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- # Copyright 2018 Vector Creations 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 typing import Any, Dict, List, Tuple
-
- from synapse.storage._base import SQLBaseStore
- from synapse.storage.database import LoggingTransaction
- from synapse.util.caches.stream_change_cache import StreamChangeCache
-
- logger = logging.getLogger(__name__)
-
-
- class StateDeltasStore(SQLBaseStore):
- # This class must be mixed in with a child class which provides the following
- # attribute. TODO: can we get static analysis to enforce this?
- _curr_state_delta_stream_cache: StreamChangeCache
-
- async def get_partial_current_state_deltas(
- self, prev_stream_id: int, max_stream_id: int
- ) -> Tuple[int, List[Dict[str, Any]]]:
- """Fetch a list of room state changes since the given stream id
-
- Each entry in the result contains the following fields:
- - stream_id (int)
- - room_id (str)
- - type (str): event type
- - state_key (str):
- - event_id (str|None): new event_id for this state key. None if the
- state has been deleted.
- - prev_event_id (str|None): previous event_id for this state key. None
- if it's new state.
-
- This may be the partial state if we're lazy joining the room.
-
- Args:
- prev_stream_id: point to get changes since (exclusive)
- max_stream_id: the point that we know has been correctly persisted
- - ie, an upper limit to return changes from.
-
- Returns:
- A tuple consisting of:
- - the stream id which these results go up to
- - list of current_state_delta_stream rows. If it is empty, we are
- up to date.
- """
- prev_stream_id = int(prev_stream_id)
-
- # check we're not going backwards
- assert (
- prev_stream_id <= max_stream_id
- ), f"New stream id {max_stream_id} is smaller than prev stream id {prev_stream_id}"
-
- if not self._curr_state_delta_stream_cache.has_any_entity_changed(
- prev_stream_id
- ):
- # if the CSDs haven't changed between prev_stream_id and now, we
- # know for certain that they haven't changed between prev_stream_id and
- # max_stream_id.
- return max_stream_id, []
-
- def get_current_state_deltas_txn(
- txn: LoggingTransaction,
- ) -> Tuple[int, List[Dict[str, Any]]]:
- # First we calculate the max stream id that will give us less than
- # N results.
- # We arbitrarily limit to 100 stream_id entries to ensure we don't
- # select toooo many.
- sql = """
- SELECT stream_id, count(*)
- FROM current_state_delta_stream
- WHERE stream_id > ? AND stream_id <= ?
- GROUP BY stream_id
- ORDER BY stream_id ASC
- LIMIT 100
- """
- txn.execute(sql, (prev_stream_id, max_stream_id))
-
- total = 0
-
- for stream_id, count in txn:
- total += count
- if total > 100:
- # We arbitrarily limit to 100 entries to ensure we don't
- # select toooo many.
- logger.debug(
- "Clipping current_state_delta_stream rows to stream_id %i",
- stream_id,
- )
- clipped_stream_id = stream_id
- break
- else:
- # if there's no problem, we may as well go right up to the max_stream_id
- clipped_stream_id = max_stream_id
-
- # Now actually get the deltas
- sql = """
- SELECT stream_id, room_id, type, state_key, event_id, prev_event_id
- FROM current_state_delta_stream
- WHERE ? < stream_id AND stream_id <= ?
- ORDER BY stream_id ASC
- """
- txn.execute(sql, (prev_stream_id, clipped_stream_id))
- return clipped_stream_id, self.db_pool.cursor_to_dict(txn)
-
- return await self.db_pool.runInteraction(
- "get_current_state_deltas", get_current_state_deltas_txn
- )
-
- def _get_max_stream_id_in_current_state_deltas_txn(
- self, txn: LoggingTransaction
- ) -> int:
- return self.db_pool.simple_select_one_onecol_txn(
- txn,
- table="current_state_delta_stream",
- keyvalues={},
- retcol="COALESCE(MAX(stream_id), -1)",
- )
-
- async def get_max_stream_id_in_current_state_deltas(self) -> int:
- return await self.db_pool.runInteraction(
- "get_max_stream_id_in_current_state_deltas",
- self._get_max_stream_id_in_current_state_deltas_txn,
- )
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