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−#!/usr/bin/env python
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−#
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−# Copyright 2007 Google Inc.
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−#
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−# Licensed under the Apache License, Version 2.0 (the "License");
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−# you may not use this file except in compliance with the License.
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−# You may obtain a copy of the License at
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−#
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−#     http://www.apache.org/licenses/LICENSE-2.0
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−#
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−# Unless required by applicable law or agreed to in writing, software
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−# distributed under the License is distributed on an "AS IS" BASIS,
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−# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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−# See the License for the specific language governing permissions and
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−# limitations under the License.
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−#
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−
+
−"""CronInfo tools.
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−
+
−A library for working with CronInfo records, describing cron entries for an
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−application. Supports loading the records from yaml.
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−"""
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−
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−
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−
+
−import logging
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−import sys
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−import traceback
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−
+
−try:
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−  import pytz
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−except ImportError:
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−  pytz = None
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−
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−from google.appengine.cron import groc
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−from google.appengine.api import validation
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−from google.appengine.api import yaml_builder
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−from google.appengine.api import yaml_listener
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−from google.appengine.api import yaml_object
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−
+
−_URL_REGEX = r'^/.*$'
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−_TIMEZONE_REGEX = r'^.{0,100}$'
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−_DESCRIPTION_REGEX = r'^.{0,499}$'
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−
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−
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−class GrocValidator(validation.Validator):
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−  """Checks that a schedule is in valid groc format."""
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−
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−  def Validate(self, value):
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−    """Validates a schedule."""
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−    if value is None:
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−      raise validation.MissingAttribute('schedule must be specified')
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−    if not isinstance(value, basestring):
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−      raise TypeError('schedule must be a string, not \'%r\''%type(value))
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−    schedule = groc.CreateParser(value)
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−    try:
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−      schedule.timespec()
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−    except groc.GrocException, e:
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−      raise validation.ValidationError('schedule \'%s\' failed to parse: %s'%(
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−          value, e.args[0]))
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−    return value
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−
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−
+
−class TimezoneValidator(validation.Validator):
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−  """Checks that a timezone can be correctly parsed and is known."""
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−
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−  def Validate(self, value):
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−    """Validates a timezone."""
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−    if value is None:
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−      return
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−    if not isinstance(value, basestring):
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−      raise TypeError('timezone must be a string, not \'%r\'' % type(value))
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−    if pytz is None:
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−      return value
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−    try:
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−      pytz.timezone(value)
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−    except pytz.UnknownTimeZoneError:
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−      raise validation.ValidationError('timezone \'%s\' is unknown' % value)
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−    except IOError:
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−      return value
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−    except:
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−      unused_e, v, t = sys.exc_info()
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−      logging.warning('pytz raised an unexpected error: %s.\n' % (v) +
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−                      'Traceback:\n' + '\n'.join(traceback.format_tb(t)))
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−      raise
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−    return value
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−
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−
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−CRON = 'cron'
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−
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−URL = 'url'
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−SCHEDULE = 'schedule'
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−TIMEZONE = 'timezone'
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−DESCRIPTION = 'description'
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−
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−
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−class MalformedCronfigurationFile(Exception):
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−  """Configuration file for Cron is malformed."""
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−  pass
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−
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−
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−class CronEntry(validation.Validated):
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−  """A cron entry describes a single cron job."""
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−  ATTRIBUTES = {
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−      URL: _URL_REGEX,
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−      SCHEDULE: GrocValidator(),
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−      TIMEZONE: TimezoneValidator(),
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−      DESCRIPTION: validation.Optional(_DESCRIPTION_REGEX)
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−  }
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−
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−
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−class CronInfoExternal(validation.Validated):
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−  """CronInfoExternal describes all cron entries for an application."""
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−  ATTRIBUTES = {
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−      CRON: validation.Optional(validation.Repeated(CronEntry))
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−  }
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−
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−
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−def LoadSingleCron(cron_info):
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−  """Load a cron.yaml file or string and return a CronInfoExternal object."""
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−  builder = yaml_object.ObjectBuilder(CronInfoExternal)
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−  handler = yaml_builder.BuilderHandler(builder)
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−  listener = yaml_listener.EventListener(handler)
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−  listener.Parse(cron_info)
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−
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−  cron_info = handler.GetResults()
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−  if len(cron_info) < 1:
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−    raise MalformedCronfigurationFile('Empty cron configuration.')
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−  if len(cron_info) > 1:
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−    raise MalformedCronfigurationFile('Multiple cron sections '
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−                                      'in configuration.')
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−  return cron_info[0]