Source code for airflow.models.taskmixin
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from abc import abstractmethod
from typing import Sequence, Union
[docs]class TaskMixin:
"""
Mixing implementing common chain methods like >> and <<.
In the following functions we use:
Task = Union[BaseOperator, XComArg]
No type annotations due to cyclic imports.
"""
@property
[docs] def roots(self):
"""Should return list of root operator List[BaseOperator]"""
raise NotImplementedError()
@property
[docs] def leaves(self):
"""Should return list of leaf operator List[BaseOperator]"""
raise NotImplementedError()
@abstractmethod
[docs] def set_upstream(self, other: Union["TaskMixin", Sequence["TaskMixin"]]):
"""Set a task or a task list to be directly upstream from the current task."""
raise NotImplementedError()
@abstractmethod
[docs] def set_downstream(self, other: Union["TaskMixin", Sequence["TaskMixin"]]):
"""Set a task or a task list to be directly downstream from the current task."""
raise NotImplementedError()
[docs] def update_relative(self, other: "TaskMixin", upstream=True) -> None:
"""
Update relationship information about another TaskMixin. Default is no-op.
Override if necessary.
"""
[docs] def __lshift__(self, other: Union["TaskMixin", Sequence["TaskMixin"]]):
"""Implements Task << Task"""
self.set_upstream(other)
return other
[docs] def __rshift__(self, other: Union["TaskMixin", Sequence["TaskMixin"]]):
"""Implements Task >> Task"""
self.set_downstream(other)
return other
[docs] def __rrshift__(self, other: Union["TaskMixin", Sequence["TaskMixin"]]):
"""Called for Task >> [Task] because list don't have __rshift__ operators."""
self.__lshift__(other)
return self
[docs] def __rlshift__(self, other: Union["TaskMixin", Sequence["TaskMixin"]]):
"""Called for Task << [Task] because list don't have __lshift__ operators."""
self.__rshift__(other)
return self