#!/usr/bin/python3
#
# Simple periodic timer with thread

import time
from threading import Timer

class PeriodicTimer(object):
  def __init__(self, interval, function, args=[], kwargs={}):
    self._timer     = None
    self.interval   = interval
    self.function   = function
    self.args       = args
    self.kwargs     = kwargs
    self.is_running = False

  def _run(self):
    self.is_running = False
    self.start()
    self.function(*self.args, **self.kwargs)

  def start(self):
    if not self.is_running:
      self._timer = Timer(self.interval, self._run)
      self._timer.start()
      self.is_running = True

  def stop(self):
    if self.is_running:
      self._timer.cancel()
      self.is_running = False

if __name__ == "__main__":
  pt = time.time()

  def func(*arg):
    global pt
    nt = time.time()
    print(arg[0], nt - pt)
    pt = nt

  tm = PeriodicTimer(0.05, func, args=['time lag='])

  print('start timer')
  tm.start()

  time.sleep(1)

  tm.stop()
  print('stop timer')