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.util;
019
020import static org.junit.Assert.assertEquals;
021import static org.junit.Assert.assertThrows;
022import static org.junit.Assert.assertTrue;
023
024import java.util.stream.IntStream;
025import org.apache.hadoop.hbase.HBaseClassTestRule;
026import org.apache.hadoop.hbase.testclassification.MiscTests;
027import org.apache.hadoop.hbase.testclassification.SmallTests;
028import org.junit.ClassRule;
029import org.junit.Test;
030import org.junit.experimental.categories.Category;
031
032@Category({ MiscTests.class, SmallTests.class })
033public class TestReservoirSample {
034
035  @ClassRule
036  public static final HBaseClassTestRule CLASS_RULE =
037    HBaseClassTestRule.forClass(TestReservoirSample.class);
038
039  @Test
040  public void test() {
041    int round = 100000;
042    int containsOne = 0;
043    for (int i = 0; i < round; i++) {
044      ReservoirSample<Integer> rs = new ReservoirSample<>(10);
045      for (int j = 0; j < 100; j++) {
046        rs.add(j);
047        if (j < 10) {
048          assertEquals(j + 1, rs.getSamplingResult().size());
049        } else {
050          assertEquals(10, rs.getSamplingResult().size());
051        }
052      }
053      if (rs.getSamplingResult().contains(1)) {
054        containsOne++;
055      }
056    }
057    // we assume a 5% error rate
058    assertTrue(containsOne > round / 10 * 0.95);
059    assertTrue(containsOne < round / 10 * 1.05);
060  }
061
062  @Test
063  public void testIterator() {
064    int round = 100000;
065    int containsOne = 0;
066    for (int i = 0; i < round; i++) {
067      ReservoirSample<Integer> rs = new ReservoirSample<>(10);
068      rs.add(IntStream.range(0, 100).mapToObj(Integer::valueOf).iterator());
069      if (rs.getSamplingResult().contains(1)) {
070        containsOne++;
071      }
072    }
073    // we assume a 5% error rate
074    assertTrue(containsOne > round / 10 * 0.95);
075    assertTrue(containsOne < round / 10 * 1.05);
076  }
077
078  @Test
079  public void testStream() {
080    int round = 100000;
081    int containsOne = 0;
082    for (int i = 0; i < round; i++) {
083      ReservoirSample<Integer> rs = new ReservoirSample<>(10);
084      rs.add(IntStream.range(0, 100).mapToObj(Integer::valueOf));
085      if (rs.getSamplingResult().contains(1)) {
086        containsOne++;
087      }
088    }
089    // we assume a 5% error rate
090    assertTrue(containsOne > round / 10 * 0.95);
091    assertTrue(containsOne < round / 10 * 1.05);
092  }
093
094  @Test
095  public void testNegativeSamplingNumber() {
096    IllegalArgumentException e =
097      assertThrows(IllegalArgumentException.class, () -> new ReservoirSample<Integer>(-1));
098    assertEquals("negative sampling number(-1) is not allowed", e.getMessage());
099  }
100}