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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.client.backoff;
19  
20  import org.apache.commons.logging.Log;
21  import org.apache.commons.logging.LogFactory;
22  import org.apache.hadoop.conf.Configuration;
23  import org.apache.hadoop.hbase.ServerName;
24  import org.apache.hadoop.hbase.classification.InterfaceAudience;
25  import org.apache.hadoop.hbase.classification.InterfaceStability;
26  import org.apache.hadoop.hbase.util.ReflectionUtils;
27  
28  @InterfaceAudience.Private
29  @InterfaceStability.Evolving
30  public final class ClientBackoffPolicyFactory {
31  
32    private static final Log LOG = LogFactory.getLog(ClientBackoffPolicyFactory.class);
33  
34    private ClientBackoffPolicyFactory() {
35    }
36  
37    public static ClientBackoffPolicy create(Configuration conf) {
38      // create the backoff policy
39      String className =
40          conf.get(ClientBackoffPolicy.BACKOFF_POLICY_CLASS, NoBackoffPolicy.class
41              .getName());
42        return ReflectionUtils.instantiateWithCustomCtor(className,
43            new Class<?>[] { Configuration.class }, new Object[] { conf });
44    }
45  
46    /**
47     * Default backoff policy that doesn't create any backoff for the client, regardless of load
48     */
49    public static class NoBackoffPolicy implements ClientBackoffPolicy {
50      public NoBackoffPolicy(Configuration conf){
51        // necessary to meet contract
52      }
53  
54      @Override
55      public long getBackoffTime(ServerName serverName, byte[] region, ServerStatistics stats) {
56        return 0;
57      }
58    }
59  }