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// Copyright 2019 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "chrome/browser/ash/arc/tracing/arc_graphics_jank_detector.h"
#include <algorithm>
namespace arc {
namespace {
// Threshold relative to the normal rate to consider the current frame as a
// jank if its duration longer than this threshold.
constexpr int kJankDetectionThresholdPercent = 190;
} // namespace
ArcGraphicsJankDetector::ArcGraphicsJankDetector(const JankCallback& callback)
: callback_(callback) {
Reset();
}
ArcGraphicsJankDetector::~ArcGraphicsJankDetector() = default;
bool ArcGraphicsJankDetector::IsEnoughSamplesToDetect(size_t num_samples) {
return num_samples >= (kWarmUpSamples + kSamplesForRateDetection);
}
void ArcGraphicsJankDetector::Reset() {
stage_ = Stage::kWarmUp;
// TODO(matvore): do not use Now directly, as this forces unit tests to use it
// also.
last_sample_time_ = base::Time::Now();
warm_up_sample_cnt_ = kWarmUpSamples;
period_fixed_ = false;
}
void ArcGraphicsJankDetector::SetPeriodFixed(const base::TimeDelta& period) {
period_ = period;
period_fixed_ = true;
stage_ = Stage::kActive;
}
void ArcGraphicsJankDetector::OnSample(base::Time timestamp) {
const base::TimeDelta delta = timestamp - last_sample_time_;
last_sample_time_ = timestamp;
// Try to detect pause and switch to warm-up stage.
if (delta >= kPauseDetectionThreshold) {
if (period_fixed_) {
return;
}
warm_up_sample_cnt_ = kWarmUpSamples;
stage_ = Stage::kWarmUp;
return;
}
if (stage_ == Stage::kWarmUp) {
DCHECK(warm_up_sample_cnt_);
if (--warm_up_sample_cnt_) {
return;
}
// Switch to rate detection.
intervals_.clear();
stage_ = Stage::kRateDetection;
return;
}
if (stage_ == Stage::kRateDetection) {
intervals_.emplace_back(std::move(delta));
if (intervals_.size() < kSamplesForRateDetection) {
return;
}
std::sort(intervals_.begin(), intervals_.end());
period_ = intervals_[intervals_.size() / 3];
stage_ = Stage::kActive;
return;
}
DCHECK_EQ(Stage::kActive, stage_);
if (delta >= period_ * kJankDetectionThresholdPercent / 100) {
callback_.Run(timestamp - delta + period_);
}
}
} // namespace arc
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