Generalise the `@cancellable` annotation so it can be used on functions other than just servlet methods. (#13662)
This commit is contained in:
parent
a160406d24
commit
7bc110a19e
|
@ -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
|
||||
|
|
Loading…
Reference in New Issue