forked from celery/celery
/
beat.py
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/
beat.py
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# -*- coding: utf-8 -*-
"""
celery.beat
~~~~~~~~~~~
The Celery periodic task scheduler.
:copyright: (c) 2009 - 2012 by Ask Solem.
:license: BSD, see LICENSE for more details.
"""
from __future__ import absolute_import
import errno
import os
import time
import shelve
import sys
import traceback
from billiard import Process, ensure_multiprocessing
from kombu.utils import reprcall
from kombu.utils.functional import maybe_promise
from . import __version__
from . import platforms
from . import signals
from . import current_app
from .app import app_or_default
from .schedules import maybe_schedule, crontab
from .utils import cached_property
from .utils.imports import instantiate
from .utils.threads import Event, Thread
from .utils.timeutils import humanize_seconds
from .utils.log import get_logger
logger = get_logger(__name__)
debug, info, error = logger.debug, logger.info, logger.error
DEFAULT_MAX_INTERVAL = 300 # 5 minutes
class SchedulingError(Exception):
"""An error occured while scheduling a task."""
class ScheduleEntry(object):
"""An entry in the scheduler.
:keyword name: see :attr:`name`.
:keyword schedule: see :attr:`schedule`.
:keyword args: see :attr:`args`.
:keyword kwargs: see :attr:`kwargs`.
:keyword options: see :attr:`options`.
:keyword last_run_at: see :attr:`last_run_at`.
:keyword total_run_count: see :attr:`total_run_count`.
:keyword relative: Is the time relative to when the server starts?
"""
#: The task name
name = None
#: The schedule (run_every/crontab)
schedule = None
#: Positional arguments to apply.
args = None
#: Keyword arguments to apply.
kwargs = None
#: Task execution options.
options = None
#: The time and date of when this task was last scheduled.
last_run_at = None
#: Total number of times this task has been scheduled.
total_run_count = 0
def __init__(self, name=None, task=None, last_run_at=None,
total_run_count=None, schedule=None, args=(), kwargs={},
options={}, relative=False):
self.name = name
self.task = task
self.args = args
self.kwargs = kwargs
self.options = options
self.schedule = maybe_schedule(schedule, relative)
self.last_run_at = last_run_at or self._default_now()
self.total_run_count = total_run_count or 0
def _default_now(self):
return current_app.now()
def _next_instance(self, last_run_at=None):
"""Returns a new instance of the same class, but with
its date and count fields updated."""
return self.__class__(**dict(self,
last_run_at=last_run_at or self._default_now(),
total_run_count=self.total_run_count + 1))
__next__ = next = _next_instance # for 2to3
def update(self, other):
"""Update values from another entry.
Does only update "editable" fields (task, schedule, args, kwargs,
options).
"""
self.__dict__.update({"task": other.task, "schedule": other.schedule,
"args": other.args, "kwargs": other.kwargs,
"options": other.options})
def is_due(self):
"""See :meth:`~celery.schedule.schedule.is_due`."""
return self.schedule.is_due(self.last_run_at)
def __iter__(self):
return vars(self).iteritems()
def __repr__(self):
return ("<Entry: %s %s {%s}" % (self.name,
reprcall(self.task, self.args or (), self.kwargs or {}),
self.schedule))
class Scheduler(object):
"""Scheduler for periodic tasks.
:keyword schedule: see :attr:`schedule`.
:keyword max_interval: see :attr:`max_interval`.
"""
Entry = ScheduleEntry
#: The schedule dict/shelve.
schedule = None
#: Maximum time to sleep between re-checking the schedule.
max_interval = DEFAULT_MAX_INTERVAL
#: How often to sync the schedule (3 minutes by default)
sync_every = 3 * 60
_last_sync = None
logger = logger # compat
def __init__(self, schedule=None, max_interval=None,
app=None, Publisher=None, lazy=False, **kwargs):
app = self.app = app_or_default(app)
self.data = maybe_promise({} if schedule is None else schedule)
self.max_interval = (max_interval
or app.conf.CELERYBEAT_MAX_LOOP_INTERVAL
or self.max_interval)
self.Publisher = Publisher or app.amqp.TaskProducer
if not lazy:
self.setup_schedule()
def install_default_entries(self, data):
entries = {}
if self.app.conf.CELERY_TASK_RESULT_EXPIRES:
if "celery.backend_cleanup" not in data:
entries["celery.backend_cleanup"] = {
"task": "celery.backend_cleanup",
"schedule": crontab("0", "4", "*"),
"options": {"expires": 12 * 3600}}
self.update_from_dict(entries)
def maybe_due(self, entry, publisher=None):
is_due, next_time_to_run = entry.is_due()
if is_due:
info("Scheduler: Sending due task %s", entry.task)
try:
result = self.apply_async(entry, publisher=publisher)
except Exception, exc:
error("Message Error: %s\n%s",
exc, traceback.format_stack(), exc_info=True)
else:
debug("%s sent. id->%s", entry.task, result.id)
return next_time_to_run
def tick(self):
"""Run a tick, that is one iteration of the scheduler.
Executes all due tasks.
"""
remaining_times = []
try:
for entry in self.schedule.itervalues():
next_time_to_run = self.maybe_due(entry, self.publisher)
if next_time_to_run:
remaining_times.append(next_time_to_run)
except RuntimeError:
pass
return min(remaining_times + [self.max_interval])
def should_sync(self):
return (not self._last_sync or
(time.time() - self._last_sync) > self.sync_every)
def reserve(self, entry):
new_entry = self.schedule[entry.name] = entry.next()
return new_entry
def apply_async(self, entry, publisher=None, **kwargs):
# Update timestamps and run counts before we actually execute,
# so we have that done if an exception is raised (doesn't schedule
# forever.)
entry = self.reserve(entry)
task = self.app.tasks.get(entry.task)
try:
if task:
result = task.apply_async(entry.args, entry.kwargs,
publisher=publisher,
**entry.options)
else:
result = self.send_task(entry.task, entry.args, entry.kwargs,
publisher=publisher,
**entry.options)
except Exception, exc:
raise SchedulingError, SchedulingError(
"Couldn't apply scheduled task %s: %s" % (
entry.name, exc)), sys.exc_info()[2]
finally:
if self.should_sync():
self._do_sync()
return result
def send_task(self, *args, **kwargs):
return self.app.send_task(*args, **kwargs)
def setup_schedule(self):
self.install_default_entries(self.data)
def _do_sync(self):
try:
debug("Celerybeat: Synchronizing schedule...")
self.sync()
finally:
self._last_sync = time.time()
def sync(self):
pass
def close(self):
self.sync()
def add(self, **kwargs):
entry = self.Entry(**kwargs)
self.schedule[entry.name] = entry
return entry
def _maybe_entry(self, name, entry):
if isinstance(entry, self.Entry):
return entry
return self.Entry(**dict(entry, name=name))
def update_from_dict(self, dict_):
self.schedule.update(dict((name, self._maybe_entry(name, entry))
for name, entry in dict_.items()))
def merge_inplace(self, b):
schedule = self.schedule
A, B = set(schedule), set(b)
# Remove items from disk not in the schedule anymore.
for key in A ^ B:
schedule.pop(key, None)
# Update and add new items in the schedule
for key in B:
entry = self.Entry(**dict(b[key], name=key))
if schedule.get(key):
schedule[key].update(entry)
else:
schedule[key] = entry
def _ensure_connected(self):
# callback called for each retry while the connection
# can't be established.
def _error_handler(exc, interval):
error("Celerybeat: Connection error: %s. "
"Trying again in %s seconds...", exc, interval)
return self.connection.ensure_connection(_error_handler,
self.app.conf.BROKER_CONNECTION_MAX_RETRIES)
def get_schedule(self):
return self.data
def set_schedule(self, schedule):
self.data = schedule
schedule = property(get_schedule, set_schedule)
@cached_property
def connection(self):
return self.app.broker_connection()
@cached_property
def publisher(self):
return self.Publisher(self._ensure_connected())
@property
def info(self):
return ""
class PersistentScheduler(Scheduler):
persistence = shelve
known_suffixes = ("", ".db", ".dat", ".bak", ".dir")
_store = None
def __init__(self, *args, **kwargs):
self.schedule_filename = kwargs.get("schedule_filename")
Scheduler.__init__(self, *args, **kwargs)
def _remove_db(self):
for suffix in self.known_suffixes:
try:
os.remove(self.schedule_filename + suffix)
except OSError, exc:
if exc.errno != errno.ENOENT:
raise
def setup_schedule(self):
try:
self._store = self.persistence.open(self.schedule_filename,
writeback=True)
entries = self._store.setdefault("entries", {})
except Exception, exc:
error("Removing corrupted schedule file %r: %r",
self.schedule_filename, exc, exc_info=True)
self._remove_db()
self._store = self.persistence.open(self.schedule_filename,
writeback=True)
else:
if "__version__" not in self._store:
self._store.clear() # remove schedule at 2.2.2 upgrade.
entries = self._store.setdefault("entries", {})
self.merge_inplace(self.app.conf.CELERYBEAT_SCHEDULE)
self.install_default_entries(self.schedule)
self._store["__version__"] = __version__
self.sync()
debug("Current schedule:\n" + "\n".join(repr(entry)
for entry in entries.itervalues()))
def get_schedule(self):
return self._store["entries"]
def set_schedule(self, schedule):
self._store["entries"] = schedule
schedule = property(get_schedule, set_schedule)
def sync(self):
if self._store is not None:
self._store.sync()
def close(self):
self.sync()
self._store.close()
@property
def info(self):
return " . db -> %s" % (self.schedule_filename, )
class Service(object):
scheduler_cls = PersistentScheduler
def __init__(self, max_interval=None, schedule_filename=None,
scheduler_cls=None, app=None):
app = self.app = app_or_default(app)
self.max_interval = (max_interval
or app.conf.CELERYBEAT_MAX_LOOP_INTERVAL)
self.scheduler_cls = scheduler_cls or self.scheduler_cls
self.schedule_filename = schedule_filename or \
app.conf.CELERYBEAT_SCHEDULE_FILENAME
self._is_shutdown = Event()
self._is_stopped = Event()
def start(self, embedded_process=False):
info("Celerybeat: Starting...")
debug("Celerybeat: Ticking with max interval->%s",
humanize_seconds(self.scheduler.max_interval))
signals.beat_init.send(sender=self)
if embedded_process:
signals.beat_embedded_init.send(sender=self)
platforms.set_process_title("celerybeat")
try:
while not self._is_shutdown.is_set():
interval = self.scheduler.tick()
debug("Celerybeat: Waking up %s.",
humanize_seconds(interval, prefix="in "))
time.sleep(interval)
except (KeyboardInterrupt, SystemExit):
self._is_shutdown.set()
finally:
self.sync()
def sync(self):
self.scheduler.close()
self._is_stopped.set()
def stop(self, wait=False):
info("Celerybeat: Shutting down...")
self._is_shutdown.set()
wait and self._is_stopped.wait() # block until shutdown done.
def get_scheduler(self, lazy=False):
filename = self.schedule_filename
scheduler = instantiate(self.scheduler_cls,
app=self.app,
schedule_filename=filename,
max_interval=self.max_interval,
lazy=lazy)
return scheduler
@cached_property
def scheduler(self):
return self.get_scheduler()
class _Threaded(Thread):
"""Embedded task scheduler using threading."""
def __init__(self, *args, **kwargs):
super(_Threaded, self).__init__()
self.service = Service(*args, **kwargs)
self.daemon = True
self.name = "Beat"
def run(self):
self.service.start()
def stop(self):
self.service.stop(wait=True)
try:
ensure_multiprocessing()
except NotImplementedError: # pragma: no cover
_Process = None
else:
class _Process(Process): # noqa
def __init__(self, *args, **kwargs):
super(_Process, self).__init__()
self.service = Service(*args, **kwargs)
self.name = "Beat"
def run(self):
platforms.signals.reset("SIGTERM")
self.service.start(embedded_process=True)
def stop(self):
self.service.stop()
self.terminate()
def EmbeddedService(*args, **kwargs):
"""Return embedded clock service.
:keyword thread: Run threaded instead of as a separate process.
Default is :const:`False`.
"""
if kwargs.pop("thread", False) or _Process is None:
# Need short max interval to be able to stop thread
# in reasonable time.
kwargs.setdefault("max_interval", 1)
return _Threaded(*args, **kwargs)
return _Process(*args, **kwargs)