This document describes the current stable version of Celery (5.2). For development docs, go here.

Source code for kombu.asynchronous.timer

"""Timer scheduling Python callbacks."""

import heapq
import sys

from collections import namedtuple
from datetime import datetime
from functools import total_ordering
from weakref import proxy as weakrefproxy
from time import monotonic

from vine.utils import wraps

from kombu.log import get_logger
from time import time as _time

try:
    from pytz import utc
except ImportError:  # pragma: no cover
    utc = None

__all__ = ('Entry', 'Timer', 'to_timestamp')

logger = get_logger(__name__)

DEFAULT_MAX_INTERVAL = 2
EPOCH = datetime.utcfromtimestamp(0).replace(tzinfo=utc)
IS_PYPY = hasattr(sys, 'pypy_version_info')

scheduled = namedtuple('scheduled', ('eta', 'priority', 'entry'))


[docs]def to_timestamp(d, default_timezone=utc, time=monotonic): """Convert datetime to timestamp. If d' is already a timestamp, then that will be used. """ if isinstance(d, datetime): if d.tzinfo is None: d = d.replace(tzinfo=default_timezone) diff = _time() - time() return max((d - EPOCH).total_seconds() - diff, 0) return d
[docs]@total_ordering class Entry: """Schedule Entry.""" if not IS_PYPY: # pragma: no cover __slots__ = ( 'fun', 'args', 'kwargs', 'tref', 'canceled', '_last_run', '__weakref__', ) def __init__(self, fun, args=None, kwargs=None): self.fun = fun self.args = args or [] self.kwargs = kwargs or {} self.tref = weakrefproxy(self) self._last_run = None self.canceled = False def __call__(self): return self.fun(*self.args, **self.kwargs)
[docs] def cancel(self): try: self.tref.canceled = True except ReferenceError: # pragma: no cover pass
def __repr__(self): return '<TimerEntry: {}(*{!r}, **{!r})'.format( self.fun.__name__, self.args, self.kwargs) # must not use hash() to order entries def __lt__(self, other): return id(self) < id(other) @property def cancelled(self): return self.canceled @cancelled.setter def cancelled(self, value): self.canceled = value
class Timer: """Async timer implementation.""" Entry = Entry on_error = None def __init__(self, max_interval=None, on_error=None, **kwargs): self.max_interval = float(max_interval or DEFAULT_MAX_INTERVAL) self.on_error = on_error or self.on_error self._queue = [] def __enter__(self): return self def __exit__(self, *exc_info): self.stop() def call_at(self, eta, fun, args=(), kwargs=None, priority=0): kwargs = {} if not kwargs else kwargs return self.enter_at(self.Entry(fun, args, kwargs), eta, priority) def call_after(self, secs, fun, args=(), kwargs=None, priority=0): kwargs = {} if not kwargs else kwargs return self.enter_after(secs, self.Entry(fun, args, kwargs), priority) def call_repeatedly(self, secs, fun, args=(), kwargs=None, priority=0): kwargs = {} if not kwargs else kwargs tref = self.Entry(fun, args, kwargs) @wraps(fun) def _reschedules(*args, **kwargs): last, now = tref._last_run, monotonic() lsince = (now - tref._last_run) if last else secs try: if lsince and lsince >= secs: tref._last_run = now return fun(*args, **kwargs) finally: if not tref.canceled: last = tref._last_run next = secs - (now - last) if last else secs self.enter_after(next, tref, priority) tref.fun = _reschedules tref._last_run = None return self.enter_after(secs, tref, priority) def enter_at(self, entry, eta=None, priority=0, time=monotonic): """Enter function into the scheduler. Arguments: entry (~kombu.asynchronous.timer.Entry): Item to enter. eta (datetime.datetime): Scheduled time. priority (int): Unused. """ if eta is None: eta = time() if isinstance(eta, datetime): try: eta = to_timestamp(eta) except Exception as exc: if not self.handle_error(exc): raise return return self._enter(eta, priority, entry) def enter_after(self, secs, entry, priority=0, time=monotonic): return self.enter_at(entry, time() + float(secs), priority) def _enter(self, eta, priority, entry, push=heapq.heappush): push(self._queue, scheduled(eta, priority, entry)) return entry def apply_entry(self, entry): try: entry() except Exception as exc: if not self.handle_error(exc): logger.error('Error in timer: %r', exc, exc_info=True) def handle_error(self, exc_info): if self.on_error: self.on_error(exc_info) return True def stop(self): pass def __iter__(self, min=min, nowfun=monotonic, pop=heapq.heappop, push=heapq.heappush): """Iterate over schedule. This iterator yields a tuple of ``(wait_seconds, entry)``, where if entry is :const:`None` the caller should wait for ``wait_seconds`` until it polls the schedule again. """ max_interval = self.max_interval queue = self._queue while 1: if queue: eventA = queue[0] now, eta = nowfun(), eventA[0] if now < eta: yield min(eta - now, max_interval), None else: eventB = pop(queue) if eventB is eventA: entry = eventA[2] if not entry.canceled: yield None, entry continue else: push(queue, eventB) else: yield None, None def clear(self): self._queue[:] = [] # atomic, without creating a new list. def cancel(self, tref): tref.cancel() def __len__(self): return len(self._queue) def __nonzero__(self): return True @property def queue(self, _pop=heapq.heappop): """Snapshot of underlying datastructure.""" events = list(self._queue) return [_pop(v) for v in [events] * len(events)] @property def schedule(self): return self