This document describes the current stable version of Celery (5.2). For development docs, go here.
Source code for celery.utils.time
"""Utilities related to dates, times, intervals, and timezones."""
import numbers
import os
import random
import time as _time
from calendar import monthrange
from datetime import date, datetime, timedelta, tzinfo
from kombu.utils.functional import reprcall
from kombu.utils.objects import cached_property
from pytz import AmbiguousTimeError, FixedOffset
from pytz import timezone as _timezone
from pytz import utc
from .functional import dictfilter
from .iso8601 import parse_iso8601
from .text import pluralize
__all__ = (
'LocalTimezone', 'timezone', 'maybe_timedelta',
'delta_resolution', 'remaining', 'rate', 'weekday',
'humanize_seconds', 'maybe_iso8601', 'is_naive',
'make_aware', 'localize', 'to_utc', 'maybe_make_aware',
'ffwd', 'utcoffset', 'adjust_timestamp',
'get_exponential_backoff_interval',
)
C_REMDEBUG = os.environ.get('C_REMDEBUG', False)
DAYNAMES = 'sun', 'mon', 'tue', 'wed', 'thu', 'fri', 'sat'
WEEKDAYS = dict(zip(DAYNAMES, range(7)))
RATE_MODIFIER_MAP = {
's': lambda n: n,
'm': lambda n: n / 60.0,
'h': lambda n: n / 60.0 / 60.0,
}
TIME_UNITS = (
('day', 60 * 60 * 24.0, lambda n: format(n, '.2f')),
('hour', 60 * 60.0, lambda n: format(n, '.2f')),
('minute', 60.0, lambda n: format(n, '.2f')),
('second', 1.0, lambda n: format(n, '.2f')),
)
ZERO = timedelta(0)
_local_timezone = None
[docs]class LocalTimezone(tzinfo):
"""Local time implementation.
Note:
Used only when the :setting:`enable_utc` setting is disabled.
"""
_offset_cache = {}
def __init__(self):
# This code is moved in __init__ to execute it as late as possible
# See get_default_timezone().
self.STDOFFSET = timedelta(seconds=-_time.timezone)
if _time.daylight:
self.DSTOFFSET = timedelta(seconds=-_time.altzone)
else:
self.DSTOFFSET = self.STDOFFSET
self.DSTDIFF = self.DSTOFFSET - self.STDOFFSET
super().__init__()
def __repr__(self):
return f'<LocalTimezone: UTC{int(self.DSTOFFSET.total_seconds() / 3600):+03d}>'
[docs] def fromutc(self, dt):
# The base tzinfo class no longer implements a DST
# offset aware .fromutc() in Python 3 (Issue #2306).
# I'd rather rely on pytz to do this, than port
# the C code from cpython's fromutc [asksol]
offset = int(self.utcoffset(dt).seconds / 60.0)
try:
tz = self._offset_cache[offset]
except KeyError:
tz = self._offset_cache[offset] = FixedOffset(offset)
return tz.fromutc(dt.replace(tzinfo=tz))
def _isdst(self, dt):
tt = (dt.year, dt.month, dt.day,
dt.hour, dt.minute, dt.second,
dt.weekday(), 0, 0)
stamp = _time.mktime(tt)
tt = _time.localtime(stamp)
return tt.tm_isdst > 0
class _Zone:
def tz_or_local(self, tzinfo=None):
# pylint: disable=redefined-outer-name
if tzinfo is None:
return self.local
return self.get_timezone(tzinfo)
def to_local(self, dt, local=None, orig=None):
if is_naive(dt):
dt = make_aware(dt, orig or self.utc)
return localize(dt, self.tz_or_local(local))
def to_system(self, dt):
# tz=None is a special case since Python 3.3, and will
# convert to the current local timezone (Issue #2306).
return dt.astimezone(tz=None)
def to_local_fallback(self, dt):
if is_naive(dt):
return make_aware(dt, self.local)
return localize(dt, self.local)
def get_timezone(self, zone):
if isinstance(zone, str):
return _timezone(zone)
return zone
@cached_property
def local(self):
return LocalTimezone()
@cached_property
def utc(self):
return self.get_timezone('UTC')
timezone = _Zone()
[docs]def maybe_timedelta(delta):
"""Convert integer to timedelta, if argument is an integer."""
if isinstance(delta, numbers.Real):
return timedelta(seconds=delta)
return delta
[docs]def delta_resolution(dt, delta):
"""Round a :class:`~datetime.datetime` to the resolution of timedelta.
If the :class:`~datetime.timedelta` is in days, the
:class:`~datetime.datetime` will be rounded to the nearest days,
if the :class:`~datetime.timedelta` is in hours the
:class:`~datetime.datetime` will be rounded to the nearest hour,
and so on until seconds, which will just return the original
:class:`~datetime.datetime`.
"""
delta = max(delta.total_seconds(), 0)
resolutions = ((3, lambda x: x / 86400),
(4, lambda x: x / 3600),
(5, lambda x: x / 60))
args = dt.year, dt.month, dt.day, dt.hour, dt.minute, dt.second
for res, predicate in resolutions:
if predicate(delta) >= 1.0:
return datetime(*args[:res], tzinfo=dt.tzinfo)
return dt
[docs]def remaining(start, ends_in, now=None, relative=False):
"""Calculate the remaining time for a start date and a timedelta.
For example, "how many seconds left for 30 seconds after start?"
Arguments:
start (~datetime.datetime): Starting date.
ends_in (~datetime.timedelta): The end delta.
relative (bool): If enabled the end time will be calculated
using :func:`delta_resolution` (i.e., rounded to the
resolution of `ends_in`).
now (Callable): Function returning the current time and date.
Defaults to :func:`datetime.utcnow`.
Returns:
~datetime.timedelta: Remaining time.
"""
now = now or datetime.utcnow()
if str(start.tzinfo) == str(now.tzinfo) and now.utcoffset() != start.utcoffset():
# DST started/ended
start = start.replace(tzinfo=now.tzinfo)
end_date = start + ends_in
if relative:
end_date = delta_resolution(end_date, ends_in).replace(microsecond=0)
ret = end_date - now
if C_REMDEBUG: # pragma: no cover
print('rem: NOW:{!r} START:{!r} ENDS_IN:{!r} END_DATE:{} REM:{}'.format(
now, start, ends_in, end_date, ret))
return ret
[docs]def rate(r):
"""Convert rate string (`"100/m"`, `"2/h"` or `"0.5/s"`) to seconds."""
if r:
if isinstance(r, str):
ops, _, modifier = r.partition('/')
return RATE_MODIFIER_MAP[modifier or 's'](float(ops)) or 0
return r or 0
return 0
[docs]def weekday(name):
"""Return the position of a weekday: 0 - 7, where 0 is Sunday.
Example:
>>> weekday('sunday'), weekday('sun'), weekday('mon')
(0, 0, 1)
"""
abbreviation = name[0:3].lower()
try:
return WEEKDAYS[abbreviation]
except KeyError:
# Show original day name in exception, instead of abbr.
raise KeyError(name)
[docs]def humanize_seconds(secs, prefix='', sep='', now='now', microseconds=False):
"""Show seconds in human form.
For example, 60 becomes "1 minute", and 7200 becomes "2 hours".
Arguments:
prefix (str): can be used to add a preposition to the output
(e.g., 'in' will give 'in 1 second', but add nothing to 'now').
now (str): Literal 'now'.
microseconds (bool): Include microseconds.
"""
secs = float(format(float(secs), '.2f'))
for unit, divider, formatter in TIME_UNITS:
if secs >= divider:
w = secs / float(divider)
return '{}{}{} {}'.format(prefix, sep, formatter(w),
pluralize(w, unit))
if microseconds and secs > 0.0:
return '{prefix}{sep}{0:.2f} seconds'.format(
secs, sep=sep, prefix=prefix)
return now
[docs]def maybe_iso8601(dt):
"""Either ``datetime | str -> datetime`` or ``None -> None``."""
if not dt:
return
if isinstance(dt, datetime):
return dt
return parse_iso8601(dt)
[docs]def is_naive(dt):
"""Return :const:`True` if :class:`~datetime.datetime` is naive."""
return dt.tzinfo is None or dt.tzinfo.utcoffset(dt) is None
[docs]def make_aware(dt, tz):
"""Set timezone for a :class:`~datetime.datetime` object."""
try:
_localize = tz.localize
except AttributeError:
return dt.replace(tzinfo=tz)
else:
# works on pytz timezones
try:
return _localize(dt, is_dst=None)
except AmbiguousTimeError:
return min(_localize(dt, is_dst=True),
_localize(dt, is_dst=False))
[docs]def localize(dt, tz):
"""Convert aware :class:`~datetime.datetime` to another timezone."""
if is_naive(dt): # Ensure timezone aware datetime
dt = make_aware(dt, tz)
if dt.tzinfo == utc:
dt = dt.astimezone(tz) # Always safe to call astimezone on utc zones
try:
_normalize = tz.normalize
except AttributeError: # non-pytz tz
return dt
else:
try:
return _normalize(dt, is_dst=None)
except TypeError:
return _normalize(dt)
except AmbiguousTimeError:
return min(_normalize(dt, is_dst=True),
_normalize(dt, is_dst=False))
[docs]def to_utc(dt):
"""Convert naive :class:`~datetime.datetime` to UTC."""
return make_aware(dt, timezone.utc)
[docs]def maybe_make_aware(dt, tz=None):
"""Convert dt to aware datetime, do nothing if dt is already aware."""
if is_naive(dt):
dt = to_utc(dt)
return localize(
dt, timezone.utc if tz is None else timezone.tz_or_local(tz),
)
return dt
[docs]class ffwd:
"""Version of ``dateutil.relativedelta`` that only supports addition."""
def __init__(self, year=None, month=None, weeks=0, weekday=None, day=None,
hour=None, minute=None, second=None, microsecond=None,
**kwargs):
# pylint: disable=redefined-outer-name
# weekday is also a function in outer scope.
self.year = year
self.month = month
self.weeks = weeks
self.weekday = weekday
self.day = day
self.hour = hour
self.minute = minute
self.second = second
self.microsecond = microsecond
self.days = weeks * 7
self._has_time = self.hour is not None or self.minute is not None
def __repr__(self):
return reprcall('ffwd', (), self._fields(weeks=self.weeks,
weekday=self.weekday))
def __radd__(self, other):
if not isinstance(other, date):
return NotImplemented
year = self.year or other.year
month = self.month or other.month
day = min(monthrange(year, month)[1], self.day or other.day)
ret = other.replace(**dict(dictfilter(self._fields()),
year=year, month=month, day=day))
if self.weekday is not None:
ret += timedelta(days=(7 - ret.weekday() + self.weekday) % 7)
return ret + timedelta(days=self.days)
def _fields(self, **extra):
return dictfilter({
'year': self.year, 'month': self.month, 'day': self.day,
'hour': self.hour, 'minute': self.minute,
'second': self.second, 'microsecond': self.microsecond,
}, **extra)
[docs]def utcoffset(time=_time, localtime=_time.localtime):
"""Return the current offset to UTC in hours."""
if localtime().tm_isdst:
return time.altzone // 3600
return time.timezone // 3600
[docs]def adjust_timestamp(ts, offset, here=utcoffset):
"""Adjust timestamp based on provided utcoffset."""
return ts - (offset - here()) * 3600
[docs]def get_exponential_backoff_interval(
factor,
retries,
maximum,
full_jitter=False
):
"""Calculate the exponential backoff wait time."""
# Will be zero if factor equals 0
countdown = min(maximum, factor * (2 ** retries))
# Full jitter according to
# https://www.awsarchitectureblog.com/2015/03/backoff.html
if full_jitter:
countdown = random.randrange(countdown + 1)
# Adjust according to maximum wait time and account for negative values.
return max(0, countdown)
