51 lines
1.8 KiB
Python
51 lines
1.8 KiB
Python
# Copyright 2016 OpenMarket Ltd
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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from typing import List, Optional, Tuple
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from synapse.storage.database import LoggingDatabaseConnection
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from synapse.storage.util.id_generators import AbstractStreamIdTracker, _load_current_id
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class SlavedIdTracker(AbstractStreamIdTracker):
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"""Tracks the "current" stream ID of a stream with a single writer.
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See `AbstractStreamIdTracker` for more details.
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Note that this class does not work correctly when there are multiple
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writers.
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"""
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def __init__(
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self,
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db_conn: LoggingDatabaseConnection,
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table: str,
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column: str,
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extra_tables: Optional[List[Tuple[str, str]]] = None,
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step: int = 1,
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):
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self.step = step
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self._current = _load_current_id(db_conn, table, column, step)
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if extra_tables:
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for table, column in extra_tables:
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self.advance(None, _load_current_id(db_conn, table, column))
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def advance(self, instance_name: Optional[str], new_id: int) -> None:
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self._current = (max if self.step > 0 else min)(self._current, new_id)
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def get_current_token(self) -> int:
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return self._current
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def get_current_token_for_writer(self, instance_name: str) -> int:
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return self.get_current_token()
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