rocksdb/monitoring/histogram_test.cc
mrambacher 12f1137355 Add a SystemClock class to capture the time functions of an Env (#7858)
Summary:
Introduces and uses a SystemClock class to RocksDB.  This class contains the time-related functions of an Env and these functions can be redirected from the Env to the SystemClock.

Many of the places that used an Env (Timer, PerfStepTimer, RepeatableThread, RateLimiter, WriteController) for time-related functions have been changed to use SystemClock instead.  There are likely more places that can be changed, but this is a start to show what can/should be done.  Over time it would be nice to migrate most (if not all) of the uses of the time functions from the Env to the SystemClock.

There are several Env classes that implement these functions.  Most of these have not been converted yet to SystemClock implementations; that will come in a subsequent PR.  It would be good to unify many of the Mock Timer implementations, so that they behave similarly and be tested similarly (some override Sleep, some use a MockSleep, etc).

Additionally, this change will allow new methods to be introduced to the SystemClock (like https://github.com/facebook/rocksdb/issues/7101 WaitFor) in a consistent manner across a smaller number of classes.

Pull Request resolved: https://github.com/facebook/rocksdb/pull/7858

Reviewed By: pdillinger

Differential Revision: D26006406

Pulled By: mrambacher

fbshipit-source-id: ed10a8abbdab7ff2e23d69d85bd25b3e7e899e90
2021-01-25 22:09:11 -08:00

234 lines
7.7 KiB
C++

// Copyright (c) 2011-present, Facebook, Inc. All rights reserved.
// This source code is licensed under both the GPLv2 (found in the
// COPYING file in the root directory) and Apache 2.0 License
// (found in the LICENSE.Apache file in the root directory).
//
#include "monitoring/histogram.h"
#include <cmath>
#include "monitoring/histogram_windowing.h"
#include "rocksdb/system_clock.h"
#include "test_util/mock_time_env.h"
#include "test_util/testharness.h"
#include "util/random.h"
namespace ROCKSDB_NAMESPACE {
class HistogramTest : public testing::Test {};
namespace {
const double kIota = 0.1;
const HistogramBucketMapper bucketMapper;
std::shared_ptr<MockSystemClock> clock =
std::make_shared<MockSystemClock>(SystemClock::Default());
}
void PopulateHistogram(Histogram& histogram,
uint64_t low, uint64_t high, uint64_t loop = 1) {
Random rnd(test::RandomSeed());
for (; loop > 0; loop--) {
for (uint64_t i = low; i <= high; i++) {
histogram.Add(i);
// sleep a random microseconds [0-10)
clock->MockSleepForMicroseconds(rnd.Uniform(10));
}
}
// make sure each data population at least take some time
clock->MockSleepForMicroseconds(1);
}
void BasicOperation(Histogram& histogram) {
PopulateHistogram(histogram, 1, 110, 10); // fill up to bucket [70, 110)
HistogramData data;
histogram.Data(&data);
ASSERT_LE(fabs(histogram.Percentile(100.0) - 110.0), kIota);
ASSERT_LE(fabs(data.percentile99 - 108.9), kIota); // 99 * 110 / 100
ASSERT_LE(fabs(data.percentile95 - 104.5), kIota); // 95 * 110 / 100
ASSERT_LE(fabs(data.median - 55.0), kIota); // 50 * 110 / 100
ASSERT_EQ(data.average, 55.5); // (1 + 110) / 2
}
void MergeHistogram(Histogram& histogram, Histogram& other) {
PopulateHistogram(histogram, 1, 100);
PopulateHistogram(other, 101, 250);
histogram.Merge(other);
HistogramData data;
histogram.Data(&data);
ASSERT_LE(fabs(histogram.Percentile(100.0) - 250.0), kIota);
ASSERT_LE(fabs(data.percentile99 - 247.5), kIota); // 99 * 250 / 100
ASSERT_LE(fabs(data.percentile95 - 237.5), kIota); // 95 * 250 / 100
ASSERT_LE(fabs(data.median - 125.0), kIota); // 50 * 250 / 100
ASSERT_EQ(data.average, 125.5); // (1 + 250) / 2
}
void EmptyHistogram(Histogram& histogram) {
ASSERT_EQ(histogram.min(), bucketMapper.LastValue());
ASSERT_EQ(histogram.max(), 0);
ASSERT_EQ(histogram.num(), 0);
ASSERT_EQ(histogram.Median(), 0.0);
ASSERT_EQ(histogram.Percentile(85.0), 0.0);
ASSERT_EQ(histogram.Average(), 0.0);
ASSERT_EQ(histogram.StandardDeviation(), 0.0);
}
void ClearHistogram(Histogram& histogram) {
for (uint64_t i = 1; i <= 100; i++) {
histogram.Add(i);
}
histogram.Clear();
ASSERT_TRUE(histogram.Empty());
ASSERT_EQ(histogram.Median(), 0);
ASSERT_EQ(histogram.Percentile(85.0), 0);
ASSERT_EQ(histogram.Average(), 0);
}
TEST_F(HistogramTest, BasicOperation) {
HistogramImpl histogram;
BasicOperation(histogram);
HistogramWindowingImpl histogramWindowing;
BasicOperation(histogramWindowing);
}
TEST_F(HistogramTest, BoundaryValue) {
HistogramImpl histogram;
// - both should be in [0, 1] bucket because we place values on bucket
// boundaries in the lower bucket.
// - all points are in [0, 1] bucket, so p50 will be 0.5
// - the test cannot be written with a single point since histogram won't
// report percentiles lower than the min or greater than the max.
histogram.Add(0);
histogram.Add(1);
ASSERT_LE(fabs(histogram.Percentile(50.0) - 0.5), kIota);
}
TEST_F(HistogramTest, MergeHistogram) {
HistogramImpl histogram;
HistogramImpl other;
MergeHistogram(histogram, other);
HistogramWindowingImpl histogramWindowing;
HistogramWindowingImpl otherWindowing;
MergeHistogram(histogramWindowing, otherWindowing);
}
TEST_F(HistogramTest, EmptyHistogram) {
HistogramImpl histogram;
EmptyHistogram(histogram);
HistogramWindowingImpl histogramWindowing;
EmptyHistogram(histogramWindowing);
}
TEST_F(HistogramTest, ClearHistogram) {
HistogramImpl histogram;
ClearHistogram(histogram);
HistogramWindowingImpl histogramWindowing;
ClearHistogram(histogramWindowing);
}
TEST_F(HistogramTest, HistogramWindowingExpire) {
uint64_t num_windows = 3;
int micros_per_window = 1000000;
uint64_t min_num_per_window = 0;
HistogramWindowingImpl
histogramWindowing(num_windows, micros_per_window, min_num_per_window);
histogramWindowing.TEST_UpdateClock(clock);
PopulateHistogram(histogramWindowing, 1, 1, 100);
clock->MockSleepForMicroseconds(micros_per_window);
ASSERT_EQ(histogramWindowing.num(), 100);
ASSERT_EQ(histogramWindowing.min(), 1);
ASSERT_EQ(histogramWindowing.max(), 1);
ASSERT_EQ(histogramWindowing.Average(), 1);
PopulateHistogram(histogramWindowing, 2, 2, 100);
clock->MockSleepForMicroseconds(micros_per_window);
ASSERT_EQ(histogramWindowing.num(), 200);
ASSERT_EQ(histogramWindowing.min(), 1);
ASSERT_EQ(histogramWindowing.max(), 2);
ASSERT_EQ(histogramWindowing.Average(), 1.5);
PopulateHistogram(histogramWindowing, 3, 3, 100);
clock->MockSleepForMicroseconds(micros_per_window);
ASSERT_EQ(histogramWindowing.num(), 300);
ASSERT_EQ(histogramWindowing.min(), 1);
ASSERT_EQ(histogramWindowing.max(), 3);
ASSERT_EQ(histogramWindowing.Average(), 2.0);
// dropping oldest window with value 1, remaining 2 ~ 4
PopulateHistogram(histogramWindowing, 4, 4, 100);
clock->MockSleepForMicroseconds(micros_per_window);
ASSERT_EQ(histogramWindowing.num(), 300);
ASSERT_EQ(histogramWindowing.min(), 2);
ASSERT_EQ(histogramWindowing.max(), 4);
ASSERT_EQ(histogramWindowing.Average(), 3.0);
// dropping oldest window with value 2, remaining 3 ~ 5
PopulateHistogram(histogramWindowing, 5, 5, 100);
clock->MockSleepForMicroseconds(micros_per_window);
ASSERT_EQ(histogramWindowing.num(), 300);
ASSERT_EQ(histogramWindowing.min(), 3);
ASSERT_EQ(histogramWindowing.max(), 5);
ASSERT_EQ(histogramWindowing.Average(), 4.0);
}
TEST_F(HistogramTest, HistogramWindowingMerge) {
uint64_t num_windows = 3;
int micros_per_window = 1000000;
uint64_t min_num_per_window = 0;
HistogramWindowingImpl
histogramWindowing(num_windows, micros_per_window, min_num_per_window);
HistogramWindowingImpl
otherWindowing(num_windows, micros_per_window, min_num_per_window);
histogramWindowing.TEST_UpdateClock(clock);
otherWindowing.TEST_UpdateClock(clock);
PopulateHistogram(histogramWindowing, 1, 1, 100);
PopulateHistogram(otherWindowing, 1, 1, 100);
clock->MockSleepForMicroseconds(micros_per_window);
PopulateHistogram(histogramWindowing, 2, 2, 100);
PopulateHistogram(otherWindowing, 2, 2, 100);
clock->MockSleepForMicroseconds(micros_per_window);
PopulateHistogram(histogramWindowing, 3, 3, 100);
PopulateHistogram(otherWindowing, 3, 3, 100);
clock->MockSleepForMicroseconds(micros_per_window);
histogramWindowing.Merge(otherWindowing);
ASSERT_EQ(histogramWindowing.num(), 600);
ASSERT_EQ(histogramWindowing.min(), 1);
ASSERT_EQ(histogramWindowing.max(), 3);
ASSERT_EQ(histogramWindowing.Average(), 2.0);
// dropping oldest window with value 1, remaining 2 ~ 4
PopulateHistogram(histogramWindowing, 4, 4, 100);
clock->MockSleepForMicroseconds(micros_per_window);
ASSERT_EQ(histogramWindowing.num(), 500);
ASSERT_EQ(histogramWindowing.min(), 2);
ASSERT_EQ(histogramWindowing.max(), 4);
// dropping oldest window with value 2, remaining 3 ~ 5
PopulateHistogram(histogramWindowing, 5, 5, 100);
clock->MockSleepForMicroseconds(micros_per_window);
ASSERT_EQ(histogramWindowing.num(), 400);
ASSERT_EQ(histogramWindowing.min(), 3);
ASSERT_EQ(histogramWindowing.max(), 5);
}
} // namespace ROCKSDB_NAMESPACE
int main(int argc, char** argv) {
::testing::InitGoogleTest(&argc, argv);
return RUN_ALL_TESTS();
}