568 lines
20 KiB
Python
568 lines
20 KiB
Python
# Copyright 2014-2016 OpenMarket Ltd
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# Copyright 2022 The Matrix.org Foundation C.I.C.
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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import logging
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from typing import (
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TYPE_CHECKING,
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Callable,
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Collection,
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Dict,
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Iterable,
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List,
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Mapping,
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Optional,
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Set,
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Tuple,
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TypeVar,
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)
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import attr
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from frozendict import frozendict
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from synapse.api.constants import EventTypes
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from synapse.types import MutableStateMap, StateKey, StateMap
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if TYPE_CHECKING:
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from typing import FrozenSet # noqa: used within quoted type hint; flake8 sad
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logger = logging.getLogger(__name__)
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# Used for generic functions below
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T = TypeVar("T")
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@attr.s(slots=True, frozen=True, auto_attribs=True)
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class StateFilter:
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"""A filter used when querying for state.
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Attributes:
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types: Map from type to set of state keys (or None). This specifies
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which state_keys for the given type to fetch from the DB. If None
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then all events with that type are fetched. If the set is empty
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then no events with that type are fetched.
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include_others: Whether to fetch events with types that do not
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appear in `types`.
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"""
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types: "frozendict[str, Optional[FrozenSet[str]]]"
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include_others: bool = False
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def __attrs_post_init__(self) -> None:
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# If `include_others` is set we canonicalise the filter by removing
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# wildcards from the types dictionary
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if self.include_others:
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# this is needed to work around the fact that StateFilter is frozen
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object.__setattr__(
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self,
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"types",
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frozendict({k: v for k, v in self.types.items() if v is not None}),
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)
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@staticmethod
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def all() -> "StateFilter":
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"""Returns a filter that fetches everything.
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Returns:
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The state filter.
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"""
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return _ALL_STATE_FILTER
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@staticmethod
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def none() -> "StateFilter":
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"""Returns a filter that fetches nothing.
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Returns:
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The new state filter.
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"""
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return _NONE_STATE_FILTER
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@staticmethod
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def from_types(types: Iterable[Tuple[str, Optional[str]]]) -> "StateFilter":
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"""Creates a filter that only fetches the given types
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Args:
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types: A list of type and state keys to fetch. A state_key of None
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fetches everything for that type
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Returns:
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The new state filter.
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"""
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type_dict: Dict[str, Optional[Set[str]]] = {}
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for typ, s in types:
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if typ in type_dict:
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if type_dict[typ] is None:
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continue
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if s is None:
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type_dict[typ] = None
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continue
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type_dict.setdefault(typ, set()).add(s) # type: ignore
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return StateFilter(
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types=frozendict(
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(k, frozenset(v) if v is not None else None)
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for k, v in type_dict.items()
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)
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)
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@staticmethod
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def from_lazy_load_member_list(members: Iterable[str]) -> "StateFilter":
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"""Creates a filter that returns all non-member events, plus the member
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events for the given users
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Args:
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members: Set of user IDs
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Returns:
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The new state filter
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"""
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return StateFilter(
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types=frozendict({EventTypes.Member: frozenset(members)}),
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include_others=True,
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)
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@staticmethod
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def freeze(
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types: Mapping[str, Optional[Collection[str]]], include_others: bool
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) -> "StateFilter":
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"""
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Returns a (frozen) StateFilter with the same contents as the parameters
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specified here, which can be made of mutable types.
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"""
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types_with_frozen_values: Dict[str, Optional[FrozenSet[str]]] = {}
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for state_types, state_keys in types.items():
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if state_keys is not None:
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types_with_frozen_values[state_types] = frozenset(state_keys)
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else:
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types_with_frozen_values[state_types] = None
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return StateFilter(
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frozendict(types_with_frozen_values), include_others=include_others
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)
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def return_expanded(self) -> "StateFilter":
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"""Creates a new StateFilter where type wild cards have been removed
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(except for memberships). The returned filter is a superset of the
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current one, i.e. anything that passes the current filter will pass
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the returned filter.
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This helps the caching as the DictionaryCache knows if it has *all* the
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state, but does not know if it has all of the keys of a particular type,
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which makes wildcard lookups expensive unless we have a complete cache.
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Hence, if we are doing a wildcard lookup, populate the cache fully so
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that we can do an efficient lookup next time.
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Note that since we have two caches, one for membership events and one for
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other events, we can be a bit more clever than simply returning
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`StateFilter.all()` if `has_wildcards()` is True.
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We return a StateFilter where:
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1. the list of membership events to return is the same
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2. if there is a wildcard that matches non-member events we
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return all non-member events
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Returns:
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The new state filter.
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"""
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if self.is_full():
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# If we're going to return everything then there's nothing to do
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return self
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if not self.has_wildcards():
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# If there are no wild cards, there's nothing to do
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return self
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if EventTypes.Member in self.types:
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get_all_members = self.types[EventTypes.Member] is None
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else:
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get_all_members = self.include_others
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has_non_member_wildcard = self.include_others or any(
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state_keys is None
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for t, state_keys in self.types.items()
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if t != EventTypes.Member
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)
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if not has_non_member_wildcard:
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# If there are no non-member wild cards we can just return ourselves
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return self
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if get_all_members:
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# We want to return everything.
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return StateFilter.all()
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elif EventTypes.Member in self.types:
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# We want to return all non-members, but only particular
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# memberships
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return StateFilter(
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types=frozendict({EventTypes.Member: self.types[EventTypes.Member]}),
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include_others=True,
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)
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else:
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# We want to return all non-members
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return _ALL_NON_MEMBER_STATE_FILTER
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def make_sql_filter_clause(self) -> Tuple[str, List[str]]:
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"""Converts the filter to an SQL clause.
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For example:
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f = StateFilter.from_types([("m.room.create", "")])
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clause, args = f.make_sql_filter_clause()
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clause == "(type = ? AND state_key = ?)"
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args == ['m.room.create', '']
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Returns:
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The SQL string (may be empty) and arguments. An empty SQL string is
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returned when the filter matches everything (i.e. is "full").
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"""
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where_clause = ""
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where_args: List[str] = []
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if self.is_full():
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return where_clause, where_args
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if not self.include_others and not self.types:
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# i.e. this is an empty filter, so we need to return a clause that
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# will match nothing
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return "1 = 2", []
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# First we build up a lost of clauses for each type/state_key combo
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clauses = []
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for etype, state_keys in self.types.items():
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if state_keys is None:
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clauses.append("(type = ?)")
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where_args.append(etype)
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continue
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for state_key in state_keys:
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clauses.append("(type = ? AND state_key = ?)")
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where_args.extend((etype, state_key))
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# This will match anything that appears in `self.types`
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where_clause = " OR ".join(clauses)
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# If we want to include stuff that's not in the types dict then we add
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# a `OR type NOT IN (...)` clause to the end.
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if self.include_others:
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if where_clause:
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where_clause += " OR "
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where_clause += "type NOT IN (%s)" % (",".join(["?"] * len(self.types)),)
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where_args.extend(self.types)
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return where_clause, where_args
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def max_entries_returned(self) -> Optional[int]:
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"""Returns the maximum number of entries this filter will return if
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known, otherwise returns None.
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For example a simple state filter asking for `("m.room.create", "")`
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will return 1, whereas the default state filter will return None.
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This is used to bail out early if the right number of entries have been
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fetched.
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"""
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if self.has_wildcards():
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return None
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return len(self.concrete_types())
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def filter_state(self, state_dict: StateMap[T]) -> MutableStateMap[T]:
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"""Returns the state filtered with by this StateFilter.
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Args:
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state: The state map to filter
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Returns:
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The filtered state map.
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This is a copy, so it's safe to mutate.
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"""
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if self.is_full():
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return dict(state_dict)
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filtered_state = {}
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for k, v in state_dict.items():
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typ, state_key = k
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if typ in self.types:
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state_keys = self.types[typ]
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if state_keys is None or state_key in state_keys:
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filtered_state[k] = v
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elif self.include_others:
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filtered_state[k] = v
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return filtered_state
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def is_full(self) -> bool:
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"""Whether this filter fetches everything or not
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Returns:
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True if the filter fetches everything.
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"""
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return self.include_others and not self.types
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def has_wildcards(self) -> bool:
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"""Whether the filter includes wildcards or is attempting to fetch
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specific state.
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Returns:
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True if the filter includes wildcards.
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"""
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return self.include_others or any(
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state_keys is None for state_keys in self.types.values()
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)
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def concrete_types(self) -> List[Tuple[str, str]]:
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"""Returns a list of concrete type/state_keys (i.e. not None) that
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will be fetched. This will be a complete list if `has_wildcards`
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returns False, but otherwise will be a subset (or even empty).
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Returns:
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A list of type/state_keys tuples.
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"""
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return [
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(t, s)
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for t, state_keys in self.types.items()
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if state_keys is not None
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for s in state_keys
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]
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def get_member_split(self) -> Tuple["StateFilter", "StateFilter"]:
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"""Return the filter split into two: one which assumes it's exclusively
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matching against member state, and one which assumes it's matching
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against non member state.
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This is useful due to the returned filters giving correct results for
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`is_full()`, `has_wildcards()`, etc, when operating against maps that
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either exclusively contain member events or only contain non-member
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events. (Which is the case when dealing with the member vs non-member
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state caches).
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Returns:
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The member and non member filters
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"""
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if EventTypes.Member in self.types:
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state_keys = self.types[EventTypes.Member]
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if state_keys is None:
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member_filter = StateFilter.all()
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else:
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member_filter = StateFilter(frozendict({EventTypes.Member: state_keys}))
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elif self.include_others:
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member_filter = StateFilter.all()
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else:
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member_filter = StateFilter.none()
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non_member_filter = StateFilter(
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types=frozendict(
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{k: v for k, v in self.types.items() if k != EventTypes.Member}
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),
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include_others=self.include_others,
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)
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return member_filter, non_member_filter
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def _decompose_into_four_parts(
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self,
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) -> Tuple[Tuple[bool, Set[str]], Tuple[Set[str], Set[StateKey]]]:
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"""
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Decomposes this state filter into 4 constituent parts, which can be
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thought of as this:
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all? - minus_wildcards + plus_wildcards + plus_state_keys
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where
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* all represents ALL state
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* minus_wildcards represents entire state types to remove
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* plus_wildcards represents entire state types to add
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* plus_state_keys represents individual state keys to add
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See `recompose_from_four_parts` for the other direction of this
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correspondence.
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"""
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is_all = self.include_others
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excluded_types: Set[str] = {t for t in self.types if is_all}
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wildcard_types: Set[str] = {t for t, s in self.types.items() if s is None}
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concrete_keys: Set[StateKey] = set(self.concrete_types())
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return (is_all, excluded_types), (wildcard_types, concrete_keys)
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@staticmethod
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def _recompose_from_four_parts(
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all_part: bool,
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minus_wildcards: Set[str],
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plus_wildcards: Set[str],
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plus_state_keys: Set[StateKey],
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) -> "StateFilter":
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"""
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Recomposes a state filter from 4 parts.
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See `decompose_into_four_parts` (the other direction of this
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correspondence) for descriptions on each of the parts.
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"""
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# {state type -> set of state keys OR None for wildcard}
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# (The same structure as that of a StateFilter.)
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new_types: Dict[str, Optional[Set[str]]] = {}
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# if we start with all, insert the excluded statetypes as empty sets
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# to prevent them from being included
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if all_part:
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new_types.update({state_type: set() for state_type in minus_wildcards})
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# insert the plus wildcards
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new_types.update({state_type: None for state_type in plus_wildcards})
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# insert the specific state keys
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for state_type, state_key in plus_state_keys:
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if state_type in new_types:
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entry = new_types[state_type]
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if entry is not None:
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entry.add(state_key)
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elif not all_part:
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# don't insert if the entire type is already included by
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# include_others as this would actually shrink the state allowed
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# by this filter.
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new_types[state_type] = {state_key}
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return StateFilter.freeze(new_types, include_others=all_part)
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def approx_difference(self, other: "StateFilter") -> "StateFilter":
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"""
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Returns a state filter which represents `self - other`.
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This is useful for determining what state remains to be pulled out of the
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database if we want the state included by `self` but already have the state
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included by `other`.
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The returned state filter
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- MUST include all state events that are included by this filter (`self`)
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unless they are included by `other`;
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- MUST NOT include state events not included by this filter (`self`); and
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- MAY be an over-approximation: the returned state filter
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MAY additionally include some state events from `other`.
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This implementation attempts to return the narrowest such state filter.
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In the case that `self` contains wildcards for state types where
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`other` contains specific state keys, an approximation must be made:
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the returned state filter keeps the wildcard, as state filters are not
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able to express 'all state keys except some given examples'.
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e.g.
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StateFilter(m.room.member -> None (wildcard))
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minus
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StateFilter(m.room.member -> {'@wombat:example.org'})
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is approximated as
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StateFilter(m.room.member -> None (wildcard))
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"""
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# We first transform self and other into an alternative representation:
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# - whether or not they include all events to begin with ('all')
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# - if so, which event types are excluded? ('excludes')
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# - which entire event types to include ('wildcards')
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# - which concrete state keys to include ('concrete state keys')
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(self_all, self_excludes), (
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self_wildcards,
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self_concrete_keys,
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) = self._decompose_into_four_parts()
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(other_all, other_excludes), (
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other_wildcards,
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other_concrete_keys,
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) = other._decompose_into_four_parts()
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# Start with an estimate of the difference based on self
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new_all = self_all
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# Wildcards from the other can be added to the exclusion filter
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new_excludes = self_excludes | other_wildcards
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# We remove wildcards that appeared as wildcards in the other
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new_wildcards = self_wildcards - other_wildcards
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# We filter out the concrete state keys that appear in the other
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# as wildcards or concrete state keys.
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new_concrete_keys = {
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(state_type, state_key)
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for (state_type, state_key) in self_concrete_keys
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if state_type not in other_wildcards
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} - other_concrete_keys
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if other_all:
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if self_all:
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# If self starts with all, then we add as wildcards any
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# types which appear in the other's exclusion filter (but
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# aren't in the self exclusion filter). This is as the other
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# filter will return everything BUT the types in its exclusion, so
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# we need to add those excluded types that also match the self
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# filter as wildcard types in the new filter.
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new_wildcards |= other_excludes.difference(self_excludes)
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# If other is an `include_others` then the difference isn't.
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new_all = False
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# (We have no need for excludes when we don't start with all, as there
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# is nothing to exclude.)
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new_excludes = set()
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# We also filter out all state types that aren't in the exclusion
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# list of the other.
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new_wildcards &= other_excludes
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new_concrete_keys = {
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(state_type, state_key)
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for (state_type, state_key) in new_concrete_keys
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if state_type in other_excludes
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}
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# Transform our newly-constructed state filter from the alternative
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# representation back into the normal StateFilter representation.
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return StateFilter._recompose_from_four_parts(
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new_all, new_excludes, new_wildcards, new_concrete_keys
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)
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|
|
|
def must_await_full_state(self, is_mine_id: Callable[[str], bool]) -> bool:
|
|
"""Check if we need to wait for full state to complete to calculate this state
|
|
|
|
If we have a state filter which is completely satisfied even with partial
|
|
state, then we don't need to await_full_state before we can return it.
|
|
|
|
Args:
|
|
is_mine_id: a callable which confirms if a given state_key matches a mxid
|
|
of a local user
|
|
"""
|
|
# if we haven't requested membership events, then it depends on the value of
|
|
# 'include_others'
|
|
if EventTypes.Member not in self.types:
|
|
return self.include_others
|
|
|
|
# if we're looking for *all* membership events, then we have to wait
|
|
member_state_keys = self.types[EventTypes.Member]
|
|
if member_state_keys is None:
|
|
return True
|
|
|
|
# otherwise, consider whose membership we are looking for. If it's entirely
|
|
# local users, then we don't need to wait.
|
|
for state_key in member_state_keys:
|
|
if not is_mine_id(state_key):
|
|
# remote user
|
|
return True
|
|
|
|
# local users only
|
|
return False
|
|
|
|
|
|
_ALL_STATE_FILTER = StateFilter(types=frozendict(), include_others=True)
|
|
_ALL_NON_MEMBER_STATE_FILTER = StateFilter(
|
|
types=frozendict({EventTypes.Member: frozenset()}), include_others=True
|
|
)
|
|
_NONE_STATE_FILTER = StateFilter(types=frozendict(), include_others=False)
|