# -*- coding: utf-8 -*-
"""
celery.app.builtins
~~~~~~~~~~~~~~~~~~~
Built-in tasks that are always available in all
app instances. E.g. chord, group and xmap.
"""
from __future__ import absolute_import
from collections import deque
from celery._state import get_current_worker_task, connect_on_app_finalize
from celery.utils import uuid
from celery.utils.log import get_logger
__all__ = []
logger = get_logger(__name__)
@connect_on_app_finalize
def add_backend_cleanup_task(app):
"""The backend cleanup task can be used to clean up the default result
backend.
If the configured backend requires periodic cleanup this task is also
automatically configured to run every day at 4am (requires
:program:`celery beat` to be running).
"""
@app.task(name='celery.backend_cleanup',
shared=False, _force_evaluate=True)
def backend_cleanup():
app.backend.cleanup()
return backend_cleanup
@connect_on_app_finalize
def add_unlock_chord_task(app):
"""This task is used by result backends without native chord support.
It joins chords by creating a task chain polling the header for completion.
"""
from celery.canvas import signature
from celery.exceptions import ChordError
from celery.result import allow_join_result, result_from_tuple
default_propagate = app.conf.CELERY_CHORD_PROPAGATES
@app.task(name='celery.chord_unlock', max_retries=None, shared=False,
default_retry_delay=1, ignore_result=True, _force_evaluate=True,
bind=True)
def unlock_chord(self, group_id, callback, interval=None, propagate=None,
max_retries=None, result=None,
Result=app.AsyncResult, GroupResult=app.GroupResult,
result_from_tuple=result_from_tuple):
# if propagate is disabled exceptions raised by chord tasks
# will be sent as part of the result list to the chord callback.
# Since 3.1 propagate will be enabled by default, and instead
# the chord callback changes state to FAILURE with the
# exception set to ChordError.
propagate = default_propagate if propagate is None else propagate
if interval is None:
interval = self.default_retry_delay
# check if the task group is ready, and if so apply the callback.
deps = GroupResult(
group_id,
[result_from_tuple(r, app=app) for r in result],
app=app,
)
j = deps.join_native if deps.supports_native_join else deps.join
try:
ready = deps.ready()
except Exception as exc:
raise self.retry(
exc=exc, countdown=interval, max_retries=max_retries,
)
else:
if not ready:
raise self.retry(countdown=interval, max_retries=max_retries)
callback = signature(callback, app=app)
try:
with allow_join_result():
ret = j(timeout=3.0, propagate=propagate)
except Exception as exc:
try:
culprit = next(deps._failed_join_report())
reason = 'Dependency {0.id} raised {1!r}'.format(
culprit, exc,
)
except StopIteration:
reason = repr(exc)
logger.error('Chord %r raised: %r', group_id, exc, exc_info=1)
app.backend.chord_error_from_stack(callback,
ChordError(reason))
else:
try:
callback.delay(ret)
except Exception as exc:
logger.error('Chord %r raised: %r', group_id, exc, exc_info=1)
app.backend.chord_error_from_stack(
callback,
exc=ChordError('Callback error: {0!r}'.format(exc)),
)
return unlock_chord
@connect_on_app_finalize
def add_map_task(app):
from celery.canvas import signature
@app.task(name='celery.map', shared=False, _force_evaluate=True)
def xmap(task, it):
task = signature(task, app=app).type
return [task(item) for item in it]
return xmap
@connect_on_app_finalize
def add_starmap_task(app):
from celery.canvas import signature
@app.task(name='celery.starmap', shared=False, _force_evaluate=True)
def xstarmap(task, it):
task = signature(task, app=app).type
return [task(*item) for item in it]
return xstarmap
@connect_on_app_finalize
def add_chunk_task(app):
from celery.canvas import chunks as _chunks
@app.task(name='celery.chunks', shared=False, _force_evaluate=True)
def chunks(task, it, n):
return _chunks.apply_chunks(task, it, n)
return chunks
@connect_on_app_finalize
def add_group_task(app):
_app = app
from celery.canvas import maybe_signature, signature
from celery.result import result_from_tuple
class Group(app.Task):
app = _app
name = 'celery.group'
accept_magic_kwargs = False
_decorated = True
def run(self, tasks, result, group_id, partial_args,
add_to_parent=True):
app = self.app
result = result_from_tuple(result, app)
# any partial args are added to all tasks in the group
taskit = (signature(task, app=app).clone(partial_args)
for i, task in enumerate(tasks))
if self.request.is_eager or app.conf.CELERY_ALWAYS_EAGER:
return app.GroupResult(
result.id,
[stask.apply(group_id=group_id) for stask in taskit],
)
with app.producer_or_acquire() as pub:
[stask.apply_async(group_id=group_id, producer=pub,
add_to_parent=False) for stask in taskit]
parent = get_current_worker_task()
if add_to_parent and parent:
parent.add_trail(result)
return result
def prepare(self, options, tasks, args, **kwargs):
options['group_id'] = group_id = (
options.setdefault('task_id', uuid()))
def prepare_member(task):
task = maybe_signature(task, app=self.app)
task.options['group_id'] = group_id
return task, task.freeze()
try:
tasks, res = list(zip(
*[prepare_member(task) for task in tasks]
))
except ValueError: # tasks empty
tasks, res = [], []
return (tasks, self.app.GroupResult(group_id, res), group_id, args)
def apply_async(self, partial_args=(), kwargs={}, **options):
if self.app.conf.CELERY_ALWAYS_EAGER:
return self.apply(partial_args, kwargs, **options)
tasks, result, gid, args = self.prepare(
options, args=partial_args, **kwargs
)
super(Group, self).apply_async((
list(tasks), result.as_tuple(), gid, args), **options
)
return result
def apply(self, args=(), kwargs={}, **options):
return super(Group, self).apply(
self.prepare(options, args=args, **kwargs),
**options).get()
return Group
@connect_on_app_finalize
def add_chain_task(app):
from celery.canvas import (
Signature, chain, chord, group, maybe_signature, maybe_unroll_group,
)
_app = app
class Chain(app.Task):
app = _app
name = 'celery.chain'
accept_magic_kwargs = False
_decorated = True
def prepare_steps(self, args, tasks):
app = self.app
steps = deque(tasks)
next_step = prev_task = prev_res = None
tasks, results = [], []
i = 0
while steps:
# First task get partial args from chain.
task = maybe_signature(steps.popleft(), app=app)
task = task.clone() if i else task.clone(args)
res = task.freeze()
i += 1
if isinstance(task, group):
task = maybe_unroll_group(task)
if isinstance(task, chain):
# splice the chain
steps.extendleft(reversed(task.tasks))
continue
elif isinstance(task, group) and steps and \
not isinstance(steps[0], group):
# automatically upgrade group(..) | s to chord(group, s)
try:
next_step = steps.popleft()
# for chords we freeze by pretending it's a normal
# task instead of a group.
res = Signature.freeze(next_step)
task = chord(task, body=next_step, task_id=res.task_id)
except IndexError:
pass # no callback, so keep as group
if prev_task:
# link previous task to this task.
prev_task.link(task)
# set the results parent attribute.
if not res.parent:
res.parent = prev_res
if not isinstance(prev_task, chord):
results.append(res)
tasks.append(task)
prev_task, prev_res = task, res
return tasks, results
def apply_async(self, args=(), kwargs={}, group_id=None, chord=None,
task_id=None, link=None, link_error=None, **options):
if self.app.conf.CELERY_ALWAYS_EAGER:
return self.apply(args, kwargs, **options)
options.pop('publisher', None)
tasks, results = self.prepare_steps(args, kwargs['tasks'])
result = results[-1]
if group_id:
tasks[-1].set(group_id=group_id)
if chord:
tasks[-1].set(chord=chord)
if task_id:
tasks[-1].set(task_id=task_id)
result = tasks[-1].type.AsyncResult(task_id)
# make sure we can do a link() and link_error() on a chain object.
if link:
tasks[-1].set(link=link)
# and if any task in the chain fails, call the errbacks
if link_error:
for task in tasks:
task.set(link_error=link_error)
tasks[0].apply_async(**options)
return result
def apply(self, args=(), kwargs={}, signature=maybe_signature,
**options):
app = self.app
last, fargs = None, args # fargs passed to first task only
for task in kwargs['tasks']:
res = signature(task, app=app).clone(fargs).apply(
last and (last.get(), ),
)
res.parent, last, fargs = last, res, None
return last
return Chain
@connect_on_app_finalize
def add_chord_task(app):
"""Every chord is executed in a dedicated task, so that the chord
can be used as a signature, and this generates the task
responsible for that."""
from celery import group
from celery.canvas import maybe_signature
_app = app
default_propagate = app.conf.CELERY_CHORD_PROPAGATES
class Chord(app.Task):
app = _app
name = 'celery.chord'
accept_magic_kwargs = False
ignore_result = False
_decorated = True
def run(self, header, body, partial_args=(), interval=None,
countdown=1, max_retries=None, propagate=None,
eager=False, **kwargs):
app = self.app
propagate = default_propagate if propagate is None else propagate
group_id = uuid()
# - convert back to group if serialized
tasks = header.tasks if isinstance(header, group) else header
header = group([
maybe_signature(s, app=app).clone() for s in tasks
], app=self.app)
# - eager applies the group inline
if eager:
return header.apply(args=partial_args, task_id=group_id)
body['chord_size'] = len(header.tasks)
results = header.freeze(group_id=group_id, chord=body).results
return self.backend.apply_chord(
header, partial_args, group_id,
body, interval=interval, countdown=countdown,
max_retries=max_retries, propagate=propagate, result=results,
)
def apply_async(self, args=(), kwargs={}, task_id=None,
group_id=None, chord=None, **options):
app = self.app
if app.conf.CELERY_ALWAYS_EAGER:
return self.apply(args, kwargs, **options)
header = kwargs.pop('header')
body = kwargs.pop('body')
header, body = (maybe_signature(header, app=app),
maybe_signature(body, app=app))
# forward certain options to body
if chord is not None:
body.options['chord'] = chord
if group_id is not None:
body.options['group_id'] = group_id
[body.link(s) for s in options.pop('link', [])]
[body.link_error(s) for s in options.pop('link_error', [])]
body_result = body.freeze(task_id)
parent = super(Chord, self).apply_async((header, body, args),
kwargs, **options)
body_result.parent = parent
return body_result
def apply(self, args=(), kwargs={}, propagate=True, **options):
body = kwargs['body']
res = super(Chord, self).apply(args, dict(kwargs, eager=True),
**options)
return maybe_signature(body, app=self.app).apply(
args=(res.get(propagate=propagate).get(), ))
return Chord