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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.util;
20  
21  import org.apache.hadoop.classification.InterfaceAudience;
22  
23  /**
24   * Uses an incrementing algorithm instead of the default.
25   */
26  @InterfaceAudience.Private
27  public class IncrementingEnvironmentEdge implements EnvironmentEdge {
28  
29    private long timeIncrement;
30  
31    /**
32     * Construct an incremental edge starting from currentTimeMillis
33     */
34    public IncrementingEnvironmentEdge() {
35      this(System.currentTimeMillis());
36    }
37  
38    /**
39     * Construct an incremental edge with an initial amount
40     * @param initialAmount the initial value to start with
41     */
42    public IncrementingEnvironmentEdge(long initialAmount) {
43      this.timeIncrement = initialAmount;
44    }
45  
46    /**
47     * {@inheritDoc}
48     * <p/>
49     * This method increments a known value for the current time each time this
50     * method is called. The first value is 1.
51     */
52    @Override
53    public synchronized long currentTime() {
54      return timeIncrement++;
55    }
56  
57    /**
58     * Increment the time by the given amount
59     */
60    public synchronized long incrementTime(long amount) {
61      timeIncrement += amount;
62      return timeIncrement;
63    }
64  }