forked-synapse/synapse/replication/tcp/streams/events.py
Richard van der Hoff 67ff7b8ba0
Improve type checking in replication.tcp.Stream (#7291)
The general idea here is to get rid of the type: ignore annotations on all of the current_token and update_function assignments, which would have caught #7290.

After a bit of experimentation, it seems like the least-awful way to do this is to pass the offending functions in as parameters to the Stream constructor. Unfortunately that means that the concrete implementations no longer have the same constructor signature as Stream itself, which means that it gets hard to correctly annotate STREAMS_MAP.

I've also introduced a couple of new types, to take out some duplication.
2020-04-17 14:49:55 +01:00

150 lines
4.4 KiB
Python

# -*- coding: utf-8 -*-
# Copyright 2017 Vector Creations Ltd
# Copyright 2019 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 heapq
from typing import Iterable, Tuple, Type
import attr
from ._base import Stream, Token, db_query_to_update_function
"""Handling of the 'events' replication stream
This stream contains rows of various types. Each row therefore contains a 'type'
identifier before the real data. For example::
RDATA events batch ["state", ["!room:id", "m.type", "", "$event:id"]]
RDATA events 12345 ["ev", ["$event:id", "!room:id", "m.type", null, null]]
An "ev" row is sent for each new event. The fields in the data part are:
* The new event id
* The room id for the event
* The type of the new event
* The state key of the event, for state events
* The event id of an event which is redacted by this event.
A "state" row is sent whenever the "current state" in a room changes. The fields in the
data part are:
* The room id for the state change
* The event type of the state which has changed
* The state_key of the state which has changed
* The event id of the new state
"""
@attr.s(slots=True, frozen=True)
class EventsStreamRow(object):
"""A parsed row from the events replication stream"""
type = attr.ib() # str: the TypeId of one of the *EventsStreamRows
data = attr.ib() # BaseEventsStreamRow
class BaseEventsStreamRow(object):
"""Base class for rows to be sent in the events stream.
Specifies how to identify, serialize and deserialize the different types.
"""
# Unique string that ids the type. Must be overriden in sub classes.
TypeId = None # type: str
@classmethod
def from_data(cls, data):
"""Parse the data from the replication stream into a row.
By default we just call the constructor with the data list as arguments
Args:
data: The value of the data object from the replication stream
"""
return cls(*data)
@attr.s(slots=True, frozen=True)
class EventsStreamEventRow(BaseEventsStreamRow):
TypeId = "ev"
event_id = attr.ib() # str
room_id = attr.ib() # str
type = attr.ib() # str
state_key = attr.ib() # str, optional
redacts = attr.ib() # str, optional
relates_to = attr.ib() # str, optional
@attr.s(slots=True, frozen=True)
class EventsStreamCurrentStateRow(BaseEventsStreamRow):
TypeId = "state"
room_id = attr.ib() # str
type = attr.ib() # str
state_key = attr.ib() # str
event_id = attr.ib() # str, optional
_EventRows = (
EventsStreamEventRow,
EventsStreamCurrentStateRow,
) # type: Tuple[Type[BaseEventsStreamRow], ...]
TypeToRow = {Row.TypeId: Row for Row in _EventRows}
class EventsStream(Stream):
"""We received a new event, or an event went from being an outlier to not
"""
NAME = "events"
def __init__(self, hs):
self._store = hs.get_datastore()
super().__init__(
self._store.get_current_events_token,
db_query_to_update_function(self._update_function),
)
async def _update_function(
self, from_token: Token, current_token: Token, limit: int
) -> Iterable[tuple]:
event_rows = await self._store.get_all_new_forward_event_rows(
from_token, current_token, limit
)
event_updates = (
(row[0], EventsStreamEventRow.TypeId, row[1:]) for row in event_rows
)
state_rows = await self._store.get_all_updated_current_state_deltas(
from_token, current_token, limit
)
state_updates = (
(row[0], EventsStreamCurrentStateRow.TypeId, row[1:]) for row in state_rows
)
all_updates = heapq.merge(event_updates, state_updates)
return all_updates
@classmethod
def parse_row(cls, row):
(typ, data) = row
data = TypeToRow[typ].from_data(data)
return EventsStreamRow(typ, data)