From 8f35f8148e1a7ce3ac249e2d2052854409f2c0d6 Mon Sep 17 00:00:00 2001 From: Erik Johnston Date: Mon, 23 Oct 2023 16:57:30 +0100 Subject: Fix bug where a new writer advances their token too quickly (#16473) * Fix bug where a new writer advances their token too quickly When starting a new writer (for e.g. persisting events), the `MultiWriterIdGenerator` doesn't have a minimum token for it as there are no rows matching that new writer in the DB. This results in the the first stream ID it acquired being announced as persisted *before* it actually finishes persisting, if another writer gets and persists a subsequent stream ID. This is due to the logic of setting the minimum persisted position to the minimum known position of across all writers, and the new writer starts off not being considered. * Fix sending out POSITIONs when our token advances without update Broke in #14820 * For replication HTTP requests, only wait for minimal position --- synapse/replication/http/_base.py | 2 +- synapse/replication/tcp/streams/_base.py | 129 +++++++++++++++-------- synapse/replication/tcp/streams/events.py | 8 +- synapse/replication/tcp/streams/federation.py | 15 ++- synapse/replication/tcp/streams/partial_state.py | 10 +- synapse/storage/util/id_generators.py | 68 +++++++++++- 6 files changed, 170 insertions(+), 62 deletions(-) (limited to 'synapse') diff --git a/synapse/replication/http/_base.py b/synapse/replication/http/_base.py index 63cf24a14d..7476839db5 100644 --- a/synapse/replication/http/_base.py +++ b/synapse/replication/http/_base.py @@ -238,7 +238,7 @@ class ReplicationEndpoint(metaclass=abc.ABCMeta): data[_STREAM_POSITION_KEY] = { "streams": { - stream.NAME: stream.current_token(local_instance_name) + stream.NAME: stream.minimal_local_current_token() for stream in streams }, "instance_name": local_instance_name, diff --git a/synapse/replication/tcp/streams/_base.py b/synapse/replication/tcp/streams/_base.py index c6088a0f99..5c4d228f3d 100644 --- a/synapse/replication/tcp/streams/_base.py +++ b/synapse/replication/tcp/streams/_base.py @@ -33,6 +33,7 @@ from synapse.replication.http.streams import ReplicationGetStreamUpdates if TYPE_CHECKING: from synapse.server import HomeServer + from synapse.storage.util.id_generators import AbstractStreamIdGenerator logger = logging.getLogger(__name__) @@ -107,22 +108,10 @@ class Stream: def __init__( self, local_instance_name: str, - current_token_function: Callable[[str], Token], update_function: UpdateFunction, ): """Instantiate a Stream - `current_token_function` and `update_function` are callbacks which - should be implemented by subclasses. - - `current_token_function` takes an instance name, which is a writer to - the stream, and returns the position in the stream of the writer (as - viewed from the current process). On the writer process this is where - the writer has successfully written up to, whereas on other processes - this is the position which we have received updates up to over - replication. (Note that most streams have a single writer and so their - implementations ignore the instance name passed in). - `update_function` is called to get updates for this stream between a pair of stream tokens. See the `UpdateFunction` type definition for more info. @@ -133,12 +122,28 @@ class Stream: update_function: callback go get stream updates, as above """ self.local_instance_name = local_instance_name - self.current_token = current_token_function self.update_function = update_function # The token from which we last asked for updates self.last_token = self.current_token(self.local_instance_name) + def current_token(self, instance_name: str) -> Token: + """This takes an instance name, which is a writer to + the stream, and returns the position in the stream of the writer (as + viewed from the current process). + """ + # We can't make this an abstract class as it makes mypy unhappy. + raise NotImplementedError() + + def minimal_local_current_token(self) -> Token: + """Tries to return a minimal current token for the local instance, + i.e. for writers this would be the last successful write. + + If local instance is not a writer (or has written yet) then falls back + to returning the normal "current token". + """ + raise NotImplementedError() + def discard_updates_and_advance(self) -> None: """Called when the stream should advance but the updates would be discarded, e.g. when there are no currently connected workers. @@ -190,6 +195,25 @@ class Stream: return updates, upto_token, limited +class _StreamFromIdGen(Stream): + """Helper class for simple streams that use a stream ID generator""" + + def __init__( + self, + local_instance_name: str, + update_function: UpdateFunction, + stream_id_gen: "AbstractStreamIdGenerator", + ): + self._stream_id_gen = stream_id_gen + super().__init__(local_instance_name, update_function) + + def current_token(self, instance_name: str) -> Token: + return self._stream_id_gen.get_current_token_for_writer(instance_name) + + def minimal_local_current_token(self) -> Token: + return self._stream_id_gen.get_minimal_local_current_token() + + def current_token_without_instance( current_token: Callable[[], int] ) -> Callable[[str], int]: @@ -242,17 +266,21 @@ class BackfillStream(Stream): self.store = hs.get_datastores().main super().__init__( hs.get_instance_name(), - self._current_token, self.store.get_all_new_backfill_event_rows, ) - def _current_token(self, instance_name: str) -> int: + def current_token(self, instance_name: str) -> Token: # The backfill stream over replication operates on *positive* numbers, # which means we need to negate it. return -self.store._backfill_id_gen.get_current_token_for_writer(instance_name) + def minimal_local_current_token(self) -> Token: + # The backfill stream over replication operates on *positive* numbers, + # which means we need to negate it. + return -self.store._backfill_id_gen.get_minimal_local_current_token() -class PresenceStream(Stream): + +class PresenceStream(_StreamFromIdGen): @attr.s(slots=True, frozen=True, auto_attribs=True) class PresenceStreamRow: user_id: str @@ -283,9 +311,7 @@ class PresenceStream(Stream): update_function = make_http_update_function(hs, self.NAME) super().__init__( - hs.get_instance_name(), - current_token_without_instance(store.get_current_presence_token), - update_function, + hs.get_instance_name(), update_function, store._presence_id_gen ) @@ -305,13 +331,18 @@ class PresenceFederationStream(Stream): ROW_TYPE = PresenceFederationStreamRow def __init__(self, hs: "HomeServer"): - federation_queue = hs.get_presence_handler().get_federation_queue() + self._federation_queue = hs.get_presence_handler().get_federation_queue() super().__init__( hs.get_instance_name(), - federation_queue.get_current_token, - federation_queue.get_replication_rows, + self._federation_queue.get_replication_rows, ) + def current_token(self, instance_name: str) -> Token: + return self._federation_queue.get_current_token(instance_name) + + def minimal_local_current_token(self) -> Token: + return self._federation_queue.get_current_token(self.local_instance_name) + class TypingStream(Stream): @attr.s(slots=True, frozen=True, auto_attribs=True) @@ -341,20 +372,25 @@ class TypingStream(Stream): update_function: Callable[ [str, int, int, int], Awaitable[Tuple[List[Tuple[int, Any]], int, bool]] ] = typing_writer_handler.get_all_typing_updates - current_token_function = typing_writer_handler.get_current_token + self.current_token_function = typing_writer_handler.get_current_token else: # Query the typing writer process update_function = make_http_update_function(hs, self.NAME) - current_token_function = hs.get_typing_handler().get_current_token + self.current_token_function = hs.get_typing_handler().get_current_token super().__init__( hs.get_instance_name(), - current_token_without_instance(current_token_function), update_function, ) + def current_token(self, instance_name: str) -> Token: + return self.current_token_function() + + def minimal_local_current_token(self) -> Token: + return self.current_token_function() -class ReceiptsStream(Stream): + +class ReceiptsStream(_StreamFromIdGen): @attr.s(slots=True, frozen=True, auto_attribs=True) class ReceiptsStreamRow: room_id: str @@ -371,12 +407,12 @@ class ReceiptsStream(Stream): store = hs.get_datastores().main super().__init__( hs.get_instance_name(), - current_token_without_instance(store.get_max_receipt_stream_id), store.get_all_updated_receipts, + store._receipts_id_gen, ) -class PushRulesStream(Stream): +class PushRulesStream(_StreamFromIdGen): """A user has changed their push rules""" @attr.s(slots=True, frozen=True, auto_attribs=True) @@ -387,20 +423,16 @@ class PushRulesStream(Stream): ROW_TYPE = PushRulesStreamRow def __init__(self, hs: "HomeServer"): - self.store = hs.get_datastores().main + store = hs.get_datastores().main super().__init__( hs.get_instance_name(), - self._current_token, - self.store.get_all_push_rule_updates, + store.get_all_push_rule_updates, + store._push_rules_stream_id_gen, ) - def _current_token(self, instance_name: str) -> int: - push_rules_token = self.store.get_max_push_rules_stream_id() - return push_rules_token - -class PushersStream(Stream): +class PushersStream(_StreamFromIdGen): """A user has added/changed/removed a pusher""" @attr.s(slots=True, frozen=True, auto_attribs=True) @@ -418,8 +450,8 @@ class PushersStream(Stream): super().__init__( hs.get_instance_name(), - current_token_without_instance(store.get_pushers_stream_token), store.get_all_updated_pushers_rows, + store._pushers_id_gen, ) @@ -447,15 +479,20 @@ class CachesStream(Stream): ROW_TYPE = CachesStreamRow def __init__(self, hs: "HomeServer"): - store = hs.get_datastores().main + self.store = hs.get_datastores().main super().__init__( hs.get_instance_name(), - store.get_cache_stream_token_for_writer, - store.get_all_updated_caches, + self.store.get_all_updated_caches, ) + def current_token(self, instance_name: str) -> Token: + return self.store.get_cache_stream_token_for_writer(instance_name) + + def minimal_local_current_token(self) -> Token: + return self.current_token(self.local_instance_name) + -class DeviceListsStream(Stream): +class DeviceListsStream(_StreamFromIdGen): """Either a user has updated their devices or a remote server needs to be told about a device update. """ @@ -473,8 +510,8 @@ class DeviceListsStream(Stream): self.store = hs.get_datastores().main super().__init__( hs.get_instance_name(), - current_token_without_instance(self.store.get_device_stream_token), self._update_function, + self.store._device_list_id_gen, ) async def _update_function( @@ -525,7 +562,7 @@ class DeviceListsStream(Stream): return updates, upper_limit_token, devices_limited or signatures_limited -class ToDeviceStream(Stream): +class ToDeviceStream(_StreamFromIdGen): """New to_device messages for a client""" @attr.s(slots=True, frozen=True, auto_attribs=True) @@ -539,12 +576,12 @@ class ToDeviceStream(Stream): store = hs.get_datastores().main super().__init__( hs.get_instance_name(), - current_token_without_instance(store.get_to_device_stream_token), store.get_all_new_device_messages, + store._device_inbox_id_gen, ) -class AccountDataStream(Stream): +class AccountDataStream(_StreamFromIdGen): """Global or per room account data was changed""" @attr.s(slots=True, frozen=True, auto_attribs=True) @@ -560,8 +597,8 @@ class AccountDataStream(Stream): self.store = hs.get_datastores().main super().__init__( hs.get_instance_name(), - current_token_without_instance(self.store.get_max_account_data_stream_id), self._update_function, + self.store._account_data_id_gen, ) async def _update_function( diff --git a/synapse/replication/tcp/streams/events.py b/synapse/replication/tcp/streams/events.py index da6d948e1b..38823113d8 100644 --- a/synapse/replication/tcp/streams/events.py +++ b/synapse/replication/tcp/streams/events.py @@ -19,10 +19,10 @@ from typing import TYPE_CHECKING, Iterable, Optional, Tuple, Type, TypeVar, cast import attr from synapse.replication.tcp.streams._base import ( - Stream, StreamRow, StreamUpdateResult, Token, + _StreamFromIdGen, ) if TYPE_CHECKING: @@ -139,7 +139,7 @@ _EventRows: Tuple[Type[BaseEventsStreamRow], ...] = ( TypeToRow = {Row.TypeId: Row for Row in _EventRows} -class EventsStream(Stream): +class EventsStream(_StreamFromIdGen): """We received a new event, or an event went from being an outlier to not""" NAME = "events" @@ -147,9 +147,7 @@ class EventsStream(Stream): def __init__(self, hs: "HomeServer"): self._store = hs.get_datastores().main super().__init__( - hs.get_instance_name(), - self._store._stream_id_gen.get_current_token_for_writer, - self._update_function, + hs.get_instance_name(), self._update_function, self._store._stream_id_gen ) async def _update_function( diff --git a/synapse/replication/tcp/streams/federation.py b/synapse/replication/tcp/streams/federation.py index 4046bdec69..7f5af5852c 100644 --- a/synapse/replication/tcp/streams/federation.py +++ b/synapse/replication/tcp/streams/federation.py @@ -18,6 +18,7 @@ import attr from synapse.replication.tcp.streams._base import ( Stream, + Token, current_token_without_instance, make_http_update_function, ) @@ -47,7 +48,7 @@ class FederationStream(Stream): # will be a real FederationSender, which has stubs for current_token and # get_replication_rows.) federation_sender = hs.get_federation_sender() - current_token = current_token_without_instance( + self.current_token_func = current_token_without_instance( federation_sender.get_current_token ) update_function: Callable[ @@ -57,15 +58,21 @@ class FederationStream(Stream): elif hs.should_send_federation(): # federation sender: Query master process update_function = make_http_update_function(hs, self.NAME) - current_token = self._stub_current_token + self.current_token_func = self._stub_current_token else: # other worker: stub out the update function (we're not interested in # any updates so when we get a POSITION we do nothing) update_function = self._stub_update_function - current_token = self._stub_current_token + self.current_token_func = self._stub_current_token - super().__init__(hs.get_instance_name(), current_token, update_function) + super().__init__(hs.get_instance_name(), update_function) + + def current_token(self, instance_name: str) -> Token: + return self.current_token_func(instance_name) + + def minimal_local_current_token(self) -> Token: + return self.current_token(self.local_instance_name) @staticmethod def _stub_current_token(instance_name: str) -> int: diff --git a/synapse/replication/tcp/streams/partial_state.py b/synapse/replication/tcp/streams/partial_state.py index a8ce5ffd72..ad181d7e93 100644 --- a/synapse/replication/tcp/streams/partial_state.py +++ b/synapse/replication/tcp/streams/partial_state.py @@ -15,7 +15,7 @@ from typing import TYPE_CHECKING import attr -from synapse.replication.tcp.streams import Stream +from synapse.replication.tcp.streams._base import _StreamFromIdGen if TYPE_CHECKING: from synapse.server import HomeServer @@ -27,7 +27,7 @@ class UnPartialStatedRoomStreamRow: room_id: str -class UnPartialStatedRoomStream(Stream): +class UnPartialStatedRoomStream(_StreamFromIdGen): """ Stream to notify about rooms becoming un-partial-stated; that is, when the background sync finishes such that we now have full state for @@ -41,8 +41,8 @@ class UnPartialStatedRoomStream(Stream): store = hs.get_datastores().main super().__init__( hs.get_instance_name(), - store.get_un_partial_stated_rooms_token, store.get_un_partial_stated_rooms_from_stream, + store._un_partial_stated_rooms_stream_id_gen, ) @@ -56,7 +56,7 @@ class UnPartialStatedEventStreamRow: rejection_status_changed: bool -class UnPartialStatedEventStream(Stream): +class UnPartialStatedEventStream(_StreamFromIdGen): """ Stream to notify about events becoming un-partial-stated. """ @@ -68,6 +68,6 @@ class UnPartialStatedEventStream(Stream): store = hs.get_datastores().main super().__init__( hs.get_instance_name(), - store.get_un_partial_stated_events_token, store.get_un_partial_stated_events_from_stream, + store._un_partial_stated_events_stream_id_gen, ) diff --git a/synapse/storage/util/id_generators.py b/synapse/storage/util/id_generators.py index d2c874b9a8..9c3eafb562 100644 --- a/synapse/storage/util/id_generators.py +++ b/synapse/storage/util/id_generators.py @@ -133,6 +133,15 @@ class AbstractStreamIdGenerator(metaclass=abc.ABCMeta): """ raise NotImplementedError() + @abc.abstractmethod + def get_minimal_local_current_token(self) -> int: + """Tries to return a minimal current token for the local instance, + i.e. for writers this would be the last successful write. + + If local instance is not a writer (or has written yet) then falls back + to returning the normal "current token". + """ + @abc.abstractmethod def get_next(self) -> AsyncContextManager[int]: """ @@ -312,6 +321,9 @@ class StreamIdGenerator(AbstractStreamIdGenerator): def get_current_token_for_writer(self, instance_name: str) -> int: return self.get_current_token() + def get_minimal_local_current_token(self) -> int: + return self.get_current_token() + class MultiWriterIdGenerator(AbstractStreamIdGenerator): """Generates and tracks stream IDs for a stream with multiple writers. @@ -408,6 +420,11 @@ class MultiWriterIdGenerator(AbstractStreamIdGenerator): # The maximum stream ID that we have seen been allocated across any writer. self._max_seen_allocated_stream_id = 1 + # The maximum position of the local instance. This can be higher than + # the corresponding position in `current_positions` table when there are + # no active writes in progress. + self._max_position_of_local_instance = self._max_seen_allocated_stream_id + self._sequence_gen = PostgresSequenceGenerator(sequence_name) # We check that the table and sequence haven't diverged. @@ -427,6 +444,16 @@ class MultiWriterIdGenerator(AbstractStreamIdGenerator): self._current_positions.values(), default=1 ) + # For the case where `stream_positions` is not up to date, + # `_persisted_upto_position` may be higher. + self._max_seen_allocated_stream_id = max( + self._max_seen_allocated_stream_id, self._persisted_upto_position + ) + + # Bump our local maximum position now that we've loaded things from the + # DB. + self._max_position_of_local_instance = self._max_seen_allocated_stream_id + if not writers: # If there have been no explicit writers given then any instance can # write to the stream. In which case, let's pre-seed our own @@ -545,6 +572,14 @@ class MultiWriterIdGenerator(AbstractStreamIdGenerator): if instance == self._instance_name: self._current_positions[instance] = stream_id + if self._writers: + # If we have explicit writers then make sure that each instance has + # a position. + for writer in self._writers: + self._current_positions.setdefault( + writer, self._persisted_upto_position + ) + cur.close() def _load_next_id_txn(self, txn: Cursor) -> int: @@ -688,6 +723,9 @@ class MultiWriterIdGenerator(AbstractStreamIdGenerator): if new_cur: curr = self._current_positions.get(self._instance_name, 0) self._current_positions[self._instance_name] = max(curr, new_cur) + self._max_position_of_local_instance = max( + curr, new_cur, self._max_position_of_local_instance + ) self._add_persisted_position(next_id) @@ -702,10 +740,26 @@ class MultiWriterIdGenerator(AbstractStreamIdGenerator): # persisted up to position. This stops Synapse from doing a full table # scan when a new writer announces itself over replication. with self._lock: - return self._return_factor * self._current_positions.get( + if self._instance_name == instance_name: + return self._return_factor * self._max_position_of_local_instance + + pos = self._current_positions.get( instance_name, self._persisted_upto_position ) + # We want to return the maximum "current token" that we can for a + # writer, this helps ensure that streams progress as fast as + # possible. + pos = max(pos, self._persisted_upto_position) + + return self._return_factor * pos + + def get_minimal_local_current_token(self) -> int: + with self._lock: + return self._return_factor * self._current_positions.get( + self._instance_name, self._persisted_upto_position + ) + def get_positions(self) -> Dict[str, int]: """Get a copy of the current positon map. @@ -774,6 +828,18 @@ class MultiWriterIdGenerator(AbstractStreamIdGenerator): self._persisted_upto_position = max(min_curr, self._persisted_upto_position) + # Advance our local max position. + self._max_position_of_local_instance = max( + self._max_position_of_local_instance, self._persisted_upto_position + ) + + if not self._unfinished_ids and not self._in_flight_fetches: + # If we don't have anything in flight, it's safe to advance to the + # max seen stream ID. + self._max_position_of_local_instance = max( + self._max_seen_allocated_stream_id, self._max_position_of_local_instance + ) + # We now iterate through the seen positions, discarding those that are # less than the current min positions, and incrementing the min position # if its exactly one greater. -- cgit 1.4.1