1 /*
2 * EL4J, the Extension Library for the J2EE, adds incremental enhancements to
3 * the spring framework, http://el4j.sf.net
4 * Copyright (C) 2006 by ELCA Informatique SA, Av. de la Harpe 22-24,
5 * 1000 Lausanne, Switzerland, http://www.elca.ch
6 *
7 * EL4J is published under the GNU Lesser General Public License (LGPL)
8 * Version 2.1. See http://www.gnu.org/licenses/
9 *
10 * This program is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 * GNU Lesser General Public License for more details.
14 *
15 * For alternative licensing, please contact info@elca.ch
16 */
17 package ch.elca.el4j.services.remoting.protocol.loadbalancing.policy;
18
19 import java.util.Calendar;
20 import java.util.Random;
21
22 import org.slf4j.Logger;
23 import org.slf4j.LoggerFactory;
24
25 import ch.elca.el4j.services.remoting.AbstractRemotingProtocol;
26 import ch.elca.el4j.services.remoting.protocol.loadbalancing.NoProtocolAvailableRTException;
27
28 /**
29 *
30 * Chooses the protocol according to a random policy. Protocols for whom a
31 * failure has been notified, are removed.
32 *
33 * @svnLink $Revision: 3883 $;$Date: 2009-08-04 15:35:01 +0200 (Di, 04. Aug 2009) $;$Author: swismer $;$URL: https://el4j.svn.sourceforge.net/svnroot/el4j/branches/el4j_3_1/el4j/framework/modules/remoting_core/src/main/java/ch/elca/el4j/services/remoting/protocol/loadbalancing/policy/RandomPolicy.java $
34 *
35 * @author Stefan Pleisch (SPL)
36 */
37 public class RandomPolicy extends AbstractPolicy {
38
39 /**
40 * Private logger.
41 */
42 private static Logger s_logger = LoggerFactory
43 .getLogger(RandomPolicy.class);
44
45 /**
46 * Random number generator.
47 */
48 private Random m_random
49 = new Random(Calendar.getInstance().getTimeInMillis());
50
51 /**
52 * {@inheritDoc}
53 */
54 @Override
55 public AbstractRemotingProtocol getNextProtocol()
56 throws NoProtocolAvailableRTException {
57 if ((m_protocols == null) || (m_protocols.length == 0)) {
58 throw new NoProtocolAvailableRTException("No protocol defined");
59 }
60 AbstractRemotingProtocol protocol
61 = m_protocols[m_random.nextInt(m_protocols.length)];
62 s_logger.debug("Returning next protocol: " + protocol);
63 return protocol;
64 }
65
66 /**
67 * {@inheritDoc}
68 */
69 public void notifyFailure(AbstractRemotingProtocol protocol) {
70 s_logger.debug("Removing protocol: " + protocol);
71 removeProtocol(protocol);
72 }
73 }