# -*- coding: utf-8 -*-
"""
sockjs.tornado.periodic
~~~~~~~~~~~~~~~~~~~~~~~
This module implements customized PeriodicCallback from tornado with
support of the sliding window.
"""
import time
import logging
LOG = logging.getLogger("tornado.general")
[docs]class Callback(object):
"""Custom implementation of the Tornado.Callback with support
of callback timeout delays.
"""
[docs] def __init__(self, callback, callback_time, io_loop):
"""Constructor.
`callback`
Callback function
`callback_time`
Callback timeout value (in milliseconds)
`io_loop`
io_loop instance
"""
self.callback = callback
self.callback_time = callback_time
self.io_loop = io_loop
self._running = False
self.next_run = None
[docs] def calculate_next_run(self):
"""Caltulate next scheduled run"""
return time.time() + self.callback_time / 1000.0
[docs] def start(self, timeout=None):
"""Start callbacks"""
self._running = True
if timeout is None:
timeout = self.calculate_next_run()
self.io_loop.add_timeout(timeout, self._run)
[docs] def stop(self):
"""Stop callbacks"""
self._running = False
[docs] def delay(self):
"""Delay callback"""
self.next_run = self.calculate_next_run()
def _run(self):
if not self._running:
return
# Support for shifting callback window
if self.next_run is not None and time.time() < self.next_run:
self.start(self.next_run)
self.next_run = None
return
next_call = None
try:
next_call = self.callback()
except (KeyboardInterrupt, SystemExit):
raise
except:
LOG.error("Error in periodic callback", exc_info=True)
if self._running:
self.start(next_call)