Source code for airflow.providers.celery.sensors.celery_queue
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from __future__ import annotations
from typing import TYPE_CHECKING
from celery.app import control
from airflow.sensors.base import BaseSensorOperator
if TYPE_CHECKING:
from airflow.utils.context import Context
[docs]class CeleryQueueSensor(BaseSensorOperator):
"""
Waits for a Celery queue to be empty.
By default, in order to be considered empty, the queue must not have
any tasks in the ``reserved``, ``scheduled`` or ``active`` states.
:param celery_queue: The name of the Celery queue to wait for.
:param target_task_id: Task id for checking
"""
def __init__(self, *, celery_queue: str, target_task_id: str | None = None, **kwargs) -> None:
super().__init__(**kwargs)
self.celery_queue = celery_queue
self.target_task_id = target_task_id
def _check_task_id(self, context: Context) -> bool:
"""
Get the Celery result from the Airflow task ID and return True if the result has finished execution.
:param context: Airflow's execution context
:return: True if task has been executed, otherwise False
"""
ti = context["ti"]
celery_result = ti.xcom_pull(task_ids=self.target_task_id)
return celery_result.ready()
[docs] def poke(self, context: Context) -> bool:
if self.target_task_id:
return self._check_task_id(context)
inspect_result = control.Inspect()
reserved = inspect_result.reserved()
scheduled = inspect_result.scheduled()
active = inspect_result.active()
try:
reserved = len(reserved[self.celery_queue])
scheduled = len(scheduled[self.celery_queue])
active = len(active[self.celery_queue])
self.log.info("Checking if celery queue %s is empty.", self.celery_queue)
return reserved == 0 and scheduled == 0 and active == 0
except KeyError:
message = f"Could not locate Celery queue {self.celery_queue}"
raise KeyError(message)