system/hwc3/VsyncThread.h

/*
 * Copyright 2022 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.
 */

#ifndef ANDROID_HWC_VSYNCTHREAD_H
#define ANDROID_HWC_VSYNCTHREAD_H

#include <aidl/android/hardware/graphics/composer3/VsyncPeriodChangeConstraints.h>
#include <aidl/android/hardware/graphics/composer3/VsyncPeriodChangeTimeline.h>
#include <android/hardware/graphics/common/1.0/types.h>

#include <chrono>
#include <mutex>
#include <optional>
#include <thread>

#include "Common.h"

namespace aidl::android::hardware::graphics::composer3::impl {

// Generates Vsync signals in software.
class VsyncThread {
 public:
  VsyncThread(int64_t id);
  virtual ~VsyncThread();

  VsyncThread(const VsyncThread&) = default;
  VsyncThread& operator=(const VsyncThread&) = default;

  VsyncThread(VsyncThread&&) = default;
  VsyncThread& operator=(VsyncThread&&) = default;

  HWC3::Error start(int32_t periodNanos);

  HWC3::Error setCallbacks(const std::shared_ptr<IComposerCallback>& callback);

  HWC3::Error setVsyncEnabled(bool enabled);

  HWC3::Error scheduleVsyncUpdate(
      int32_t newVsyncPeriod,
      const VsyncPeriodChangeConstraints& newVsyncPeriodChangeConstraints,
      VsyncPeriodChangeTimeline* timeline);

 private:
  HWC3::Error stop();

  void threadLoop();

  std::chrono::nanoseconds updateVsyncPeriodLocked(
      std::chrono::time_point<std::chrono::steady_clock> now);

  const int64_t mDisplayId;

  std::thread mThread;

  std::mutex mStateMutex;

  std::atomic<bool> mShuttingDown{false};

  std::shared_ptr<IComposerCallback> mCallbacks;

  bool mVsyncEnabled = false;
  std::chrono::nanoseconds mVsyncPeriod;
  std::chrono::time_point<std::chrono::steady_clock> mPreviousVsync;

  struct PendingUpdate {
    std::chrono::nanoseconds period;
    std::chrono::time_point<std::chrono::steady_clock> updateAfter;
  };
  std::optional<PendingUpdate> mPendingUpdate;
};

}  // namespace aidl::android::hardware::graphics::composer3::impl

#endif