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1   /**
2    *
3    * Licensed to the Apache Software Foundation (ASF) under one
4    * or more contributor license agreements.  See the NOTICE file
5    * distributed with this work for additional information
6    * regarding copyright ownership.  The ASF licenses this file
7    * to you under the Apache License, Version 2.0 (the
8    * "License"); you may not use this file except in compliance
9    * with the License.  You may obtain a copy of the License at
10   *
11   *     http://www.apache.org/licenses/LICENSE-2.0
12   *
13   * Unless required by applicable law or agreed to in writing, software
14   * distributed under the License is distributed on an "AS IS" BASIS,
15   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
16   * See the License for the specific language governing permissions and
17   * limitations under the License.
18   */
19  package org.apache.hadoop.hbase.client;
20  
21  import java.util.Arrays;
22  import java.util.Random;
23  
24  import org.apache.hadoop.hbase.classification.InterfaceAudience;
25  import org.apache.hadoop.hbase.HConstants;
26  
27  /**
28   * NonceGenerator implementation that uses client ID hash + random int as nonce group,
29   * and random numbers as nonces.
30   */
31  @InterfaceAudience.Private
32  public class PerClientRandomNonceGenerator implements NonceGenerator {
33    private final Random rdm = new Random();
34    private final long clientId;
35  
36    public PerClientRandomNonceGenerator() {
37      byte[] clientIdBase = ClientIdGenerator.generateClientId();
38      this.clientId = (((long)Arrays.hashCode(clientIdBase)) << 32) + rdm.nextInt();
39    }
40  
41    public long getNonceGroup() {
42      return this.clientId;
43    }
44  
45    public long newNonce() {
46      long result = HConstants.NO_NONCE;
47      do {
48        result = rdm.nextLong();
49      } while (result == HConstants.NO_NONCE);
50      return result;
51    }
52  }