"""Timezone aware Cron schedule Implementation."""
import pytz
from collections import namedtuple
import datetime as dt
from celery import schedules
schedstate = namedtuple("schedstate", ("is_due", "next"))
[docs]class TzAwareCrontab(schedules.crontab):
"""Timezone Aware Crontab."""
def __init__(
self,
minute="*",
hour="*",
day_of_week="*",
day_of_month="*",
month_of_year="*",
tz=pytz.utc,
app=None,
):
"""Overwrite Crontab constructor to include a timezone argument."""
self.tz = tz
nowfun = self.nowfunc
super().__init__(
minute=minute,
hour=hour,
day_of_week=day_of_week,
day_of_month=day_of_month,
month_of_year=month_of_year,
# tz=tz,
nowfun=nowfun,
app=app,
)
[docs] def nowfunc(self):
return self.tz.normalize(pytz.utc.localize(dt.datetime.utcnow()))
[docs] def is_due(self, last_run_at):
"""Calculate when the next run will take place.
Return tuple of (is_due, next_time_to_check).
The last_run_at argument needs to be timezone aware.
"""
# convert last_run_at to the schedule timezone
last_run_at = last_run_at.astimezone(self.tz)
rem_delta = self.remaining_estimate(last_run_at)
rem = max(rem_delta.total_seconds(), 0)
due = rem == 0
if due:
rem_delta = self.remaining_estimate(self.now())
rem = max(rem_delta.total_seconds(), 0)
return schedstate(due, rem)
# Needed to support pickling
def __repr__(self):
return """<crontab: {0._orig_minute} {0._orig_hour} \
{0._orig_day_of_week} {0._orig_day_of_month} \
{0._orig_month_of_year} (m/h/d/dM/MY), {0.tz}>""".format(
self
)
def __reduce__(self):
return (
self.__class__,
(
self._orig_minute,
self._orig_hour,
self._orig_day_of_week,
self._orig_day_of_month,
self._orig_month_of_year,
self.tz,
),
None,
)
def __eq__(self, other):
if isinstance(other, schedules.crontab):
return (
other.month_of_year == self.month_of_year
and other.day_of_month == self.day_of_month
and other.day_of_week == self.day_of_week
and other.hour == self.hour
and other.minute == self.minute
and other.tz == self.tz
)
return NotImplemented