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RandomLoadBalancer.java
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1 /*
2  * Copyright (c) 2010-2012 Grid Dynamics Consulting Services, Inc, All Rights Reserved
3  * http://www.griddynamics.com
4  *
5  * This library is free software; you can redistribute it and/or modify it under the terms of
6  * the Apache License; either
7  * version 2.0 of the License, or any later version.
8  *
9  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
10  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
11  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
12  * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE
13  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
14  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
15  * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
16  * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
17  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
18  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
19  */
20 
21 package com.griddynamics.jagger.invoker;
22 
23 import com.google.common.collect.AbstractIterator;
24 import com.griddynamics.jagger.util.Pair;
25 import java.util.Iterator;
26 import java.util.Random;
27 
38 public class RandomLoadBalancer<Q, E> extends PairSupplierFactoryLoadBalancer<Q, E> {
39 
40  private long randomSeed;
41 
42  public void setRandomSeed(long randomSeed) {
43  this.randomSeed = randomSeed;
44  }
45 
46  public long getRandomSeed() {
47  return randomSeed;
48  }
49 
55  @Override
56  public Iterator<Pair<Q, E>> provide() {
57 
58  return new AbstractIterator<Pair<Q,E>>() {
59 
60  private PairSupplier<Q, E> pairs = getPairSupplier();
61  private int size = pairs.size();
62  private Random random = new Random(randomSeed++);
63 
64  @Override
65  protected Pair<Q, E> computeNext() {
66  return pairs.get(random.nextInt(size));
67  }
68 
69  @Override
70  public String toString() {
71  return "RandomLoadBalancer iterator";
72  }
73  };
74  }
75 }