# -*- 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.
#
import os
# inspect.signature is only available in Python 3. funcsigs.signature is
# a backport.
try:
import inspect
signature = inspect.signature
except AttributeError:
import funcsigs
signature = funcsigs.signature
from copy import copy
from functools import wraps
from airflow.exceptions import AirflowException
def apply_defaults(func):
"""
Function decorator that Looks for an argument named "default_args", and
fills the unspecified arguments from it.
Since python2.* isn't clear about which arguments are missing when
calling a function, and that this can be quite confusing with multi-level
inheritance and argument defaults, this decorator also alerts with
specific information about the missing arguments.
"""
import airflow.models
# Cache inspect.signature for the wrapper closure to avoid calling it
# at every decorated invocation. This is separate sig_cache created
# per decoration, i.e. each function decorated using apply_defaults will
# have a different sig_cache.
sig_cache = signature(func)
non_optional_args = {
name for (name, param) in sig_cache.parameters.items()
if param.default == param.empty and
param.name != 'self' and
param.kind not in (param.VAR_POSITIONAL, param.VAR_KEYWORD)}
@wraps(func)
def wrapper(*args, **kwargs):
if len(args) > 1:
raise AirflowException(
"Use keyword arguments when initializing operators")
dag_args = {}
dag_params = {}
dag = kwargs.get('dag', None) or airflow.models._CONTEXT_MANAGER_DAG
if dag:
dag_args = copy(dag.default_args) or {}
dag_params = copy(dag.params) or {}
params = {}
if 'params' in kwargs:
params = kwargs['params']
dag_params.update(params)
default_args = {}
if 'default_args' in kwargs:
default_args = kwargs['default_args']
if 'params' in default_args:
dag_params.update(default_args['params'])
del default_args['params']
dag_args.update(default_args)
default_args = dag_args
for arg in sig_cache.parameters:
if arg not in kwargs and arg in default_args:
kwargs[arg] = default_args[arg]
missing_args = list(non_optional_args - set(kwargs))
if missing_args:
msg = "Argument {0} is required".format(missing_args)
raise AirflowException(msg)
kwargs['params'] = dag_params
result = func(*args, **kwargs)
return result
return wrapper
if 'BUILDING_AIRFLOW_DOCS' in os.environ:
# flake8: noqa: F811
# Monkey patch hook to get good function headers while building docs
[docs] apply_defaults = lambda x: x
class cached_property:
"""
A decorator creating a property, the value of which is calculated only once and cached for later use.
"""
def __init__(self, func):
self.func = func
self.__doc__ = getattr(func, '__doc__')
def __get__(self, instance, cls=None):
if instance is None:
return self
result = self.func(instance)
instance.__dict__[self.func.__name__] = result
return result