planetstack/observer/syncstep.py

   1 import os
   2 import base64
   3 from datetime import datetime
   4 from planetstack.config import Config
   5 from util.logger import Logger, logging
   6
   7 logger = Logger(level=logging.INFO)
   8
   9 class FailedDependency(Exception):
  10     pass
  11
  12 class SyncStep:
  13     """ A PlanetStack Sync step.
  14
  15     Attributes:
  16         psmodel        Model name the step synchronizes
  17         dependencies    list of names of models that must be synchronized first if the current model depends on them
  18     """
  19     slow=False
  20     def get_prop(prop):
  21         try:
  22             sync_config_dir = Config().sync_config_dir
  23         except:
  24             sync_config_dir = '/etc/planetstack/sync'
  25         prop_config_path = '/'.join(sync_config_dir,self.name,prop)
  26         return open(prop_config_path).read().rstrip()
  27
  28     def __init__(self, **args):
  29         """Initialize a sync step
  30            Keyword arguments:
  31                    name -- Name of the step
  32                 provides -- PlanetStack models sync'd by this step
  33         """
  34         dependencies = []
  35         self.driver = args.get('driver')
  36         try:
  37             self.soft_deadline = int(self.get_prop('soft_deadline_seconds'))
  38         except:
  39             self.soft_deadline = 5 # 5 seconds
  40
  41         return
  42
  43     def fetch_pending(self):
  44         return []
  45         #return Sliver.objects.filter(ip=None)
  46
  47     def check_dependencies(self, obj, failed):
  48         for dep in self.dependencies:
  49             peer_name = dep[0].lower() + dep[1:]    # django names are camelCased with the first letter lower
  50             peer_object = getattr(obj, peer_name)
  51             if (peer_object.pk==failed.pk):
  52                 raise FailedDependency
  53
  54     def call(self, failed=[]):
  55         pending = self.fetch_pending()
  56         for o in pending:
  57             try:
  58                 for f in failed:
  59                     self.check_dependencies(o,f) # Raises exception if failed
  60                 self.sync_record(o)
  61                 o.enacted = datetime.now() # Is this the same timezone? XXX
  62                 o.save(update_fields=['enacted'])
  63             except:
  64                 logger.log_exc("sync step %s failed!" % self.__name__)
  65                 failed.append(o)
  66
  67         return failed
  68
  69     def __call__(self, **args):
  70         return self.call(**args)