From 75574726a766f09d955c05672d400c65cb341810 Mon Sep 17 00:00:00 2001 From: Sean Quah <8349537+squahtx@users.noreply.github.com> Date: Fri, 4 Mar 2022 15:37:02 +0000 Subject: [PATCH] Add type hints for `ObservableDeferred` attributes (#12159) Signed-off-by: Sean Quah --- changelog.d/12159.misc | 1 + synapse/util/async_helpers.py | 14 +++++++++++--- 2 files changed, 12 insertions(+), 3 deletions(-) create mode 100644 changelog.d/12159.misc diff --git a/changelog.d/12159.misc b/changelog.d/12159.misc new file mode 100644 index 000000000..30500f2fd --- /dev/null +++ b/changelog.d/12159.misc @@ -0,0 +1 @@ +Add type hints for `ObservableDeferred` attributes. diff --git a/synapse/util/async_helpers.py b/synapse/util/async_helpers.py index 60c03a66f..a9f67dcba 100644 --- a/synapse/util/async_helpers.py +++ b/synapse/util/async_helpers.py @@ -40,7 +40,7 @@ from typing import ( ) import attr -from typing_extensions import ContextManager +from typing_extensions import ContextManager, Literal from twisted.internet import defer from twisted.internet.defer import CancelledError @@ -96,6 +96,10 @@ class ObservableDeferred(Generic[_T], AbstractObservableDeferred[_T]): __slots__ = ["_deferred", "_observers", "_result"] + _deferred: "defer.Deferred[_T]" + _observers: Union[List["defer.Deferred[_T]"], Tuple[()]] + _result: Union[None, Tuple[Literal[True], _T], Tuple[Literal[False], Failure]] + def __init__(self, deferred: "defer.Deferred[_T]", consumeErrors: bool = False): object.__setattr__(self, "_deferred", deferred) object.__setattr__(self, "_result", None) @@ -158,12 +162,14 @@ class ObservableDeferred(Generic[_T], AbstractObservableDeferred[_T]): effect the underlying deferred. """ if not self._result: + assert isinstance(self._observers, list) d: "defer.Deferred[_T]" = defer.Deferred() self._observers.append(d) return d + elif self._result[0]: + return defer.succeed(self._result[1]) else: - success, res = self._result - return defer.succeed(res) if success else defer.fail(res) + return defer.fail(self._result[1]) def observers(self) -> "Collection[defer.Deferred[_T]]": return self._observers @@ -175,6 +181,8 @@ class ObservableDeferred(Generic[_T], AbstractObservableDeferred[_T]): return self._result is not None and self._result[0] is True def get_result(self) -> Union[_T, Failure]: + if self._result is None: + raise ValueError(f"{self!r} has no result yet") return self._result[1] def __getattr__(self, name: str) -> Any: