services/surfaceflinger/Scheduler/Scheduler.h

/*
 * Copyright 2018 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
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#pragma once

#include <atomic>
#include <functional>
#include <memory>
#include <mutex>
#include <optional>
#include <unordered_map>

#include <ui/GraphicTypes.h>

#include "EventControlThread.h"
#include "EventThread.h"
#include "LayerHistory.h"
#include "OneShotTimer.h"
#include "RefreshRateConfigs.h"
#include "SchedulerUtils.h"

namespace android {

using namespace std::chrono_literals;

class DispSync;
class FenceTime;
class InjectVSyncSource;
struct DisplayStateInfo;

class ISchedulerCallback {
public:
    virtual ~ISchedulerCallback() = default;
    virtual void changeRefreshRate(const scheduler::RefreshRateConfigs::RefreshRate&,
                                   scheduler::RefreshRateConfigEvent) = 0;
    virtual void repaintEverythingForHWC() = 0;
};

class Scheduler {
public:
    using RefreshRate = scheduler::RefreshRateConfigs::RefreshRate;
    using ConfigEvent = scheduler::RefreshRateConfigEvent;

    // Indicates whether to start the transaction early, or at vsync time.
    enum class TransactionStart { EARLY, NORMAL };

    Scheduler(impl::EventControlThread::SetVSyncEnabledFunction,
              const scheduler::RefreshRateConfigs&, ISchedulerCallback& schedulerCallback);

    virtual ~Scheduler();

    DispSync& getPrimaryDispSync();

    using ConnectionHandle = scheduler::ConnectionHandle;
    ConnectionHandle createConnection(const char* connectionName, nsecs_t phaseOffsetNs,
                                      nsecs_t offsetThresholdForNextVsync,
                                      impl::EventThread::InterceptVSyncsCallback);

    sp<IDisplayEventConnection> createDisplayEventConnection(ConnectionHandle,
                                                             ISurfaceComposer::ConfigChanged);

    sp<EventThreadConnection> getEventConnection(ConnectionHandle);

    void onHotplugReceived(ConnectionHandle, PhysicalDisplayId, bool connected);
    void onConfigChanged(ConnectionHandle, PhysicalDisplayId, HwcConfigIndexType configId);

    void onScreenAcquired(ConnectionHandle);
    void onScreenReleased(ConnectionHandle);

    // Modifies phase offset in the event thread.
    void setPhaseOffset(ConnectionHandle, nsecs_t phaseOffset);

    void getDisplayStatInfo(DisplayStatInfo* stats);

    // Returns injector handle if injection has toggled, or an invalid handle otherwise.
    ConnectionHandle enableVSyncInjection(bool enable);

    // Returns false if injection is disabled.
    bool injectVSync(nsecs_t when);

    void enableHardwareVsync();
    void disableHardwareVsync(bool makeUnavailable);

    // Resyncs the scheduler to hardware vsync.
    // If makeAvailable is true, then hardware vsync will be turned on.
    // Otherwise, if hardware vsync is not already enabled then this method will
    // no-op.
    // The period is the vsync period from the current display configuration.
    void resyncToHardwareVsync(bool makeAvailable, nsecs_t period);
    void resync();

    // Passes a vsync sample to DispSync. periodFlushed will be true if
    // DispSync detected that the vsync period changed, and false otherwise.
    void addResyncSample(nsecs_t timestamp, bool* periodFlushed);
    void addPresentFence(const std::shared_ptr<FenceTime>&);
    void setIgnorePresentFences(bool ignore);
    nsecs_t getDispSyncExpectedPresentTime();

    // Layers are registered on creation, and unregistered when the weak reference expires.
    void registerLayer(Layer*);
    void recordLayerHistory(Layer*, nsecs_t presentTime);

    // Detects content using layer history, and selects a matching refresh rate.
    void chooseRefreshRateForContent();

    bool isIdleTimerEnabled() const { return mIdleTimer.has_value(); }
    void resetIdleTimer();

    // Function that resets the touch timer.
    void notifyTouchEvent();

    void setDisplayPowerState(bool normal);

    void dump(std::string&) const;
    void dump(ConnectionHandle, std::string&) const;

    // Get the appropriate refresh for current conditions.
    std::optional<HwcConfigIndexType> getPreferredConfigId();

    // Notifies the scheduler about a refresh rate timeline change.
    void onNewVsyncPeriodChangeTimeline(const HWC2::VsyncPeriodChangeTimeline& timeline);

    // Notifies the scheduler when the display was refreshed
    void onDisplayRefreshed(nsecs_t timestamp);

private:
    friend class TestableScheduler;

    // In order to make sure that the features don't override themselves, we need a state machine
    // to keep track which feature requested the config change.
    enum class ContentDetectionState { Off, On };
    enum class TimerState { Reset, Expired };
    enum class TouchState { Inactive, Active };

    // Used by tests to inject mocks.
    Scheduler(std::unique_ptr<DispSync>, std::unique_ptr<EventControlThread>,
              const scheduler::RefreshRateConfigs&, ISchedulerCallback& schedulerCallback);

    std::unique_ptr<VSyncSource> makePrimaryDispSyncSource(const char* name, nsecs_t phaseOffsetNs,
                                                           nsecs_t offsetThresholdForNextVsync);

    // Create a connection on the given EventThread.
    ConnectionHandle createConnection(std::unique_ptr<EventThread>);
    sp<EventThreadConnection> createConnectionInternal(EventThread*,
                                                       ISurfaceComposer::ConfigChanged);

    // Update feature state machine to given state when corresponding timer resets or expires.
    void kernelIdleTimerCallback(TimerState);
    void idleTimerCallback(TimerState);
    void touchTimerCallback(TimerState);
    void displayPowerTimerCallback(TimerState);

    // handles various timer features to change the refresh rate.
    template <class T>
    void handleTimerStateChanged(T* currentState, T newState, bool eventOnContentDetection);

    void setVsyncPeriod(nsecs_t period);

    HwcConfigIndexType calculateRefreshRateType() REQUIRES(mFeatureStateLock);

    // Stores EventThread associated with a given VSyncSource, and an initial EventThreadConnection.
    struct Connection {
        sp<EventThreadConnection> connection;
        std::unique_ptr<EventThread> thread;
    };

    ConnectionHandle::Id mNextConnectionHandleId = 0;
    std::unordered_map<ConnectionHandle, Connection> mConnections;

    bool mInjectVSyncs = false;
    InjectVSyncSource* mVSyncInjector = nullptr;
    ConnectionHandle mInjectorConnectionHandle;

    std::mutex mHWVsyncLock;
    bool mPrimaryHWVsyncEnabled GUARDED_BY(mHWVsyncLock) = false;
    bool mHWVsyncAvailable GUARDED_BY(mHWVsyncLock) = false;

    std::atomic<nsecs_t> mLastResyncTime = 0;

    std::unique_ptr<DispSync> mPrimaryDispSync;
    std::unique_ptr<EventControlThread> mEventControlThread;

    // Used to choose refresh rate if content detection is enabled.
    std::optional<scheduler::LayerHistory> mLayerHistory;

    // Whether to use idle timer callbacks that support the kernel timer.
    const bool mSupportKernelTimer;

    // Timer that records time between requests for next vsync.
    std::optional<scheduler::OneShotTimer> mIdleTimer;
    // Timer used to monitor touch events.
    std::optional<scheduler::OneShotTimer> mTouchTimer;
    // Timer used to monitor display power mode.
    std::optional<scheduler::OneShotTimer> mDisplayPowerTimer;

    ISchedulerCallback& mSchedulerCallback;

    // In order to make sure that the features don't override themselves, we need a state machine
    // to keep track which feature requested the config change.
    std::mutex mFeatureStateLock;

    struct {
        ContentDetectionState contentDetection = ContentDetectionState::Off;
        TimerState idleTimer = TimerState::Reset;
        TouchState touch = TouchState::Inactive;
        TimerState displayPowerTimer = TimerState::Expired;

        std::optional<HwcConfigIndexType> configId;
        uint32_t contentRefreshRate = 0;

        bool isDisplayPowerStateNormal = true;
    } mFeatures GUARDED_BY(mFeatureStateLock);

    const scheduler::RefreshRateConfigs& mRefreshRateConfigs;

    std::mutex mVsyncTimelineLock;
    std::optional<HWC2::VsyncPeriodChangeTimeline> mLastVsyncPeriodChangeTimeline
            GUARDED_BY(mVsyncTimelineLock);
    static constexpr std::chrono::nanoseconds MAX_VSYNC_APPLIED_TIME = 200ms;
};

} // namespace android