p2pool/util/variable.py

   1 import itertools
   2
   3 from twisted.internet import defer
   4
   5 class Event(object):
   6     def __init__(self):
   7         self.observers = {}
   8         self.one_time_observers = {}
   9         self.id_generator = itertools.count()
  10
  11     def watch(self, func):
  12         id = self.id_generator.next()
  13         self.observers[id] = func
  14         return id
  15     def unwatch(self, id):
  16         self.observers.pop(id)
  17
  18     def watch_one_time(self, func):
  19         id = self.id_generator.next()
  20         self.one_time_observers[id] = func
  21         return id
  22     def unwatch_one_time(self, id):
  23         self.one_time_observers.pop(id)
  24
  25     def happened(self, event=None):
  26         for func in self.observers.itervalues():
  27             func(event)
  28
  29         one_time_observers = self.one_time_observers
  30         self.one_time_observers = {}
  31         for func in one_time_observers.itervalues():
  32             func(event)
  33
  34     def get_deferred(self):
  35         df = defer.Deferred()
  36         self.watch_one_time(df.callback)
  37         return df
  38
  39 class Variable(object):
  40     def __init__(self, value):
  41         self.value = value
  42         self.changed = Event()
  43
  44     def set(self, value):
  45         if value == self.value:
  46             return
  47
  48         self.value = value
  49         self.changed.happened(value)
  50
  51     def get_not_none(self):
  52         if self.value is not None:
  53             return defer.succeed(self.value)
  54         else:
  55             df = defer.Deferred()
  56             self.changed.watch_one_time(df.callback)
  57             return df