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 errno
  
  import psutil
  
  from builtins import input
  from past.builtins import basestring
  from datetime import datetime
  from functools import reduce
  import os
  import re
  import signal
  
  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 = {'yes', 'y'}
      no = {'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 chunks(items, chunk_size):
      """
      Yield successive chunks of a given size from a list of items
      """
      if chunk_size <= 0:
          raise ValueError('Chunk size must be a positive integer')
      for i in range(0, len(items), chunk_size):
          yield items[i:i + chunk_size]
  
  
  def reduce_in_chunks(fn, iterable, initializer, chunk_size=0):
      """
      Reduce the given list of items by splitting it into chunks
      of the given size and passing each chunk through the reducer
      """
      if len(iterable) == 0:
          return initializer
      if chunk_size == 0:
          chunk_size = len(iterable)
      return reduce(fn, chunks(iterable, chunk_size), initializer)
  
  
  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 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):
      """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)
  
      try:
          pg = os.getpgid(pid)
      except OSError as err:
          # Skip if not such process - we experience a race and it just terminated
          if err.errno == errno.ESRCH:
              return
          raise
  
      log.info("Sending %s to GPID %s", sig, pg)
      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
  
  
  def render_log_filename(ti, try_number, filename_template):
      """
      Given task instance, try_number, filename_template, return the rendered log
      filename
  
      :param ti: task instance
      :param try_number: try_number of the task
      :param filename_template: filename template, which can be jinja template or
          python string template
      """
      filename_template, filename_jinja_template = parse_template_string(filename_template)
      if filename_jinja_template:
          jinja_context = ti.get_template_context()
          jinja_context['try_number'] = try_number
          return filename_jinja_template.render(**jinja_context)
  
      return filename_template.format(dag_id=ti.dag_id,
                                      task_id=ti.task_id,
                                      execution_date=ti.execution_date.isoformat(),
                                      try_number=try_number)
  