@@ -0,0 +1 @@ | |||
Generalise the `@cancellable` annotation so it can be used on functions other than just servlet methods. |
@@ -21,7 +21,7 @@ from typing import TYPE_CHECKING, Any, Awaitable, Callable, Dict, Optional, Tupl | |||
from synapse.api.errors import Codes, FederationDeniedError, SynapseError | |||
from synapse.api.urls import FEDERATION_V1_PREFIX | |||
from synapse.http.server import HttpServer, ServletCallback, is_method_cancellable | |||
from synapse.http.server import HttpServer, ServletCallback | |||
from synapse.http.servlet import parse_json_object_from_request | |||
from synapse.http.site import SynapseRequest | |||
from synapse.logging.context import run_in_background | |||
@@ -34,6 +34,7 @@ from synapse.logging.opentracing import ( | |||
whitelisted_homeserver, | |||
) | |||
from synapse.types import JsonDict | |||
from synapse.util.cancellation import is_function_cancellable | |||
from synapse.util.ratelimitutils import FederationRateLimiter | |||
from synapse.util.stringutils import parse_and_validate_server_name | |||
@@ -375,7 +376,7 @@ class BaseFederationServlet: | |||
if code is None: | |||
continue | |||
if is_method_cancellable(code): | |||
if is_function_cancellable(code): | |||
# The wrapper added by `self._wrap` will inherit the cancellable flag, | |||
# but the wrapper itself does not support cancellation yet. | |||
# Once resolved, the cancellation tests in | |||
@@ -33,7 +33,6 @@ from typing import ( | |||
Optional, | |||
Pattern, | |||
Tuple, | |||
TypeVar, | |||
Union, | |||
) | |||
@@ -64,6 +63,7 @@ from synapse.logging.context import defer_to_thread, preserve_fn, run_in_backgro | |||
from synapse.logging.opentracing import active_span, start_active_span, trace_servlet | |||
from synapse.util import json_encoder | |||
from synapse.util.caches import intern_dict | |||
from synapse.util.cancellation import is_function_cancellable | |||
from synapse.util.iterutils import chunk_seq | |||
if TYPE_CHECKING: | |||
@@ -94,68 +94,6 @@ HTML_ERROR_TEMPLATE = """<!DOCTYPE html> | |||
HTTP_STATUS_REQUEST_CANCELLED = 499 | |||
F = TypeVar("F", bound=Callable[..., Any]) | |||
_cancellable_method_names = frozenset( | |||
{ | |||
# `RestServlet`, `BaseFederationServlet` and `BaseFederationServerServlet` | |||
# methods | |||
"on_GET", | |||
"on_PUT", | |||
"on_POST", | |||
"on_DELETE", | |||
# `_AsyncResource`, `DirectServeHtmlResource` and `DirectServeJsonResource` | |||
# methods | |||
"_async_render_GET", | |||
"_async_render_PUT", | |||
"_async_render_POST", | |||
"_async_render_DELETE", | |||
"_async_render_OPTIONS", | |||
# `ReplicationEndpoint` methods | |||
"_handle_request", | |||
} | |||
) | |||
def cancellable(method: F) -> F: | |||
"""Marks a servlet method as cancellable. | |||
Methods with this decorator will be cancelled if the client disconnects before we | |||
finish processing the request. | |||
During cancellation, `Deferred.cancel()` will be invoked on the `Deferred` wrapping | |||
the method. The `cancel()` call will propagate down to the `Deferred` that is | |||
currently being waited on. That `Deferred` will raise a `CancelledError`, which will | |||
propagate up, as per normal exception handling. | |||
Before applying this decorator to a new endpoint, you MUST recursively check | |||
that all `await`s in the function are on `async` functions or `Deferred`s that | |||
handle cancellation cleanly, otherwise a variety of bugs may occur, ranging from | |||
premature logging context closure, to stuck requests, to database corruption. | |||
Usage: | |||
class SomeServlet(RestServlet): | |||
@cancellable | |||
async def on_GET(self, request: SynapseRequest) -> ...: | |||
... | |||
""" | |||
if method.__name__ not in _cancellable_method_names and not any( | |||
method.__name__.startswith(prefix) for prefix in _cancellable_method_names | |||
): | |||
raise ValueError( | |||
"@cancellable decorator can only be applied to servlet methods." | |||
) | |||
method.cancellable = True # type: ignore[attr-defined] | |||
return method | |||
def is_method_cancellable(method: Callable[..., Any]) -> bool: | |||
"""Checks whether a servlet method has the `@cancellable` flag.""" | |||
return getattr(method, "cancellable", False) | |||
def return_json_error( | |||
f: failure.Failure, request: SynapseRequest, config: Optional[HomeServerConfig] | |||
) -> None: | |||
@@ -389,7 +327,7 @@ class _AsyncResource(resource.Resource, metaclass=abc.ABCMeta): | |||
method_handler = getattr(self, "_async_render_%s" % (request_method,), None) | |||
if method_handler: | |||
request.is_render_cancellable = is_method_cancellable(method_handler) | |||
request.is_render_cancellable = is_function_cancellable(method_handler) | |||
raw_callback_return = method_handler(request) | |||
@@ -551,7 +489,7 @@ class JsonResource(DirectServeJsonResource): | |||
async def _async_render(self, request: SynapseRequest) -> Tuple[int, Any]: | |||
callback, servlet_classname, group_dict = self._get_handler_for_request(request) | |||
request.is_render_cancellable = is_method_cancellable(callback) | |||
request.is_render_cancellable = is_function_cancellable(callback) | |||
# Make sure we have an appropriate name for this handler in prometheus | |||
# (rather than the default of JsonResource). | |||
@@ -26,12 +26,13 @@ from twisted.web.server import Request | |||
from synapse.api.errors import HttpResponseException, SynapseError | |||
from synapse.http import RequestTimedOutError | |||
from synapse.http.server import HttpServer, is_method_cancellable | |||
from synapse.http.server import HttpServer | |||
from synapse.http.site import SynapseRequest | |||
from synapse.logging import opentracing | |||
from synapse.logging.opentracing import trace_with_opname | |||
from synapse.types import JsonDict | |||
from synapse.util.caches.response_cache import ResponseCache | |||
from synapse.util.cancellation import is_function_cancellable | |||
from synapse.util.stringutils import random_string | |||
if TYPE_CHECKING: | |||
@@ -311,7 +312,7 @@ class ReplicationEndpoint(metaclass=abc.ABCMeta): | |||
url_args = list(self.PATH_ARGS) | |||
method = self.METHOD | |||
if self.CACHE and is_method_cancellable(self._handle_request): | |||
if self.CACHE and is_function_cancellable(self._handle_request): | |||
raise Exception( | |||
f"{self.__class__.__name__} has been marked as cancellable, but CACHE " | |||
"is set. The cancellable flag would have no effect." | |||
@@ -359,6 +360,6 @@ class ReplicationEndpoint(metaclass=abc.ABCMeta): | |||
# The `@cancellable` decorator may be applied to `_handle_request`. But we | |||
# told `HttpServer.register_paths` that our handler is `_check_auth_and_handle`, | |||
# so we have to set up the cancellable flag ourselves. | |||
request.is_render_cancellable = is_method_cancellable(self._handle_request) | |||
request.is_render_cancellable = is_function_cancellable(self._handle_request) | |||
return await self._handle_request(request, **kwargs) |
@@ -37,7 +37,7 @@ from synapse.api.errors import ( | |||
) | |||
from synapse.api.filtering import Filter | |||
from synapse.events.utils import format_event_for_client_v2 | |||
from synapse.http.server import HttpServer, cancellable | |||
from synapse.http.server import HttpServer | |||
from synapse.http.servlet import ( | |||
ResolveRoomIdMixin, | |||
RestServlet, | |||
@@ -57,6 +57,7 @@ from synapse.storage.state import StateFilter | |||
from synapse.streams.config import PaginationConfig | |||
from synapse.types import JsonDict, StreamToken, ThirdPartyInstanceID, UserID | |||
from synapse.util import json_decoder | |||
from synapse.util.cancellation import cancellable | |||
from synapse.util.stringutils import parse_and_validate_server_name, random_string | |||
if TYPE_CHECKING: | |||
@@ -0,0 +1,56 @@ | |||
# Copyright 2022 The Matrix.org Foundation C.I.C. | |||
# | |||
# Licensed under the Apache License, Version 2.0 (the "License"); | |||
# you may not use this file except in compliance with the License. | |||
# You may obtain a copy of the License at | |||
# | |||
# http://www.apache.org/licenses/LICENSE-2.0 | |||
# | |||
# Unless required by applicable law or agreed to in writing, software | |||
# distributed under the License is distributed on an "AS IS" BASIS, | |||
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. | |||
# See the License for the specific language governing permissions and | |||
# limitations under the License. | |||
from typing import Any, Callable, TypeVar | |||
F = TypeVar("F", bound=Callable[..., Any]) | |||
def cancellable(function: F) -> F: | |||
"""Marks a function as cancellable. | |||
Servlet methods with this decorator will be cancelled if the client disconnects before we | |||
finish processing the request. | |||
Although this annotation is particularly useful for servlet methods, it's also | |||
useful for intermediate functions, where it documents the fact that the function has | |||
been audited for cancellation safety and needs to preserve that. | |||
This then simplifies auditing new functions that call those same intermediate | |||
functions. | |||
During cancellation, `Deferred.cancel()` will be invoked on the `Deferred` wrapping | |||
the method. The `cancel()` call will propagate down to the `Deferred` that is | |||
currently being waited on. That `Deferred` will raise a `CancelledError`, which will | |||
propagate up, as per normal exception handling. | |||
Before applying this decorator to a new function, you MUST recursively check | |||
that all `await`s in the function are on `async` functions or `Deferred`s that | |||
handle cancellation cleanly, otherwise a variety of bugs may occur, ranging from | |||
premature logging context closure, to stuck requests, to database corruption. | |||
See the documentation page on Cancellation for more information. | |||
Usage: | |||
class SomeServlet(RestServlet): | |||
@cancellable | |||
async def on_GET(self, request: SynapseRequest) -> ...: | |||
... | |||
""" | |||
function.cancellable = True # type: ignore[attr-defined] | |||
return function | |||
def is_function_cancellable(function: Callable[..., Any]) -> bool: | |||
"""Checks whether a servlet method has the `@cancellable` flag.""" | |||
return getattr(function, "cancellable", False) |
@@ -18,9 +18,10 @@ from typing import Dict, List, Tuple | |||
from synapse.api.errors import Codes | |||
from synapse.federation.transport.server import BaseFederationServlet | |||
from synapse.federation.transport.server._base import Authenticator, _parse_auth_header | |||
from synapse.http.server import JsonResource, cancellable | |||
from synapse.http.server import JsonResource | |||
from synapse.server import HomeServer | |||
from synapse.types import JsonDict | |||
from synapse.util.cancellation import cancellable | |||
from synapse.util.ratelimitutils import FederationRateLimiter | |||
from tests import unittest | |||
@@ -18,7 +18,6 @@ from typing import Tuple | |||
from unittest.mock import Mock | |||
from synapse.api.errors import Codes, SynapseError | |||
from synapse.http.server import cancellable | |||
from synapse.http.servlet import ( | |||
RestServlet, | |||
parse_json_object_from_request, | |||
@@ -28,6 +27,7 @@ from synapse.http.site import SynapseRequest | |||
from synapse.rest.client._base import client_patterns | |||
from synapse.server import HomeServer | |||
from synapse.types import JsonDict | |||
from synapse.util.cancellation import cancellable | |||
from tests import unittest | |||
from tests.http.server._base import test_disconnect | |||
@@ -18,11 +18,12 @@ from typing import Tuple | |||
from twisted.web.server import Request | |||
from synapse.api.errors import Codes | |||
from synapse.http.server import JsonResource, cancellable | |||
from synapse.http.server import JsonResource | |||
from synapse.replication.http import REPLICATION_PREFIX | |||
from synapse.replication.http._base import ReplicationEndpoint | |||
from synapse.server import HomeServer | |||
from synapse.types import JsonDict | |||
from synapse.util.cancellation import cancellable | |||
from tests import unittest | |||
from tests.http.server._base import test_disconnect | |||
@@ -26,12 +26,12 @@ from synapse.http.server import ( | |||
DirectServeJsonResource, | |||
JsonResource, | |||
OptionsResource, | |||
cancellable, | |||
) | |||
from synapse.http.site import SynapseRequest, SynapseSite | |||
from synapse.logging.context import make_deferred_yieldable | |||
from synapse.types import JsonDict | |||
from synapse.util import Clock | |||
from synapse.util.cancellation import cancellable | |||
from tests import unittest | |||
from tests.http.server._base import test_disconnect | |||