1 /**
2 * Licensed to the Apache Software Foundation (ASF) under one
3 * or more contributor license agreements. See the NOTICE file
4 * distributed with this work for additional information
5 * regarding copyright ownership. The ASF licenses this file
6 * to you under the Apache License, Version 2.0 (the
7 * "License"); you may not use this file except in compliance
8 * with the License. You may obtain a copy of the License at
9 *
10 * http://www.apache.org/licenses/LICENSE-2.0
11 *
12 * Unless required by applicable law or agreed to in writing, software
13 * distributed under the License is distributed on an "AS IS" BASIS,
14 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
15 * See the License for the specific language governing permissions and
16 * limitations under the License.
17 */
18 package org.apache.hadoop.hbase.master.balancer;
19
20 import org.apache.hadoop.hbase.classification.InterfaceAudience;
21 import org.apache.hadoop.conf.Configuration;
22 import org.apache.hadoop.hbase.HConstants;
23 import org.apache.hadoop.hbase.master.LoadBalancer;
24 import org.apache.hadoop.util.ReflectionUtils;
25
26 /**
27 * The class that creates a load balancer from a conf.
28 */
29 @InterfaceAudience.Private
30 public class LoadBalancerFactory {
31
32 /**
33 * The default {@link LoadBalancer} class.
34 *
35 * @return The Class for the default {@link LoadBalancer}.
36 */
37 public static Class<? extends LoadBalancer> getDefaultLoadBalancerClass() {
38 return StochasticLoadBalancer.class;
39 }
40
41 /**
42 * Create a loadbalancer from the given conf.
43 * @param conf
44 * @return A {@link LoadBalancer}
45 */
46 public static LoadBalancer getLoadBalancer(Configuration conf) {
47
48 // Create the balancer
49 Class<? extends LoadBalancer> balancerKlass =
50 conf.getClass(HConstants.HBASE_MASTER_LOADBALANCER_CLASS, getDefaultLoadBalancerClass(),
51 LoadBalancer.class);
52 return ReflectionUtils.newInstance(balancerKlass, conf);
53
54 }
55 }