synapse-product/synapse/replication/http/send_event.py
Erik Johnston 1531b214fc
Add ability to wait for replication streams (#7542)
The idea here is that if an instance persists an event via the replication HTTP API it can return before we receive that event over replication, which can lead to races where code assumes that persisting an event immediately updates various caches (e.g. current state of the room).

Most of Synapse doesn't hit such races, so we don't do the waiting automagically, instead we do so where necessary to avoid unnecessary delays. We may decide to change our minds here if it turns out there are a lot of subtle races going on.

People probably want to look at this commit by commit.
2020-05-22 14:21:54 +01:00

131 lines
4.6 KiB
Python

# -*- coding: utf-8 -*-
# Copyright 2018 New Vector 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
from twisted.internet import defer
from synapse.api.room_versions import KNOWN_ROOM_VERSIONS
from synapse.events import make_event_from_dict
from synapse.events.snapshot import EventContext
from synapse.http.servlet import parse_json_object_from_request
from synapse.replication.http._base import ReplicationEndpoint
from synapse.types import Requester, UserID
from synapse.util.metrics import Measure
logger = logging.getLogger(__name__)
class ReplicationSendEventRestServlet(ReplicationEndpoint):
"""Handles events newly created on workers, including persisting and
notifying.
The API looks like:
POST /_synapse/replication/send_event/:event_id/:txn_id
{
"event": { .. serialized event .. },
"room_version": .., // "1", "2", "3", etc: the version of the room
// containing the event
"event_format_version": .., // 1,2,3 etc: the event format version
"internal_metadata": { .. serialized internal_metadata .. },
"rejected_reason": .., // The event.rejected_reason field
"context": { .. serialized event context .. },
"requester": { .. serialized requester .. },
"ratelimit": true,
"extra_users": [],
}
"""
NAME = "send_event"
PATH_ARGS = ("event_id",)
def __init__(self, hs):
super(ReplicationSendEventRestServlet, self).__init__(hs)
self.event_creation_handler = hs.get_event_creation_handler()
self.store = hs.get_datastore()
self.storage = hs.get_storage()
self.clock = hs.get_clock()
@staticmethod
@defer.inlineCallbacks
def _serialize_payload(
event_id, store, event, context, requester, ratelimit, extra_users
):
"""
Args:
event_id (str)
store (DataStore)
requester (Requester)
event (FrozenEvent)
context (EventContext)
ratelimit (bool)
extra_users (list(UserID)): Any extra users to notify about event
"""
serialized_context = yield context.serialize(event, store)
payload = {
"event": event.get_pdu_json(),
"room_version": event.room_version.identifier,
"event_format_version": event.format_version,
"internal_metadata": event.internal_metadata.get_dict(),
"rejected_reason": event.rejected_reason,
"context": serialized_context,
"requester": requester.serialize(),
"ratelimit": ratelimit,
"extra_users": [u.to_string() for u in extra_users],
}
return payload
async def _handle_request(self, request, event_id):
with Measure(self.clock, "repl_send_event_parse"):
content = parse_json_object_from_request(request)
event_dict = content["event"]
room_ver = KNOWN_ROOM_VERSIONS[content["room_version"]]
internal_metadata = content["internal_metadata"]
rejected_reason = content["rejected_reason"]
event = make_event_from_dict(
event_dict, room_ver, internal_metadata, rejected_reason
)
requester = Requester.deserialize(self.store, content["requester"])
context = EventContext.deserialize(self.storage, content["context"])
ratelimit = content["ratelimit"]
extra_users = [UserID.from_string(u) for u in content["extra_users"]]
if requester.user:
request.authenticated_entity = requester.user.to_string()
logger.info(
"Got event to send with ID: %s into room: %s", event.event_id, event.room_id
)
stream_id = await self.event_creation_handler.persist_and_notify_client_event(
requester, event, context, ratelimit=ratelimit, extra_users=extra_users
)
return 200, {"stream_id": stream_id}
def register_servlets(hs, http_server):
ReplicationSendEventRestServlet(hs).register(http_server)