Source code for airflow.models.skipmixin

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from typing import Iterable, Union

from airflow.models.taskinstance import TaskInstance
from airflow.utils import timezone
from airflow.utils.log.logging_mixin import LoggingMixin
from airflow.utils.session import create_session, provide_session
from airflow.utils.state import State

# The key used by SkipMixin to store XCom data.
[docs]XCOM_SKIPMIXIN_KEY = "skipmixin_key"
# The dictionary key used to denote task IDs that are skipped
[docs]XCOM_SKIPMIXIN_SKIPPED = "skipped"
# The dictionary key used to denote task IDs that are followed
[docs]XCOM_SKIPMIXIN_FOLLOWED = "followed"
[docs]class SkipMixin(LoggingMixin): """A Mixin to skip Tasks Instances"""
[docs] def _set_state_to_skipped(self, dag_run, execution_date, tasks, 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() 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, ) else: if execution_date is None: raise ValueError("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)
[docs] def skip( self, dag_run, execution_date, tasks, session=None, ): """ 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 self._set_state_to_skipped(dag_run, execution_date, tasks, session) session.commit() # SkipMixin may not necessarily have a task_id attribute. Only store to XCom if one is available. try: task_id = self.task_id except AttributeError: 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, execution_date=dag_run.execution_date, session=session,
[docs] def skip_all_except(self, ti: TaskInstance, branch_task_ids: Union[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. """"Following branch %s", branch_task_ids) if isinstance(branch_task_ids, str): branch_task_ids = {branch_task_ids} branch_task_ids = set(branch_task_ids) dag_run = ti.get_dagrun() task = ti.task dag = task.dag downstream_tasks = 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]"Skipping tasks %s", [t.task_id for t in skip_tasks]) with create_session() as session: self._set_state_to_skipped(dag_run, ti.execution_date, 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})

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