# -*- coding: utf-8 -*-
#
# 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 airflow.models.taskinstance import TaskInstance
from airflow.utils import timezone
from airflow.utils.db import provide_session
from airflow.utils.log.logging_mixin import LoggingMixin
from airflow.utils.state import State
import six
from typing import Union, Iterable, Set
class SkipMixin(LoggingMixin):
@provide_session
def skip(self, dag_run, execution_date, tasks, session=None):
"""
Sets tasks instances to skipped from the same dag run.
:param dag_run: the DagRun for which to set the tasks to skipped
:param execution_date: execution_date
:param tasks: tasks to skip (not task_ids)
:param session: db session to use
"""
if not tasks:
return
task_ids = [d.task_id for d in tasks]
now = timezone.utcnow()
if dag_run:
session.query(TaskInstance).filter(
TaskInstance.dag_id == dag_run.dag_id,
TaskInstance.execution_date == dag_run.execution_date,
TaskInstance.task_id.in_(task_ids)
).update({TaskInstance.state: State.SKIPPED,
TaskInstance.start_date: now,
TaskInstance.end_date: now},
synchronize_session=False)
session.commit()
else:
assert execution_date is not None, "Execution date is None and no dag run"
self.log.warning("No DAG RUN present this should not happen")
# this is defensive against dag runs that are not complete
for task in tasks:
ti = TaskInstance(task, execution_date=execution_date)
ti.state = State.SKIPPED
ti.start_date = now
ti.end_date = now
session.merge(ti)
session.commit()
def skip_all_except(self, ti, branch_task_ids):
# type: (TaskInstance, Union[str, Iterable[str]]) -> None
"""
This method implements the logic for a branching operator; given a single
task ID or list of task IDs to follow, this skips all other tasks
immediately downstream of this operator.
"""
self.log.info("Following branch %s", branch_task_ids)
if isinstance(branch_task_ids, six.string_types):
branch_task_ids = [branch_task_ids]
dag_run = ti.get_dagrun()
task = ti.task
dag = task.dag
downstream_tasks = task.downstream_list
if downstream_tasks:
# Also check downstream tasks of the branch task. In case the task to skip
# is also a downstream task of the branch task, we exclude it from skipping.
branch_downstream_task_ids = set() # type: Set[str]
for b in branch_task_ids:
branch_downstream_task_ids.update(dag.
get_task(b).
get_flat_relative_ids(upstream=False))
skip_tasks = [t for t in downstream_tasks
if t.task_id not in branch_task_ids and
t.task_id not in branch_downstream_task_ids]
self.log.info("Skipping tasks %s", [t.task_id for t in skip_tasks])
self.skip(dag_run, ti.execution_date, skip_tasks)