potiuk commented on a change in pull request #6950: [AIRFLOW-6392] Remove
cyclic dependency baseoperator <-> helpers
URL: https://github.com/apache/airflow/pull/6950#discussion_r361906152
##########
File path: airflow/utils/helpers.py
##########
@@ -142,83 +135,6 @@ def as_flattened_list(iterable):
return [e for i in iterable for e in i]
-def chain(*tasks):
- r"""
- Given a number of tasks, builds a dependency chain.
- Support mix airflow.models.BaseOperator and
List[airflow.models.BaseOperator].
- If you want to chain between two List[airflow.models.BaseOperator], have to
- make sure they have same length.
-
- chain(t1, [t2, t3], [t4, t5], t6)
-
- is equivalent to
-
- / -> t2 -> t4 \
- t1 -> t6
- \ -> t3 -> t5 /
-
- t1.set_downstream(t2)
- t1.set_downstream(t3)
- t2.set_downstream(t4)
- t3.set_downstream(t5)
- t4.set_downstream(t6)
- t5.set_downstream(t6)
-
- :param tasks: List of tasks or List[airflow.models.BaseOperator] to set
dependencies
- :type tasks: List[airflow.models.BaseOperator] or
airflow.models.BaseOperator
- """
- from airflow.models.baseoperator import BaseOperator
- for index, up_task in enumerate(tasks[:-1]):
- down_task = tasks[index + 1]
- if isinstance(up_task, BaseOperator):
- up_task.set_downstream(down_task)
- elif isinstance(down_task, BaseOperator):
- down_task.set_upstream(up_task)
- else:
- if not isinstance(up_task, Iterable) or not isinstance(down_task,
Iterable):
- raise TypeError(
- 'Chain not supported between instances of {up_type} and
{down_type}'.format(
- up_type=type(up_task), down_type=type(down_task)))
- elif len(up_task) != len(down_task):
- raise AirflowException(
- 'Chain not supported different length Iterable but get
{up_len} and {down_len}'.format(
- up_len=len(up_task), down_len=len(down_task)))
- else:
- for up, down in zip(up_task, down_task):
- up.set_downstream(down)
-
-
-def cross_downstream(from_tasks, to_tasks):
- r"""
- Set downstream dependencies for all tasks in from_tasks to all tasks in
to_tasks.
- E.g.: cross_downstream(from_tasks=[t1, t2, t3], to_tasks=[t4, t5, t6])
- Is equivalent to:
-
- t1 --> t4
- \ /
- t2 -X> t5
- / \
- t3 --> t6
-
- t1.set_downstream(t4)
- t1.set_downstream(t5)
- t1.set_downstream(t6)
- t2.set_downstream(t4)
- t2.set_downstream(t5)
- t2.set_downstream(t6)
- t3.set_downstream(t4)
- t3.set_downstream(t5)
- t3.set_downstream(t6)
-
- :param from_tasks: List of tasks to start from.
- :type from_tasks: List[airflow.models.BaseOperator]
- :param to_tasks: List of tasks to set as downstream dependencies.
- :type to_tasks: List[airflow.models.BaseOperator]
- """
- for task in from_tasks:
- task.set_downstream(to_tasks)
-
-
def pprinttable(rows):
Review comment:
It's unrelated :)
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