manifold/util/callback.py

   1 from manifold.operators      import LAST_RECORD
   2 import threading
   3
   4 #------------------------------------------------------------------
   5 # Class callback
   6 #------------------------------------------------------------------
   7
   8 class Callback:
   9     def __init__(self, deferred=None, router=None, cache_id=None):
  10     #def __init__(self, deferred=None, event=None, router=None, cache_id=None):
  11         self.results = []
  12         self._deferred = deferred
  13
  14         #if not self.event:
  15         self.event = threading.Event()
  16         #else:
  17         #    self.event = event
  18
  19         # Used for caching...
  20         self.router = router
  21         self.cache_id = cache_id
  22
  23     def __call__(self, value):
  24         # End of the list of records sent by Gateway
  25         if value == LAST_RECORD:
  26             if self.cache_id:
  27                 # Add query results to cache (expires in 30min)
  28                 #print "Result added to cached under id", self.cache_id
  29                 self.router.cache[self.cache_id] = (self.results, time.time() + CACHE_LIFETIME)
  30
  31             if self._deferred:
  32                 # Send results back using deferred object
  33                 self._deferred.callback(self.results)
  34             else:
  35                 # Not using deferred, trigger the event to return results
  36                 self.event.set()
  37             return self.event
  38
  39         # Not LAST_RECORD add the value to the results
  40         self.results.append(value)
  41
  42     def wait(self):
  43         self.event.wait()
  44         self.event.clear()
  45
  46     def get_results(self):
  47         self.wait()
  48         return self.results
  49