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.client;
019
020import java.util.Arrays;
021import java.util.concurrent.ThreadLocalRandom;
022import org.apache.hadoop.hbase.HConstants;
023import org.apache.yetus.audience.InterfaceAudience;
024
025/**
026 * NonceGenerator implementation that uses client ID hash + random int as nonce group, and random
027 * numbers as nonces.
028 */
029@InterfaceAudience.Private
030public final class PerClientRandomNonceGenerator implements NonceGenerator {
031
032  private static final PerClientRandomNonceGenerator INST = new PerClientRandomNonceGenerator();
033
034  private final long clientId;
035
036  private PerClientRandomNonceGenerator() {
037    byte[] clientIdBase = ClientIdGenerator.generateClientId();
038    this.clientId =
039      (((long) Arrays.hashCode(clientIdBase)) << 32) + ThreadLocalRandom.current().nextInt();
040  }
041
042  @Override
043  public long getNonceGroup() {
044    return this.clientId;
045  }
046
047  @Override
048  public long newNonce() {
049    long result = HConstants.NO_NONCE;
050    do {
051      result = ThreadLocalRandom.current().nextLong();
052    } while (result == HConstants.NO_NONCE);
053    return result;
054  }
055
056  /**
057   * Get the singleton nonce generator.
058   */
059  public static PerClientRandomNonceGenerator get() {
060    return INST;
061  }
062}