synapse-product/synapse/handlers/relations.py

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# Copyright 2021 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.
import logging
from typing import TYPE_CHECKING, Dict, Iterable, Optional, cast
import attr
from frozendict import frozendict
from synapse.api.constants import RelationTypes
from synapse.api.errors import SynapseError
from synapse.events import EventBase
from synapse.types import JsonDict, Requester, StreamToken
if TYPE_CHECKING:
from synapse.server import HomeServer
from synapse.storage.databases.main import DataStore
logger = logging.getLogger(__name__)
@attr.s(slots=True, frozen=True, auto_attribs=True)
class _ThreadAggregation:
# The latest event in the thread.
latest_event: EventBase
# The latest edit to the latest event in the thread.
latest_edit: Optional[EventBase]
# The total number of events in the thread.
count: int
# True if the current user has sent an event to the thread.
current_user_participated: bool
@attr.s(slots=True, auto_attribs=True)
class BundledAggregations:
"""
The bundled aggregations for an event.
Some values require additional processing during serialization.
"""
annotations: Optional[JsonDict] = None
references: Optional[JsonDict] = None
replace: Optional[EventBase] = None
thread: Optional[_ThreadAggregation] = None
def __bool__(self) -> bool:
return bool(self.annotations or self.references or self.replace or self.thread)
class RelationsHandler:
def __init__(self, hs: "HomeServer"):
self._main_store = hs.get_datastores().main
self._auth = hs.get_auth()
self._clock = hs.get_clock()
self._event_handler = hs.get_event_handler()
self._event_serializer = hs.get_event_client_serializer()
async def get_relations(
self,
requester: Requester,
event_id: str,
room_id: str,
relation_type: Optional[str] = None,
event_type: Optional[str] = None,
aggregation_key: Optional[str] = None,
limit: int = 5,
direction: str = "b",
from_token: Optional[StreamToken] = None,
to_token: Optional[StreamToken] = None,
) -> JsonDict:
"""Get related events of a event, ordered by topological ordering.
TODO Accept a PaginationConfig instead of individual pagination parameters.
Args:
requester: The user requesting the relations.
event_id: Fetch events that relate to this event ID.
room_id: The room the event belongs to.
relation_type: Only fetch events with this relation type, if given.
event_type: Only fetch events with this event type, if given.
aggregation_key: Only fetch events with this aggregation key, if given.
limit: Only fetch the most recent `limit` events.
direction: Whether to fetch the most recent first (`"b"`) or the
oldest first (`"f"`).
from_token: Fetch rows from the given token, or from the start if None.
to_token: Fetch rows up to the given token, or up to the end if None.
Returns:
The pagination chunk.
"""
user_id = requester.user.to_string()
await self._auth.check_user_in_room_or_world_readable(
room_id, user_id, allow_departed_users=True
)
# This gets the original event and checks that a) the event exists and
# b) the user is allowed to view it.
event = await self._event_handler.get_event(requester.user, room_id, event_id)
if event is None:
raise SynapseError(404, "Unknown parent event.")
pagination_chunk = await self._main_store.get_relations_for_event(
event_id=event_id,
event=event,
room_id=room_id,
relation_type=relation_type,
event_type=event_type,
aggregation_key=aggregation_key,
limit=limit,
direction=direction,
from_token=from_token,
to_token=to_token,
)
events = await self._main_store.get_events_as_list(
[c["event_id"] for c in pagination_chunk.chunk]
)
now = self._clock.time_msec()
# Do not bundle aggregations when retrieving the original event because
# we want the content before relations are applied to it.
original_event = self._event_serializer.serialize_event(
event, now, bundle_aggregations=None
)
# The relations returned for the requested event do include their
# bundled aggregations.
aggregations = await self.get_bundled_aggregations(
events, requester.user.to_string()
)
serialized_events = self._event_serializer.serialize_events(
events, now, bundle_aggregations=aggregations
)
return_value = await pagination_chunk.to_dict(self._main_store)
return_value["chunk"] = serialized_events
return_value["original_event"] = original_event
return return_value
async def _get_bundled_aggregation_for_event(
self, event: EventBase, user_id: str
) -> Optional[BundledAggregations]:
"""Generate bundled aggregations for an event.
Note that this does not use a cache, but depends on cached methods.
Args:
event: The event to calculate bundled aggregations for.
user_id: The user requesting the bundled aggregations.
Returns:
The bundled aggregations for an event, if bundled aggregations are
enabled and the event can have bundled aggregations.
"""
# Do not bundle aggregations for an event which represents an edit or an
# annotation. It does not make sense for them to have related events.
relates_to = event.content.get("m.relates_to")
if isinstance(relates_to, (dict, frozendict)):
relation_type = relates_to.get("rel_type")
if relation_type in (RelationTypes.ANNOTATION, RelationTypes.REPLACE):
return None
event_id = event.event_id
room_id = event.room_id
# The bundled aggregations to include, a mapping of relation type to a
# type-specific value. Some types include the direct return type here
# while others need more processing during serialization.
aggregations = BundledAggregations()
annotations = await self._main_store.get_aggregation_groups_for_event(
event_id, room_id
)
if annotations.chunk:
aggregations.annotations = await annotations.to_dict(
cast("DataStore", self)
)
references = await self._main_store.get_relations_for_event(
event_id, event, room_id, RelationTypes.REFERENCE, direction="f"
)
if references.chunk:
aggregations.references = await references.to_dict(cast("DataStore", self))
# Store the bundled aggregations in the event metadata for later use.
return aggregations
async def get_bundled_aggregations(
self, events: Iterable[EventBase], user_id: str
) -> Dict[str, BundledAggregations]:
"""Generate bundled aggregations for events.
Args:
events: The iterable of events to calculate bundled aggregations for.
user_id: The user requesting the bundled aggregations.
Returns:
A map of event ID to the bundled aggregation for the event. Not all
events may have bundled aggregations in the results.
"""
# De-duplicate events by ID to handle the same event requested multiple times.
#
# State events do not get bundled aggregations.
events_by_id = {
event.event_id: event for event in events if not event.is_state()
}
# event ID -> bundled aggregation in non-serialized form.
results: Dict[str, BundledAggregations] = {}
# Fetch other relations per event.
for event in events_by_id.values():
event_result = await self._get_bundled_aggregation_for_event(event, user_id)
if event_result:
results[event.event_id] = event_result
# Fetch any edits (but not for redacted events).
edits = await self._main_store.get_applicable_edits(
[
event_id
for event_id, event in events_by_id.items()
if not event.internal_metadata.is_redacted()
]
)
for event_id, edit in edits.items():
results.setdefault(event_id, BundledAggregations()).replace = edit
# Fetch thread summaries.
summaries = await self._main_store.get_thread_summaries(events_by_id.keys())
# Only fetch participated for a limited selection based on what had
# summaries.
participated = await self._main_store.get_threads_participated(
[event_id for event_id, summary in summaries.items() if summary], user_id
)
for event_id, summary in summaries.items():
if summary:
thread_count, latest_thread_event, edit = summary
results.setdefault(
event_id, BundledAggregations()
).thread = _ThreadAggregation(
latest_event=latest_thread_event,
latest_edit=edit,
count=thread_count,
# If there's a thread summary it must also exist in the
# participated dictionary.
current_user_participated=participated[event_id],
)
return results