class Task(BaseTask):
abstract = True
__bound__ = False
# In old Celery the @task decorator didn't exist, so one would create
# classes instead and use them directly (e.g. MyTask.apply_async()).
# the use of classmethods was a hack so that it was not necessary
# to instantiate the class before using it, but it has only
# given us pain (like all magic).
for name in _COMPAT_CLASSMETHODS:
locals()[name] = reclassmethod(getattr(BaseTask, name))
app = class_property(_get_app, bind) # noqa
class Task(object):
"""Task base class.
When called tasks apply the :meth:`run` method. This method must
be defined by all tasks (that is unless the :meth:`__call__` method
is overridden).
"""
__metaclass__ = TaskType
__trace__ = None
__v2_compat__ = False # set by old base in celery.task.base
ErrorMail = ErrorMail
MaxRetriesExceededError = MaxRetriesExceededError
#: Execution strategy used, or the qualified name of one.
Strategy = 'celery.worker.strategy:default'
#: This is the instance bound to if the task is a method of a class.
__self__ = None
#: The application instance associated with this task class.
_app = None
#: Name of the task.
name = None
#: If :const:`True` the task is an abstract base class.
abstract = True
#: If disabled the worker will not forward magic keyword arguments.
#: Deprecated and scheduled for removal in v4.0.
accept_magic_kwargs = False
#: Maximum number of retries before giving up. If set to :const:`None`,
#: it will **never** stop retrying.
max_retries = 3
#: Default time in seconds before a retry of the task should be
#: executed. 3 minutes by default.
default_retry_delay = 3 * 60
#: Rate limit for this task type. Examples: :const:`None` (no rate
#: limit), `'100/s'` (hundred tasks a second), `'100/m'` (hundred tasks
#: a minute),`'100/h'` (hundred tasks an hour)
rate_limit = None
#: If enabled the worker will not store task state and return values
#: for this task. Defaults to the :setting:`CELERY_IGNORE_RESULT`
#: setting.
ignore_result = None
#: When enabled errors will be stored even if the task is otherwise
#: configured to ignore results.
store_errors_even_if_ignored = None
#: If enabled an email will be sent to :setting:`ADMINS` whenever a task
#: of this type fails.
send_error_emails = None
#: The name of a serializer that are registered with
#: :mod:`kombu.serialization.registry`. Default is `'pickle'`.
serializer = None
#: Hard time limit.
#: Defaults to the :setting:`CELERYD_TASK_TIME_LIMIT` setting.
time_limit = None
#: Soft time limit.
#: Defaults to the :setting:`CELERYD_TASK_SOFT_TIME_LIMIT` setting.
soft_time_limit = None
#: The result store backend used for this task.
backend = None
#: If disabled this task won't be registered automatically.
autoregister = True
#: If enabled the task will report its status as 'started' when the task
#: is executed by a worker. Disabled by default as the normal behaviour
#: is to not report that level of granularity. Tasks are either pending,
#: finished, or waiting to be retried.
#:
#: Having a 'started' status can be useful for when there are long
#: running tasks and there is a need to report which task is currently
#: running.
#:
#: The application default can be overridden using the
#: :setting:`CELERY_TRACK_STARTED` setting.
track_started = None
#: When enabled messages for this task will be acknowledged **after**
#: the task has been executed, and not *just before* which is the
#: default behavior.
#:
#: Please note that this means the task may be executed twice if the
#: worker crashes mid execution (which may be acceptable for some
#: applications).
#:
#: The application default can be overridden with the
#: :setting:`CELERY_ACKS_LATE` setting.
acks_late = None
#: Default task expiry time.
expires = None
#: Some may expect a request to exist even if the task has not been
#: called. This should probably be deprecated.
_default_request = None
__bound__ = False
from_config = (
('send_error_emails', 'CELERY_SEND_TASK_ERROR_EMAILS'),
('serializer', 'CELERY_TASK_SERIALIZER'),
('rate_limit', 'CELERY_DEFAULT_RATE_LIMIT'),
('track_started', 'CELERY_TRACK_STARTED'),
('acks_late', 'CELERY_ACKS_LATE'),
('ignore_result', 'CELERY_IGNORE_RESULT'),
('store_errors_even_if_ignored',
'CELERY_STORE_ERRORS_EVEN_IF_IGNORED'),
)
__bound__ = False
# - Tasks are lazily bound, so that configuration is not set
# - until the task is actually used
@classmethod
def bind(self, app):
was_bound, self.__bound__ = self.__bound__, True
self._app = app
conf = app.conf
for attr_name, config_name in self.from_config:
if getattr(self, attr_name, None) is None:
setattr(self, attr_name, conf[config_name])
if self.accept_magic_kwargs is None:
self.accept_magic_kwargs = app.accept_magic_kwargs
if self.backend is None:
self.backend = app.backend
# decorate with annotations from config.
if not was_bound:
self.annotate()
from celery.utils.threads import LocalStack
self.request_stack = LocalStack()
# PeriodicTask uses this to add itself to the PeriodicTask schedule.
self.on_bound(app)
return app
@classmethod
def on_bound(self, app):
"""This method can be defined to do additional actions when the
task class is bound to an app."""
pass
@classmethod
def _get_app(self):
if not self.__bound__ or self._app is None:
# The app property's __set__ method is not called
# if Task.app is set (on the class), so must bind on use.
self.bind(current_app)
return self._app
app = class_property(_get_app, bind)
@classmethod
def annotate(self):
for d in resolve_all_annotations(self.app.annotations, self):
for key, value in d.iteritems():
if key.startswith('@'):
self.add_around(key[1:], value)
else:
setattr(self, key, value)
@classmethod
def add_around(self, attr, around):
orig = getattr(self, attr)
if getattr(orig, '__wrapped__', None):
orig = orig.__wrapped__
meth = around(orig)
meth.__wrapped__ = orig
setattr(self, attr, meth)
def __call__(self, *args, **kwargs):
_task_stack.push(self)
self.push_request()
try:
# add self if this is a bound task
if self.__self__ is not None:
return self.run(self.__self__, *args, **kwargs)
return self.run(*args, **kwargs)
finally:
self.pop_request()
_task_stack.pop()
# - tasks are pickled into the name of the task only, and the reciever
# - simply grabs it from the local registry.
def __reduce__(self):
return (_unpickle_task, (self.name, ), None)
def run(self, *args, **kwargs):
"""The body of the task executed by workers."""
raise NotImplementedError('Tasks must define the run method.')
def start_strategy(self, app, consumer):
return instantiate(self.Strategy, self, app, consumer)
def delay(self, *args, **kwargs):
"""Star argument version of :meth:`apply_async`.
Does not support the extra options enabled by :meth:`apply_async`.
:param \*args: positional arguments passed on to the task.
:param \*\*kwargs: keyword arguments passed on to the task.
:returns :class:`celery.result.AsyncResult`:
"""
return self.apply_async(args, kwargs)
def apply_async(self,
args=None,
kwargs=None,
task_id=None,
producer=None,
connection=None,
router=None,
link=None,
link_error=None,
publisher=None,
add_to_parent=True,
**options):
"""Apply tasks asynchronously by sending a message.
:keyword args: The positional arguments to pass on to the
task (a :class:`list` or :class:`tuple`).
:keyword kwargs: The keyword arguments to pass on to the
task (a :class:`dict`)
:keyword countdown: Number of seconds into the future that the
task should execute. Defaults to immediate
execution (do not confuse with the
`immediate` flag, as they are unrelated).
:keyword eta: A :class:`~datetime.datetime` object describing
the absolute time and date of when the task should
be executed. May not be specified if `countdown`
is also supplied. (Do not confuse this with the
`immediate` flag, as they are unrelated).
:keyword expires: Either a :class:`int`, describing the number of
seconds, or a :class:`~datetime.datetime` object
that describes the absolute time and date of when
the task should expire. The task will not be
executed after the expiration time.
:keyword connection: Re-use existing broker connection instead
of establishing a new one.
:keyword retry: If enabled sending of the task message will be retried
in the event of connection loss or failure. Default
is taken from the :setting:`CELERY_TASK_PUBLISH_RETRY`
setting. Note you need to handle the
producer/connection manually for this to work.
:keyword retry_policy: Override the retry policy used. See the
:setting:`CELERY_TASK_PUBLISH_RETRY` setting.
:keyword routing_key: Custom routing key used to route the task to a
worker server. If in combination with a
``queue`` argument only used to specify custom
routing keys to topic exchanges.
:keyword queue: The queue to route the task to. This must be a key
present in :setting:`CELERY_QUEUES`, or
:setting:`CELERY_CREATE_MISSING_QUEUES` must be
enabled. See :ref:`guide-routing` for more
information.
:keyword exchange: Named custom exchange to send the task to.
Usually not used in combination with the ``queue``
argument.
:keyword priority: The task priority, a number between 0 and 9.
Defaults to the :attr:`priority` attribute.
:keyword serializer: A string identifying the default
serialization method to use. Can be `pickle`,
`json`, `yaml`, `msgpack` or any custom
serialization method that has been registered
with :mod:`kombu.serialization.registry`.
Defaults to the :attr:`serializer` attribute.
:keyword compression: A string identifying the compression method
to use. Can be one of ``zlib``, ``bzip2``,
or any custom compression methods registered with
:func:`kombu.compression.register`. Defaults to
the :setting:`CELERY_MESSAGE_COMPRESSION`
setting.
:keyword link: A single, or a list of subtasks to apply if the
task exits successfully.
:keyword link_error: A single, or a list of subtasks to apply
if an error occurs while executing the task.
:keyword producer: :class:[email protected]` instance to use.
:keyword add_to_parent: If set to True (default) and the task
is applied while executing another task, then the result
will be appended to the parent tasks ``request.children``
attribute.
:keyword publisher: Deprecated alias to ``producer``.
Also supports all keyword arguments supported by
:meth:`kombu.messaging.Producer.publish`.
.. note::
If the :setting:`CELERY_ALWAYS_EAGER` setting is set, it will
be replaced by a local :func:`apply` call instead.
"""
producer = producer or publisher
app = self._get_app()
router = router or self.app.amqp.router
conf = app.conf
# add 'self' if this is a bound method.
if self.__self__ is not None:
args = (self.__self__, ) + tuple(args)
if conf.CELERY_ALWAYS_EAGER:
return self.apply(args,
kwargs,
task_id=task_id,
link=link,
link_error=link_error,
**options)
options = dict(extract_exec_options(self), **options)
options = router.route(options, self.name, args, kwargs)
if connection:
producer = app.amqp.TaskProducer(connection)
with app.producer_or_acquire(producer) as P:
task_id = P.publish_task(self.name,
args,
kwargs,
task_id=task_id,
callbacks=maybe_list(link),
errbacks=maybe_list(link_error),
**options)
result = self.AsyncResult(task_id)
if add_to_parent:
parent = get_current_worker_task()
if parent:
parent.request.children.append(result)
return result
def subtask_from_request(self,
request=None,
args=None,
kwargs=None,
**extra_options):
request = self.request if request is None else request
args = request.args if args is None else args
kwargs = request.kwargs if kwargs is None else kwargs
delivery_info = request.delivery_info or {}
options = {
'task_id': request.id,
'link': request.callbacks,
'link_error': request.errbacks,
'exchange': delivery_info.get('exchange'),
'routing_key': delivery_info.get('routing_key')
}
return self.subtask(args, kwargs, options, type=self, **extra_options)
def retry(self,
args=None,
kwargs=None,
exc=None,
throw=True,
eta=None,
countdown=None,
max_retries=None,
**options):
"""Retry the task.
:param args: Positional arguments to retry with.
:param kwargs: Keyword arguments to retry with.
:keyword exc: Custom exception to report when the max restart
limit has been exceeded (default:
:exc:`~celery.exceptions.MaxRetriesExceededError`).
If this argument is set and retry is called while
an exception was raised (``sys.exc_info()`` is set)
it will attempt to reraise the current exception.
If no exception was raised it will raise the ``exc``
argument provided.
:keyword countdown: Time in seconds to delay the retry for.
:keyword eta: Explicit time and date to run the retry at
(must be a :class:`~datetime.datetime` instance).
:keyword max_retries: If set, overrides the default retry limit.
:keyword \*\*options: Any extra options to pass on to
meth:`apply_async`.
:keyword throw: If this is :const:`False`, do not raise the
:exc:`~celery.exceptions.RetryTaskError` exception,
that tells the worker to mark the task as being
retried. Note that this means the task will be
marked as failed if the task raises an exception,
or successful if it returns.
:raises celery.exceptions.RetryTaskError: To tell the worker that
the task has been re-sent for retry. This always happens,
unless the `throw` keyword argument has been explicitly set
to :const:`False`, and is considered normal operation.
**Example**
.. code-block:: python
>>> @task()
>>> def tweet(auth, message):
... twitter = Twitter(oauth=auth)
... try:
... twitter.post_status_update(message)
... except twitter.FailWhale, exc:
... # Retry in 5 minutes.
... raise tweet.retry(countdown=60 * 5, exc=exc)
Although the task will never return above as `retry` raises an
exception to notify the worker, we use `return` in front of the retry
to convey that the rest of the block will not be executed.
"""
request = self.request
retries = request.retries + 1
max_retries = self.max_retries if max_retries is None else max_retries
# Not in worker or emulated by (apply/always_eager),
# so just raise the original exception.
if request.called_directly:
maybe_reraise() # raise orig stack if PyErr_Occurred
raise exc or RetryTaskError('Task can be retried', None)
if not eta and countdown is None:
countdown = self.default_retry_delay
S = self.subtask_from_request(request,
args,
kwargs,
countdown=countdown,
eta=eta,
retries=retries,
**options)
if max_retries is not None and retries > max_retries:
if exc:
maybe_reraise()
raise self.MaxRetriesExceededError(
"""Can't retry %s[%s] args:%s kwargs:%s""" %
(self.name, request.id, S.args, S.kwargs))
# If task was executed eagerly using apply(),
# then the retry must also be executed eagerly.
S.apply().get() if request.is_eager else S.apply_async()
ret = RetryTaskError(exc=exc, when=eta or countdown)
if throw:
raise ret
return ret
def apply(self,
args=None,
kwargs=None,
link=None,
link_error=None,
**options):
"""Execute this task locally, by blocking until the task returns.
:param args: positional arguments passed on to the task.
:param kwargs: keyword arguments passed on to the task.
:keyword throw: Re-raise task exceptions. Defaults to
the :setting:`CELERY_EAGER_PROPAGATES_EXCEPTIONS`
setting.
:rtype :class:`celery.result.EagerResult`:
"""
# trace imports Task, so need to import inline.
from celery.task.trace import eager_trace_task
app = self._get_app()
args = args or ()
# add 'self' if this is a bound method.
if self.__self__ is not None:
args = (self.__self__, ) + tuple(args)
kwargs = kwargs or {}
task_id = options.get('task_id') or uuid()
retries = options.get('retries', 0)
throw = app.either('CELERY_EAGER_PROPAGATES_EXCEPTIONS',
options.pop('throw', None))
# Make sure we get the task instance, not class.
task = app._tasks[self.name]
request = {
'id': task_id,
'retries': retries,
'is_eager': True,
'logfile': options.get('logfile'),
'loglevel': options.get('loglevel', 0),
'callbacks': maybe_list(link),
'errbacks': maybe_list(link_error),
'delivery_info': {
'is_eager': True
}
}
if self.accept_magic_kwargs:
default_kwargs = {
'task_name': task.name,
'task_id': task_id,
'task_retries': retries,
'task_is_eager': True,
'logfile': options.get('logfile'),
'loglevel': options.get('loglevel', 0),
'delivery_info': {
'is_eager': True
}
}
supported_keys = fun_takes_kwargs(task.run, default_kwargs)
extend_with = dict((key, val)
for key, val in default_kwargs.items()
if key in supported_keys)
kwargs.update(extend_with)
tb = None
retval, info = eager_trace_task(task,
task_id,
args,
kwargs,
request=request,
propagate=throw)
if isinstance(retval, ExceptionInfo):
retval, tb = retval.exception, retval.traceback
state = states.SUCCESS if info is None else info.state
return EagerResult(task_id, retval, state, traceback=tb)
def AsyncResult(self, task_id, **kwargs):
"""Get AsyncResult instance for this kind of task.
:param task_id: Task id to get result for.
"""
return self._get_app().AsyncResult(task_id,
backend=self.backend,
task_name=self.name,
**kwargs)
def subtask(self, args=None, *starargs, **starkwargs):
"""Returns :class:`~celery.subtask` object for
this task, wrapping arguments and execution options
for a single task invocation."""
return subtask(self, args, *starargs, **starkwargs)
def s(self, *args, **kwargs):
"""``.s(*a, **k) -> .subtask(a, k)``"""
return self.subtask(args, kwargs)
def si(self, *args, **kwargs):
"""``.si(*a, **k) -> .subtask(a, k, immutable=True)``"""
return self.subtask(args, kwargs, immutable=True)
def chunks(self, it, n):
"""Creates a :class:`~celery.canvas.chunks` task for this task."""
from celery import chunks
return chunks(self.s(), it, n)
def map(self, it):
"""Creates a :class:`~celery.canvas.xmap` task from ``it``."""
from celery import xmap
return xmap(self.s(), it)
def starmap(self, it):
"""Creates a :class:`~celery.canvas.xstarmap` task from ``it``."""
from celery import xstarmap
return xstarmap(self.s(), it)
def update_state(self, task_id=None, state=None, meta=None):
"""Update task state.
:keyword task_id: Id of the task to update, defaults to the
id of the current task
:keyword state: New state (:class:`str`).
:keyword meta: State metadata (:class:`dict`).
"""
if task_id is None:
task_id = self.request.id
self.backend.store_result(task_id, meta, state)
def on_success(self, retval, task_id, args, kwargs):
"""Success handler.
Run by the worker if the task executes successfully.
:param retval: The return value of the task.
:param task_id: Unique id of the executed task.
:param args: Original arguments for the executed task.
:param kwargs: Original keyword arguments for the executed task.
The return value of this handler is ignored.
"""
pass
def on_retry(self, exc, task_id, args, kwargs, einfo):
"""Retry handler.
This is run by the worker when the task is to be retried.
:param exc: The exception sent to :meth:`retry`.
:param task_id: Unique id of the retried task.
:param args: Original arguments for the retried task.
:param kwargs: Original keyword arguments for the retried task.
:keyword einfo: :class:`~celery.datastructures.ExceptionInfo`
instance, containing the traceback.
The return value of this handler is ignored.
"""
pass
def on_failure(self, exc, task_id, args, kwargs, einfo):
"""Error handler.
This is run by the worker when the task fails.
:param exc: The exception raised by the task.
:param task_id: Unique id of the failed task.
:param args: Original arguments for the task that failed.
:param kwargs: Original keyword arguments for the task
that failed.
:keyword einfo: :class:`~celery.datastructures.ExceptionInfo`
instance, containing the traceback.
The return value of this handler is ignored.
"""
pass
def after_return(self, status, retval, task_id, args, kwargs, einfo):
"""Handler called after the task returns.
:param status: Current task state.
:param retval: Task return value/exception.
:param task_id: Unique id of the task.
:param args: Original arguments for the task that failed.
:param kwargs: Original keyword arguments for the task
that failed.
:keyword einfo: :class:`~celery.datastructures.ExceptionInfo`
instance, containing the traceback (if any).
The return value of this handler is ignored.
"""
pass
def send_error_email(self, context, exc, **kwargs):
if self.send_error_emails and \
not getattr(self, 'disable_error_emails', None):
self.ErrorMail(self, **kwargs).send(context, exc)
def push_request(self, *args, **kwargs):
self.request_stack.push(Context(*args, **kwargs))
def pop_request(self):
self.request_stack.pop()
def __repr__(self):
"""`repr(task)`"""
if self.__self__:
return '<bound task %s of %r>' % (self.name, self.__self__)
return '<@task: %s>' % (self.name, )
def _get_request(self):
"""Get current request object."""
req = self.request_stack.top
if req is None:
# task was not called, but some may still expect a request
# to be there, perhaps that should be deprecated.
if self._default_request is None:
self._default_request = Context()
return self._default_request
return req
request = property(_get_request)
@property
def __name__(self):
return self.__class__.__name__
class Task(BaseTask):
"""Deprecated Task base class.
Modern applications should use :class:`celery.Task` instead.
"""
abstract = True
__bound__ = False
#- Deprecated compat. attributes -:
queue = None
routing_key = None
exchange = None
exchange_type = None
delivery_mode = None
mandatory = False
immediate = False
priority = None
type = "regular"
error_whitelist = ()
disable_error_emails = False
from_config = BaseTask.from_config + (
("exchange_type", "CELERY_DEFAULT_EXCHANGE_TYPE"),
("delivery_mode", "CELERY_DEFAULT_DELIVERY_MODE"),
("error_whitelist", "CELERY_TASK_ERROR_WHITELIST"),
)
# In old Celery the @task decorator didn't exist, so one would create
# classes instead and use them directly (e.g. MyTask.apply_async()).
# the use of classmethods was a hack so that it was not necessary
# to instantiate the class before using it, but it has only
# given us pain (like all magic).
for name in _COMPAT_CLASSMETHODS:
locals()[name] = reclassmethod(getattr(BaseTask, name))
@classmethod
def _get_request(self):
return self.request_stack.top
request = class_property(_get_request)
#: Deprecated alias to :attr:`logger``.
get_logger = reclassmethod(BaseTask._get_logger)
@classmethod
def establish_connection(self, connect_timeout=None):
"""Deprecated method used to get a broker connection.
Should be replaced with :meth:`@Celery.broker_connection`
instead, or by acquiring connections from the connection pool:
.. code-block:: python
# using the connection pool
with celery.pool.acquire(block=True) as conn:
...
# establish fresh connection
with celery.broker_connection() as conn:
...
"""
return self._get_app().broker_connection(
connect_timeout=connect_timeout)
def get_publisher(self,
connection=None,
exchange=None,
connect_timeout=None,
exchange_type=None,
**options):
"""Deprecated method to get the task publisher (now called producer).
Should be replaced with :class:`@amqp.TaskProducer`:
.. code-block:: python
with celery.broker_connection() as conn:
with celery.amqp.TaskProducer(conn) as prod:
my_task.apply_async(producer=prod)
"""
exchange = self.exchange if exchange is None else exchange
if exchange_type is None:
exchange_type = self.exchange_type
connection = connection or self.establish_connection(connect_timeout)
return self._get_app().amqp.TaskProducer(
connection,
exchange=exchange and Exchange(exchange, exchange_type),
routing_key=self.routing_key,
**options)
@classmethod
def get_consumer(self, connection=None, queues=None, **kwargs):
"""Deprecated method used to get consumer for the queue
this task is sent to.
Should be replaced with :class:`@amqp.TaskConsumer` instead:
"""
Q = self._get_app().amqp
connection = connection or self.establish_connection()
if queues is None:
queues = Q.queues[self.queue] if self.queue else Q.default_queue
return Q.TaskConsumer(connection, queues, **kwargs)