system.py 文件源码

def start_time(pid):
  """
  Provides the unix timestamp when the given process started.

  :param int pid: process id of the process to be queried

  :returns: **float** for the unix timestamp when the process began, **None**
    if it can't be determined
  """

  if not isinstance(pid, int) or pid < 0:
    return None

  if stem.util.proc.is_available():
    try:
      return float(stem.util.proc.stats(pid, stem.util.proc.Stat.START_TIME)[0])
    except IOError:
      pass

  try:
    ps_results = call('ps -p %s -o etime' % pid, [])

    if len(ps_results) >= 2:
      etime = ps_results[1].strip()
      return time.time() - stem.util.str_tools.parse_short_time_label(etime)
  except:
    pass

  return None