target
72: cursor = ((cursor + 1) % targets.size());
73: }
74: clusterFamily.setCursor(cursor);
75:
76: return targets.get(cursor);
77: }
78:
79: }
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