diff options
Diffstat (limited to 'synapse/util')
| -rw-r--r-- | synapse/util/async_helpers.py | 34 |
1 files changed, 18 insertions, 16 deletions
diff --git a/synapse/util/async_helpers.py b/synapse/util/async_helpers.py index 5df80ea8e7..96efc5f3e3 100644 --- a/synapse/util/async_helpers.py +++ b/synapse/util/async_helpers.py @@ -22,11 +22,11 @@ from typing import ( Any, Awaitable, Callable, + Collection, Dict, Generic, Hashable, Iterable, - List, Optional, Set, TypeVar, @@ -76,12 +76,17 @@ class ObservableDeferred(Generic[_T]): def __init__(self, deferred: "defer.Deferred[_T]", consumeErrors: bool = False): object.__setattr__(self, "_deferred", deferred) object.__setattr__(self, "_result", None) - object.__setattr__(self, "_observers", set()) + object.__setattr__(self, "_observers", []) def callback(r): object.__setattr__(self, "_result", (True, r)) - while self._observers: - observer = self._observers.pop() + + # once we have set _result, no more entries will be added to _observers, + # so it's safe to replace it with the empty tuple. + observers = self._observers + object.__setattr__(self, "_observers", ()) + + for observer in observers: try: observer.callback(r) except Exception as e: @@ -95,12 +100,16 @@ class ObservableDeferred(Generic[_T]): def errback(f): object.__setattr__(self, "_result", (False, f)) - while self._observers: + + # once we have set _result, no more entries will be added to _observers, + # so it's safe to replace it with the empty tuple. + observers = self._observers + object.__setattr__(self, "_observers", ()) + + for observer in observers: # This is a little bit of magic to correctly propagate stack # traces when we `await` on one of the observer deferreds. f.value.__failure__ = f - - observer = self._observers.pop() try: observer.errback(f) except Exception as e: @@ -127,20 +136,13 @@ class ObservableDeferred(Generic[_T]): """ if not self._result: d: "defer.Deferred[_T]" = defer.Deferred() - - def remove(r): - self._observers.discard(d) - return r - - d.addBoth(remove) - - self._observers.add(d) + self._observers.append(d) return d else: success, res = self._result return defer.succeed(res) if success else defer.fail(res) - def observers(self) -> "List[defer.Deferred[_T]]": + def observers(self) -> "Collection[defer.Deferred[_T]]": return self._observers def has_called(self) -> bool: |