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# Copyright 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.
from typing import List, Optional, Tuple
from synapse.storage.types import Connection
from synapse.storage.util.id_generators import _load_current_id
class SlavedIdTracker:
def __init__(
self,
db_conn: Connection,
table: str,
column: str,
extra_tables: Optional[List[Tuple[str, str]]] = None,
step: int = 1,
):
self.step = step
self._current = _load_current_id(db_conn, table, column, step)
if extra_tables:
for table, column in extra_tables:
self.advance(None, _load_current_id(db_conn, table, column))
def advance(self, instance_name: Optional[str], new_id: int):
self._current = (max if self.step > 0 else min)(self._current, new_id)
def get_current_token(self) -> int:
"""
Returns:
int
"""
return self._current
def get_current_token_for_writer(self, instance_name: str) -> int:
"""Returns the position of the given writer.
For streams with single writers this is equivalent to
`get_current_token`.
"""
return self.get_current_token()
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