001/*
002 * Copyright 2009 Red Hat, Inc.
003 * Red Hat licenses this file to you under the Apache License, version
004 * 2.0 (the "License"); you may not use this file except in compliance
005 * with the License.  You may obtain a copy of the License at
006 *    http://www.apache.org/licenses/LICENSE-2.0
007 * Unless required by applicable law or agreed to in writing, software
008 * distributed under the License is distributed on an "AS IS" BASIS,
009 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
010 * implied.  See the License for the specific language governing
011 * permissions and limitations under the License.
012 */
013
014package org.hornetq.api.core.client.loadbalance;
015
016import org.hornetq.utils.Random;
017
018/**
019 * RoundRobinConnectionLoadBalancingPolicy corresponds to a round-robin load-balancing policy.
020 * 
021 * <br>
022 * The first call to {@link #select(int)} will return a random integer between {@code 0} (inclusive) and {@code max} (exclusive).
023 * Subsequent calls will then return an integer in a round-robin fashion.
024 *
025 * @author <a href="mailto:tim.fox@jboss.com">Tim Fox</a>
026 * 
027 * Created 28 Nov 2008 10:21:08
028 *
029 *
030 */
031public class RoundRobinConnectionLoadBalancingPolicy implements ConnectionLoadBalancingPolicy
032{
033   private final Random random = new Random();
034
035   private boolean first = true;
036
037   private int pos;
038
039   public int select(final int max)
040   {
041      if (first)
042      {
043         // We start on a random one
044         pos = random.getRandom().nextInt(max);
045
046         first = false;
047      }
048      else
049      {
050         pos++;
051
052         if (pos >= max)
053         {
054            pos = 0;
055         }
056      }
057
058      return pos;
059   }
060}