From 5cfb0045955f8b5e9e8a1e0505fa2b5ed4f7bde2 Mon Sep 17 00:00:00 2001 From: Sean Quah <8349537+squahtx@users.noreply.github.com> Date: Tue, 10 May 2022 14:06:08 +0100 Subject: [PATCH] Add ability to cancel disconnected requests to `SynapseRequest` (#12588) Signed-off-by: Sean Quah --- changelog.d/12588.misc | 1 + synapse/http/site.py | 24 +++++++++++++++++++++++- 2 files changed, 24 insertions(+), 1 deletion(-) create mode 100644 changelog.d/12588.misc diff --git a/changelog.d/12588.misc b/changelog.d/12588.misc new file mode 100644 index 000000000000..f62d5c8e210c --- /dev/null +++ b/changelog.d/12588.misc @@ -0,0 +1 @@ +Add ability to cancel disconnected requests to `SynapseRequest`. diff --git a/synapse/http/site.py b/synapse/http/site.py index 0b85a57d7787..f7f1c5704285 100644 --- a/synapse/http/site.py +++ b/synapse/http/site.py @@ -19,6 +19,7 @@ import attr from zope.interface import implementer +from twisted.internet.defer import Deferred from twisted.internet.interfaces import IAddress, IReactorTime from twisted.python.failure import Failure from twisted.web.http import HTTPChannel @@ -91,6 +92,13 @@ def __init__( # we can't yet create the logcontext, as we don't know the method. self.logcontext: Optional[LoggingContext] = None + # The `Deferred` to cancel if the client disconnects early. Expected to be set + # by `Resource.render`. + self.render_deferred: Optional["Deferred[None]"] = None + # A boolean indicating whether `_render_deferred` should be cancelled if the + # client disconnects early. Expected to be set during `Resource.render`. + self.is_render_cancellable = False + global _next_request_seq self.request_seq = _next_request_seq _next_request_seq += 1 @@ -357,7 +365,21 @@ def connectionLost(self, reason: Union[Failure, Exception]) -> None: {"event": "client connection lost", "reason": str(reason.value)} ) - if not self._is_processing: + if self._is_processing: + if self.is_render_cancellable: + if self.render_deferred is not None: + # Throw a cancellation into the request processing, in the hope + # that it will finish up sooner than it normally would. + # The `self.processing()` context manager will call + # `_finished_processing()` when done. + with PreserveLoggingContext(): + self.render_deferred.cancel() + else: + logger.error( + "Connection from client lost, but have no Deferred to " + "cancel even though the request is marked as cancellable." + ) + else: self._finished_processing() def _started_processing(self, servlet_name: str) -> None: