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* Copyright 2019 The Android Open Source Project
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* See the License for the specific language governing permissions and
* limitations under the License.
#pragma once
#include <utils/Timers.h>
#include "VSyncDispatch.h"
namespace android::scheduler {
* VSyncTracker is an interface for providing estimates on future Vsync signal times based on
* historical vsync timing data.
class VSyncTracker {
virtual ~VSyncTracker();
* Adds a known timestamp from a vsync timing source (HWVsync signal, present fence)
* to the model.
* \param [in] timestamp The timestamp when the vsync signal was.
* \return True if the timestamp was consistent with the internal model,
* False otherwise
virtual bool addVsyncTimestamp(nsecs_t timestamp) = 0;
* Access the next anticipated vsync time such that the anticipated time >= timePoint.
* This will always give the best accurate at the time of calling; multiple
* calls with the same timePoint might give differing values if the internal model
* is updated.
* \param [in] timePoint The point in time after which to estimate a vsync event.
* \return A prediction of the timestamp of a vsync event.
virtual nsecs_t nextAnticipatedVSyncTimeFrom(nsecs_t timePoint) const = 0;
* The current period of the vsync signal.
* \return The current period of the vsync signal
virtual nsecs_t currentPeriod() const = 0;
* Inform the tracker that the period is changing and the tracker needs to recalibrate itself.
* \param [in] period The period that the system is changing into.
virtual void setPeriod(nsecs_t period) = 0;
/* Inform the tracker that the samples it has are not accurate for prediction. */
virtual void resetModel() = 0;
virtual void dump(std::string& result) const = 0;
VSyncTracker(VSyncTracker const&) = delete;
VSyncTracker& operator=(VSyncTracker const&) = delete;
VSyncTracker() = default;
} // namespace android::scheduler