text: #
  # Licensed to the Apache Software Foundation (ASF) under one
  # or more contributor license agreements.  See the NOTICE file
  # distributed with this work for additional information
  # regarding copyright ownership.  The ASF licenses this file
  # to you under the Apache License, Version 2.0 (the
  # "License"); you may not use this file except in compliance
  # with the License.  You may obtain a copy of the License at
  #
  #   http://www.apache.org/licenses/LICENSE-2.0
  #
  # Unless required by applicable law or agreed to in writing,
  # software distributed under the License is distributed on an
  # "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
  # KIND, either express or implied.  See the License for the
  # specific language governing permissions and limitations
  # under the License.
  
  from typing import TYPE_CHECKING, Optional
  
  from celery.app import control
  
  from airflow.sensors.base import BaseSensorOperator
  
  if TYPE_CHECKING:
      from airflow.utils.context import Context
  
  
  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.
      :type celery_queue: str
      :param target_task_id: Task id for checking
      :type target_task_id: str
      """
  
      def __init__(self, *, celery_queue: str, target_task_id: Optional[str] = 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:
          """
          Gets the returned Celery result from the Airflow task
          ID provided to the sensor, and returns True if the
          celery result has been finished execution.
  
          :param context: Airflow's execution context
          :type context: dict
          :return: True if task has been executed, otherwise False
          :rtype: bool
          """
          ti = context['ti']
          celery_result = ti.xcom_pull(task_ids=self.target_task_id)
          return celery_result.ready()
  
      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:
              raise KeyError(f'Could not locate Celery queue {self.celery_queue}')
  