jyoung/common/realtime.py

"""Utilities for reading real time clocks and keeping soft real time constraints."""
import gc
import os
import time
from collections import deque

from setproctitle import getproctitle

from openpilot.system.hardware import PC


# time step for each process
DT_CTRL = 0.01  # controlsd
DT_MDL = 0.05  # model
DT_TRML = 0.5  # thermald and manager
DT_DMON = 0.05  # driver monitoring


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))


def set_core_affinity(cores: list[int]) -> None:
  if not PC:
    os.sched_setaffinity(0, cores)


def config_realtime_process(cores: int | list[int], priority: int) -> None:
  gc.disable()
  set_realtime_priority(priority)
  c = cores if isinstance(cores, list) else [cores, ]
  set_core_affinity(c)


class Ratekeeper:
  def __init__(self, rate: float, print_delay_threshold: float | None = 0.0) -> None:
    """Rate in Hz for ratekeeping. print_delay_threshold must be nonnegative."""
    self._interval = 1. / rate
    self._next_frame_time = time.monotonic() + self._interval
    self._print_delay_threshold = print_delay_threshold
    self._frame = 0
    self._remaining = 0.0
    self._process_name = getproctitle()
    self._dts = deque([self._interval], maxlen=100)
    self._last_monitor_time = time.monotonic()

  @property
  def frame(self) -> int:
    return self._frame

  @property
  def remaining(self) -> float:
    return self._remaining

  @property
  def lagging(self) -> bool:
    avg_dt = sum(self._dts) / len(self._dts)
    expected_dt = self._interval * (1 / 0.9)
    return avg_dt > expected_dt

  # 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

  # Monitors the cumulative lag, but does not enforce a rate
  def monitor_time(self) -> bool:
    prev = self._last_monitor_time
    self._last_monitor_time = time.monotonic()
    self._dts.append(self._last_monitor_time - prev)

    lagged = False
    remaining = self._next_frame_time - time.monotonic()
    self._next_frame_time += self._interval
    if self._print_delay_threshold is not None and remaining < -self._print_delay_threshold:
      print(f"{self._process_name} lagging by {-remaining * 1000:.2f} ms")
      lagged = True
    self._frame += 1
    self._remaining = remaining
    return lagged