# Copyright 2014-2016 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. from abc import ABC, abstractmethod from typing import TYPE_CHECKING, List, Optional, Tuple import attr from immutabledict import immutabledict from synapse.appservice import ApplicationService from synapse.events import EventBase from synapse.types import JsonDict, StateMap if TYPE_CHECKING: from synapse.storage.controllers import StorageControllers from synapse.storage.databases import StateGroupDataStore from synapse.storage.databases.main import DataStore from synapse.types.state import StateFilter class UnpersistedEventContextBase(ABC): """ This is a base class for EventContext and UnpersistedEventContext, objects which hold information relevant to storing an associated event. Note that an UnpersistedEventContexts must be converted into an EventContext before it is suitable to send to the db with its associated event. Attributes: _storage: storage controllers for interfacing with the database app_service: If the associated event is being sent by a (local) application service, that app service. """ def __init__(self, storage_controller: "StorageControllers"): self._storage: "StorageControllers" = storage_controller self.app_service: Optional[ApplicationService] = None @abstractmethod async def persist( self, event: EventBase, ) -> "EventContext": """ A method to convert an UnpersistedEventContext to an EventContext, suitable for sending to the database with the associated event. """ pass @abstractmethod async def get_prev_state_ids( self, state_filter: Optional["StateFilter"] = None ) -> StateMap[str]: """ Gets the room state at the event (ie not including the event if the event is a state event). Args: state_filter: specifies the type of state event to fetch from DB, example: EventTypes.JoinRules """ pass @attr.s(slots=True, auto_attribs=True) class EventContext(UnpersistedEventContextBase): """ Holds information relevant to persisting an event Attributes: rejected: A rejection reason if the event was rejected, else None _state_group: The ID of the state group for this event. Note that state events are persisted with a state group which includes the new event, so this is effectively the state *after* the event in question. For a *rejected* state event, where the state of the rejected event is ignored, this state_group should never make it into the event_to_state_groups table. Indeed, inspecting this value for a rejected state event is almost certainly incorrect. For an outlier, where we don't have the state at the event, this will be None. Note that this is a private attribute: it should be accessed via the ``state_group`` property. state_group_before_event: The ID of the state group representing the state of the room before this event. If this is a non-state event, this will be the same as ``state_group``. If it's a state event, it will be the same as ``prev_group``. If ``state_group`` is None (ie, the event is an outlier), ``state_group_before_event`` will always also be ``None``. state_delta_due_to_event: If `state_group` and `state_group_before_event` are not None then this is the delta of the state between the two groups. prev_group: If it is known, ``state_group``'s prev_group. Note that this being None does not necessarily mean that ``state_group`` does not have a prev_group! If the event is a state event, this is normally the same as ``state_group_before_event``. If ``state_group`` is None (ie, the event is an outlier), ``prev_group`` will always also be ``None``. Note that this *not* (necessarily) the state group associated with ``_prev_state_ids``. delta_ids: If ``prev_group`` is not None, the state delta between ``prev_group`` and ``state_group``. partial_state: if True, we may be storing this event with a temporary, incomplete state. """ _storage: "StorageControllers" rejected: Optional[str] = None _state_group: Optional[int] = None state_group_before_event: Optional[int] = None _state_delta_due_to_event: Optional[StateMap[str]] = None prev_group: Optional[int] = None delta_ids: Optional[StateMap[str]] = None app_service: Optional[ApplicationService] = None partial_state: bool = False @staticmethod def with_state( storage: "StorageControllers", state_group: Optional[int], state_group_before_event: Optional[int], state_delta_due_to_event: Optional[StateMap[str]], partial_state: bool, prev_group: Optional[int] = None, delta_ids: Optional[StateMap[str]] = None, ) -> "EventContext": return EventContext( storage=storage, state_group=state_group, state_group_before_event=state_group_before_event, state_delta_due_to_event=state_delta_due_to_event, prev_group=prev_group, delta_ids=delta_ids, partial_state=partial_state, ) @staticmethod def for_outlier( storage: "StorageControllers", ) -> "EventContext": """Return an EventContext instance suitable for persisting an outlier event""" return EventContext(storage=storage) async def persist(self, event: EventBase) -> "EventContext": return self async def serialize(self, event: EventBase, store: "DataStore") -> JsonDict: """Converts self to a type that can be serialized as JSON, and then deserialized by `deserialize` Args: event: The event that this context relates to Returns: The serialized event. """ return { "state_group": self._state_group, "state_group_before_event": self.state_group_before_event, "rejected": self.rejected, "prev_group": self.prev_group, "state_delta_due_to_event": _encode_state_dict( self._state_delta_due_to_event ), "delta_ids": _encode_state_dict(self.delta_ids), "app_service_id": self.app_service.id if self.app_service else None, "partial_state": self.partial_state, } @staticmethod def deserialize(storage: "StorageControllers", input: JsonDict) -> "EventContext": """Converts a dict that was produced by `serialize` back into a EventContext. Args: storage: Used to convert AS ID to AS object and fetch state. input: A dict produced by `serialize` Returns: The event context. """ context = EventContext( # We use the state_group and prev_state_id stuff to pull the # current_state_ids out of the DB and construct prev_state_ids. storage=storage, state_group=input["state_group"], state_group_before_event=input["state_group_before_event"], prev_group=input["prev_group"], state_delta_due_to_event=_decode_state_dict( input["state_delta_due_to_event"] ), delta_ids=_decode_state_dict(input["delta_ids"]), rejected=input["rejected"], partial_state=input.get("partial_state", False), ) app_service_id = input["app_service_id"] if app_service_id: context.app_service = storage.main.get_app_service_by_id(app_service_id) return context @property def state_group(self) -> Optional[int]: """The ID of the state group for this event. Note that state events are persisted with a state group which includes the new event, so this is effectively the state *after* the event in question. For an outlier, where we don't have the state at the event, this will be None. It is an error to access this for a rejected event, since rejected state should not make it into the room state. Accessing this property will raise an exception if ``rejected`` is set. """ if self.rejected: raise RuntimeError("Attempt to access state_group of rejected event") return self._state_group async def get_current_state_ids( self, state_filter: Optional["StateFilter"] = None ) -> Optional[StateMap[str]]: """ Gets the room state map, including this event - ie, the state in ``state_group`` It is an error to access this for a rejected event, since rejected state should not make it into the room state. This method will raise an exception if ``rejected`` is set. Arg: state_filter: specifies the type of state event to fetch from DB, example: EventTypes.JoinRules Returns: Returns None if state_group is None, which happens when the associated event is an outlier. Maps a (type, state_key) to the event ID of the state event matching this tuple. """ if self.rejected: raise RuntimeError("Attempt to access state_ids of rejected event") assert self._state_delta_due_to_event is not None prev_state_ids = await self.get_prev_state_ids(state_filter) if self._state_delta_due_to_event: prev_state_ids = dict(prev_state_ids) prev_state_ids.update(self._state_delta_due_to_event) return prev_state_ids async def get_prev_state_ids( self, state_filter: Optional["StateFilter"] = None ) -> StateMap[str]: """ Gets the room state map, excluding this event. For a non-state event, this will be the same as get_current_state_ids(). Args: state_filter: specifies the type of state event to fetch from DB, example: EventTypes.JoinRules Returns: Returns {} if state_group is None, which happens when the associated event is an outlier. Maps a (type, state_key) to the event ID of the state event matching this tuple. """ assert self.state_group_before_event is not None return await self._storage.state.get_state_ids_for_group( self.state_group_before_event, state_filter ) @attr.s(slots=True, auto_attribs=True) class UnpersistedEventContext(UnpersistedEventContextBase): """ The event context holds information about the state groups for an event. It is important to remember that an event technically has two state groups: the state group before the event, and the state group after the event. If the event is not a state event, the state group will not change (ie the state group before the event will be the same as the state group after the event), but if it is a state event the state group before the event will differ from the state group after the event. This is a version of an EventContext before the new state group (if any) has been computed and stored. It contains information about the state before the event (which also may be the information after the event, if the event is not a state event). The UnpersistedEventContext must be converted into an EventContext by calling the method 'persist' on it before it is suitable to be sent to the DB for processing. state_group_after_event: The state group after the event. This will always be None until it is persisted. If the event is not a state event, this will be the same as state_group_before_event. state_group_before_event: The ID of the state group representing the state of the room before this event. state_delta_due_to_event: If the event is a state event, then this is the delta of the state between `state_group` and `state_group_before_event` prev_group_for_state_group_before_event: If it is known, ``state_group_before_event``'s previous state group. delta_ids_to_state_group_before_event: If ``prev_group_for_state_group_before_event`` is not None, the state delta between ``prev_group_for_state_group_before_event`` and ``state_group_before_event``. partial_state: Whether the event has partial state. state_map_before_event: A map of the state before the event, i.e. the state at `state_group_before_event` """ _storage: "StorageControllers" state_group_before_event: Optional[int] state_group_after_event: Optional[int] state_delta_due_to_event: Optional[dict] prev_group_for_state_group_before_event: Optional[int] delta_ids_to_state_group_before_event: Optional[StateMap[str]] partial_state: bool state_map_before_event: Optional[StateMap[str]] = None @classmethod async def batch_persist_unpersisted_contexts( cls, events_and_context: List[Tuple[EventBase, "UnpersistedEventContextBase"]], room_id: str, last_known_state_group: int, datastore: "StateGroupDataStore", ) -> List[Tuple[EventBase, EventContext]]: """ Takes a list of events and their associated unpersisted contexts and persists the unpersisted contexts, returning a list of events and persisted contexts. Note that all the events must be in a linear chain (ie a <- b <- c). Args: events_and_context: A list of events and their unpersisted contexts room_id: the room_id for the events last_known_state_group: the last persisted state group datastore: a state datastore """ amended_events_and_context = await datastore.store_state_deltas_for_batched( events_and_context, room_id, last_known_state_group ) events_and_persisted_context = [] for event, unpersisted_context in amended_events_and_context: if event.is_state(): context = EventContext( storage=unpersisted_context._storage, state_group=unpersisted_context.state_group_after_event, state_group_before_event=unpersisted_context.state_group_before_event, state_delta_due_to_event=unpersisted_context.state_delta_due_to_event, partial_state=unpersisted_context.partial_state, prev_group=unpersisted_context.state_group_before_event, delta_ids=unpersisted_context.state_delta_due_to_event, ) else: context = EventContext( storage=unpersisted_context._storage, state_group=unpersisted_context.state_group_after_event, state_group_before_event=unpersisted_context.state_group_before_event, state_delta_due_to_event=unpersisted_context.state_delta_due_to_event, partial_state=unpersisted_context.partial_state, prev_group=unpersisted_context.prev_group_for_state_group_before_event, delta_ids=unpersisted_context.delta_ids_to_state_group_before_event, ) events_and_persisted_context.append((event, context)) return events_and_persisted_context async def get_prev_state_ids( self, state_filter: Optional["StateFilter"] = None ) -> StateMap[str]: """ Gets the room state map, excluding this event. Args: state_filter: specifies the type of state event to fetch from DB Returns: Maps a (type, state_key) to the event ID of the state event matching this tuple. """ if self.state_map_before_event: return self.state_map_before_event assert self.state_group_before_event is not None return await self._storage.state.get_state_ids_for_group( self.state_group_before_event, state_filter ) async def persist(self, event: EventBase) -> EventContext: """ Creates a full `EventContext` for the event, persisting any referenced state that has not yet been persisted. Args: event: event that the EventContext is associated with. Returns: An EventContext suitable for sending to the database with the event for persisting """ assert self.partial_state is not None # If we have a full set of state for before the event but don't have a state # group for that state, we need to get one if self.state_group_before_event is None: assert self.state_map_before_event state_group_before_event = await self._storage.state.store_state_group( event.event_id, event.room_id, prev_group=self.prev_group_for_state_group_before_event, delta_ids=self.delta_ids_to_state_group_before_event, current_state_ids=self.state_map_before_event, ) self.state_group_before_event = state_group_before_event # if the event isn't a state event the state group doesn't change if not self.state_delta_due_to_event: state_group_after_event = self.state_group_before_event # otherwise if it is a state event we need to get a state group for it else: state_group_after_event = await self._storage.state.store_state_group( event.event_id, event.room_id, prev_group=self.state_group_before_event, delta_ids=self.state_delta_due_to_event, current_state_ids=None, ) return EventContext.with_state( storage=self._storage, state_group=state_group_after_event, state_group_before_event=self.state_group_before_event, state_delta_due_to_event=self.state_delta_due_to_event, partial_state=self.partial_state, prev_group=self.state_group_before_event, delta_ids=self.state_delta_due_to_event, ) def _encode_state_dict( state_dict: Optional[StateMap[str]], ) -> Optional[List[Tuple[str, str, str]]]: """Since dicts of (type, state_key) -> event_id cannot be serialized in JSON we need to convert them to a form that can. """ if state_dict is None: return None return [(etype, state_key, v) for (etype, state_key), v in state_dict.items()] def _decode_state_dict( input: Optional[List[Tuple[str, str, str]]] ) -> Optional[StateMap[str]]: """Decodes a state dict encoded using `_encode_state_dict` above""" if input is None: return None return immutabledict({(etype, state_key): v for etype, state_key, v in input})