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- # 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, Dict, List, Optional, Tuple
- import attr
- from immutabledict import immutabledict
- from synapse.appservice import ApplicationService
- from synapse.events import EventBase
- from synapse.logging.opentracing import tag_args, trace
- 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.
- state_group_deltas: If not empty, this is a dict collecting a mapping of the state
- difference between state groups.
- The keys are a tuple of two integers: the initial group and final state group.
- The corresponding value is a state map representing the state delta between
- these state groups.
- The dictionary is expected to have at most two entries with state groups of:
- 1. The state group before the event and after the event.
- 2. The state group preceding the state group before the event and the
- state group before the event.
- This information is collected and stored as part of an optimization for persisting
- events.
- partial_state: if True, we may be storing this event with a temporary,
- incomplete state.
- """
- _storage: "StorageControllers"
- state_group_deltas: Dict[Tuple[int, int], StateMap[str]]
- 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
- 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,
- state_group_deltas: Dict[Tuple[int, int], StateMap[str]],
- ) -> "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,
- state_group_deltas=state_group_deltas,
- 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, state_group_deltas={})
- 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,
- "state_group_deltas": _encode_state_group_delta(self.state_group_deltas),
- "state_delta_due_to_event": _encode_state_dict(
- self._state_delta_due_to_event
- ),
- "app_service_id": self.app_service.id if self.app_service else None,
- "partial_state": self.partial_state,
- # add dummy delta_ids and prev_group for backwards compatibility
- "delta_ids": None,
- "prev_group": None,
- }
- @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.
- """
- # workaround for backwards/forwards compatibility: if the input doesn't have a value
- # for "state_group_deltas" just assign an empty dict
- state_group_deltas = input.get("state_group_deltas", None)
- if state_group_deltas:
- state_group_deltas = _decode_state_group_delta(state_group_deltas)
- else:
- state_group_deltas = {}
- 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"],
- state_group_deltas=state_group_deltas,
- state_delta_due_to_event=_decode_state_dict(
- input["state_delta_due_to_event"]
- ),
- 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
- @trace
- @tag_args
- 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
- @trace
- @tag_args
- 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[StateMap[str]]
- 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:
- state_group_deltas = unpersisted_context._build_state_group_deltas()
- 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,
- state_group_deltas=state_group_deltas,
- )
- 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:
- self.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:
- self.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,
- )
- state_group_deltas = self._build_state_group_deltas()
- return EventContext.with_state(
- storage=self._storage,
- state_group=self.state_group_after_event,
- state_group_before_event=self.state_group_before_event,
- state_delta_due_to_event=self.state_delta_due_to_event,
- state_group_deltas=state_group_deltas,
- partial_state=self.partial_state,
- )
- def _build_state_group_deltas(self) -> Dict[Tuple[int, int], StateMap]:
- """
- Collect deltas between the state groups associated with this context
- """
- state_group_deltas = {}
- # if we know the state group before the event and after the event, add them and the
- # state delta between them to state_group_deltas
- if self.state_group_before_event and self.state_group_after_event:
- # if we have the state groups we should have the delta
- assert self.state_delta_due_to_event is not None
- state_group_deltas[
- (
- self.state_group_before_event,
- self.state_group_after_event,
- )
- ] = self.state_delta_due_to_event
- # the state group before the event may also have a state group which precedes it, if
- # we have that and the state group before the event, add them and the state
- # delta between them to state_group_deltas
- if (
- self.prev_group_for_state_group_before_event
- and self.state_group_before_event
- ):
- # if we have both state groups we should have the delta between them
- assert self.delta_ids_to_state_group_before_event is not None
- state_group_deltas[
- (
- self.prev_group_for_state_group_before_event,
- self.state_group_before_event,
- )
- ] = self.delta_ids_to_state_group_before_event
- return state_group_deltas
- def _encode_state_group_delta(
- state_group_delta: Dict[Tuple[int, int], StateMap[str]]
- ) -> List[Tuple[int, int, Optional[List[Tuple[str, str, str]]]]]:
- if not state_group_delta:
- return []
- state_group_delta_encoded = []
- for key, value in state_group_delta.items():
- state_group_delta_encoded.append((key[0], key[1], _encode_state_dict(value)))
- return state_group_delta_encoded
- def _decode_state_group_delta(
- input: List[Tuple[int, int, List[Tuple[str, str, str]]]]
- ) -> Dict[Tuple[int, int], StateMap[str]]:
- if not input:
- return {}
- state_group_deltas = {}
- for state_group_1, state_group_2, state_dict in input:
- state_map = _decode_state_dict(state_dict)
- assert state_map is not None
- state_group_deltas[(state_group_1, state_group_2)] = state_map
- return state_group_deltas
- 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})
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