text: """Utilities for reading real time clocks and keeping soft real time constraints."""
  import gc
  import os
  import time
  import multiprocessing
  from typing import Optional
  
  # modification sync:
  # from common.clock import sec_since_boot  # pylint: disable=no-name-in-module, import-error
  import zmq
  def sec_since_boot():
      if not hasattr(sec_since_boot, 'frames_received'):
          return 0.0
      return max(0.0, (sec_since_boot.frames_received.value-1)*0.01)
  # modification sync:
  
  from selfdrive.hardware import PC, TICI
  
  
  # time step for each process
  DT_CTRL = 0.01  # controlsd
  DT_MDL = 0.05  # model
  DT_TRML = 0.5  # thermald and manager
  
  # driver monitoring
  if TICI:
    DT_DMON = 0.05
  else:
    DT_DMON = 0.1
  
  
  class Priority:
    # CORE 2
    # - modeld = 55
    # - camerad = 54
    CTRL_LOW = 51 # plannerd & radard
  
    # CORE 3
    # - boardd = 55
    CTRL_HIGH = 53
  
  
  def set_realtime_priority(level: int) -> None:
    if not PC:
      os.sched_setscheduler(0, os.SCHED_FIFO, os.sched_param(level))  # type: ignore[attr-defined]
  
  
  def set_core_affinity(core: int) -> None:
    if not PC:
      os.sched_setaffinity(0, [core,])
  
  
  def config_realtime_process(core: int, priority: int) -> None:
    gc.disable()
    set_realtime_priority(priority)
    set_core_affinity(core)
  
  
  class Ratekeeper:
    def __init__(self, rate: int, print_delay_threshold: Optional[float] = 0.0) -> None:
      """Rate in Hz for ratekeeping. print_delay_threshold must be nonnegative."""
      self._interval = 1. / rate
      self._next_frame_time = sec_since_boot() + self._interval
      self._print_delay_threshold = print_delay_threshold
      self._frame = 0
      self._remaining = 0.0
      self._process_name = multiprocessing.current_process().name
  
    @property
    def frame(self) -> int:
      return self._frame
  
    @property
    def remaining(self) -> float:
      return self._remaining
  
    # Maintain loop rate by calling this at the end of each loop
    def keep_time(self) -> bool:
      lagged = self.monitor_time()
      if self._remaining > 0:
        time.sleep(self._remaining)
      return lagged
  
    # this only monitor the cumulative lag, but does not enforce a rate
    def monitor_time(self) -> bool:
      lagged = False
      remaining = self._next_frame_time - sec_since_boot()
      self._next_frame_time += self._interval
      if self._print_delay_threshold is not None and remaining < -self._print_delay_threshold:
        print("%s lagging by %.2f ms" % (self._process_name, -remaining * 1000))
        lagged = True
      self._frame += 1
      self._remaining = remaining
      return lagged
  
  # addition sync:
  def main():
    context = zmq.Context()
    socket = context.socket(zmq.PAIR)
    while True:
        try:
            socket.bind("tcp://*:5561")
            break
        except:
            subprocess.run("kill $(lsof -t -i:" + str(5561) + ")", shell=True)
    while True:
      hi = int(socket.recv())
      with sec_since_boot.frames_received.get_lock():
        if hi == 0:
            sec_since_boot.frames_received.value = 1
        else:
            sec_since_boot.frames_received.value += 1
      assert(sec_since_boot.frames_received.value-1 == hi)
      socket.send(b" ")
  if __name__ == "__main__":
    main()
  # addition sync:
  