This document describes the current stable version of Celery (5.3). For development docs, go here.

Source code for celery.schedules

"""Schedules define the intervals at which periodic tasks run."""

import numbers
import re
from bisect import bisect, bisect_left
from collections import namedtuple
from import Iterable
from datetime import datetime, timedelta

from kombu.utils.objects import cached_property

from . import current_app
from .utils.collections import AttributeDict
from .utils.time import (ffwd, humanize_seconds, localize, maybe_make_aware, maybe_timedelta, remaining, timezone,

__all__ = (
    'ParseException', 'schedule', 'crontab', 'crontab_parser',
    'maybe_schedule', 'solar',

schedstate = namedtuple('schedstate', ('is_due', 'next'))

Invalid crontab pattern.  Valid range is {min}-{max}. \
'{value}' was found.\

Argument cronspec needs to be of any of the following types: \
int, str, or an iterable type. {type!r} was given.\

CRON_REPR = """\
<crontab: {0._orig_minute} {0._orig_hour} {0._orig_day_of_month} {0._orig_month_of_year} \
{0._orig_day_of_week} (m/h/dM/MY/d)>\

Argument latitude {lat} is invalid, must be between -90 and 90.\

Argument longitude {lon} is invalid, must be between -180 and 180.\

Argument event "{event}" is invalid, must be one of {all_events}.\

def cronfield(s):
    return '*' if s is None else s

[docs]class ParseException(Exception): """Raised by :class:`crontab_parser` when the input can't be parsed."""
class BaseSchedule: def __init__(self, nowfun=None, app=None): self.nowfun = nowfun self._app = app def now(self): return (self.nowfun or def remaining_estimate(self, last_run_at): raise NotImplementedError() def is_due(self, last_run_at): raise NotImplementedError() def maybe_make_aware(self, dt): return maybe_make_aware(dt, @property def app(self): return self._app or current_app._get_current_object() @app.setter def app(self, app): self._app = app @cached_property def tz(self): return @cached_property def utc_enabled(self): return def to_local(self, dt): if not self.utc_enabled: return timezone.to_local_fallback(dt) return dt def __eq__(self, other): if isinstance(other, BaseSchedule): return other.nowfun == self.nowfun return NotImplemented
[docs]class schedule(BaseSchedule): """Schedule for periodic task. Arguments: run_every (float, ~datetime.timedelta): Time interval. relative (bool): If set to True the run time will be rounded to the resolution of the interval. nowfun (Callable): Function returning the current date and time (:class:`~datetime.datetime`). app (Celery): Celery app instance. """ relative = False def __init__(self, run_every=None, relative=False, nowfun=None, app=None): self.run_every = maybe_timedelta(run_every) self.relative = relative super().__init__(nowfun=nowfun, app=app)
[docs] def remaining_estimate(self, last_run_at): return remaining( self.maybe_make_aware(last_run_at), self.run_every, self.maybe_make_aware(, self.relative, )
[docs] def is_due(self, last_run_at): """Return tuple of ``(is_due, next_time_to_check)``. Notes: - next time to check is in seconds. - ``(True, 20)``, means the task should be run now, and the next time to check is in 20 seconds. - ``(False, 12.3)``, means the task is not due, but that the scheduler should check again in 12.3 seconds. The next time to check is used to save energy/CPU cycles, it does not need to be accurate but will influence the precision of your schedule. You must also keep in mind the value of :setting:`beat_max_loop_interval`, that decides the maximum number of seconds the scheduler can sleep between re-checking the periodic task intervals. So if you have a task that changes schedule at run-time then your next_run_at check will decide how long it will take before a change to the schedule takes effect. The max loop interval takes precedence over the next check at value returned. .. admonition:: Scheduler max interval variance The default max loop interval may vary for different schedulers. For the default scheduler the value is 5 minutes, but for example the :pypi:`django-celery-beat` database scheduler the value is 5 seconds. """ last_run_at = self.maybe_make_aware(last_run_at) rem_delta = self.remaining_estimate(last_run_at) remaining_s = max(rem_delta.total_seconds(), 0) if remaining_s == 0: return schedstate(is_due=True, next=self.seconds) return schedstate(is_due=False, next=remaining_s)
def __repr__(self): return f'<freq: {self.human_seconds}>' def __eq__(self, other): if isinstance(other, schedule): return self.run_every == other.run_every return self.run_every == other def __reduce__(self): return self.__class__, (self.run_every, self.relative, self.nowfun) @property def seconds(self): return max(self.run_every.total_seconds(), 0) @property def human_seconds(self): return humanize_seconds(self.seconds)
[docs]class crontab_parser: """Parser for Crontab expressions. Any expression of the form 'groups' (see BNF grammar below) is accepted and expanded to a set of numbers. These numbers represent the units of time that the Crontab needs to run on: .. code-block:: bnf digit :: '0'..'9' dow :: 'a'..'z' number :: digit+ | dow+ steps :: number range :: number ( '-' number ) ? numspec :: '*' | range expr :: numspec ( '/' steps ) ? groups :: expr ( ',' expr ) * The parser is a general purpose one, useful for parsing hours, minutes and day of week expressions. Example usage: .. code-block:: pycon >>> minutes = crontab_parser(60).parse('*/15') [0, 15, 30, 45] >>> hours = crontab_parser(24).parse('*/4') [0, 4, 8, 12, 16, 20] >>> day_of_week = crontab_parser(7).parse('*') [0, 1, 2, 3, 4, 5, 6] It can also parse day of month and month of year expressions if initialized with a minimum of 1. Example usage: .. code-block:: pycon >>> days_of_month = crontab_parser(31, 1).parse('*/3') [1, 4, 7, 10, 13, 16, 19, 22, 25, 28, 31] >>> months_of_year = crontab_parser(12, 1).parse('*/2') [1, 3, 5, 7, 9, 11] >>> months_of_year = crontab_parser(12, 1).parse('2-12/2') [2, 4, 6, 8, 10, 12] The maximum possible expanded value returned is found by the formula: :math:`max_ + min_ - 1` """ ParseException = ParseException _range = r'(\w+?)-(\w+)' _steps = r'/(\w+)?' _star = r'\*' def __init__(self, max_=60, min_=0): self.max_ = max_ self.min_ = min_ self.pats = ( (re.compile(self._range + self._steps), self._range_steps), (re.compile(self._range), self._expand_range), (re.compile(self._star + self._steps), self._star_steps), (re.compile('^' + self._star + '$'), self._expand_star), )
[docs] def parse(self, spec): acc = set() for part in spec.split(','): if not part: raise self.ParseException('empty part') acc |= set(self._parse_part(part)) return acc
def _parse_part(self, part): for regex, handler in self.pats: m = regex.match(part) if m: return handler(m.groups()) return self._expand_range((part,)) def _expand_range(self, toks): fr = self._expand_number(toks[0]) if len(toks) > 1: to = self._expand_number(toks[1]) if to < fr: # Wrap around max_ if necessary return (list(range(fr, self.min_ + self.max_)) + list(range(self.min_, to + 1))) return list(range(fr, to + 1)) return [fr] def _range_steps(self, toks): if len(toks) != 3 or not toks[2]: raise self.ParseException('empty filter') return self._expand_range(toks[:2])[::int(toks[2])] def _star_steps(self, toks): if not toks or not toks[0]: raise self.ParseException('empty filter') return self._expand_star()[::int(toks[0])] def _expand_star(self, *args): return list(range(self.min_, self.max_ + self.min_)) def _expand_number(self, s): if isinstance(s, str) and s[0] == '-': raise self.ParseException('negative numbers not supported') try: i = int(s) except ValueError: try: i = weekday(s) except KeyError: raise ValueError(f'Invalid weekday literal {s!r}.') max_val = self.min_ + self.max_ - 1 if i > max_val: raise ValueError( f'Invalid end range: {i} > {max_val}.') if i < self.min_: raise ValueError( f'Invalid beginning range: {i} < {self.min_}.') return i
[docs]class crontab(BaseSchedule): """Crontab schedule. A Crontab can be used as the ``run_every`` value of a periodic task entry to add :manpage:`crontab(5)`-like scheduling. Like a :manpage:`cron(5)`-job, you can specify units of time of when you'd like the task to execute. It's a reasonably complete implementation of :command:`cron`'s features, so it should provide a fair degree of scheduling needs. You can specify a minute, an hour, a day of the week, a day of the month, and/or a month in the year in any of the following formats: .. attribute:: minute - A (list of) integers from 0-59 that represent the minutes of an hour of when execution should occur; or - A string representing a Crontab pattern. This may get pretty advanced, like ``minute='*/15'`` (for every quarter) or ``minute='1,13,30-45,50-59/2'``. .. attribute:: hour - A (list of) integers from 0-23 that represent the hours of a day of when execution should occur; or - A string representing a Crontab pattern. This may get pretty advanced, like ``hour='*/3'`` (for every three hours) or ``hour='0,8-17/2'`` (at midnight, and every two hours during office hours). .. attribute:: day_of_week - A (list of) integers from 0-6, where Sunday = 0 and Saturday = 6, that represent the days of a week that execution should occur. - A string representing a Crontab pattern. This may get pretty advanced, like ``day_of_week='mon-fri'`` (for weekdays only). (Beware that ``day_of_week='*/2'`` does not literally mean 'every two days', but 'every day that is divisible by two'!) .. attribute:: day_of_month - A (list of) integers from 1-31 that represents the days of the month that execution should occur. - A string representing a Crontab pattern. This may get pretty advanced, such as ``day_of_month='2-30/2'`` (for every even numbered day) or ``day_of_month='1-7,15-21'`` (for the first and third weeks of the month). .. attribute:: month_of_year - A (list of) integers from 1-12 that represents the months of the year during which execution can occur. - A string representing a Crontab pattern. This may get pretty advanced, such as ``month_of_year='*/3'`` (for the first month of every quarter) or ``month_of_year='2-12/2'`` (for every even numbered month). .. attribute:: nowfun Function returning the current date and time (:class:`~datetime.datetime`). .. attribute:: app The Celery app instance. It's important to realize that any day on which execution should occur must be represented by entries in all three of the day and month attributes. For example, if ``day_of_week`` is 0 and ``day_of_month`` is every seventh day, only months that begin on Sunday and are also in the ``month_of_year`` attribute will have execution events. Or, ``day_of_week`` is 1 and ``day_of_month`` is '1-7,15-21' means every first and third Monday of every month present in ``month_of_year``. """ def __init__(self, minute='*', hour='*', day_of_week='*', day_of_month='*', month_of_year='*', **kwargs): self._orig_minute = cronfield(minute) self._orig_hour = cronfield(hour) self._orig_day_of_week = cronfield(day_of_week) self._orig_day_of_month = cronfield(day_of_month) self._orig_month_of_year = cronfield(month_of_year) self._orig_kwargs = kwargs self.hour = self._expand_cronspec(hour, 24) self.minute = self._expand_cronspec(minute, 60) self.day_of_week = self._expand_cronspec(day_of_week, 7) self.day_of_month = self._expand_cronspec(day_of_month, 31, 1) self.month_of_year = self._expand_cronspec(month_of_year, 12, 1) super().__init__(**kwargs) @staticmethod def _expand_cronspec(cronspec, max_, min_=0): """Expand cron specification. Takes the given cronspec argument in one of the forms: .. code-block:: text int (like 7) str (like '3-5,*/15', '*', or 'monday') set (like {0,15,30,45} list (like [8-17]) And convert it to an (expanded) set representing all time unit values on which the Crontab triggers. Only in case of the base type being :class:`str`, parsing occurs. (It's fast and happens only once for each Crontab instance, so there's no significant performance overhead involved.) For the other base types, merely Python type conversions happen. The argument ``max_`` is needed to determine the expansion of ``*`` and ranges. The argument ``min_`` is needed to determine the expansion of ``*`` and ranges for 1-based cronspecs, such as day of month or month of year. The default is sufficient for minute, hour, and day of week. """ if isinstance(cronspec, numbers.Integral): result = {cronspec} elif isinstance(cronspec, str): result = crontab_parser(max_, min_).parse(cronspec) elif isinstance(cronspec, set): result = cronspec elif isinstance(cronspec, Iterable): result = set(cronspec) else: raise TypeError(CRON_INVALID_TYPE.format(type=type(cronspec))) # assure the result does not precede the min or exceed the max for number in result: if number >= max_ + min_ or number < min_: raise ValueError(CRON_PATTERN_INVALID.format( min=min_, max=max_ - 1 + min_, value=number)) return result def _delta_to_next(self, last_run_at, next_hour, next_minute): """Find next delta. Takes a :class:`~datetime.datetime` of last run, next minute and hour, and returns a :class:`~celery.utils.time.ffwd` for the next scheduled day and time. Only called when ``day_of_month`` and/or ``month_of_year`` cronspec is specified to further limit scheduled task execution. """ datedata = AttributeDict(year=last_run_at.year) days_of_month = sorted(self.day_of_month) months_of_year = sorted(self.month_of_year) def day_out_of_range(year, month, day): try: datetime(year=year, month=month, day=day) except ValueError: return True return False def is_before_last_run(year, month, day): return self.maybe_make_aware(datetime(year, month, day)) < last_run_at def roll_over(): for _ in range(2000): flag = (datedata.dom == len(days_of_month) or day_out_of_range(datedata.year, months_of_year[datedata.moy], days_of_month[datedata.dom]) or (is_before_last_run(datedata.year, months_of_year[datedata.moy], days_of_month[datedata.dom]))) if flag: datedata.dom = 0 datedata.moy += 1 if datedata.moy == len(months_of_year): datedata.moy = 0 datedata.year += 1 else: break else: # Tried 2000 times, we're most likely in an infinite loop raise RuntimeError('unable to rollover, ' 'time specification is probably invalid') if last_run_at.month in self.month_of_year: datedata.dom = bisect(days_of_month, datedata.moy = bisect_left(months_of_year, last_run_at.month) else: datedata.dom = 0 datedata.moy = bisect(months_of_year, last_run_at.month) if datedata.moy == len(months_of_year): datedata.moy = 0 roll_over() while 1: th = datetime(year=datedata.year, month=months_of_year[datedata.moy], day=days_of_month[datedata.dom]) if th.isoweekday() % 7 in self.day_of_week: break datedata.dom += 1 roll_over() return ffwd(year=datedata.year, month=months_of_year[datedata.moy], day=days_of_month[datedata.dom], hour=next_hour, minute=next_minute, second=0, microsecond=0) def __repr__(self): return CRON_REPR.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._orig_kwargs) def __setstate__(self, state): # Calling super's init because the kwargs aren't necessarily passed in # the same form as they are stored by the superclass super().__init__(**state)
[docs] def remaining_delta(self, last_run_at, tz=None, ffwd=ffwd): # caching global ffwd last_run_at = self.maybe_make_aware(last_run_at) now = self.maybe_make_aware( dow_num = last_run_at.isoweekday() % 7 # Sunday is day 0, not day 7 execute_this_date = ( last_run_at.month in self.month_of_year and in self.day_of_month and dow_num in self.day_of_week ) execute_this_hour = ( execute_this_date and == and last_run_at.month == now.month and last_run_at.year == now.year and last_run_at.hour in self.hour and last_run_at.minute < max(self.minute) ) if execute_this_hour: next_minute = min(minute for minute in self.minute if minute > last_run_at.minute) delta = ffwd(minute=next_minute, second=0, microsecond=0) else: next_minute = min(self.minute) execute_today = (execute_this_date and last_run_at.hour < max(self.hour)) if execute_today: next_hour = min(hour for hour in self.hour if hour > last_run_at.hour) delta = ffwd(hour=next_hour, minute=next_minute, second=0, microsecond=0) else: next_hour = min(self.hour) all_dom_moy = (self._orig_day_of_month == '*' and self._orig_month_of_year == '*') if all_dom_moy: next_day = min([day for day in self.day_of_week if day > dow_num] or self.day_of_week) add_week = next_day == dow_num delta = ffwd( weeks=add_week and 1 or 0, weekday=(next_day - 1) % 7, hour=next_hour, minute=next_minute, second=0, microsecond=0, ) else: delta = self._delta_to_next(last_run_at, next_hour, next_minute) return self.to_local(last_run_at), delta, self.to_local(now)
[docs] def remaining_estimate(self, last_run_at, ffwd=ffwd): """Estimate of next run time. Returns when the periodic task should run next as a :class:`~datetime.timedelta`. """ # pylint: disable=redefined-outer-name # caching global ffwd return remaining(*self.remaining_delta(last_run_at, ffwd=ffwd))
[docs] def is_due(self, last_run_at): """Return tuple of ``(is_due, next_time_to_run)``. If :setting:`beat_cron_starting_deadline` has been specified, the scheduler will make sure that the `last_run_at` time is within the deadline. This prevents tasks that could have been run according to the crontab, but didn't, from running again unexpectedly. Note: Next time to run is in seconds. SeeAlso: :meth:`celery.schedules.schedule.is_due` for more information. """ rem_delta = self.remaining_estimate(last_run_at) rem_secs = rem_delta.total_seconds() rem = max(rem_secs, 0) due = rem == 0 deadline_secs = has_passed_deadline = False if deadline_secs is not None: # Make sure we're looking at the latest possible feasible run # date when checking the deadline. last_date_checked = last_run_at last_feasible_rem_secs = rem_secs while rem_secs < 0: last_date_checked = last_date_checked + abs(rem_delta) rem_delta = self.remaining_estimate(last_date_checked) rem_secs = rem_delta.total_seconds() if rem_secs < 0: last_feasible_rem_secs = rem_secs # if rem_secs becomes 0 or positive, second-to-last # last_date_checked must be the last feasible run date. # Check if the last feasible date is within the deadline # for running has_passed_deadline = -last_feasible_rem_secs > deadline_secs if has_passed_deadline: # Should not be due if we've passed the deadline for looking # at past runs due = False if due or has_passed_deadline: rem_delta = self.remaining_estimate( rem = max(rem_delta.total_seconds(), 0) return schedstate(due, rem)
def __eq__(self, other): if isinstance(other, 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 super().__eq__(other) ) return NotImplemented
[docs]def maybe_schedule(s, relative=False, app=None): """Return schedule from number, timedelta, or actual schedule.""" if s is not None: if isinstance(s, numbers.Number): s = timedelta(seconds=s) if isinstance(s, timedelta): return schedule(s, relative, app=app) else: = app return s
[docs]class solar(BaseSchedule): """Solar event. A solar event can be used as the ``run_every`` value of a periodic task entry to schedule based on certain solar events. Notes: Available event values are: - ``dawn_astronomical`` - ``dawn_nautical`` - ``dawn_civil`` - ``sunrise`` - ``solar_noon`` - ``sunset`` - ``dusk_civil`` - ``dusk_nautical`` - ``dusk_astronomical`` Arguments: event (str): Solar event that triggers this task. See note for available values. lat (int): The latitude of the observer. lon (int): The longitude of the observer. nowfun (Callable): Function returning the current date and time as a class:`~datetime.datetime`. app (Celery): Celery app instance. """ _all_events = { 'dawn_astronomical', 'dawn_nautical', 'dawn_civil', 'sunrise', 'solar_noon', 'sunset', 'dusk_civil', 'dusk_nautical', 'dusk_astronomical', } _horizons = { 'dawn_astronomical': '-18', 'dawn_nautical': '-12', 'dawn_civil': '-6', 'sunrise': '-0:34', 'solar_noon': '0', 'sunset': '-0:34', 'dusk_civil': '-6', 'dusk_nautical': '-12', 'dusk_astronomical': '18', } _methods = { 'dawn_astronomical': 'next_rising', 'dawn_nautical': 'next_rising', 'dawn_civil': 'next_rising', 'sunrise': 'next_rising', 'solar_noon': 'next_transit', 'sunset': 'next_setting', 'dusk_civil': 'next_setting', 'dusk_nautical': 'next_setting', 'dusk_astronomical': 'next_setting', } _use_center_l = { 'dawn_astronomical': True, 'dawn_nautical': True, 'dawn_civil': True, 'sunrise': False, 'solar_noon': False, 'sunset': False, 'dusk_civil': True, 'dusk_nautical': True, 'dusk_astronomical': True, } def __init__(self, event, lat, lon, **kwargs): self.ephem = __import__('ephem') self.event = event = lat self.lon = lon super().__init__(**kwargs) if event not in self._all_events: raise ValueError(SOLAR_INVALID_EVENT.format( event=event, all_events=', '.join(sorted(self._all_events)), )) if lat < -90 or lat > 90: raise ValueError(SOLAR_INVALID_LATITUDE.format(lat=lat)) if lon < -180 or lon > 180: raise ValueError(SOLAR_INVALID_LONGITUDE.format(lon=lon)) cal = self.ephem.Observer() = str(lat) cal.lon = str(lon) cal.elev = 0 cal.horizon = self._horizons[event] cal.pressure = 0 = cal self.method = self._methods[event] self.use_center = self._use_center_l[event] def __reduce__(self): return self.__class__, (self.event,, self.lon) def __repr__(self): return '<solar: {} at latitude {}, longitude: {}>'.format( self.event,, self.lon, )
[docs] def remaining_estimate(self, last_run_at): """Return estimate of next time to run. Returns: ~datetime.timedelta: when the periodic task should run next, or if it shouldn't run today (e.g., the sun does not rise today), returns the time when the next check should take place. """ last_run_at = self.maybe_make_aware(last_run_at) last_run_at_utc = localize(last_run_at, timezone.utc) = last_run_at_utc try: if self.use_center: next_utc = getattr(, self.method)( self.ephem.Sun(), start=last_run_at_utc, use_center=self.use_center ) else: next_utc = getattr(, self.method)( self.ephem.Sun(), start=last_run_at_utc ) except self.ephem.CircumpolarError: # pragma: no cover # Sun won't rise/set today. Check again tomorrow # (specifically, after the next anti-transit). next_utc = ( + timedelta(minutes=1) ) next = self.maybe_make_aware(next_utc.datetime()) now = self.maybe_make_aware( delta = next - now return delta
[docs] def is_due(self, last_run_at): """Return tuple of ``(is_due, next_time_to_run)``. Note: next time to run is in seconds. See Also: :meth:`celery.schedules.schedule.is_due` for more information. """ 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( rem = max(rem_delta.total_seconds(), 0) return schedstate(due, rem)
def __eq__(self, other): if isinstance(other, solar): return ( other.event == self.event and == and other.lon == self.lon ) return NotImplemented