This document describes the current stable version of Celery (3.1). For development docs, go here.
Source code for kombu.async.timer
# -*- coding: utf-8 -*-
"""
kombu.async.timer
=================
Timer scheduling Python callbacks.
"""
from __future__ import absolute_import
import heapq
import sys
from collections import namedtuple
from datetime import datetime
from functools import wraps
from time import time
from weakref import proxy as weakrefproxy
from kombu.five import monotonic
from kombu.log import get_logger
from kombu.utils.compat import timedelta_seconds
try:
from pytz import utc
except ImportError:
utc = None
DEFAULT_MAX_INTERVAL = 2
EPOCH = datetime.utcfromtimestamp(0).replace(tzinfo=utc)
IS_PYPY = hasattr(sys, 'pypy_version_info')
logger = get_logger(__name__)
__all__ = ['Entry', 'Timer', 'to_timestamp']
scheduled = namedtuple('scheduled', ('eta', 'priority', 'entry'))
[docs]def to_timestamp(d, default_timezone=utc):
if isinstance(d, datetime):
if d.tzinfo is None:
d = d.replace(tzinfo=default_timezone)
return timedelta_seconds(d - EPOCH)
return d
[docs]class Entry(object):
if not IS_PYPY: # pragma: no cover
__slots__ = (
'fun', 'args', 'kwargs', 'tref', 'cancelled',
'_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.cancelled = False
def __call__(self):
return self.fun(*self.args, **self.kwargs)
[docs] def cancel(self):
try:
self.tref.cancelled = True
except ReferenceError: # pragma: no cover
pass
def __repr__(self):
return '<TimerEntry: {0}(*{1!r}, **{2!r})'.format(
self.fun.__name__, self.args, self.kwargs)
def __hash__(self):
return hash((self.fun, repr(self.args), repr(self.kwargs)))
# must not use hash() to order entries
def __lt__(self, other):
return id(self) < id(other)
def __gt__(self, other):
return id(self) > id(other)
def __le__(self, other):
return id(self) <= id(other)
def __ge__(self, other):
return id(self) >= id(other)
def __eq__(self, other):
return hash(self) == hash(other)
def __ne__(self, other):
return not self.__eq__(other)
class Timer(object):
"""ETA scheduler."""
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={}, priority=0):
return self.enter_at(self.Entry(fun, args, kwargs), eta, priority)
def call_after(self, secs, fun, args=(), kwargs={}, priority=0):
return self.enter_after(secs, self.Entry(fun, args, kwargs), priority)
def call_repeatedly(self, secs, fun, args=(), kwargs={}, priority=0):
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.cancelled:
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=time):
"""Enter function into the scheduler.
:param entry: Item to enter.
:keyword eta: Scheduled time as a :class:`datetime.datetime` object.
:keyword priority: 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=time):
return self.enter_at(entry, time() + 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=time,
pop=heapq.heappop, push=heapq.heappush):
"""This iterator yields a tuple of ``(entry, wait_seconds)``,
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.cancelled:
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