001/*
002 * Licensed to the Apache Software Foundation (ASF) under one
003 * or more contributor license agreements.  See the NOTICE file
004 * distributed with this work for additional information
005 * regarding copyright ownership.  The ASF licenses this file
006 * to you under the Apache License, Version 2.0 (the
007 * "License"); you may not use this file except in compliance
008 * with the License.  You may obtain a copy of the License at
009 *
010 *     http://www.apache.org/licenses/LICENSE-2.0
011 *
012 * Unless required by applicable law or agreed to in writing, software
013 * distributed under the License is distributed on an "AS IS" BASIS,
014 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
015 * See the License for the specific language governing permissions and
016 * limitations under the License.
017 */
018package org.apache.hadoop.hbase.ipc;
019
020import java.util.List;
021import java.util.concurrent.BlockingQueue;
022import java.util.concurrent.ThreadLocalRandom;
023import org.apache.hadoop.conf.Configuration;
024import org.apache.yetus.audience.InterfaceAudience;
025import org.apache.yetus.audience.InterfaceStability;
026
027/**
028 * Queue balancer that just randomly selects a queue in the range [0, num queues).
029 */
030@InterfaceAudience.Private
031@InterfaceStability.Stable
032public class RandomQueueBalancer implements QueueBalancer {
033  private final int queueSize;
034  private final List<BlockingQueue<CallRunner>> queues;
035
036  public RandomQueueBalancer(Configuration conf, String executorName,
037    List<BlockingQueue<CallRunner>> queues) {
038    this.queueSize = queues.size();
039    this.queues = queues;
040  }
041
042  @Override
043  public int getNextQueue(CallRunner callRunner) {
044    return ThreadLocalRandom.current().nextInt(queueSize);
045  }
046
047  /**
048   * Exposed for use in tests
049   */
050  List<BlockingQueue<CallRunner>> getQueues() {
051    return queues;
052  }
053}