YugabyteDB (2.13.0.0-b42, bfc6a6643e7399ac8a0e81d06a3ee6d6571b33ab)

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#include <gtest/gtest.h>

#include "yb/util/hdr_histogram.h"

#include "yb/util/test_util.h"

namespace yb {

static const int kSigDigits = 2;

class HdrHistogramTest : public YBTest {

};

TEST_F(HdrHistogramTest, SimpleTest) {

  uint64_t highest_val = 10000LU;

  HdrHistogram hist(highest_val, kSigDigits);

  ASSERT_EQ(0, hist.CountInBucketForValue(1));

  hist.Increment(1);

  ASSERT_EQ(1, hist.CountInBucketForValue(1));

  hist.IncrementBy(1, 3);

  ASSERT_EQ(4, hist.CountInBucketForValue(1));

  hist.Increment(10);

  ASSERT_EQ(1, hist.CountInBucketForValue(10));

  hist.Increment(20);

  ASSERT_EQ(1, hist.CountInBucketForValue(20));

  ASSERT_EQ(0, hist.CountInBucketForValue(1000));

  hist.Increment(1000);

  hist.Increment(1001);

  ASSERT_EQ(2, hist.CountInBucketForValue(1000));

  ASSERT_EQ(1 + 1 * 3 + 10 + 20 + 1000 + 1001,

            hist.TotalSum());

}

TEST_F(HdrHistogramTest, TestCoordinatedOmission) {

  uint64_t interval = 1000;

  int loop_iters = 100;

  int64_t normal_value = 10;

  HdrHistogram hist(1000000LU, kSigDigits);

  for (int i = 1; i <= loop_iters; i++) {

    // Simulate a periodic "large value" that would exhibit coordinated

    // omission were this loop to sleep on 'interval'.

    int64_t value = (i % normal_value == 0) ? interval * 10 : normal_value;

    hist.IncrementWithExpectedInterval(value, interval);

  }

  ASSERT_EQ(loop_iters - (loop_iters / normal_value),

            hist.CountInBucketForValue(normal_value));

  for (auto i = interval; i <= interval * 10; i += interval) {

    ASSERT_EQ(loop_iters / normal_value, hist.CountInBucketForValue(i));

  }

}

static const int kExpectedSum =

  10 * 80 + 100 * 10 + 1000 * 5 + 10000 * 3 + 100000 * 1 + 1000000 * 1;

static const int kExpectedMax = 1000000;

static const int kExpectedCount = 100;

static const int kExpectedMin = 10;

static void load_percentiles(HdrHistogram* hist) {

  hist->IncrementBy(10, 80);

  hist->IncrementBy(100, 10);

  hist->IncrementBy(1000, 5);

  hist->IncrementBy(10000, 3);

  hist->IncrementBy(100000, 1);

  hist->IncrementBy(1000000, 1);

}

static void validate_percentiles(HdrHistogram* hist, uint64_t specified_max) {

  double expected_mean =

    static_cast<double>(kExpectedSum) / (80 + 10 + 5 + 3 + 1 + 1);

  ASSERT_EQ(kExpectedMin, hist->MinValue());

  ASSERT_EQ(kExpectedMax, hist->MaxValue());

  ASSERT_EQ(kExpectedSum, hist->TotalSum());

  ASSERT_NEAR(expected_mean, hist->MeanValue(), 0.001);

  ASSERT_EQ(kExpectedCount, hist->TotalCount());

  ASSERT_EQ(10, hist->ValueAtPercentile(80));

  ASSERT_EQ(kExpectedCount, hist->ValueAtPercentile(90));

  ASSERT_EQ(hist->LowestEquivalentValue(specified_max), hist->ValueAtPercentile(99));

  ASSERT_EQ(hist->LowestEquivalentValue(specified_max), hist->ValueAtPercentile(99.99));

  ASSERT_EQ(hist->LowestEquivalentValue(specified_max), hist->ValueAtPercentile(100));

}

TEST_F(HdrHistogramTest, PercentileAndCopyTest) {

  uint64_t specified_max = 10000;

  HdrHistogram hist(specified_max, kSigDigits);

  load_percentiles(&hist);

  ASSERT_NO_FATALS(validate_percentiles(&hist, specified_max));

  HdrHistogram copy(hist);

  ASSERT_NO_FATALS(validate_percentiles(&copy, specified_max));

  ASSERT_EQ(hist.TotalSum(), copy.TotalSum());

}

} // namespace yb