70 lines
2.0 KiB
Python
70 lines
2.0 KiB
Python
|
from __future__ import unicode_literals, print_function
|
||
|
|
from twisted.internet.defer import Deferred
|
||
|
|
from twisted.python.failure import Failure
|
||
|
|
|
||
|
|
NoResult = object()
|
||
|
|
|
||
|
|
class OneShotObserver(object):
|
||
|
|
def __init__(self, eventual_queue):
|
||
|
|
self._eq = eventual_queue
|
||
|
|
self._result = NoResult
|
||
|
|
self._observers = [] # list of Deferreds
|
||
|
|
|
||
|
|
def when_fired(self):
|
||
|
|
d = Deferred()
|
||
|
|
self._observers.append(d)
|
||
|
|
self._maybe_call_observers()
|
||
|
|
return d
|
||
|
|
|
||
|
|
def fire(self, result):
|
||
|
|
assert self._result is NoResult
|
||
|
|
self._result = result
|
||
|
|
self._maybe_call_observers()
|
||
|
|
|
||
|
|
def _maybe_call_observers(self):
|
||
|
|
if self._result is NoResult:
|
||
|
|
return
|
||
|
|
observers, self._observers = self._observers, []
|
||
|
|
for d in observers:
|
||
|
|
self._eq.eventually(d.callback, self._result)
|
||
|
|
|
||
|
|
def error(self, f):
|
||
|
|
# errors will override an existing result
|
||
|
|
assert isinstance(f, Failure)
|
||
|
|
self._result = f
|
||
|
|
self._maybe_call_observers()
|
||
|
|
|
||
|
|
def fire_if_not_fired(self, result):
|
||
|
|
if self._result is NoResult:
|
||
|
|
self.fire(result)
|
||
|
|
|
||
|
|
class SequenceObserver(object):
|
||
|
|
def __init__(self, eventual_queue):
|
||
|
|
self._eq = eventual_queue
|
||
|
|
self._error = None
|
||
|
|
self._results = []
|
||
|
|
self._observers = []
|
||
|
|
|
||
|
|
def when_next_event(self):
|
||
|
|
d = Deferred()
|
||
|
|
if self._error:
|
||
|
|
self._eq.eventually(d.errback, self._error)
|
||
|
|
elif self._results:
|
||
|
|
result = self._results.pop(0)
|
||
|
|
self._eq.eventually(d.callback, result)
|
||
|
|
else:
|
||
|
|
self._observers.append(d)
|
||
|
|
return d
|
||
|
|
|
||
|
|
def fire(self, result):
|
||
|
|
if isinstance(result, Failure):
|
||
|
|
self._error = result
|
||
|
|
for d in self._observers:
|
||
|
|
self._eq.eventually(d.errback, self._error)
|
||
|
|
self._observers = []
|
||
|
|
else:
|
||
|
|
self._results.append(result)
|
||
|
|
if self._observers:
|
||
|
|
d = self._observers.pop(0)
|
||
|
|
self._eq.eventually(d.callback, self._results.pop(0))
|