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// Copyright 2023 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef CC_METRICS_PREDICTOR_JANK_TRACKER_H_
#define CC_METRICS_PREDICTOR_JANK_TRACKER_H_
#include <optional>
#include "base/time/time.h"
#include "cc/cc_export.h"
#include "cc/metrics/event_metrics.h"
#include "cc/metrics/scroll_jank_ukm_reporter.h"
namespace cc {
class CC_EXPORT PredictorJankTracker {
public:
PredictorJankTracker();
~PredictorJankTracker();
PredictorJankTracker(const PredictorJankTracker&) = delete;
PredictorJankTracker& operator=(const PredictorJankTracker);
// Emits predictor scroll jank metrics for every frame relative
// to the previous and the next frame.
// For more details about the how a frame is deemed janky after
// delta prediction is applied please check:
// http://doc/1Y0u0Tq5eUZff75nYUzQVw6JxmbZAW9m64pJidmnGWsY
void ReportLatestScrollDelta(float delta,
base::TimeTicks presentation_ts,
base::TimeDelta vsync_interval,
std::optional<EventMetrics::TraceId> trace_id);
// Whenever a new scroll starts, data inside this class will be erased
// as it should be comparing neighbouring frames only.
void ResetCurrentScrollReporting();
void set_scroll_jank_ukm_reporter(
ScrollJankUkmReporter* scroll_jank_ukm_reporter) {
scroll_jank_ukm_reporter_ = scroll_jank_ukm_reporter;
}
static float GetSlowScrollDeltaThreshold();
static float GetSlowScrollJankyThreshold();
static float GetFastScrollJankyThreshold();
private:
// The metric works by storing a sliding window of the previous two
// frames, this function moves the sliding window storing the newer
// frame information.
void StoreLatestFrameData(float delta,
base::TimeTicks presentation_ts,
std::optional<EventMetrics::TraceId> trace_id);
void ReportJankyFrame(float next_delta,
float janky_value,
bool contains_missed_vsyncs,
bool slow_scroll,
std::optional<EventMetrics::TraceId> trace_id);
// Finds if a sequence of 3 consecutive frames were presnted in
// consecutive vsyncs, or some vsyncs were missed.
bool ContainsMissedVSync(base::TimeTicks& presentation_ts,
base::TimeDelta& vsync_interval);
void ReportJankyFramePercentage();
// Data holder for deltas and presentation timestamps in previous frames
struct FrameData {
// Delta for the previous frame in pixels.
float prev_delta_ = 0;
// The EventLatency event_trace_id value if available.
std::optional<EventMetrics::TraceId> prev_trace_id_;
// Delta for the current frame in pixels.
float cur_delta_ = 0;
// The EventLatency event_trace_id value if available.
std::optional<EventMetrics::TraceId> cur_trace_id_;
// Presentation timestamp of the previous frame.
base::TimeTicks prev_presentation_ts_;
// Presentation timestamp for the currentframe.
base::TimeTicks cur_presentation_ts_;
} frame_data_;
float total_frames_ = 0;
float janky_frames_ = 0;
raw_ptr<ScrollJankUkmReporter> scroll_jank_ukm_reporter_ = nullptr;
};
} // namespace cc
#endif // CC_METRICS_PREDICTOR_JANK_TRACKER_H_
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