Image ReadImage(tjhandle tj, int width, int height, int quality = 75) {
    static std::vector< char > img;
    static int count = 0;
    img.resize(3 * width * height);
    glReadBuffer(GL_FRONT);
#ifdef TIME_READPIXEL    
    using namespace std::chrono;
    steady_clock::time_point t = steady_clock::now(); 
#endif    
    glReadPixels(0, 0, width, height, GL_RGB, GL_UNSIGNED_BYTE, &img[0]);
#ifdef TIME_READPIXEL    
    const milliseconds E =
                        duration_cast< milliseconds >(steady_clock::now() - t);
    cout << E.count() << ' '; //doesn't flush, prints after closing window                    
#endif    

    char* out = nullptr; 
    unsigned long size = 0;
    tjCompress2(tj,
        (unsigned char*) &img[0],
        width,
        3 * width,
        height,
        TJPF_RGB,
        (unsigned char **) &out,
        &size,
        TJSAMP_444,
        quality,
        0); 
       
    return Image(ImagePtr((char*) out, TJDeleter()), size, count++);
}

void FunctionScheduler::addFunctionUniformDistribution(
    Function<void()>&& cb,
    milliseconds minInterval,
    milliseconds maxInterval,
    StringPiece nameID,
    milliseconds startDelay) {
  addFunctionGenericDistribution(
      std::move(cb),
      UniformDistributionFunctor(minInterval, maxInterval),
      nameID.str(),
      to<std::string>(
          "[", minInterval.count(), " , ", maxInterval.count(), "] ms"),
      startDelay);
}

        void SocketImpl::set_timeout( const milliseconds& value )
        {
            tcp::socket::native_handle_type native_socket(0);

#ifdef BUILD_SSL
            
            if ( m_socket not_eq nullptr )
            {
#endif
                native_socket = m_socket->native_handle( );
#ifdef BUILD_SSL
            }
            else
            {
                native_socket = m_ssl_socket->lowest_layer( ).native_handle( );
            }
            
#endif
            struct timeval timeout = { 0, 0 };
            timeout.tv_usec = static_cast< long >( value.count( ) * 1000 );
            
            int status = setsockopt( native_socket, SOL_SOCKET, SO_SNDTIMEO, reinterpret_cast< char* >( &timeout ), sizeof( timeout ) );
            
            if ( status == -1 and m_logger not_eq nullptr )
            {
                m_logger->log( Logger::Level::WARNING, "Failed to set socket option, send timeout." );
            }
            
            status = setsockopt( native_socket, SOL_SOCKET, SO_RCVTIMEO, reinterpret_cast< char* >( &timeout ), sizeof( timeout ) );
            
            if ( status == -1 and m_logger not_eq nullptr )
            {
                m_logger->log( Logger::Level::WARNING, "Failed to set socket option, receive timeout." );
            }
        }

void FunctionScheduler::addFunction(Function<void()>&& cb,
                                    milliseconds interval,
                                    StringPiece nameID,
                                    milliseconds startDelay) {
  addFunctionGenericDistribution(
      std::move(cb),
      ConstIntervalFunctor(interval),
      nameID.str(),
      to<std::string>(interval.count(), "ms"),
      startDelay);
}

log_entry::log_entry(logger& l, logger::LogLevel level):
    mLogger(l),
    mLevel(level)
{
    if(mLevel < 0) return;
    using namespace std::chrono;
    const milliseconds ms = duration_cast<milliseconds>(system_clock::now().time_since_epoch());
    const seconds s = duration_cast<seconds>(ms);
    const std::time_t t = s.count();
    const std::size_t fractional_seconds = ms.count() % 1000;

    mLogger.lock();
    const char timeFormat[] = "%Y-%m-%d %H:%M:%S";
    const size_t buffSize = 100;
    char buff[buffSize];
    if(0 != std::strftime(buff, buffSize, timeFormat, std::localtime(&t)))
    {
        mLogger.get() << buff;
    }
    else
    {
        size_t dBuffSize = buffSize;
        std::unique_ptr<char[]> dbuff;
        do
        {
            dBuffSize *= 2;
            dbuff.reset(new char[dBuffSize]);
        }
        while(0 == std::strftime(dbuff.get(), dBuffSize, timeFormat, std::localtime(&t)));
        mLogger.get() << dbuff.get();
    }
    mLogger.get() << '.' << fractional_seconds << " ";

    if(level >= 0 && level <= logger::logDEBUG)
    {
        const char* levels[] = {"ERROR","WARNING","INFO","DEBUG"};
        mLogger.get() << levels[level];
    }
    mLogger.get() << ": ";
}

bool
WeightedLoadBalancerStrategy::mySendInterest(const Interest& interest,
                                             shared_ptr<MyMeasurementInfo>& measurementsEntryInfo,
                                             shared_ptr<pit::Entry>& pitEntry)
{
  typedef MyMeasurementInfo::WeightedFaceSetByDelay WeightedFaceSetByDelay;

  const WeightedFaceSetByDelay& facesByDelay =
    measurementsEntryInfo->weightedFaces.get<MyMeasurementInfo::ByDelay>();

  const milliseconds totalDelay = measurementsEntryInfo->totalDelay;
  const milliseconds inverseTotalDelay =
    MyMeasurementInfo::calculateInverseDelaySum(measurementsEntryInfo);


  boost::random::uniform_int_distribution<> dist(0, inverseTotalDelay.count());
  const uint64_t selection = dist(m_randomGenerator);

  NFD_LOG_TRACE("selection = " << selection);

  uint64_t cumulativeWeight = 0;

  for (WeightedFaceSetByDelay::const_iterator i = facesByDelay.begin();
       i != facesByDelay.end();
       ++i)
    {
      NFD_LOG_TRACE("cumulative weight = " << cumulativeWeight);
      // weight = inverted delay measurement
      const uint64_t weight = totalDelay.count() - i->lastDelay.count();
      cumulativeWeight += weight;

      if(selection <= cumulativeWeight && pitEntry->canForwardTo(i->face))
        {
          NFD_LOG_TRACE("fowarding " << interest.getName() << " out face " << i->face.getId());
          this->sendInterest(pitEntry, this->getFace(i->face.getId()));
          return true;
        }
    }
  return false;
}

Image ReadImage(int width, int height,
                   float quality = 100) {
    static std::vector< char > img;
    static int count = 0;
    img.resize(3 * width * height);
    glReadBuffer(GL_FRONT);
#ifdef TIME_READPIXEL    
    using namespace std::chrono;
    steady_clock::time_point t = steady_clock::now(); 
#endif    
    glReadPixels(0, 0, width, height, GL_RGB, GL_UNSIGNED_BYTE, &img[0]);
#ifdef TIME_READPIXEL    
    const milliseconds E =
                        duration_cast< milliseconds >(steady_clock::now() - t);
    cout << E.count() << ' '; //doesn't flush, prints after closing window                    
#endif    
    uint8_t* out;
    const size_t size = 
        WebPEncodeRGB((uint8_t*) &img[0], width, height, 3 * width,
                       quality, &out);               
    return Image(ImagePtr((char*) out, WebpDeleter()), size, count++);
}

void Transition::update(milliseconds elapsed)
{
	switch (state_)
	{
	case State::empty:
	case State::full:
		return;
	case State::increase:
		progress_ += static_cast<float>(elapsed.count()) / time_to_complete_.count();
		if (progress_ >= 1.0f) {
			progress_ = 1.0f;
			state_ = State::full;
		}
		break;
	case State::decrease:
		progress_ -= static_cast<float>(elapsed.count()) / time_to_complete_.count();
		if (progress_ <= 0.0f) {
			progress_ = 0.0f;
			state_ = State::empty;
		}
		break;
	}
}

void AppState::initTimerEngine() {
    const milliseconds interval(1);
    const milliseconds dueTime(0);

    //创建定时器,无属性,自动复位,匿名
    HANDLE handle = CreateWaitableTimer(NULL, FALSE, NULL);

    LARGE_INTEGER liDueTime;
    liDueTime.QuadPart = -(nanoseconds(dueTime).count() / 100);

    if (!SetWaitableTimer(handle, &liDueTime, interval.count(), NULL, NULL, FALSE)) {
        throw std::runtime_error("dispatcherTimerEngine init error!");
    }

    DispatcherTimerEngine& engine = DispatcherTimerEngine::instance();
    engine.setInterval(interval);
    engine.start(dueTime);

    //添加等待对象,以及触发事件
    addEventHandle(handle, std::bind(&DispatcherTimerEngine::update, &engine));
}

void SimpleThinkingWriter::output(const ChessBoard& board,
                                  const SearchResult& result,
                                  const vector<Move>& main_variation,
                                  const int nodes,
                                  const milliseconds& time,
                                  const Searcher::depth_t depth)
{
  if (!post()) {
    return;
  }
  ostringstream oss;
  int turn_number = board.turn_number();
  int ply = 0;
  if (board.turn_color() == Color::Black) {
    oss << turn_number << ". ... ";
    ++turn_number;
    ++ply;
  }
  for (const Move move : main_variation) {
    if (ply % 2 == 0) {
      oss << " " << turn_number << ".";
      ++turn_number;
    }
    oss << " " << move.source() << move.destination();
    if (move.is_promotion()) {
      oss << PieceSet::instance().piece(move.created_piece()).symbol(Color::Black);
    }
    ++ply;
  }
  const int score = board.turn_color() == Color::White ? result.score : -result.score;
  m_writer->thinking_output(depth,
                            score,
                            time.count() / 10,
                            nodes,
                            oss.str());

} // namespace olaf

 void set_resend_interval(socket &s, milliseconds i)
 { s.setopt(REQ, REQ_RESEND_IVL, static_cast<int>(i.count())); }

//.........这里部分代码省略.........
    return DefWindowProc(hwnd, uMsg, wParam, lParam);
}

void AppState::initWindow() {
    const wchar_t WINDOW_CLASS_NAME[] = L"Sample Window Class";

    WNDCLASSW wc = { };

    wc.lpfnWndProc = windowProc;
    wc.hInstance = hInstance_;
    wc.lpszClassName = WINDOW_CLASS_NAME;

    if (!RegisterClassW(&wc)) {
        throw std::runtime_error("RegisterClassW error!");
    }

    windowHwnd = CreateWindowExW(
            0, // Optional window styles.
            WINDOW_CLASS_NAME, // Window class
            L"dddd", //Window Title
            WS_OVERLAPPEDWINDOW, // Window style
            // Size and position
            CW_USEDEFAULT, CW_USEDEFAULT, CW_USEDEFAULT, CW_USEDEFAULT, NULL, // Parent window
            NULL, // Menu
            hInstance_, // Instance handle
            NULL // Additional application data
            );
    if (!windowHwnd) {
        throw std::runtime_error("CreateWindowExW error!");
    }
}

void AppState::initTimerEngine() {
    const milliseconds interval(1);
    const milliseconds dueTime(0);

    //创建定时器,无属性,自动复位,匿名
    HANDLE handle = CreateWaitableTimer(NULL, FALSE, NULL);

    LARGE_INTEGER liDueTime;
    liDueTime.QuadPart = -(nanoseconds(dueTime).count() / 100);

    if (!SetWaitableTimer(handle, &liDueTime, interval.count(), NULL, NULL, FALSE)) {
        throw std::runtime_error("dispatcherTimerEngine init error!");
    }

    DispatcherTimerEngine& engine = DispatcherTimerEngine::instance();
    engine.setInterval(interval);
    engine.start(dueTime);

    //添加等待对象,以及触发事件
    addEventHandle(handle, std::bind(&DispatcherTimerEngine::update, &engine));
}

void AppState::initInputDevices() {
    //创建DirectInput8对象
    IDirectInput8A* direct_input;
    dx::throwIfFailed(
        DirectInput8Create(
            hInstance_,
            DIRECTINPUT_VERSION,
            IID_IDirectInput8,
            (void **) &direct_input,
            nullptr)
    );
    direct_input_.reset(direct_input);

void sleep_for(milliseconds d) {
  // usleep is nanoseconds.
  usleep (d.count() * 1000);
}

Timer::Timer(milliseconds expiration_time, bool start_active) :
    current_time_{ start_active ? 0 :  expiration_time.count() + 1},
    expiration_time_{expiration_time}
{
    timers_.insert(this);
}

void PoolingAcceptor::onTimer(const milliseconds& delta) {
	LOG(INFO)<< "[" << __FUNCTION__ << "] " << delta.count();
}

milliseconds abs(const milliseconds& t) {
	return milliseconds(abs(t.count()));
}

void TimedAxisController::setInterval(unsigned int interval)
{
	assert(interval < MAX_MILLI.count());
	this->interval = milliseconds(interval);
}

//.........这里部分代码省略.........
    //texture coordinate buffer
    GLuint texbo;  
    glGenBuffers(1, &texbo);

    glBindBuffer(GL_ARRAY_BUFFER, texbo);
    glBufferData(GL_ARRAY_BUFFER, 12 * sizeof(real_t),
                 &texcoord[0], GL_STATIC_DRAW);
    glVertexAttribPointer(1, 2, GL_FLOAT, GL_FALSE, 0, 0);
    glBindBuffer(GL_ARRAY_BUFFER, 0); 

    glBindVertexArray(0); 


    // create texture 
    std::vector< float > tc(SIZE * SIZE, 0.5f);
    GLuint tex;
    glGenTextures(1, &tex);

    glBindTexture(GL_TEXTURE_2D, tex);
   
    glTexImage2D(GL_TEXTURE_2D,
                 0,
                 GL_RED,
                 SIZE,
                 SIZE,
                 0,
                 GL_RED,
                 GL_FLOAT,
                 &tc[0]);
   
    //optional
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
    //required
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR); 

    glBindTexture(GL_TEXTURE_2D, 0);


//OPENGL RENDERING SHADERS
   
    GLuint glprogram = create_program(vertexShaderSrc, fragmentShaderSrc);

    //enable gl program
    glUseProgram(glprogram);

    //extract ids of shader variables
    GLint mvpID = glGetUniformLocation(glprogram, "MVP");

    GLint textureID = glGetUniformLocation(glprogram, "cltexture");

    GLint frameID = glGetUniformLocation(glprogram, "frame");

    
    //only need texture unit 0
    glActiveTexture(GL_TEXTURE0);
    glBindTexture(GL_TEXTURE_2D, tex);
    glUniform1i(textureID, 0);

    //beckground color        
    glClearColor(0.0f, 0.0f, 0.4f, 0.0f);

//RENDER LOOP    
    //rendering & simulation loop
    UserData data(vao, quadvbo, texbo, mvpID, frameID, context, 0);
    glfwSetWindowUserPointer(window, &data); 
    int width = 0;
    int height = 0;
    using namespace std::chrono;
    const milliseconds T(20);
    while (!glfwWindowShouldClose(window)) {
        steady_clock::time_point t = steady_clock::now(); 
        glfwGetFramebufferSize(window, &width, &height);      
        Draw(window, data, width, height);
        glfwSwapBuffers(window);
        data.context->SetServiceDataSync(ReadImage(tj, width, height, 100));
        ++data.frame;
        const milliseconds E =
                        duration_cast< milliseconds >(steady_clock::now() - t);
#ifdef TIME_RENDER_STEP
        cout << E.count() << ' ';
#endif                                
        std::this_thread::sleep_for(
            max(duration_values<milliseconds>::zero(), T - E));
        glfwPollEvents();
    }
    
//CLEANUP
    glDeleteBuffers(1, &quadvbo);
    glDeleteBuffers(1, &texbo);
    glDeleteTextures(1, &tex);
    glfwDestroyWindow(window);

    glfwTerminate();
    is.wait();
    tjDestroy(tj);
    exit(EXIT_SUCCESS);
    return 0;
}

int main(int argc, char **argv)
{
    if (argc < 4) {
        puts("Usage: ./out $num_passengers $capacity $time_interval $cycles");
        exit(1);
    }

    int num_passengers = stoi(argv[1]),
        capacity       = stoi(argv[2]),
        time_interval  = stoi(argv[3]),
        cycles         = stoi(argv[4]);
    pthread_t passenger_threads[num_passengers];
    pthread_t coaster_thread;
    s = high_resolution_clock::now();

    RollerCoaster coaster_car = RollerCoaster(capacity, time_interval, cycles);
    Passenger* passengers[num_passengers];
    pthread_create(&coaster_thread, NULL, roller_coaster, (void*) &coaster_car);
    for (int i = 0; i < num_passengers; ++i) {
        passengers[i] = new Passenger(i + 1, coaster_car);
        pthread_create(&passenger_threads[i], NULL, passenger, (void*) passengers[i]);
    }
    for (int i = 0; i < num_passengers; ++i) pthread_join(passenger_threads[i], NULL);
    pthread_join(coaster_thread, NULL);

    cout << "Total waiting time of all passengers: " << wait_time.count() << " millisec\n";

    return 0;
}