1# Copyright 2017 New Vector Ltd
2#
3# Licensed under the Apache License, Version 2.0 (the "License");
4# you may not use this file except in compliance with the License.
5# You may obtain a copy of the License at
6#
7#     http://www.apache.org/licenses/LICENSE-2.0
8#
9# Unless required by applicable law or agreed to in writing, software
10# distributed under the License is distributed on an "AS IS" BASIS,
11# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12# See the License for the specific language governing permissions and
13# limitations under the License.
14
15from typing import TYPE_CHECKING, Any, Awaitable, Callable, Optional, Tuple
16
17from twisted.web.server import Request
18
19from synapse.http.server import DirectServeJsonResource
20
21if TYPE_CHECKING:
22    from synapse.server import HomeServer
23
24
25class AdditionalResource(DirectServeJsonResource):
26    """Resource wrapper for additional_resources
27
28    If the user has configured additional_resources, we need to wrap the
29    handler class with a Resource so that we can map it into the resource tree.
30
31    This class is also where we wrap the request handler with logging, metrics,
32    and exception handling.
33    """
34
35    def __init__(
36        self,
37        hs: "HomeServer",
38        handler: Callable[[Request], Awaitable[Optional[Tuple[int, Any]]]],
39    ):
40        """Initialise AdditionalResource
41
42        The ``handler`` should return a deferred which completes when it has
43        done handling the request. It should write a response with
44        ``request.write()``, and call ``request.finish()``.
45
46        Args:
47            hs: homeserver
48            handler ((twisted.web.server.Request) -> twisted.internet.defer.Deferred):
49                function to be called to handle the request.
50        """
51        super().__init__()
52        self._handler = handler
53
54    async def _async_render(self, request: Request) -> Optional[Tuple[int, Any]]:
55        # Cheekily pass the result straight through, so we don't need to worry
56        # if its an awaitable or not.
57        return await self._handler(request)
58