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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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