1 #!/usr/bin/env python

     2 #

     3 # Copyright 2007 Google Inc.

     4 #

     5 # Licensed under the Apache License, Version 2.0 (the "License");

     6 # you may not use this file except in compliance with the License.

     7 # You may obtain a copy of the License at

     8 #

     9 #     http://www.apache.org/licenses/LICENSE-2.0

    10 #

    11 # Unless required by applicable law or agreed to in writing, software

    12 # distributed under the License is distributed on an "AS IS" BASIS,

    13 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

    14 # See the License for the specific language governing permissions and

    15 # limitations under the License.

    16 #

    17 

    18 """CronInfo tools.

    19 

    20 A library for working with CronInfo records, describing cron entries for an

    21 application. Supports loading the records from yaml.

    22 """

    23 

    24 

    25 

    26 from google.appengine.cron import groc

    27 from google.appengine.api import validation

    28 from google.appengine.api import yaml_builder

    29 from google.appengine.api import yaml_listener

    30 from google.appengine.api import yaml_object

    31 

    32 _URL_REGEX = r'^/.*$'

    33 

    34 

    35 _TIMEZONE_REGEX = r'^.{0,100}$'

    36 

    37 _DESCRIPTION_REGEX = r'^.{0,499}$'

    38 

    39 

    40 class GrocValidator(validation.Validator):

    41   """Checks that a schedule is in valid groc format."""

    42 

    43   def Validate(self, value):

    44     """Validates a schedule."""

    45     if value is None:

    46       raise validation.MissingAttribute('schedule must be specified')

    47     if not isinstance(value, basestring):

    48       raise TypeError('schedule must be a string, not \'%r\''%type(value))

    49     schedule = groc.CreateParser(value)

    50     try:

    51       schedule.timespec()

    52     except groc.GrocException, e:

    53       raise validation.ValidationError('schedule \'%s\' failed to parse: %s'%(

    54           value, e.args[0]))

    55     return value

    56 

    57 

    58 CRON = 'cron'

    59 

    60 URL = 'url'

    61 SCHEDULE = 'schedule'

    62 TIMEZONE = 'timezone'

    63 DESCRIPTION = 'description'

    64 

    65 

    66 class MalformedCronfigurationFile(Exception):

    67   """Configuration file for Cron is malformed."""

    68   pass

    69 

    70 

    71 class CronEntry(validation.Validated):

    72   """A cron entry describes a single cron job."""

    73   ATTRIBUTES = {

    74       URL: _URL_REGEX,

    75       SCHEDULE: GrocValidator(),

    76       TIMEZONE: validation.Optional(_TIMEZONE_REGEX),

    77       DESCRIPTION: validation.Optional(_DESCRIPTION_REGEX)

    78   }

    79 

    80 

    81 class CronInfoExternal(validation.Validated):

    82   """CronInfoExternal describes all cron entries for an application."""

    83   ATTRIBUTES = {

    84       CRON: validation.Optional(validation.Repeated(CronEntry))

    85   }

    86 

    87 

    88 def LoadSingleCron(cron_info):

    89   """Load a cron.yaml file or string and return a CronInfoExternal object."""

    90   builder = yaml_object.ObjectBuilder(CronInfoExternal)

    91   handler = yaml_builder.BuilderHandler(builder)

    92   listener = yaml_listener.EventListener(handler)

    93   listener.Parse(cron_info)

    94 

    95   cron_info = handler.GetResults()

    96   if len(cron_info) < 1:

    97     raise MalformedCronfigurationFile('Empty cron configuration.')

    98   if len(cron_info) > 1:

    99     raise MalformedCronfigurationFile('Multiple cron sections '

   100                                       'in configuration.')

   101   return cron_info[0]