Remove experimental MSC2716 implementation to incrementally import history into existing rooms (#15748)

Context for why we're removing the implementation:

 - https://github.com/matrix-org/matrix-spec-proposals/pull/2716#issuecomment-1487441010
 - https://github.com/matrix-org/matrix-spec-proposals/pull/2716#issuecomment-1504262734

Anyone wanting to continue MSC2716, should also address these leftover tasks: https://github.com/matrix-org/synapse/issues/10737

Closes https://github.com/matrix-org/synapse/issues/10737 in the fact that it is not longer necessary to track those things.

2 files changed, 0 insertions, 256 deletions

diff --git a/synapse/rest/client/room_batch.py b/synapse/rest/client/room_batch.py
deleted file mode 100644
index 69f85112d8..0000000000
--- a/synapse/rest/client/room_batch.py
+++ /dev/null
@@ -1,254 +0,0 @@
-# Copyright 2016 OpenMarket Ltd
-#
-# 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.
-
-import logging
-import re
-from http import HTTPStatus
-from typing import TYPE_CHECKING, Tuple
-
-from synapse.api.constants import EventContentFields
-from synapse.api.errors import AuthError, Codes, SynapseError
-from synapse.http.server import HttpServer
-from synapse.http.servlet import (
-    RestServlet,
-    assert_params_in_dict,
-    parse_json_object_from_request,
-    parse_string,
-    parse_strings_from_args,
-)
-from synapse.http.site import SynapseRequest
-from synapse.types import JsonDict
-
-if TYPE_CHECKING:
-    from synapse.server import HomeServer
-
-logger = logging.getLogger(__name__)
-
-
-class RoomBatchSendEventRestServlet(RestServlet):
-    """
-    API endpoint which can insert a batch of events historically back in time
-    next to the given `prev_event`.
-
-    `batch_id` comes from `next_batch_id `in the response of the batch send
-    endpoint and is derived from the "insertion" events added to each batch.
-    It's not required for the first batch send.
-
-    `state_events_at_start` is used to define the historical state events
-    needed to auth the events like join events. These events will float
-    outside of the normal DAG as outlier's and won't be visible in the chat
-    history which also allows us to insert multiple batches without having a bunch
-    of `@mxid joined the room` noise between each batch.
-
-    `events` is chronological list of events you want to insert.
-    There is a reverse-chronological constraint on batches so once you insert
-    some messages, you can only insert older ones after that.
-    tldr; Insert batches from your most recent history -> oldest history.
-
-    POST /_matrix/client/unstable/org.matrix.msc2716/rooms/<roomID>/batch_send?prev_event_id=<eventID>&batch_id=<batchID>
-    {
-        "events": [ ... ],
-        "state_events_at_start": [ ... ]
-    }
-    """
-
-    PATTERNS = (
-        re.compile(
-            "^/_matrix/client/unstable/org.matrix.msc2716"
-            "/rooms/(?P<room_id>[^/]*)/batch_send$"
-        ),
-    )
-    CATEGORY = "Client API requests"
-
-    def __init__(self, hs: "HomeServer"):
-        super().__init__()
-        self.store = hs.get_datastores().main
-        self.event_creation_handler = hs.get_event_creation_handler()
-        self.auth = hs.get_auth()
-        self.room_batch_handler = hs.get_room_batch_handler()
-
-    async def on_POST(
-        self, request: SynapseRequest, room_id: str
-    ) -> Tuple[int, JsonDict]:
-        requester = await self.auth.get_user_by_req(request, allow_guest=False)
-
-        if not requester.app_service:
-            raise AuthError(
-                HTTPStatus.FORBIDDEN,
-                "Only application services can use the /batchsend endpoint",
-            )
-
-        body = parse_json_object_from_request(request)
-        assert_params_in_dict(body, ["state_events_at_start", "events"])
-
-        assert request.args is not None
-        prev_event_ids_from_query = parse_strings_from_args(
-            request.args, "prev_event_id"
-        )
-        batch_id_from_query = parse_string(request, "batch_id")
-
-        if prev_event_ids_from_query is None:
-            raise SynapseError(
-                HTTPStatus.BAD_REQUEST,
-                "prev_event query parameter is required when inserting historical messages back in time",
-                errcode=Codes.MISSING_PARAM,
-            )
-
-        if await self.store.is_partial_state_room(room_id):
-            raise SynapseError(
-                HTTPStatus.BAD_REQUEST,
-                "Cannot insert history batches until we have fully joined the room",
-                errcode=Codes.UNABLE_DUE_TO_PARTIAL_STATE,
-            )
-
-        # Verify the batch_id_from_query corresponds to an actual insertion event
-        # and have the batch connected.
-        if batch_id_from_query:
-            corresponding_insertion_event_id = (
-                await self.store.get_insertion_event_id_by_batch_id(
-                    room_id, batch_id_from_query
-                )
-            )
-            if corresponding_insertion_event_id is None:
-                raise SynapseError(
-                    HTTPStatus.BAD_REQUEST,
-                    "No insertion event corresponds to the given ?batch_id",
-                    errcode=Codes.INVALID_PARAM,
-                )
-
-        # Make sure that the prev_event_ids exist and aren't outliers - ie, they are
-        # regular parts of the room DAG where we know the state.
-        non_outlier_prev_events = await self.store.have_events_in_timeline(
-            prev_event_ids_from_query
-        )
-        for prev_event_id in prev_event_ids_from_query:
-            if prev_event_id not in non_outlier_prev_events:
-                raise SynapseError(
-                    HTTPStatus.BAD_REQUEST,
-                    "prev_event %s does not exist, or is an outlier" % (prev_event_id,),
-                    errcode=Codes.INVALID_PARAM,
-                )
-
-        # For the event we are inserting next to (`prev_event_ids_from_query`),
-        # find the most recent state events that allowed that message to be
-        # sent. We will use that as a base to auth our historical messages
-        # against.
-        state_event_ids = await self.room_batch_handler.get_most_recent_full_state_ids_from_event_id_list(
-            prev_event_ids_from_query
-        )
-
-        state_event_ids_at_start = []
-        # Create and persist all of the state events that float off on their own
-        # before the batch. These will most likely be all of the invite/member
-        # state events used to auth the upcoming historical messages.
-        if body["state_events_at_start"]:
-            state_event_ids_at_start = (
-                await self.room_batch_handler.persist_state_events_at_start(
-                    state_events_at_start=body["state_events_at_start"],
-                    room_id=room_id,
-                    initial_state_event_ids=state_event_ids,
-                    app_service_requester=requester,
-                )
-            )
-            # Update our ongoing auth event ID list with all of the new state we
-            # just created
-            state_event_ids.extend(state_event_ids_at_start)
-
-        inherited_depth = await self.room_batch_handler.inherit_depth_from_prev_ids(
-            prev_event_ids_from_query
-        )
-
-        events_to_create = body["events"]
-
-        # Figure out which batch to connect to. If they passed in
-        # batch_id_from_query let's use it. The batch ID passed in comes
-        # from the batch_id in the "insertion" event from the previous batch.
-        last_event_in_batch = events_to_create[-1]
-        base_insertion_event = None
-        if batch_id_from_query:
-            batch_id_to_connect_to = batch_id_from_query
-        # Otherwise, create an insertion event to act as a starting point.
-        #
-        # We don't always have an insertion event to start hanging more history
-        # off of (ideally there would be one in the main DAG, but that's not the
-        # case if we're wanting to add history to e.g. existing rooms without
-        # an insertion event), in which case we just create a new insertion event
-        # that can then get pointed to by a "marker" event later.
-        else:
-            base_insertion_event_dict = (
-                self.room_batch_handler.create_insertion_event_dict(
-                    sender=requester.user.to_string(),
-                    room_id=room_id,
-                    origin_server_ts=last_event_in_batch["origin_server_ts"],
-                )
-            )
-            base_insertion_event_dict["prev_events"] = prev_event_ids_from_query.copy()
-
-            (
-                base_insertion_event,
-                _,
-            ) = await self.event_creation_handler.create_and_send_nonmember_event(
-                await self.room_batch_handler.create_requester_for_user_id_from_app_service(
-                    base_insertion_event_dict["sender"],
-                    requester.app_service,
-                ),
-                base_insertion_event_dict,
-                prev_event_ids=base_insertion_event_dict.get("prev_events"),
-                # Also set the explicit state here because we want to resolve
-                # any `state_events_at_start` here too. It's not strictly
-                # necessary to accomplish anything but if someone asks for the
-                # state at this point, we probably want to show them the
-                # historical state that was part of this batch.
-                state_event_ids=state_event_ids,
-                historical=True,
-                depth=inherited_depth,
-            )
-
-            batch_id_to_connect_to = base_insertion_event.content[
-                EventContentFields.MSC2716_NEXT_BATCH_ID
-            ]
-
-        # Create and persist all of the historical events as well as insertion
-        # and batch meta events to make the batch navigable in the DAG.
-        event_ids, next_batch_id = await self.room_batch_handler.handle_batch_of_events(
-            events_to_create=events_to_create,
-            room_id=room_id,
-            batch_id_to_connect_to=batch_id_to_connect_to,
-            inherited_depth=inherited_depth,
-            initial_state_event_ids=state_event_ids,
-            app_service_requester=requester,
-        )
-
-        insertion_event_id = event_ids[0]
-        batch_event_id = event_ids[-1]
-        historical_event_ids = event_ids[1:-1]
-
-        response_dict = {
-            "state_event_ids": state_event_ids_at_start,
-            "event_ids": historical_event_ids,
-            "next_batch_id": next_batch_id,
-            "insertion_event_id": insertion_event_id,
-            "batch_event_id": batch_event_id,
-        }
-        if base_insertion_event is not None:
-            response_dict["base_insertion_event_id"] = base_insertion_event.event_id
-
-        return HTTPStatus.OK, response_dict
-
-
-def register_servlets(hs: "HomeServer", http_server: HttpServer) -> None:
-    msc2716_enabled = hs.config.experimental.msc2716_enabled
-
-    if msc2716_enabled:
-        RoomBatchSendEventRestServlet(hs).register(http_server)
diff --git a/synapse/rest/client/versions.py b/synapse/rest/client/versions.py
index 1910648755..95400ba570 100644
--- a/synapse/rest/client/versions.py
+++ b/synapse/rest/client/versions.py
@@ -102,8 +102,6 @@ class VersionsRestServlet(RestServlet):
                     "org.matrix.msc2285.stable": True,  # TODO: Remove when MSC2285 becomes a part of the spec
                     # Supports filtering of /publicRooms by room type as per MSC3827
                     "org.matrix.msc3827.stable": True,
-                    # Adds support for importing historical messages as per MSC2716
-                    "org.matrix.msc2716": self.config.experimental.msc2716_enabled,
                     # Adds support for thread relations, per MSC3440.
                     "org.matrix.msc3440.stable": True,  # TODO: remove when "v1.3" is added above
                     # Support for thread read receipts & notification counts.