Add class which periodically computes statistics.

webrtc/video/stats_counter_unittest.cc

+/*
+ *  Copyright (c) 2016 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#include "webrtc/video/stats_counter.h"
+
+#include "testing/gtest/include/gtest/gtest.h"
+
+#include "webrtc/system_wrappers/include/clock.h"
+
+namespace webrtc {
+namespace {
+const int kProcessIntervalMs = 2000;
+
+class AvgEncodeTimeMsObserver : public StatsCounterObserver {
+ public:
+  AvgEncodeTimeMsObserver() : num_calls_(0), last_sample_(-1) {}
+  void OnMetricUpdated(int sample) override {
+    // RTC_HISTOGRAM_COUNTS_1000("WebRTC.Video.AvgEncodeTimeMs", sample);
+    ++num_calls_;
+    last_sample_ = sample;
+  }
+  int num_calls_;
+  int last_sample_;
+};
+}  // namespace
+
+class StatsCounterTest : public ::testing::Test {
+ protected:
+  StatsCounterTest() : clock_(1234) {}
+
+  void AddSampleAndAdvance(int sample, int interval_ms, AvgCounter* counter) {
+    counter->Add(sample);
+    clock_.AdvanceTimeMilliseconds(interval_ms);
+  }
+
+  void SetSampleAndAdvance(int sample,
+                           int interval_ms,
+                           RateAccCounter* counter) {
+    counter->Set(sample);
+    clock_.AdvanceTimeMilliseconds(interval_ms);
+  }
+
+  void VerifyStatsIsNotSet(const StatsCounter::Histogram::Stats& stats) {
+    EXPECT_EQ(0, stats.num_samples);
+    EXPECT_EQ(-1, stats.min);
+    EXPECT_EQ(-1, stats.max);
+    EXPECT_EQ(-1, stats.average);
+    EXPECT_EQ(-1, stats.percentile10);
+    EXPECT_EQ(-1, stats.percentile50);
+    EXPECT_EQ(-1, stats.percentile90);
+  }
+
+  SimulatedClock clock_;
+};
+
+TEST_F(StatsCounterTest, NoSamples) {
+  AvgCounter counter(&clock_, 10, 10, nullptr);
+  StatsCounter::Histogram::Stats stats = counter.GetStats();
+  VerifyStatsIsNotSet(stats);
+}
+
+TEST_F(StatsCounterTest, TestMetric_AvgCounter) {
+  AvgCounter counter(&clock_, 50, 50, nullptr);
+  counter.Add(4);
+  counter.Add(8);
+  counter.Add(9);
+  clock_.AdvanceTimeMilliseconds(kProcessIntervalMs);
+  // Trigger process (sample included in next interval).
+  counter.Add(111);
+  StatsCounter::Histogram::Stats stats = counter.GetStats();
+  // [7:1]  metric: average per interval
+  EXPECT_EQ(1, stats.num_samples);
+  EXPECT_EQ(7, stats.min);
+  EXPECT_EQ(7, stats.max);
+  EXPECT_EQ(7, stats.average);
+}
+
+TEST_F(StatsCounterTest, TestMetric_PercentCounter) {
+  PercentCounter counter(&clock_, nullptr);
+  counter.Add(true);
+  counter.Add(false);
+  clock_.AdvanceTimeMilliseconds(kProcessIntervalMs);
+  // Trigger process (sample included in next interval).
+  counter.Add(false);
+  StatsCounter::Histogram::Stats stats = counter.GetStats();
+  // [50:1]  metric: percentage per interval
+  EXPECT_EQ(1, stats.num_samples);
+  EXPECT_EQ(50, stats.min);
+  EXPECT_EQ(50, stats.max);
+}
+
+TEST_F(StatsCounterTest, TestMetric_PermilleCounter) {
+  PermilleCounter counter(&clock_, 1001, nullptr);
+  counter.Add(true);
+  counter.Add(false);
+  clock_.AdvanceTimeMilliseconds(kProcessIntervalMs);
+  // Trigger process (sample included in next interval).
+  counter.Add(false);
+  StatsCounter::Histogram::Stats stats = counter.GetStats();
+  // [500:1]  metric: permille per interval
+  EXPECT_EQ(1, stats.num_samples);
+  EXPECT_EQ(500, stats.min);
+  EXPECT_EQ(500, stats.max);
+}
+
+TEST_F(StatsCounterTest, TestMetric_RateCounter) {
+  RateCounter counter(&clock_, 1000, 1000, true, nullptr);
+  counter.Add(186);
+  counter.Add(350);
+  counter.Add(22);
+  clock_.AdvanceTimeMilliseconds(kProcessIntervalMs);
+  // Trigger process (sample included in next interval).
+  counter.Add(111);
+  StatsCounter::Histogram::Stats stats = counter.GetStats();
+  // [279:1]  metric: rate per interval, (186+350+22)/2sec = 279 samples/sec
+  EXPECT_EQ(1, stats.num_samples);
+  EXPECT_EQ(279, stats.min);
+  EXPECT_EQ(279, stats.max);
+}
+
+TEST_F(StatsCounterTest, TestMetric_RateAccCounter) {
+  RateAccCounter counter(&clock_, 1000, 1000, true, nullptr);
+  counter.Set(175);
+  counter.Set(188);
+  clock_.AdvanceTimeMilliseconds(kProcessIntervalMs);
+  // Trigger process (sample included in next interval).
+  counter.Set(192);
+  StatsCounter::Histogram::Stats stats = counter.GetStats();
+  // [94:1]  metric: rate per interval, (188-0)/2sec = 94 samples/sec
+  EXPECT_EQ(1, stats.num_samples);
+  EXPECT_EQ(94, stats.min);
+  EXPECT_EQ(94, stats.max);
+}
+
+TEST_F(StatsCounterTest, TestRegisterObserver) {
+  AvgEncodeTimeMsObserver* observer = new AvgEncodeTimeMsObserver();
+  const int kSample = 22;
+  AvgCounter counter(&clock_, 50, 50, observer);
+  AddSampleAndAdvance(kSample, kProcessIntervalMs, &counter);
+  // Trigger process (sample included in next interval).
+  counter.Add(111);
+  EXPECT_EQ(1, observer->num_calls_);
+  EXPECT_EQ(kSample, observer->last_sample_);
+}
+
+TEST_F(StatsCounterTest, VerifyProcessInterval) {
+  AvgCounter counter(&clock_, 10, 10, nullptr);
+  counter.Add(4);
+  clock_.AdvanceTimeMilliseconds(kProcessIntervalMs - 1);
+  // Try trigger process (interval has not passed).
+  counter.Add(8);
+  StatsCounter::Histogram::Stats stats = counter.GetStats();
+  VerifyStatsIsNotSet(stats);
+  // Make process interval pass.
+  clock_.AdvanceTimeMilliseconds(1);
+  // Trigger process (sample included in next interval).
+  counter.Add(111);
+  stats = counter.GetStats();
+  // [6:1]
+  EXPECT_EQ(1, stats.num_samples);
+  EXPECT_EQ(6, stats.min);
+  EXPECT_EQ(6, stats.max);
+}
+
+TEST_F(StatsCounterTest, TestHistogramUnderflow) {
+  const int kMin = 0;
+  const int kMax = 100;
+  const int kSample = -1;
+  // 8 buckets: [0-1),[1-2),[2-4),[4-9),[9-20),[20-45),[45-100),[100-inf)
+  AvgCounter counter(&clock_, 8, kMax, nullptr);
+  AddSampleAndAdvance(kSample, kProcessIntervalMs, &counter);
+  // Trigger process (sample included in next interval).
+  counter.Add(111);
+  StatsCounter::Histogram::Stats stats = counter.GetStats();
+  // [0:1],[1:0],[2:0],[4:0],[9:0],[20:0],[45:0],[100:0]
+  EXPECT_EQ(1, stats.num_samples);
+  EXPECT_EQ(kSample, stats.min);
+  EXPECT_EQ(kSample, stats.max);
+  EXPECT_EQ(kSample, stats.average);
+  EXPECT_EQ(kMin, stats.percentile10);
+  EXPECT_EQ(kMin, stats.percentile50);
+  EXPECT_EQ(kMin, stats.percentile90);
+}
+
+TEST_F(StatsCounterTest, TestHistogramOverflow) {
+  const int kMax = 100;
+  const int kSample = kMax + 1;
+  // 8 buckets: [0-1),[1-2),[2-4),[4-9),[9-20),[20-45),[45-100),[100-inf)
+  AvgCounter counter(&clock_, 8, kMax, nullptr);
+  AddSampleAndAdvance(kSample, kProcessIntervalMs, &counter);
+  // Trigger process (sample included in next interval).
+  counter.Add(111);
+  StatsCounter::Histogram::Stats stats = counter.GetStats();
+  // [0:0],[1:0],[2:0],[4:0],[9:0],[20:0],[45:0],[100:1]
+  EXPECT_EQ(1, stats.num_samples);
+  EXPECT_EQ(kSample, stats.min);
+  EXPECT_EQ(kSample, stats.max);
+  EXPECT_EQ(kSample, stats.average);
+  EXPECT_EQ(kMax, stats.percentile10);
+  EXPECT_EQ(kMax, stats.percentile50);
+  EXPECT_EQ(kMax, stats.percentile90);
+}
+
+TEST_F(StatsCounterTest, TestStats_LinearBuckets) {
+  AvgCounter counter(&clock_, 100, 100, nullptr);
+  const int kSample1 = 1;
+  const int kSample2 = 4;
+  const int kSample3 = 8;
+  const int kSample4 = kSample3;
+  const int kSample5 = 50;
+  AddSampleAndAdvance(kSample1, kProcessIntervalMs, &counter);
+  AddSampleAndAdvance(kSample2, kProcessIntervalMs, &counter);
+  AddSampleAndAdvance(kSample3, kProcessIntervalMs, &counter);
+  AddSampleAndAdvance(kSample4, kProcessIntervalMs, &counter);
+  AddSampleAndAdvance(kSample5, kProcessIntervalMs, &counter);
+  // Trigger process (sample included in next interval).
+  counter.Add(111);
+  StatsCounter::Histogram::Stats stats = counter.GetStats();
+  // [1:1],[4:1],[8:2],[50:1]
+  EXPECT_EQ(5, stats.num_samples);
+  EXPECT_EQ(kSample1, stats.min);
+  EXPECT_EQ(kSample5, stats.max);
+  EXPECT_EQ(14, stats.average);
+  EXPECT_EQ(kSample1, stats.percentile10);
+  EXPECT_EQ(kSample3, stats.percentile50);
+  EXPECT_EQ(kSample5, stats.percentile90);
+}
+
+TEST_F(StatsCounterTest, TestStats_ExponentialBuckets) {
+  AvgCounter counter(&clock_, 10, 50, nullptr);
+  const int kSample1 = 1;
+  const int kSample2 = 4;
+  const int kSample3 = 9;
+  const int kSample4 = kSample3;
+  const int kSample5 = 50;
+  AddSampleAndAdvance(kSample1, kProcessIntervalMs, &counter);
+  AddSampleAndAdvance(kSample2, kProcessIntervalMs, &counter);
+  AddSampleAndAdvance(kSample3, kProcessIntervalMs, &counter);
+  AddSampleAndAdvance(kSample4, kProcessIntervalMs, &counter);
+  AddSampleAndAdvance(kSample5, kProcessIntervalMs, &counter);
+  // Trigger process (sample included in next interval).
+  counter.Add(111);
+  StatsCounter::Histogram::Stats stats = counter.GetStats();
+  // [0:0],[1:1],[2:0],[3:1],[5:0],[8:2],[13:0],[20:0],[32:0],[50:1]
+  EXPECT_EQ(5, stats.num_samples);
+  EXPECT_EQ(kSample1, stats.min);
+  EXPECT_EQ(kSample5, stats.max);
+  EXPECT_EQ(15, stats.average);
+  EXPECT_EQ(kSample1, stats.percentile10);
+  EXPECT_EQ(kSample3 + 1, stats.percentile50);  // Mid bin size used.
+  EXPECT_EQ(kSample5, stats.percentile90);
+}
+
+TEST_F(StatsCounterTest, TestGetStatsTwice) {
+  const int kSample1 = 4;
+  const int kSample2 = 7;
+  AvgCounter counter(&clock_, 20, 50, nullptr);
+  AddSampleAndAdvance(kSample1, kProcessIntervalMs, &counter);
+  // Trigger process (sample included in next interval).
+  counter.Add(kSample2);
+  StatsCounter::Histogram::Stats stats = counter.GetStats();
+  // [0:0],[1:0],[2:0],[3:0],[4:1],[5:0],[6:0],[7:0],[8:0],[9:0],...
+  EXPECT_EQ(1, stats.num_samples);
+  EXPECT_EQ(kSample1, stats.min);
+  EXPECT_EQ(kSample1, stats.max);
+  // Trigger process (sample included in next interval).
+  clock_.AdvanceTimeMilliseconds(kProcessIntervalMs);
+  counter.Add(111);
+  stats = counter.GetStats();
+  // [0:0],[1:0],[2:0],[3:0],[4:1],[5:0],[6:0],[7:1],[8:0],[9:0],...
+  EXPECT_EQ(2, stats.num_samples);
+  EXPECT_EQ(kSample1, stats.min);
+  EXPECT_EQ(kSample2, stats.max);
+  EXPECT_EQ(6, stats.average);
+  EXPECT_EQ(kSample1, stats.percentile10);
+  EXPECT_EQ(kSample1, stats.percentile50);
+  EXPECT_EQ(kSample2, stats.percentile90);
+}
+
+TEST_F(StatsCounterTest, TestRateAccCounter) {
+  const int kSample1 = 200;   //  200 / 2 sec
+  const int kSample2 = 800;   //  600 / 2 sec
+  const int kSample3 = 1800;  // 1000 / 2 sec
+  RateAccCounter counter(&clock_, 1000, 1000, true, nullptr);
+  SetSampleAndAdvance(kSample1, kProcessIntervalMs, &counter);
+  SetSampleAndAdvance(kSample2, kProcessIntervalMs, &counter);
+  SetSampleAndAdvance(kSample3, kProcessIntervalMs, &counter);
+  // Trigger process (sample included in next interval).
+  counter.Set(2000);
+  StatsCounter::Histogram::Stats stats = counter.GetStats();
+  // [100:1],[300:1],[500:1]
+  EXPECT_EQ(3, stats.num_samples);
+  EXPECT_EQ(100, stats.min);
+  EXPECT_EQ(500, stats.max);
+  EXPECT_EQ(300, stats.average);
+}
+
+TEST_F(StatsCounterTest, TestRateAccCounter_NegativeRateIgnored) {
+  const int kSample1 = 200;  //  200 / 2 sec
+  const int kSample2 = 100;  // -100 / 2 sec - negative ignored
+  const int kSample3 = 700;  //  600 / 2 sec
+  RateAccCounter counter(&clock_, 1000, 1000, true, nullptr);
+  SetSampleAndAdvance(kSample1, kProcessIntervalMs, &counter);
+  SetSampleAndAdvance(kSample2, kProcessIntervalMs, &counter);
+  SetSampleAndAdvance(kSample3, kProcessIntervalMs, &counter);
+  // Trigger process (sample included in next interval).
+  counter.Set(2000);
+  StatsCounter::Histogram::Stats stats = counter.GetStats();
+  // [100:1],[300:1]
+  EXPECT_EQ(2, stats.num_samples);
+  EXPECT_EQ(100, stats.min);
+  EXPECT_EQ(300, stats.max);
+  EXPECT_EQ(200, stats.average);
+}
+
+TEST_F(StatsCounterTest, IntervalsWithoutSamplesIgnored_AvgCounter) {
+  AvgCounter counter(&clock_, 10, 10, nullptr);
+  AddSampleAndAdvance(6, kProcessIntervalMs * 4 - 1, &counter);
+  // Trigger process (sample included in next interval).
+  counter.Add(8);
+  StatsCounter::Histogram::Stats stats = counter.GetStats();
+  // [6:1],  two intervals without samples passed.
+  EXPECT_EQ(1, stats.num_samples);
+  EXPECT_EQ(6, stats.min);
+  EXPECT_EQ(6, stats.max);
+  // Make last interval pass.
+  clock_.AdvanceTimeMilliseconds(1);
+  counter.Add(111);  // Trigger process (sample included in next interval).
+  stats = counter.GetStats();
+  // [6:1],[8:1]
+  EXPECT_EQ(2, stats.num_samples);
+  EXPECT_EQ(6, stats.min);
+  EXPECT_EQ(8, stats.max);
+}
+
+TEST_F(StatsCounterTest, IntervalsWithoutSamplesIgnored_RateCounter) {
+  const int kSample1 = 50;  //  50 / 2 sec
+  const int kSample2 = 20;  //  20 / 2 sec
+  RateCounter counter(&clock_, 1000, 1000, false, nullptr);
+  counter.Add(kSample1);
+  clock_.AdvanceTimeMilliseconds(kProcessIntervalMs * 4 - 1);
+  // Trigger process (sample included in next interval).
+  counter.Add(kSample2);
+  StatsCounter::Histogram::Stats stats = counter.GetStats();
+  // [25:1],  two intervals without samples passed.
+  EXPECT_EQ(1, stats.num_samples);
+  EXPECT_EQ(25, stats.min);
+  EXPECT_EQ(25, stats.max);
+  // Make last interval pass.
+  clock_.AdvanceTimeMilliseconds(1);
+  counter.Add(111);  // Trigger process (sample included in next interval).
+  stats = counter.GetStats();
+  // [10:1],[25:1]
+  EXPECT_EQ(2, stats.num_samples);
+  EXPECT_EQ(10, stats.min);
+  EXPECT_EQ(25, stats.max);
+}
+
+TEST_F(StatsCounterTest, RateCounter_IntervalsWithoutSamplesIncluded) {
+  const int kSample1 = 50;  //  50 / 2 sec
+  const int kSample2 = 20;  //  20 / 2 sec
+  RateCounter counter(&clock_, 1000, 1000, true, nullptr);
+  counter.Add(kSample1);
+  clock_.AdvanceTimeMilliseconds(kProcessIntervalMs * 3 - 1);
+  // Trigger process (sample included in next interval).
+  counter.Add(kSample2);
+  StatsCounter::Histogram::Stats stats = counter.GetStats();
+  // [0:1],[25:1],  one interval without samples passed.
+  EXPECT_EQ(2, stats.num_samples);
+  EXPECT_EQ(0, stats.min);
+  EXPECT_EQ(25, stats.max);
+  // Make last interval pass.
+  clock_.AdvanceTimeMilliseconds(1);
+  counter.Add(111);  // Trigger process (sample included in next interval).
+  stats = counter.GetStats();
+  // [0:1],[10:1],[25:1]
+  EXPECT_EQ(3, stats.num_samples);
+  EXPECT_EQ(0, stats.min);
+  EXPECT_EQ(25, stats.max);
+  EXPECT_EQ(10, stats.percentile50);
+}
+
+}  // namespace webrtc