async.py 文件源码

def event_loop(catch_signals = (signal.SIGINT, signal.SIGTERM)):
  """
  Replacement for asyncore.loop(), adding timer and signal support.
  """
  old_signal_handlers = {}
  while True:
    save_sigs = len(old_signal_handlers) == 0
    try:
      for sig in catch_signals:
        old = signal.signal(sig, _raiseExitNow)
        if save_sigs:
          old_signal_handlers[sig] = old
      while asyncore.socket_map or timer_queue:
        t = timer.seconds_until_wakeup()
        if debug_event_timing:
          logger.debug("Dismissing to asyncore.poll(), t = %s, q = %r", t, timer_queue)
        asyncore.poll(t, asyncore.socket_map)
        timer.runq()
        if timer.gc_debug:
          gc.collect()
          if gc.garbage:
            for i in gc.garbage:
              logger.debug("GC-cycle %r", i)
            del gc.garbage[:]
    except ExitNow:
      break
    except SystemExit:
      raise
    except ValueError, e:
      if str(e) == "filedescriptor out of range in select()":
        logger.error("Something is badly wrong, select() thinks we gave it a bad file descriptor.")
        logger.error("Content of asyncore.socket_map:")
        for fd in sorted(asyncore.socket_map.iterkeys()):
          logger.error("  fd %s obj %r", fd, asyncore.socket_map[fd])
        logger.error("Not safe to continue due to risk of spin loop on select().  Exiting.")
        sys.exit(1)
      logger.exception("event_loop() exited with exception %r, this is not supposed to happen, restarting")
    except Exception, e:
      logger.exception("event_loop() exited with exception %r, this is not supposed to happen, restarting")
    else:
      break
    finally:
      for sig in old_signal_handlers:
        signal.signal(sig, old_signal_handlers[sig])