# -*- coding: utf-8 -*- # 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. import logging from collections import namedtuple from typing import Dict, Iterable, List, Set, Tuple from twisted.internet import defer from synapse.api.constants import EventTypes from synapse.storage._base import SQLBaseStore from synapse.storage.data_stores.state.bg_updates import StateBackgroundUpdateStore from synapse.storage.database import Database from synapse.storage.state import StateFilter from synapse.storage.types import Cursor from synapse.storage.util.sequence import build_sequence_generator from synapse.types import StateMap from synapse.util.caches.descriptors import cached from synapse.util.caches.dictionary_cache import DictionaryCache logger = logging.getLogger(__name__) MAX_STATE_DELTA_HOPS = 100 class _GetStateGroupDelta( namedtuple("_GetStateGroupDelta", ("prev_group", "delta_ids")) ): """Return type of get_state_group_delta that implements __len__, which lets us use the itrable flag when caching """ __slots__ = [] def __len__(self): return len(self.delta_ids) if self.delta_ids else 0 class StateGroupDataStore(StateBackgroundUpdateStore, SQLBaseStore): """A data store for fetching/storing state groups. """ def __init__(self, database: Database, db_conn, hs): super(StateGroupDataStore, self).__init__(database, db_conn, hs) # Originally the state store used a single DictionaryCache to cache the # event IDs for the state types in a given state group to avoid hammering # on the state_group* tables. # # The point of using a DictionaryCache is that it can cache a subset # of the state events for a given state group (i.e. a subset of the keys for a # given dict which is an entry in the cache for a given state group ID). # # However, this poses problems when performing complicated queries # on the store - for instance: "give me all the state for this group, but # limit members to this subset of users", as DictionaryCache's API isn't # rich enough to say "please cache any of these fields, apart from this subset". # This is problematic when lazy loading members, which requires this behaviour, # as without it the cache has no choice but to speculatively load all # state events for the group, which negates the efficiency being sought. # # Rather than overcomplicating DictionaryCache's API, we instead split the # state_group_cache into two halves - one for tracking non-member events, # and the other for tracking member_events. This means that lazy loading # queries can be made in a cache-friendly manner by querying both caches # separately and then merging the result. So for the example above, you # would query the members cache for a specific subset of state keys # (which DictionaryCache will handle efficiently and fine) and the non-members # cache for all state (which DictionaryCache will similarly handle fine) # and then just merge the results together. # # We size the non-members cache to be smaller than the members cache as the # vast majority of state in Matrix (today) is member events. self._state_group_cache = DictionaryCache( "*stateGroupCache*", # TODO: this hasn't been tuned yet 50000, ) self._state_group_members_cache = DictionaryCache( "*stateGroupMembersCache*", 500000, ) def get_max_state_group_txn(txn: Cursor): txn.execute("SELECT COALESCE(max(id), 0) FROM state_groups") return txn.fetchone()[0] self._state_group_seq_gen = build_sequence_generator( self.database_engine, get_max_state_group_txn, "state_group_id_seq" ) @cached(max_entries=10000, iterable=True) def get_state_group_delta(self, state_group): """Given a state group try to return a previous group and a delta between the old and the new. Returns: (prev_group, delta_ids), where both may be None. """ def _get_state_group_delta_txn(txn): prev_group = self.db.simple_select_one_onecol_txn( txn, table="state_group_edges", keyvalues={"state_group": state_group}, retcol="prev_state_group", allow_none=True, ) if not prev_group: return _GetStateGroupDelta(None, None) delta_ids = self.db.simple_select_list_txn( txn, table="state_groups_state", keyvalues={"state_group": state_group}, retcols=("type", "state_key", "event_id"), ) return _GetStateGroupDelta( prev_group, {(row["type"], row["state_key"]): row["event_id"] for row in delta_ids}, ) return self.db.runInteraction( "get_state_group_delta", _get_state_group_delta_txn ) @defer.inlineCallbacks def _get_state_groups_from_groups( self, groups: List[int], state_filter: StateFilter ): """Returns the state groups for a given set of groups from the database, filtering on types of state events. Args: groups: list of state group IDs to query state_filter: The state filter used to fetch state from the database. Returns: Deferred[Dict[int, StateMap[str]]]: Dict of state group to state map. """ results = {} chunks = [groups[i : i + 100] for i in range(0, len(groups), 100)] for chunk in chunks: res = yield self.db.runInteraction( "_get_state_groups_from_groups", self._get_state_groups_from_groups_txn, chunk, state_filter, ) results.update(res) return results def _get_state_for_group_using_cache(self, cache, group, state_filter): """Checks if group is in cache. See `_get_state_for_groups` Args: cache(DictionaryCache): the state group cache to use group(int): The state group to lookup state_filter (StateFilter): The state filter used to fetch state from the database. Returns 2-tuple (`state_dict`, `got_all`). `got_all` is a bool indicating if we successfully retrieved all requests state from the cache, if False we need to query the DB for the missing state. """ is_all, known_absent, state_dict_ids = cache.get(group) if is_all or state_filter.is_full(): # Either we have everything or want everything, either way # `is_all` tells us whether we've gotten everything. return state_filter.filter_state(state_dict_ids), is_all # tracks whether any of our requested types are missing from the cache missing_types = False if state_filter.has_wildcards(): # We don't know if we fetched all the state keys for the types in # the filter that are wildcards, so we have to assume that we may # have missed some. missing_types = True else: # There aren't any wild cards, so `concrete_types()` returns the # complete list of event types we're wanting. for key in state_filter.concrete_types(): if key not in state_dict_ids and key not in known_absent: missing_types = True break return state_filter.filter_state(state_dict_ids), not missing_types @defer.inlineCallbacks def _get_state_for_groups( self, groups: Iterable[int], state_filter: StateFilter = StateFilter.all() ): """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 from the database. Returns: Deferred[Dict[int, StateMap[str]]]: Dict of state group to state map. """ member_filter, non_member_filter = state_filter.get_member_split() # Now we look them up in the member and non-member caches ( non_member_state, incomplete_groups_nm, ) = yield self._get_state_for_groups_using_cache( groups, self._state_group_cache, state_filter=non_member_filter ) ( member_state, incomplete_groups_m, ) = yield self._get_state_for_groups_using_cache( groups, self._state_group_members_cache, state_filter=member_filter ) state = dict(non_member_state) for group in groups: state[group].update(member_state[group]) # Now fetch any missing groups from the database incomplete_groups = incomplete_groups_m | incomplete_groups_nm if not incomplete_groups: return state cache_sequence_nm = self._state_group_cache.sequence cache_sequence_m = self._state_group_members_cache.sequence # Help the cache hit ratio by expanding the filter a bit db_state_filter = state_filter.return_expanded() group_to_state_dict = yield self._get_state_groups_from_groups( list(incomplete_groups), state_filter=db_state_filter ) # Now lets update the caches self._insert_into_cache( group_to_state_dict, db_state_filter, cache_seq_num_members=cache_sequence_m, cache_seq_num_non_members=cache_sequence_nm, ) # And finally update the result dict, by filtering out any extra # stuff we pulled out of the database. for group, group_state_dict in group_to_state_dict.items(): # We just replace any existing entries, as we will have loaded # everything we need from the database anyway. state[group] = state_filter.filter_state(group_state_dict) return state def _get_state_for_groups_using_cache( self, groups: Iterable[int], cache: DictionaryCache, state_filter: StateFilter ) -> Tuple[Dict[int, StateMap[str]], Set[int]]: """Gets the state at each of a list of state groups, optionally filtering by type/state_key, querying from a specific cache. Args: groups: list of state groups for which we want to get the state. cache: the cache of group ids to state dicts which we will pass through - either the normal state cache or the specific members state cache. state_filter: The state filter used to fetch state from the database. Returns: Tuple of dict of state_group_id to state map of entries in the cache, and the state group ids either missing from the cache or incomplete. """ results = {} incomplete_groups = set() for group in set(groups): state_dict_ids, got_all = self._get_state_for_group_using_cache( cache, group, state_filter ) results[group] = state_dict_ids if not got_all: incomplete_groups.add(group) return results, incomplete_groups def _insert_into_cache( self, group_to_state_dict, state_filter, cache_seq_num_members, cache_seq_num_non_members, ): """Inserts results from querying the database into the relevant cache. Args: group_to_state_dict (dict): The new entries pulled from database. Map from state group to state dict state_filter (StateFilter): The state filter used to fetch state from the database. cache_seq_num_members (int): Sequence number of member cache since last lookup in cache cache_seq_num_non_members (int): Sequence number of member cache since last lookup in cache """ # We need to work out which types we've fetched from the DB for the # member vs non-member caches. This should be as accurate as possible, # but can be an underestimate (e.g. when we have wild cards) member_filter, non_member_filter = state_filter.get_member_split() if member_filter.is_full(): # We fetched all member events member_types = None else: # `concrete_types()` will only return a subset when there are wild # cards in the filter, but that's fine. member_types = member_filter.concrete_types() if non_member_filter.is_full(): # We fetched all non member events non_member_types = None else: non_member_types = non_member_filter.concrete_types() for group, group_state_dict in group_to_state_dict.items(): state_dict_members = {} state_dict_non_members = {} for k, v in group_state_dict.items(): if k[0] == EventTypes.Member: state_dict_members[k] = v else: state_dict_non_members[k] = v self._state_group_members_cache.update( cache_seq_num_members, key=group, value=state_dict_members, fetched_keys=member_types, ) self._state_group_cache.update( cache_seq_num_non_members, key=group, value=state_dict_non_members, fetched_keys=non_member_types, ) def store_state_group( self, event_id, room_id, prev_group, delta_ids, current_state_ids ): """Store a new set of state, returning a newly assigned state group. Args: event_id (str): The event ID for which the state was calculated room_id (str) prev_group (int|None): A previous state group for the room, optional. delta_ids (dict|None): The delta between state at `prev_group` and `current_state_ids`, if `prev_group` was given. Same format as `current_state_ids`. current_state_ids (dict): The state to store. Map of (type, state_key) to event_id. Returns: Deferred[int]: The state group ID """ def _store_state_group_txn(txn): if current_state_ids is None: # AFAIK, this can never happen raise Exception("current_state_ids cannot be None") state_group = self._state_group_seq_gen.get_next_id_txn(txn) self.db.simple_insert_txn( txn, table="state_groups", values={"id": state_group, "room_id": room_id, "event_id": event_id}, ) # We persist as a delta if we can, while also ensuring the chain # of deltas isn't tooo long, as otherwise read performance degrades. if prev_group: is_in_db = self.db.simple_select_one_onecol_txn( txn, table="state_groups", keyvalues={"id": prev_group}, retcol="id", allow_none=True, ) if not is_in_db: raise Exception( "Trying to persist state with unpersisted prev_group: %r" % (prev_group,) ) potential_hops = self._count_state_group_hops_txn(txn, prev_group) if prev_group and potential_hops < MAX_STATE_DELTA_HOPS: self.db.simple_insert_txn( txn, table="state_group_edges", values={"state_group": state_group, "prev_state_group": prev_group}, ) self.db.simple_insert_many_txn( txn, table="state_groups_state", values=[ { "state_group": state_group, "room_id": room_id, "type": key[0], "state_key": key[1], "event_id": state_id, } for key, state_id in delta_ids.items() ], ) else: self.db.simple_insert_many_txn( txn, table="state_groups_state", values=[ { "state_group": state_group, "room_id": room_id, "type": key[0], "state_key": key[1], "event_id": state_id, } for key, state_id in current_state_ids.items() ], ) # Prefill the state group caches with this group. # It's fine to use the sequence like this as the state group map # is immutable. (If the map wasn't immutable then this prefill could # race with another update) current_member_state_ids = { s: ev for (s, ev) in current_state_ids.items() if s[0] == EventTypes.Member } txn.call_after( self._state_group_members_cache.update, self._state_group_members_cache.sequence, key=state_group, value=dict(current_member_state_ids), ) current_non_member_state_ids = { s: ev for (s, ev) in current_state_ids.items() if s[0] != EventTypes.Member } txn.call_after( self._state_group_cache.update, self._state_group_cache.sequence, key=state_group, value=dict(current_non_member_state_ids), ) return state_group return self.db.runInteraction("store_state_group", _store_state_group_txn) def purge_unreferenced_state_groups( self, room_id: str, state_groups_to_delete ) -> defer.Deferred: """Deletes no longer referenced state groups and de-deltas any state groups that reference them. Args: room_id: The room the state groups belong to (must all be in the same room). state_groups_to_delete (Collection[int]): Set of all state groups to delete. """ return self.db.runInteraction( "purge_unreferenced_state_groups", self._purge_unreferenced_state_groups, room_id, state_groups_to_delete, ) def _purge_unreferenced_state_groups(self, txn, room_id, state_groups_to_delete): logger.info( "[purge] found %i state groups to delete", len(state_groups_to_delete) ) rows = self.db.simple_select_many_txn( txn, table="state_group_edges", column="prev_state_group", iterable=state_groups_to_delete, keyvalues={}, retcols=("state_group",), ) remaining_state_groups = { row["state_group"] for row in rows if row["state_group"] not in state_groups_to_delete } logger.info( "[purge] de-delta-ing %i remaining state groups", len(remaining_state_groups), ) # Now we turn the state groups that reference to-be-deleted state # groups to non delta versions. for sg in remaining_state_groups: logger.info("[purge] de-delta-ing remaining state group %s", sg) curr_state = self._get_state_groups_from_groups_txn(txn, [sg]) curr_state = curr_state[sg] self.db.simple_delete_txn( txn, table="state_groups_state", keyvalues={"state_group": sg} ) self.db.simple_delete_txn( txn, table="state_group_edges", keyvalues={"state_group": sg} ) self.db.simple_insert_many_txn( txn, table="state_groups_state", values=[ { "state_group": sg, "room_id": room_id, "type": key[0], "state_key": key[1], "event_id": state_id, } for key, state_id in curr_state.items() ], ) logger.info("[purge] removing redundant state groups") txn.executemany( "DELETE FROM state_groups_state WHERE state_group = ?", ((sg,) for sg in state_groups_to_delete), ) txn.executemany( "DELETE FROM state_groups WHERE id = ?", ((sg,) for sg in state_groups_to_delete), ) @defer.inlineCallbacks def get_previous_state_groups(self, state_groups): """Fetch the previous groups of the given state groups. Args: state_groups (Iterable[int]) Returns: Deferred[dict[int, int]]: mapping from state group to previous state group. """ rows = yield self.db.simple_select_many_batch( table="state_group_edges", column="prev_state_group", iterable=state_groups, keyvalues={}, retcols=("prev_state_group", "state_group"), desc="get_previous_state_groups", ) return {row["state_group"]: row["prev_state_group"] for row in rows} def purge_room_state(self, room_id, state_groups_to_delete): """Deletes all record of a room from state tables Args: room_id (str): state_groups_to_delete (list[int]): State groups to delete """ return self.db.runInteraction( "purge_room_state", self._purge_room_state_txn, room_id, state_groups_to_delete, ) def _purge_room_state_txn(self, txn, room_id, state_groups_to_delete): # first we have to delete the state groups states logger.info("[purge] removing %s from state_groups_state", room_id) self.db.simple_delete_many_txn( txn, table="state_groups_state", column="state_group", iterable=state_groups_to_delete, keyvalues={}, ) # ... and the state group edges logger.info("[purge] removing %s from state_group_edges", room_id) self.db.simple_delete_many_txn( txn, table="state_group_edges", column="state_group", iterable=state_groups_to_delete, keyvalues={}, ) # ... and the state groups logger.info("[purge] removing %s from state_groups", room_id) self.db.simple_delete_many_txn( txn, table="state_groups", column="id", iterable=state_groups_to_delete, keyvalues={}, )