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Only store data in caches, not "smart" objects (#9845)

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Erik Johnston 2021-04-23 11:47:07 +01:00 committed by GitHub
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3 changed files with 180 additions and 139 deletions
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changelog.d/9845.misc Normal file
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@ -0,0 +1 @@
Only store the raw data in the in-memory caches, rather than objects that include references to e.g. the data stores.

159
synapse/push/bulk_push_rule_evaluator.py
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@ -106,6 +106,10 @@ class BulkPushRuleEvaluator:
self.store = hs.get_datastore()
self.auth = hs.get_auth()
# Used by `RulesForRoom` to ensure only one thing mutates the cache at a
# time. Keyed off room_id.
self._rules_linearizer = Linearizer(name="rules_for_room")
self.room_push_rule_cache_metrics = register_cache(
"cache",
"room_push_rule_cache",
@ -123,7 +127,16 @@ class BulkPushRuleEvaluator:
dict of user_id -> push_rules
"""
room_id = event.room_id
rules_for_room = self._get_rules_for_room(room_id)
rules_for_room_data = self._get_rules_for_room(room_id)
rules_for_room = RulesForRoom(
hs=self.hs,
room_id=room_id,
rules_for_room_cache=self._get_rules_for_room.cache,
room_push_rule_cache_metrics=self.room_push_rule_cache_metrics,
linearizer=self._rules_linearizer,
cached_data=rules_for_room_data,
)
rules_by_user = await rules_for_room.get_rules(event, context)
@ -142,17 +155,12 @@ class BulkPushRuleEvaluator:
return rules_by_user
@lru_cache()
def _get_rules_for_room(self, room_id: str) -> "RulesForRoom":
"""Get the current RulesForRoom object for the given room id"""
# It's important that RulesForRoom gets added to self._get_rules_for_room.cache
def _get_rules_for_room(self, room_id: str) -> "RulesForRoomData":
"""Get the current RulesForRoomData object for the given room id"""
# It's important that the RulesForRoomData object gets added to self._get_rules_for_room.cache
# before any lookup methods get called on it as otherwise there may be
# a race if invalidate_all gets called (which assumes its in the cache)
return RulesForRoom(
self.hs,
room_id,
self._get_rules_for_room.cache,
self.room_push_rule_cache_metrics,
)
return RulesForRoomData()
async def _get_power_levels_and_sender_level(
self, event: EventBase, context: EventContext
@ -282,11 +290,49 @@ def _condition_checker(
return True
@attr.s(slots=True)
class RulesForRoomData:
"""The data stored in the cache by `RulesForRoom`.
We don't store `RulesForRoom` directly in the cache as we want our caches to
*only* include data, and not references to e.g. the data stores.
"""
# event_id -> (user_id, state)
member_map = attr.ib(type=Dict[str, Tuple[str, str]], factory=dict)
# user_id -> rules
rules_by_user = attr.ib(type=Dict[str, List[Dict[str, dict]]], factory=dict)
# The last state group we updated the caches for. If the state_group of
# a new event comes along, we know that we can just return the cached
# result.
# On invalidation of the rules themselves (if the user changes them),
# we invalidate everything and set state_group to `object()`
state_group = attr.ib(type=Union[object, int], factory=object)
# A sequence number to keep track of when we're allowed to update the
# cache. We bump the sequence number when we invalidate the cache. If
# the sequence number changes while we're calculating stuff we should
# not update the cache with it.
sequence = attr.ib(type=int, default=0)
# A cache of user_ids that we *know* aren't interesting, e.g. user_ids
# owned by AS's, or remote users, etc. (I.e. users we will never need to
# calculate push for)
# These never need to be invalidated as we will never set up push for
# them.
uninteresting_user_set = attr.ib(type=Set[str], factory=set)
class RulesForRoom:
"""Caches push rules for users in a room.
This efficiently handles users joining/leaving the room by not invalidating
the entire cache for the room.
A new instance is constructed for each call to
`BulkPushRuleEvaluator._get_rules_for_event`, with the cached data from
previous calls passed in.
"""
def __init__(
@ -295,6 +341,8 @@ class RulesForRoom:
room_id: str,
rules_for_room_cache: LruCache,
room_push_rule_cache_metrics: CacheMetric,
linearizer: Linearizer,
cached_data: RulesForRoomData,
):
"""
Args:
@ -303,38 +351,21 @@ class RulesForRoom:
rules_for_room_cache: The cache object that caches these
RoomsForUser objects.
room_push_rule_cache_metrics: The metrics object
linearizer: The linearizer used to ensure only one thing mutates
the cache at a time. Keyed off room_id
cached_data: Cached data from previous calls to `self.get_rules`,
can be mutated.
"""
self.room_id = room_id
self.is_mine_id = hs.is_mine_id
self.store = hs.get_datastore()
self.room_push_rule_cache_metrics = room_push_rule_cache_metrics
self.linearizer = Linearizer(name="rules_for_room")
# Used to ensure only one thing mutates the cache at a time. Keyed off
# room_id.
self.linearizer = linearizer
# event_id -> (user_id, state)
self.member_map = {} # type: Dict[str, Tuple[str, str]]
# user_id -> rules
self.rules_by_user = {} # type: Dict[str, List[Dict[str, dict]]]
# The last state group we updated the caches for. If the state_group of
# a new event comes along, we know that we can just return the cached
# result.
# On invalidation of the rules themselves (if the user changes them),
# we invalidate everything and set state_group to `object()`
self.state_group = object()
# A sequence number to keep track of when we're allowed to update the
# cache. We bump the sequence number when we invalidate the cache. If
# the sequence number changes while we're calculating stuff we should
# not update the cache with it.
self.sequence = 0
# A cache of user_ids that we *know* aren't interesting, e.g. user_ids
# owned by AS's, or remote users, etc. (I.e. users we will never need to
# calculate push for)
# These never need to be invalidated as we will never set up push for
# them.
self.uninteresting_user_set = set() # type: Set[str]
self.data = cached_data
# We need to be clever on the invalidating caches callbacks, as
# otherwise the invalidation callback holds a reference to the object,
@ -352,25 +383,25 @@ class RulesForRoom:
"""
state_group = context.state_group
if state_group and self.state_group == state_group:
if state_group and self.data.state_group == state_group:
logger.debug("Using cached rules for %r", self.room_id)
self.room_push_rule_cache_metrics.inc_hits()
return self.rules_by_user
return self.data.rules_by_user
with (await self.linearizer.queue(())):
if state_group and self.state_group == state_group:
with (await self.linearizer.queue(self.room_id)):
if state_group and self.data.state_group == state_group:
logger.debug("Using cached rules for %r", self.room_id)
self.room_push_rule_cache_metrics.inc_hits()
return self.rules_by_user
return self.data.rules_by_user
self.room_push_rule_cache_metrics.inc_misses()
ret_rules_by_user = {}
missing_member_event_ids = {}
if state_group and self.state_group == context.prev_group:
if state_group and self.data.state_group == context.prev_group:
# If we have a simple delta then we can reuse most of the previous
# results.
ret_rules_by_user = self.rules_by_user
ret_rules_by_user = self.data.rules_by_user
current_state_ids = context.delta_ids
push_rules_delta_state_cache_metric.inc_hits()
@ -393,24 +424,24 @@ class RulesForRoom:
if typ != EventTypes.Member:
continue
if user_id in self.uninteresting_user_set:
if user_id in self.data.uninteresting_user_set:
continue
if not self.is_mine_id(user_id):
self.uninteresting_user_set.add(user_id)
self.data.uninteresting_user_set.add(user_id)
continue
if self.store.get_if_app_services_interested_in_user(user_id):
self.uninteresting_user_set.add(user_id)
self.data.uninteresting_user_set.add(user_id)
continue
event_id = current_state_ids[key]
res = self.member_map.get(event_id, None)
res = self.data.member_map.get(event_id, None)
if res:
user_id, state = res
if state == Membership.JOIN:
rules = self.rules_by_user.get(user_id, None)
rules = self.data.rules_by_user.get(user_id, None)
if rules:
ret_rules_by_user[user_id] = rules
continue
@ -430,7 +461,7 @@ class RulesForRoom:
else:
# The push rules didn't change but lets update the cache anyway
self.update_cache(
self.sequence,
self.data.sequence,
members={}, # There were no membership changes
rules_by_user=ret_rules_by_user,
state_group=state_group,
@ -461,7 +492,7 @@ class RulesForRoom:
for. Used when updating the cache.
event: The event we are currently computing push rules for.
"""
sequence = self.sequence
sequence = self.data.sequence
rows = await self.store.get_membership_from_event_ids(member_event_ids.values())
@ -501,23 +532,11 @@ class RulesForRoom:
self.update_cache(sequence, members, ret_rules_by_user, state_group)
def invalidate_all(self) -> None:
# Note: Don't hand this function directly to an invalidation callback
# as it keeps a reference to self and will stop this instance from being
# GC'd if it gets dropped from the rules_to_user cache. Instead use
# `self.invalidate_all_cb`
logger.debug("Invalidating RulesForRoom for %r", self.room_id)
self.sequence += 1
self.state_group = object()
self.member_map = {}
self.rules_by_user = {}
push_rules_invalidation_counter.inc()
def update_cache(self, sequence, members, rules_by_user, state_group) -> None:
if sequence == self.sequence:
self.member_map.update(members)
self.rules_by_user = rules_by_user
self.state_group = state_group
if sequence == self.data.sequence:
self.data.member_map.update(members)
self.data.rules_by_user = rules_by_user
self.data.state_group = state_group
@attr.attrs(slots=True, frozen=True)
@ -535,6 +554,10 @@ class _Invalidation:
room_id = attr.ib(type=str)
def __call__(self) -> None:
rules = self.cache.get(self.room_id, None, update_metrics=False)
if rules:
rules.invalidate_all()
rules_data = self.cache.get(self.room_id, None, update_metrics=False)
if rules_data:
rules_data.sequence += 1
rules_data.state_group = object()
rules_data.member_map = {}
rules_data.rules_by_user = {}
push_rules_invalidation_counter.inc()

159
synapse/storage/databases/main/roommember.py
View file

@ -23,8 +23,11 @@ from typing import (
Optional,
Set,
Tuple,
Union,
)
import attr
from synapse.api.constants import EventTypes, Membership
from synapse.events import EventBase
from synapse.events.snapshot import EventContext
@ -43,7 +46,7 @@ from synapse.storage.roommember import (
ProfileInfo,
RoomsForUser,
)
from synapse.types import PersistedEventPosition, get_domain_from_id
from synapse.types import PersistedEventPosition, StateMap, get_domain_from_id
from synapse.util.async_helpers import Linearizer
from synapse.util.caches import intern_string
from synapse.util.caches.descriptors import _CacheContext, cached, cachedList
@ -63,6 +66,10 @@ class RoomMemberWorkerStore(EventsWorkerStore):
def __init__(self, database: DatabasePool, db_conn, hs):
super().__init__(database, db_conn, hs)
# Used by `_get_joined_hosts` to ensure only one thing mutates the cache
# at a time. Keyed by room_id.
self._joined_host_linearizer = Linearizer("_JoinedHostsCache")
# Is the current_state_events.membership up to date? Or is the
# background update still running?
self._current_state_events_membership_up_to_date = False
@ -740,19 +747,82 @@ class RoomMemberWorkerStore(EventsWorkerStore):
@cached(num_args=2, max_entries=10000, iterable=True)
async def _get_joined_hosts(
self, room_id, state_group, current_state_ids, state_entry
):
# We don't use `state_group`, its there so that we can cache based
# on it. However, its important that its never None, since two current_state's
# with a state_group of None are likely to be different.
self,
room_id: str,
state_group: int,
current_state_ids: StateMap[str],
state_entry: "_StateCacheEntry",
) -> FrozenSet[str]:
# We don't use `state_group`, its there so that we can cache based on
# it. However, its important that its never None, since two
# current_state's with a state_group of None are likely to be different.
#
# The `state_group` must match the `state_entry.state_group` (if not None).
assert state_group is not None
assert state_entry.state_group is None or state_entry.state_group == state_group
# We use a secondary cache of previous work to allow us to build up the
# joined hosts for the given state group based on previous state groups.
#
# We cache one object per room containing the results of the last state
# group we got joined hosts for. The idea is that generally
# `get_joined_hosts` is called with the "current" state group for the
# room, and so consecutive calls will be for consecutive state groups
# which point to the previous state group.
cache = await self._get_joined_hosts_cache(room_id)
return await cache.get_destinations(state_entry)
# If the state group in the cache matches, we already have the data we need.
if state_entry.state_group == cache.state_group:
return frozenset(cache.hosts_to_joined_users)
# Since we'll mutate the cache we need to lock.
with (await self._joined_host_linearizer.queue(room_id)):
if state_entry.state_group == cache.state_group:
# Same state group, so nothing to do. We've already checked for
# this above, but the cache may have changed while waiting on
# the lock.
pass
elif state_entry.prev_group == cache.state_group:
# The cached work is for the previous state group, so we work out
# the delta.
for (typ, state_key), event_id in state_entry.delta_ids.items():
if typ != EventTypes.Member:
continue
host = intern_string(get_domain_from_id(state_key))
user_id = state_key
known_joins = cache.hosts_to_joined_users.setdefault(host, set())
event = await self.get_event(event_id)
if event.membership == Membership.JOIN:
known_joins.add(user_id)
else:
known_joins.discard(user_id)
if not known_joins:
cache.hosts_to_joined_users.pop(host, None)
else:
# The cache doesn't match the state group or prev state group,
# so we calculate the result from first principles.
joined_users = await self.get_joined_users_from_state(
room_id, state_entry
)
cache.hosts_to_joined_users = {}
for user_id in joined_users:
host = intern_string(get_domain_from_id(user_id))
cache.hosts_to_joined_users.setdefault(host, set()).add(user_id)
if state_entry.state_group:
cache.state_group = state_entry.state_group
else:
cache.state_group = object()
return frozenset(cache.hosts_to_joined_users)
@cached(max_entries=10000)
def _get_joined_hosts_cache(self, room_id: str) -> "_JoinedHostsCache":
return _JoinedHostsCache(self, room_id)
return _JoinedHostsCache()
@cached(num_args=2)
async def did_forget(self, user_id: str, room_id: str) -> bool:
@ -1062,71 +1132,18 @@ class RoomMemberStore(RoomMemberWorkerStore, RoomMemberBackgroundUpdateStore):
await self.db_pool.runInteraction("forget_membership", f)
@attr.s(slots=True)
class _JoinedHostsCache:
"""Cache for joined hosts in a room that is optimised to handle updates
via state deltas.
"""
"""The cached data used by the `_get_joined_hosts_cache`."""
def __init__(self, store, room_id):
self.store = store
self.room_id = room_id
# Dict of host to the set of their users in the room at the state group.
hosts_to_joined_users = attr.ib(type=Dict[str, Set[str]], factory=dict)
self.hosts_to_joined_users = {}
self.state_group = object()
self.linearizer = Linearizer("_JoinedHostsCache")
self._len = 0
async def get_destinations(self, state_entry: "_StateCacheEntry") -> Set[str]:
"""Get set of destinations for a state entry
Args:
state_entry
Returns:
The destinations as a set.
"""
if state_entry.state_group == self.state_group:
return frozenset(self.hosts_to_joined_users)
with (await self.linearizer.queue(())):
if state_entry.state_group == self.state_group:
pass
elif state_entry.prev_group == self.state_group:
for (typ, state_key), event_id in state_entry.delta_ids.items():
if typ != EventTypes.Member:
continue
host = intern_string(get_domain_from_id(state_key))
user_id = state_key
known_joins = self.hosts_to_joined_users.setdefault(host, set())
event = await self.store.get_event(event_id)
if event.membership == Membership.JOIN:
known_joins.add(user_id)
else:
known_joins.discard(user_id)
if not known_joins:
self.hosts_to_joined_users.pop(host, None)
else:
joined_users = await self.store.get_joined_users_from_state(
self.room_id, state_entry
)
self.hosts_to_joined_users = {}
for user_id in joined_users:
host = intern_string(get_domain_from_id(user_id))
self.hosts_to_joined_users.setdefault(host, set()).add(user_id)
if state_entry.state_group:
self.state_group = state_entry.state_group
else:
self.state_group = object()
self._len = sum(len(v) for v in self.hosts_to_joined_users.values())
return frozenset(self.hosts_to_joined_users)
# The state group `hosts_to_joined_users` is derived from. Will be an object
# if the instance is newly created or if the state is not based on a state
# group. (An object is used as a sentinel value to ensure that it never is
# equal to anything else).
state_group = attr.ib(type=Union[object, int], factory=object)
def __len__(self):
return self._len
return sum(len(v) for v in self.hosts_to_joined_users.values())