| # |
| # 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. |
| |
| import warnings |
| from typing import TYPE_CHECKING, Iterable, List, Optional, Sequence, Union, cast |
| |
| from airflow.models.taskinstance import TaskInstance |
| from airflow.utils import timezone |
| from airflow.utils.log.logging_mixin import LoggingMixin |
| from airflow.utils.session import NEW_SESSION, create_session, provide_session |
| from airflow.utils.state import State |
| |
| if TYPE_CHECKING: |
| from pendulum import DateTime |
| from sqlalchemy import Session |
| |
| from airflow.models.baseoperator import BaseOperator |
| from airflow.models.dagrun import DagRun |
| |
| # The key used by SkipMixin to store XCom data. |
| XCOM_SKIPMIXIN_KEY = "skipmixin_key" |
| |
| # The dictionary key used to denote task IDs that are skipped |
| XCOM_SKIPMIXIN_SKIPPED = "skipped" |
| |
| # The dictionary key used to denote task IDs that are followed |
| XCOM_SKIPMIXIN_FOLLOWED = "followed" |
| |
| |
| class SkipMixin(LoggingMixin): |
| """A Mixin to skip Tasks Instances""" |
| |
| def _set_state_to_skipped(self, dag_run: "DagRun", tasks: "Iterable[BaseOperator]", session: "Session"): |
| """Used internally to set state of task instances to skipped from the same dag run.""" |
| task_ids = [d.task_id for d in tasks] |
| now = timezone.utcnow() |
| |
| session.query(TaskInstance).filter( |
| TaskInstance.dag_id == dag_run.dag_id, |
| TaskInstance.run_id == dag_run.run_id, |
| TaskInstance.task_id.in_(task_ids), |
| ).update( |
| { |
| TaskInstance.state: State.SKIPPED, |
| TaskInstance.start_date: now, |
| TaskInstance.end_date: now, |
| }, |
| synchronize_session=False, |
| ) |
| |
| @provide_session |
| def skip( |
| self, |
| dag_run: "DagRun", |
| execution_date: "DateTime", |
| tasks: Sequence["BaseOperator"], |
| session: "Session" = NEW_SESSION, |
| ): |
| """ |
| Sets tasks instances to skipped from the same dag run. |
| |
| If this instance has a `task_id` attribute, store the list of skipped task IDs to XCom |
| so that NotPreviouslySkippedDep knows these tasks should be skipped when they |
| are cleared. |
| |
| :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 |
| |
| if execution_date and not dag_run: |
| from airflow.models.dagrun import DagRun |
| |
| warnings.warn( |
| "Passing an execution_date to `skip()` is deprecated in favour of passing a dag_run", |
| DeprecationWarning, |
| stacklevel=2, |
| ) |
| |
| dag_run = ( |
| session.query(DagRun) |
| .filter( |
| DagRun.dag_id == tasks[0].dag_id, |
| DagRun.execution_date == execution_date, |
| ) |
| .one() |
| ) |
| elif execution_date and dag_run and execution_date != dag_run.execution_date: |
| raise ValueError( |
| "execution_date has a different value to dag_run.execution_date -- please only pass dag_run" |
| ) |
| |
| if dag_run is None: |
| raise ValueError("dag_run is required") |
| |
| self._set_state_to_skipped(dag_run, tasks, session) |
| session.commit() |
| |
| # SkipMixin may not necessarily have a task_id attribute. Only store to XCom if one is available. |
| task_id: Optional[str] = getattr(self, "task_id", None) |
| if task_id is not None: |
| from airflow.models.xcom import XCom |
| |
| XCom.set( |
| key=XCOM_SKIPMIXIN_KEY, |
| value={XCOM_SKIPMIXIN_SKIPPED: [d.task_id for d in tasks]}, |
| task_id=task_id, |
| dag_id=dag_run.dag_id, |
| run_id=dag_run.run_id, |
| session=session, |
| ) |
| |
| def skip_all_except(self, ti: TaskInstance, branch_task_ids: Union[None, str, Iterable[str]]): |
| """ |
| 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. |
| |
| branch_task_ids is stored to XCom so that NotPreviouslySkippedDep knows skipped tasks or |
| newly added tasks should be skipped when they are cleared. |
| """ |
| self.log.info("Following branch %s", branch_task_ids) |
| if isinstance(branch_task_ids, str): |
| branch_task_ids = {branch_task_ids} |
| elif branch_task_ids is None: |
| branch_task_ids = () |
| |
| branch_task_ids = set(branch_task_ids) |
| |
| dag_run = ti.get_dagrun() |
| task = ti.task |
| dag = task.dag |
| if TYPE_CHECKING: |
| assert dag |
| |
| # At runtime, the downstream list will only be operators |
| downstream_tasks = cast("List[BaseOperator]", task.downstream_list) |
| |
| if downstream_tasks: |
| # For a branching workflow that looks like this, when "branch" does skip_all_except("task1"), |
| # we intuitively expect both "task1" and "join" to execute even though strictly speaking, |
| # "join" is also immediately downstream of "branch" and should have been skipped. Therefore, |
| # we need a special case here for such empty branches: Check downstream tasks of branch_task_ids. |
| # In case the task to skip is also downstream of branch_task_ids, we add it to branch_task_ids and |
| # exclude it from skipping. |
| # |
| # branch -----> join |
| # \ ^ |
| # v / |
| # task1 |
| # |
| for branch_task_id in list(branch_task_ids): |
| branch_task_ids.update(dag.get_task(branch_task_id).get_flat_relative_ids(upstream=False)) |
| |
| skip_tasks = [t for t in downstream_tasks if t.task_id not in branch_task_ids] |
| follow_task_ids = [t.task_id for t in downstream_tasks if t.task_id in branch_task_ids] |
| |
| self.log.info("Skipping tasks %s", [t.task_id for t in skip_tasks]) |
| with create_session() as session: |
| self._set_state_to_skipped(dag_run, skip_tasks, session=session) |
| # For some reason, session.commit() needs to happen before xcom_push. |
| # Otherwise the session is not committed. |
| session.commit() |
| ti.xcom_push(key=XCOM_SKIPMIXIN_KEY, value={XCOM_SKIPMIXIN_FOLLOWED: follow_task_ids}) |