doc/core/howto/listings/pb/cache_classes.py

   1 #!/usr/bin/env python
   2
   3 # Copyright (c) Twisted Matrix Laboratories.
   4 # See LICENSE for details.
   5
   6 from twisted.spread import pb
   7
   8 class MasterDuckPond(pb.Cacheable):
   9     def __init__(self, ducks):
  10         self.observers = []
  11         self.ducks = ducks
  12     def count(self):
  13         print "I have [%d] ducks" % len(self.ducks)
  14     def addDuck(self, duck):
  15         self.ducks.append(duck)
  16         for o in self.observers: o.callRemote('addDuck', duck)
  17     def removeDuck(self, duck):
  18         self.ducks.remove(duck)
  19         for o in self.observers: o.callRemote('removeDuck', duck)
  20     def getStateToCacheAndObserveFor(self, perspective, observer):
  21         self.observers.append(observer)
  22         # you should ignore pb.Cacheable-specific state, like self.observers
  23         return self.ducks # in this case, just a list of ducks
  24     def stoppedObserving(self, perspective, observer):
  25         self.observers.remove(observer)
  26
  27 class SlaveDuckPond(pb.RemoteCache):
  28     # This is a cache of a remote MasterDuckPond
  29     def count(self):
  30         return len(self.cacheducks)
  31     def getDucks(self):
  32         return self.cacheducks
  33     def setCopyableState(self, state):
  34         print " cache - sitting, er, setting ducks"
  35         self.cacheducks = state
  36     def observe_addDuck(self, newDuck):
  37         print " cache - addDuck"
  38         self.cacheducks.append(newDuck)
  39     def observe_removeDuck(self, deadDuck):
  40         print " cache - removeDuck"
  41         self.cacheducks.remove(deadDuck)
  42
  43 pb.setUnjellyableForClass(MasterDuckPond, SlaveDuckPond)