p2pool/util/variable.py

   1 import itertools
   2
   3 from twisted.internet import defer, reactor
   4 from twisted.python import failure, log
   5
   6 class Event(object):
   7     def __init__(self):
   8         self.observers = {}
   9         self.one_time_observers = {}
  10         self.id_generator = itertools.count()
  11
  12     def watch(self, func):
  13         id = self.id_generator.next()
  14         self.observers[id] = func
  15         return id
  16     def unwatch(self, id):
  17         self.observers.pop(id)
  18
  19     def watch_one_time(self, func):
  20         id = self.id_generator.next()
  21         self.one_time_observers[id] = func
  22         return id
  23     def unwatch_one_time(self, id):
  24         self.one_time_observers.pop(id)
  25
  26     def happened(self, event=None):
  27         for id, func in sorted(self.observers.iteritems()):
  28             try:
  29                 func(event)
  30             except:
  31                 log.err(None, "Error while processing Event callbacks:")
  32
  33         one_time_observers = self.one_time_observers
  34         self.one_time_observers = {}
  35         for id, func in sorted(one_time_observers.iteritems()):
  36             try:
  37                 func(event)
  38             except:
  39                 log.err(None, "Error while processing Event callbacks:")
  40
  41     def get_deferred(self, timeout=None):
  42         df = defer.Deferred()
  43         id1 = self.watch_one_time(df.callback)
  44         if timeout is not None:
  45             def do_timeout():
  46                 df.errback(failure.Failure(defer.TimeoutError()))
  47                 self.unwatch_one_time(id1)
  48                 self.unwatch_one_time(x)
  49             delay = reactor.callLater(timeout, do_timeout)
  50             x = self.watch_one_time(lambda value: delay.cancel())
  51         return df
  52
  53 class Variable(object):
  54     def __init__(self, value):
  55         self.value = value
  56         self.changed = Event()
  57
  58     def set(self, value):
  59         if value == self.value:
  60             return
  61
  62         self.value = value
  63         self.changed.happened(value)
  64
  65     def get_not_none(self):
  66         if self.value is not None:
  67             return defer.succeed(self.value)
  68         else:
  69             df = defer.Deferred()
  70             self.changed.watch_one_time(df.callback)
  71             return df