MatrixSynapse/synapse/storage/state.py

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2016-01-07 05:26:29 +01:00
# Copyright 2014-2016 OpenMarket Ltd
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#
# 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,
Awaitable,
Collection,
Dict,
Iterable,
List,
Mapping,
Optional,
Set,
Tuple,
TypeVar,
)
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import attr
from frozendict import frozendict
from synapse.api.constants import EventTypes
from synapse.events import EventBase
from synapse.types import MutableStateMap, StateKey, StateMap
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if TYPE_CHECKING:
from typing import FrozenSet # noqa: used within quoted type hint; flake8 sad
from synapse.server import HomeServer
from synapse.storage.databases import Databases
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logger = logging.getLogger(__name__)
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# Used for generic functions below
T = TypeVar("T")
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@attr.s(slots=True, frozen=True, auto_attribs=True)
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class StateFilter:
"""A filter used when querying for state.
Attributes:
types: Map from type to set of state keys (or None). This specifies
which state_keys for the given type to fetch from the DB. If None
then all events with that type are fetched. If the set is empty
then no events with that type are fetched.
include_others: Whether to fetch events with types that do not
appear in `types`.
"""
types: "frozendict[str, Optional[FrozenSet[str]]]"
include_others: bool = False
def __attrs_post_init__(self):
# If `include_others` is set we canonicalise the filter by removing
# wildcards from the types dictionary
if self.include_others:
# this is needed to work around the fact that StateFilter is frozen
object.__setattr__(
self,
"types",
frozendict({k: v for k, v in self.types.items() if v is not None}),
)
@staticmethod
def all() -> "StateFilter":
"""Returns a filter that fetches everything.
Returns:
The state filter.
"""
return _ALL_STATE_FILTER
@staticmethod
def none() -> "StateFilter":
"""Returns a filter that fetches nothing.
Returns:
The new state filter.
"""
return _NONE_STATE_FILTER
@staticmethod
def from_types(types: Iterable[Tuple[str, Optional[str]]]) -> "StateFilter":
"""Creates a filter that only fetches the given types
Args:
types: A list of type and state keys to fetch. A state_key of None
fetches everything for that type
Returns:
The new state filter.
"""
type_dict: Dict[str, Optional[Set[str]]] = {}
for typ, s in types:
if typ in type_dict:
if type_dict[typ] is None:
continue
if s is None:
type_dict[typ] = None
continue
type_dict.setdefault(typ, set()).add(s) # type: ignore
return StateFilter(
types=frozendict(
(k, frozenset(v) if v is not None else None)
for k, v in type_dict.items()
)
)
@staticmethod
def from_lazy_load_member_list(members: Iterable[str]) -> "StateFilter":
"""Creates a filter that returns all non-member events, plus the member
events for the given users
Args:
members: Set of user IDs
Returns:
The new state filter
"""
return StateFilter(
types=frozendict({EventTypes.Member: frozenset(members)}),
include_others=True,
)
@staticmethod
def freeze(types: Mapping[str, Optional[Collection[str]]], include_others: bool):
"""
Returns a (frozen) StateFilter with the same contents as the parameters
specified here, which can be made of mutable types.
"""
types_with_frozen_values: Dict[str, Optional[FrozenSet[str]]] = {}
for state_types, state_keys in types.items():
if state_keys is not None:
types_with_frozen_values[state_types] = frozenset(state_keys)
else:
types_with_frozen_values[state_types] = None
return StateFilter(
frozendict(types_with_frozen_values), include_others=include_others
)
def return_expanded(self) -> "StateFilter":
"""Creates a new StateFilter where type wild cards have been removed
(except for memberships). The returned filter is a superset of the
current one, i.e. anything that passes the current filter will pass
the returned filter.
This helps the caching as the DictionaryCache knows if it has *all* the
state, but does not know if it has all of the keys of a particular type,
which makes wildcard lookups expensive unless we have a complete cache.
Hence, if we are doing a wildcard lookup, populate the cache fully so
that we can do an efficient lookup next time.
Note that since we have two caches, one for membership events and one for
other events, we can be a bit more clever than simply returning
`StateFilter.all()` if `has_wildcards()` is True.
We return a StateFilter where:
1. the list of membership events to return is the same
2. if there is a wildcard that matches non-member events we
return all non-member events
Returns:
The new state filter.
"""
if self.is_full():
# If we're going to return everything then there's nothing to do
return self
if not self.has_wildcards():
# If there are no wild cards, there's nothing to do
return self
if EventTypes.Member in self.types:
get_all_members = self.types[EventTypes.Member] is None
else:
get_all_members = self.include_others
has_non_member_wildcard = self.include_others or any(
state_keys is None
for t, state_keys in self.types.items()
if t != EventTypes.Member
)
if not has_non_member_wildcard:
# If there are no non-member wild cards we can just return ourselves
return self
if get_all_members:
# We want to return everything.
return StateFilter.all()
else:
# We want to return all non-members, but only particular
# memberships
return StateFilter(
types=frozendict({EventTypes.Member: self.types[EventTypes.Member]}),
include_others=True,
)
def make_sql_filter_clause(self) -> Tuple[str, List[str]]:
"""Converts the filter to an SQL clause.
For example:
f = StateFilter.from_types([("m.room.create", "")])
clause, args = f.make_sql_filter_clause()
clause == "(type = ? AND state_key = ?)"
args == ['m.room.create', '']
Returns:
The SQL string (may be empty) and arguments. An empty SQL string is
returned when the filter matches everything (i.e. is "full").
"""
where_clause = ""
where_args: List[str] = []
if self.is_full():
return where_clause, where_args
if not self.include_others and not self.types:
# i.e. this is an empty filter, so we need to return a clause that
# will match nothing
return "1 = 2", []
# First we build up a lost of clauses for each type/state_key combo
clauses = []
for etype, state_keys in self.types.items():
if state_keys is None:
clauses.append("(type = ?)")
where_args.append(etype)
continue
for state_key in state_keys:
clauses.append("(type = ? AND state_key = ?)")
where_args.extend((etype, state_key))
# This will match anything that appears in `self.types`
where_clause = " OR ".join(clauses)
# If we want to include stuff that's not in the types dict then we add
# a `OR type NOT IN (...)` clause to the end.
if self.include_others:
if where_clause:
where_clause += " OR "
where_clause += "type NOT IN (%s)" % (",".join(["?"] * len(self.types)),)
where_args.extend(self.types)
return where_clause, where_args
def max_entries_returned(self) -> Optional[int]:
"""Returns the maximum number of entries this filter will return if
known, otherwise returns None.
For example a simple state filter asking for `("m.room.create", "")`
will return 1, whereas the default state filter will return None.
This is used to bail out early if the right number of entries have been
fetched.
"""
if self.has_wildcards():
return None
return len(self.concrete_types())
def filter_state(self, state_dict: StateMap[T]) -> MutableStateMap[T]:
"""Returns the state filtered with by this StateFilter.
Args:
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state: The state map to filter
Returns:
The filtered state map.
This is a copy, so it's safe to mutate.
"""
if self.is_full():
return dict(state_dict)
filtered_state = {}
for k, v in state_dict.items():
typ, state_key = k
if typ in self.types:
state_keys = self.types[typ]
if state_keys is None or state_key in state_keys:
filtered_state[k] = v
elif self.include_others:
filtered_state[k] = v
return filtered_state
def is_full(self) -> bool:
"""Whether this filter fetches everything or not
Returns:
True if the filter fetches everything.
"""
return self.include_others and not self.types
def has_wildcards(self) -> bool:
"""Whether the filter includes wildcards or is attempting to fetch
specific state.
Returns:
True if the filter includes wildcards.
"""
return self.include_others or any(
state_keys is None for state_keys in self.types.values()
)
def concrete_types(self) -> List[Tuple[str, str]]:
"""Returns a list of concrete type/state_keys (i.e. not None) that
will be fetched. This will be a complete list if `has_wildcards`
returns False, but otherwise will be a subset (or even empty).
Returns:
A list of type/state_keys tuples.
"""
return [
(t, s)
for t, state_keys in self.types.items()
if state_keys is not None
for s in state_keys
]
def get_member_split(self) -> Tuple["StateFilter", "StateFilter"]:
"""Return the filter split into two: one which assumes it's exclusively
matching against member state, and one which assumes it's matching
against non member state.
This is useful due to the returned filters giving correct results for
`is_full()`, `has_wildcards()`, etc, when operating against maps that
either exclusively contain member events or only contain non-member
events. (Which is the case when dealing with the member vs non-member
state caches).
Returns:
The member and non member filters
"""
if EventTypes.Member in self.types:
state_keys = self.types[EventTypes.Member]
if state_keys is None:
member_filter = StateFilter.all()
else:
member_filter = StateFilter(frozendict({EventTypes.Member: state_keys}))
elif self.include_others:
member_filter = StateFilter.all()
else:
member_filter = StateFilter.none()
non_member_filter = StateFilter(
types=frozendict(
{k: v for k, v in self.types.items() if k != EventTypes.Member}
),
include_others=self.include_others,
)
return member_filter, non_member_filter
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def _decompose_into_four_parts(
self,
) -> Tuple[Tuple[bool, Set[str]], Tuple[Set[str], Set[StateKey]]]:
"""
Decomposes this state filter into 4 constituent parts, which can be
thought of as this:
all? - minus_wildcards + plus_wildcards + plus_state_keys
where
* all represents ALL state
* minus_wildcards represents entire state types to remove
* plus_wildcards represents entire state types to add
* plus_state_keys represents individual state keys to add
See `recompose_from_four_parts` for the other direction of this
correspondence.
"""
is_all = self.include_others
excluded_types: Set[str] = {t for t in self.types if is_all}
wildcard_types: Set[str] = {t for t, s in self.types.items() if s is None}
concrete_keys: Set[StateKey] = set(self.concrete_types())
return (is_all, excluded_types), (wildcard_types, concrete_keys)
@staticmethod
def _recompose_from_four_parts(
all_part: bool,
minus_wildcards: Set[str],
plus_wildcards: Set[str],
plus_state_keys: Set[StateKey],
) -> "StateFilter":
"""
Recomposes a state filter from 4 parts.
See `decompose_into_four_parts` (the other direction of this
correspondence) for descriptions on each of the parts.
"""
# {state type -> set of state keys OR None for wildcard}
# (The same structure as that of a StateFilter.)
new_types: Dict[str, Optional[Set[str]]] = {}
# if we start with all, insert the excluded statetypes as empty sets
# to prevent them from being included
if all_part:
new_types.update({state_type: set() for state_type in minus_wildcards})
# insert the plus wildcards
new_types.update({state_type: None for state_type in plus_wildcards})
# insert the specific state keys
for state_type, state_key in plus_state_keys:
if state_type in new_types:
entry = new_types[state_type]
if entry is not None:
entry.add(state_key)
elif not all_part:
# don't insert if the entire type is already included by
# include_others as this would actually shrink the state allowed
# by this filter.
new_types[state_type] = {state_key}
return StateFilter.freeze(new_types, include_others=all_part)
def approx_difference(self, other: "StateFilter") -> "StateFilter":
"""
Returns a state filter which represents `self - other`.
This is useful for determining what state remains to be pulled out of the
database if we want the state included by `self` but already have the state
included by `other`.
The returned state filter
- MUST include all state events that are included by this filter (`self`)
unless they are included by `other`;
- MUST NOT include state events not included by this filter (`self`); and
- MAY be an over-approximation: the returned state filter
MAY additionally include some state events from `other`.
This implementation attempts to return the narrowest such state filter.
In the case that `self` contains wildcards for state types where
`other` contains specific state keys, an approximation must be made:
the returned state filter keeps the wildcard, as state filters are not
able to express 'all state keys except some given examples'.
e.g.
StateFilter(m.room.member -> None (wildcard))
minus
StateFilter(m.room.member -> {'@wombat:example.org'})
is approximated as
StateFilter(m.room.member -> None (wildcard))
"""
# We first transform self and other into an alternative representation:
# - whether or not they include all events to begin with ('all')
# - if so, which event types are excluded? ('excludes')
# - which entire event types to include ('wildcards')
# - which concrete state keys to include ('concrete state keys')
(self_all, self_excludes), (
self_wildcards,
self_concrete_keys,
) = self._decompose_into_four_parts()
(other_all, other_excludes), (
other_wildcards,
other_concrete_keys,
) = other._decompose_into_four_parts()
# Start with an estimate of the difference based on self
new_all = self_all
# Wildcards from the other can be added to the exclusion filter
new_excludes = self_excludes | other_wildcards
# We remove wildcards that appeared as wildcards in the other
new_wildcards = self_wildcards - other_wildcards
# We filter out the concrete state keys that appear in the other
# as wildcards or concrete state keys.
new_concrete_keys = {
(state_type, state_key)
for (state_type, state_key) in self_concrete_keys
if state_type not in other_wildcards
} - other_concrete_keys
if other_all:
if self_all:
# If self starts with all, then we add as wildcards any
# types which appear in the other's exclusion filter (but
# aren't in the self exclusion filter). This is as the other
# filter will return everything BUT the types in its exclusion, so
# we need to add those excluded types that also match the self
# filter as wildcard types in the new filter.
new_wildcards |= other_excludes.difference(self_excludes)
# If other is an `include_others` then the difference isn't.
new_all = False
# (We have no need for excludes when we don't start with all, as there
# is nothing to exclude.)
new_excludes = set()
# We also filter out all state types that aren't in the exclusion
# list of the other.
new_wildcards &= other_excludes
new_concrete_keys = {
(state_type, state_key)
for (state_type, state_key) in new_concrete_keys
if state_type in other_excludes
}
# Transform our newly-constructed state filter from the alternative
# representation back into the normal StateFilter representation.
return StateFilter._recompose_from_four_parts(
new_all, new_excludes, new_wildcards, new_concrete_keys
)
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_ALL_STATE_FILTER = StateFilter(types=frozendict(), include_others=True)
_NONE_STATE_FILTER = StateFilter(types=frozendict(), include_others=False)
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class StateGroupStorage:
"""High level interface to fetching state for event."""
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def __init__(self, hs: "HomeServer", stores: "Databases"):
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self.stores = stores
async def get_state_group_delta(
self, state_group: int
) -> Tuple[Optional[int], Optional[StateMap[str]]]:
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"""Given a state group try to return a previous group and a delta between
the old and the new.
Args:
state_group: The state group used to retrieve state deltas.
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Returns:
A tuple of the previous group and a state map of the event IDs which
make up the delta between the old and new state groups.
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"""
state_group_delta = await self.stores.state.get_state_group_delta(state_group)
return state_group_delta.prev_group, state_group_delta.delta_ids
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async def get_state_groups_ids(
self, _room_id: str, event_ids: Iterable[str]
) -> Dict[int, MutableStateMap[str]]:
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"""Get the event IDs of all the state for the state groups for the given events
Args:
_room_id: id of the room for these events
event_ids: ids of the events
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Returns:
dict of state_group_id -> (dict of (type, state_key) -> event id)
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"""
if not event_ids:
return {}
event_to_groups = await self.stores.main._get_state_group_for_events(event_ids)
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groups = set(event_to_groups.values())
group_to_state = await self.stores.state._get_state_for_groups(groups)
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return group_to_state
async def get_state_ids_for_group(self, state_group: int) -> StateMap[str]:
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"""Get the event IDs of all the state in the given state group
Args:
state_group: A state group for which we want to get the state IDs.
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Returns:
Resolves to a map of (type, state_key) -> event_id
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"""
group_to_state = await self._get_state_for_groups((state_group,))
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return group_to_state[state_group]
async def get_state_groups(
self, room_id: str, event_ids: Iterable[str]
) -> Dict[int, List[EventBase]]:
"""Get the state groups for the given list of event_ids
Args:
room_id: ID of the room for these events.
event_ids: The event IDs to retrieve state for.
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Returns:
dict of state_group_id -> list of state events.
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"""
if not event_ids:
return {}
group_to_ids = await self.get_state_groups_ids(room_id, event_ids)
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state_event_map = await self.stores.main.get_events(
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[
ev_id
for group_ids in group_to_ids.values()
for ev_id in group_ids.values()
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],
get_prev_content=False,
)
return {
group: [
state_event_map[v]
for v in event_id_map.values()
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if v in state_event_map
]
for group, event_id_map in group_to_ids.items()
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}
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def _get_state_groups_from_groups(
self, groups: List[int], state_filter: StateFilter
) -> Awaitable[Dict[int, StateMap[str]]]:
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"""Returns the state groups for a given set of groups, filtering on
types of state events.
Args:
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groups: list of state group IDs to query
state_filter: The state filter used to fetch state
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from the database.
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Returns:
Dict of state group to state map.
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"""
return self.stores.state._get_state_groups_from_groups(groups, state_filter)
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async def get_state_for_events(
self, event_ids: Iterable[str], state_filter: Optional[StateFilter] = None
) -> Dict[str, StateMap[EventBase]]:
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"""Given a list of event_ids and type tuples, return a list of state
dicts for each event.
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Args:
event_ids: The events to fetch the state of.
state_filter: The state filter used to fetch state.
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Returns:
A dict of (event_id) -> (type, state_key) -> [state_events]
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"""
event_to_groups = await self.stores.main._get_state_group_for_events(event_ids)
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groups = set(event_to_groups.values())
group_to_state = await self.stores.state._get_state_for_groups(
groups, state_filter or StateFilter.all()
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)
state_event_map = await self.stores.main.get_events(
[ev_id for sd in group_to_state.values() for ev_id in sd.values()],
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get_prev_content=False,
)
event_to_state = {
event_id: {
k: state_event_map[v]
for k, v in group_to_state[group].items()
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if v in state_event_map
}
for event_id, group in event_to_groups.items()
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}
return {event: event_to_state[event] for event in event_ids}
async def get_state_ids_for_events(
self, event_ids: Iterable[str], state_filter: Optional[StateFilter] = None
) -> Dict[str, StateMap[str]]:
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"""
Get the state dicts corresponding to a list of events, containing the event_ids
of the state events (as opposed to the events themselves)
Args:
event_ids: events whose state should be returned
state_filter: The state filter used to fetch state from the database.
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Returns:
A dict from event_id -> (type, state_key) -> event_id
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"""
event_to_groups = await self.stores.main._get_state_group_for_events(event_ids)
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groups = set(event_to_groups.values())
group_to_state = await self.stores.state._get_state_for_groups(
groups, state_filter or StateFilter.all()
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)
event_to_state = {
event_id: group_to_state[group]
for event_id, group in event_to_groups.items()
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}
return {event: event_to_state[event] for event in event_ids}
async def get_state_for_event(
self, event_id: str, state_filter: Optional[StateFilter] = None
) -> StateMap[EventBase]:
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"""
Get the state dict corresponding to a particular event
Args:
event_id: event whose state should be returned
state_filter: The state filter used to fetch state from the database.
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Returns:
A dict from (type, state_key) -> state_event
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"""
state_map = await self.get_state_for_events(
[event_id], state_filter or StateFilter.all()
)
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return state_map[event_id]
async def get_state_ids_for_event(
self, event_id: str, state_filter: Optional[StateFilter] = None
) -> StateMap[str]:
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"""
Get the state dict corresponding to a particular event
Args:
event_id: event whose state should be returned
state_filter: The state filter used to fetch state from the database.
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Returns:
A dict from (type, state_key) -> state_event_id
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"""
state_map = await self.get_state_ids_for_events(
[event_id], state_filter or StateFilter.all()
)
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return state_map[event_id]
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def _get_state_for_groups(
self, groups: Iterable[int], state_filter: Optional[StateFilter] = None
) -> Awaitable[Dict[int, MutableStateMap[str]]]:
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"""Gets the state at each of a list of state groups, optionally
filtering by type/state_key
Args:
groups: list of state groups for which we want to get the state.
state_filter: The state filter used to fetch state.
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from the database.
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Returns:
Dict of state group to state map.
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"""
return self.stores.state._get_state_for_groups(
groups, state_filter or StateFilter.all()
)
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async def store_state_group(
self,
event_id: str,
room_id: str,
prev_group: Optional[int],
delta_ids: Optional[StateMap[str]],
current_state_ids: StateMap[str],
) -> int:
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"""Store a new set of state, returning a newly assigned state group.
Args:
event_id: The event ID for which the state was calculated.
room_id: ID of the room for which the state was calculated.
prev_group: A previous state group for the room, optional.
delta_ids: The delta between state at `prev_group` and
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`current_state_ids`, if `prev_group` was given. Same format as
`current_state_ids`.
current_state_ids: The state to store. Map of (type, state_key)
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to event_id.
Returns:
The state group ID
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"""
return await self.stores.state.store_state_group(
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event_id, room_id, prev_group, delta_ids, current_state_ids
)