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1   /**
2    * Copyright The Apache Software Foundation
3    *
4    * Licensed to the Apache Software Foundation (ASF) under one
5    * or more contributor license agreements.  See the NOTICE file
6    * distributed with this work for additional information
7    * regarding copyright ownership.  The ASF licenses this file
8    * to you under the Apache License, Version 2.0 (the
9    * "License"); you may not use this file except in compliance
10   * with the License.  You may obtain a copy of the License at
11   *
12   *     http://www.apache.org/licenses/LICENSE-2.0
13   *
14   * Unless required by applicable law or agreed to in writing, software
15   * distributed under the License is distributed on an "AS IS" BASIS,
16   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
17   * See the License for the specific language governing permissions and
18   * limitations under the License.
19   */
20  package org.apache.hadoop.hbase.client;
21  
22  import org.apache.hadoop.hbase.SmallTests;
23  import org.junit.Test;
24  import org.junit.experimental.categories.Category;
25  
26  import java.util.Set;
27  import java.util.TreeSet;
28  
29  import static org.junit.Assert.assertTrue;
30  
31  @Category(SmallTests.class)
32  public class TestConnectionUtils {
33  
34    @Test
35    public void testRetryTimeJitter() {
36      long[] retries = new long[200];
37      long baseTime = 1000000;  //Larger number than reality to help test randomness.
38      long maxTimeExpected = (long) (baseTime * 1.01f);
39      for (int i = 0; i < retries.length; i++) {
40        retries[i] = ConnectionUtils.getPauseTime(baseTime, 0);
41      }
42  
43      Set<Long> retyTimeSet = new TreeSet<Long>();
44      for (long l : retries) {
45        /*make sure that there is some jitter but only 1%*/
46        assertTrue(l >= baseTime);
47        assertTrue(l <= maxTimeExpected);
48        // Add the long to the set
49        retyTimeSet.add(l);
50      }
51  
52      //Make sure that most are unique.  some overlap will happen
53      assertTrue(retyTimeSet.size() > (retries.length * 0.80));
54    }
55  
56  }