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.master.balancer;
019
020import org.apache.hadoop.conf.Configuration;
021import org.apache.hadoop.hbase.HConstants;
022import org.apache.hadoop.hbase.master.LoadBalancer;
023import org.apache.hadoop.hbase.util.ReflectionUtils;
024import org.apache.yetus.audience.InterfaceAudience;
025
026/**
027 * The class that creates a load balancer from a conf.
028 */
029@InterfaceAudience.Private
030public class LoadBalancerFactory {
031
032  /**
033   * The default {@link LoadBalancer} class.
034   * @return The Class for the default {@link LoadBalancer}.
035   */
036  public static Class<? extends LoadBalancer> getDefaultLoadBalancerClass() {
037    return StochasticLoadBalancer.class;
038  }
039
040  /**
041   * Create a loadbalancer from the given conf. n * @return A {@link LoadBalancer}
042   */
043  public static LoadBalancer getLoadBalancer(Configuration conf) {
044    // Create the balancer
045    Class<? extends LoadBalancer> balancerKlass =
046      conf.getClass(HConstants.HBASE_MASTER_LOADBALANCER_CLASS, getDefaultLoadBalancerClass(),
047        LoadBalancer.class);
048    return ReflectionUtils.newInstance(balancerKlass);
049  }
050}