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:
|
