text: # -*- 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.
  #
  from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  from __future__ import unicode_literals
  
  import psutil
  
  from builtins import input
  from past.builtins import basestring
  from datetime import datetime
  import getpass
  import imp
  import os
  import re
  import signal
  import subprocess
  import sys
  import warnings
  
  from jinja2 import Template
  
  from airflow import configuration
  from airflow.exceptions import AirflowException
  
  # When killing processes, time to wait after issuing a SIGTERM before issuing a
  # SIGKILL.
  DEFAULT_TIME_TO_WAIT_AFTER_SIGTERM = configuration.conf.getint(
      'core', 'KILLED_TASK_CLEANUP_TIME'
  )
  
  
  def validate_key(k, max_length=250):
      if not isinstance(k, basestring):
          raise TypeError("The key has to be a string")
      elif len(k) > max_length:
          raise AirflowException(
              "The key has to be less than {0} characters".format(max_length))
      elif not re.match(r'^[A-Za-z0-9_\-\.]+$', k):
          raise AirflowException(
              "The key ({k}) has to be made of alphanumeric characters, dashes, "
              "dots and underscores exclusively".format(**locals()))
      else:
          return True
  
  
  def alchemy_to_dict(obj):
      """
      Transforms a SQLAlchemy model instance into a dictionary
      """
      if not obj:
          return None
      d = {}
      for c in obj.__table__.columns:
          value = getattr(obj, c.name)
          if type(value) == datetime:
              value = value.isoformat()
          d[c.name] = value
      return d
  
  
  def ask_yesno(question):
      yes = set(['yes', 'y'])
      no = set(['no', 'n'])
  
      done = False
      print(question)
      while not done:
          choice = input().lower()
          if choice in yes:
              return True
          elif choice in no:
              return False
          else:
              print("Please respond by yes or no.")
  
  
  def is_in(obj, l):
      """
      Checks whether an object is one of the item in the list.
      This is different from ``in`` because ``in`` uses __cmp__ when
      present. Here we change based on the object itself
      """
      for item in l:
          if item is obj:
              return True
      return False
  
  
  def is_container(obj):
      """
      Test if an object is a container (iterable) but not a string
      """
      return hasattr(obj, '__iter__') and not isinstance(obj, basestring)
  
  
  def as_tuple(obj):
      """
      If obj is a container, returns obj as a tuple.
      Otherwise, returns a tuple containing obj.
      """
      if is_container(obj):
          return tuple(obj)
      else:
          return tuple([obj])
  
  
  def as_flattened_list(iterable):
      """
      Return an iterable with one level flattened
  
      >>> as_flattened_list((('blue', 'red'), ('green', 'yellow', 'pink')))
      ['blue', 'red', 'green', 'yellow', 'pink']
      """
      return [e for i in iterable for e in i]
  
  
  def chain(*tasks):
      """
      Given a number of tasks, builds a dependency chain.
  
      chain(task_1, task_2, task_3, task_4)
  
      is equivalent to
  
      task_1.set_downstream(task_2)
      task_2.set_downstream(task_3)
      task_3.set_downstream(task_4)
      """
      for up_task, down_task in zip(tasks[:-1], tasks[1:]):
          up_task.set_downstream(down_task)
  
  
  def pprinttable(rows):
      """Returns a pretty ascii table from tuples
  
      If namedtuple are used, the table will have headers
      """
      if not rows:
          return
      if hasattr(rows[0], '_fields'):  # if namedtuple
          headers = rows[0]._fields
      else:
          headers = ["col{}".format(i) for i in range(len(rows[0]))]
      lens = [len(s) for s in headers]
  
      for row in rows:
          for i in range(len(rows[0])):
              slenght = len("{}".format(row[i]))
              if slenght > lens[i]:
                  lens[i] = slenght
      formats = []
      hformats = []
      for i in range(len(rows[0])):
          if isinstance(rows[0][i], int):
              formats.append("%%%dd" % lens[i])
          else:
              formats.append("%%-%ds" % lens[i])
          hformats.append("%%-%ds" % lens[i])
      pattern = " | ".join(formats)
      hpattern = " | ".join(hformats)
      separator = "-+-".join(['-' * n for n in lens])
      s = ""
      s += separator + '\n'
      s += (hpattern % tuple(headers)) + '\n'
      s += separator + '\n'
  
      def f(t):
          return "{}".format(t) if isinstance(t, basestring) else t
  
      for line in rows:
          s += pattern % tuple(f(t) for t in line) + '\n'
      s += separator + '\n'
      return s
  
  
  def reap_process_group(pid, log, sig=signal.SIGTERM,
                         timeout=DEFAULT_TIME_TO_WAIT_AFTER_SIGTERM):
      """
      Tries really hard to terminate all children (including grandchildren). Will send
      sig (SIGTERM) to the process group of pid. If any process is alive after timeout
      a SIGKILL will be send.
  
      :param log: log handler
      :param pid: pid to kill
      :param sig: signal type
      :param timeout: how much time a process has to terminate
      """
      def on_terminate(p):
          log.info("Process %s (%s) terminated with exit code %s", p, p.pid, p.returncode)
  
      if pid == os.getpid():
          raise RuntimeError("I refuse to kill myself")
  
      parent = psutil.Process(pid)
  
      children = parent.children(recursive=True)
      children.append(parent)
  
      log.info("Sending %s to GPID %s", sig, os.getpgid(pid))
      os.killpg(os.getpgid(pid), sig)
  
      gone, alive = psutil.wait_procs(children, timeout=timeout, callback=on_terminate)
  
      if alive:
          for p in alive:
              log.warn("process %s (%s) did not respond to SIGTERM. Trying SIGKILL", p, pid)
  
          os.killpg(os.getpgid(pid), signal.SIGKILL)
  
          gone, alive = psutil.wait_procs(alive, timeout=timeout, callback=on_terminate)
          if alive:
              for p in alive:
                  log.error("Process %s (%s) could not be killed. Giving up.", p, p.pid)
  
  
  def parse_template_string(template_string):
      if "{{" in template_string:  # jinja mode
          return None, Template(template_string)
      else:
          return template_string, None
  
  
  class AirflowImporter(object):
      """
      Importer that dynamically loads a class and module from its parent. This
      allows Airflow to support ``from airflow.operators import BashOperator``
      even though BashOperator is actually in
      ``airflow.operators.bash_operator``.
  
      The importer also takes over for the parent_module by wrapping it. This is
      required to support attribute-based usage:
  
      .. code:: python
  
          from airflow import operators
          operators.BashOperator(...)
      """
  
      def __init__(self, parent_module, module_attributes):
          """
          :param parent_module: The string package name of the parent module. For
              example, 'airflow.operators'
          :type parent_module: string
          :param module_attributes: The file to class mappings for all importable
              classes.
          :type module_attributes: string
          """
          self._parent_module = parent_module
          self._attribute_modules = self._build_attribute_modules(module_attributes)
          self._loaded_modules = {}
  
          # Wrap the module so we can take over __getattr__.
          sys.modules[parent_module.__name__] = self
  
      @staticmethod
      def _build_attribute_modules(module_attributes):
          """
          Flips and flattens the module_attributes dictionary from:
  
              module => [Attribute, ...]
  
          To:
  
              Attribute => module
  
          This is useful so that we can find the module to use, given an
          attribute.
          """
          attribute_modules = {}
  
          for module, attributes in list(module_attributes.items()):
              for attribute in attributes:
                  attribute_modules[attribute] = module
  
          return attribute_modules
  
      def _load_attribute(self, attribute):
          """
          Load the class attribute if it hasn't been loaded yet, and return it.
          """
          module = self._attribute_modules.get(attribute, False)
  
          if not module:
              # This shouldn't happen. The check happens in find_modules, too.
              raise ImportError(attribute)
          elif module not in self._loaded_modules:
              # Note that it's very important to only load a given modules once.
              # If they are loaded more than once, the memory reference to the
              # class objects changes, and Python thinks that an object of type
              # Foo that was declared before Foo's module was reloaded is no
              # longer the same type as Foo after it's reloaded.
              path = os.path.realpath(self._parent_module.__file__)
              folder = os.path.dirname(path)
              f, filename, description = imp.find_module(module, [folder])
              self._loaded_modules[module] = imp.load_module(module, f, filename, description)
  
              # This functionality is deprecated, and AirflowImporter should be
              # removed in 2.0.
              warnings.warn(
                  "Importing {i} directly from {m} has been "
                  "deprecated. Please import from "
                  "'{m}.[operator_module]' instead. Support for direct "
                  "imports will be dropped entirely in Airflow 2.0.".format(
                      i=attribute, m=self._parent_module),
                  DeprecationWarning)
  
          loaded_module = self._loaded_modules[module]
  
          return getattr(loaded_module, attribute)
  
      def __getattr__(self, attribute):
          """
          Get an attribute from the wrapped module. If the attribute doesn't
          exist, try and import it as a class from a submodule.
  
          This is a Python trick that allows the class to pretend it's a module,
          so that attribute-based usage works:
  
              from airflow import operators
              operators.BashOperator(...)
  
          It also allows normal from imports to work:
  
              from airflow.operators.bash_operator import BashOperator
          """
          if hasattr(self._parent_module, attribute):
              # Always default to the parent module if the attribute exists.
              return getattr(self._parent_module, attribute)
          elif attribute in self._attribute_modules:
              # Try and import the attribute if it's got a module defined.
              loaded_attribute = self._load_attribute(attribute)
              setattr(self, attribute, loaded_attribute)
              return loaded_attribute
  
          raise AttributeError
  