planetstack/observer/syncstep.py

   1 import os
   2 import base64
   3 from planetstack.config import Config
   4
   5 class FailedDependency(Exception):
   6     pass
   7
   8 class SyncStep:
   9     """ A PlanetStack Sync step.
  10
  11     Attributes:
  12         psmodel        Model name the step synchronizes
  13         dependencies    list of names of models that must be synchronized first if the current model depends on them
  14     """
  15     slow=False
  16     def get_prop(prop):
  17         try:
  18             sync_config_dir = Config().sync_config_dir
  19         except:
  20             sync_config_dir = '/etc/planetstack/sync'
  21         prop_config_path = '/'.join(sync_config_dir,self.name,prop)
  22         return open(prop_config_path).read().rstrip()
  23
  24     def __init__(self, **args):
  25         """Initialize a sync step
  26            Keyword arguments:
  27                    name -- Name of the step
  28                 provides -- PlanetStack models sync'd by this step
  29         """
  30         dependencies = []
  31         self.driver = args.get('driver')
  32         try:
  33             self.soft_deadline = int(self.get_prop('soft_deadline_seconds'))
  34         except:
  35             self.soft_deadline = 5 # 5 seconds
  36
  37         return
  38
  39     def fetch_pending(self):
  40         return Sliver.objects.filter(ip=None)
  41
  42     def check_dependencies(self, obj):
  43         for dep in self.dependencies:
  44             peer_object = getattr(obj, dep.name.lowercase())
  45             if (peer_object.pk==dep.pk):
  46                 raise DependencyFailed
  47
  48     def call(self, failed=[]):
  49         pending = self.fetch_pending()
  50         for o in pending:
  51             if (not self.depends_on(o, failed)):
  52                 try:
  53                     check_dependencies(o) # Raises exception if failed
  54                     self.sync_record(o)
  55                     o.enacted = datetime.now() # Is this the same timezone? XXX
  56                     o.save(update_fields=['enacted'])
  57                 except:
  58                     failed.append(o)
  59         return failed
  60
  61     def __call__(self):
  62         return self.call()