forked-synapse/synapse/storage/schema/main/delta/59/15locks.sql
2023-11-21 15:29:58 -05:00

57 lines
2.3 KiB
SQL

--
-- This file is licensed under the Affero General Public License (AGPL) version 3.
--
-- Copyright (C) 2023 New Vector, Ltd
--
-- This program is free software: you can redistribute it and/or modify
-- it under the terms of the GNU Affero General Public License as
-- published by the Free Software Foundation, either version 3 of the
-- License, or (at your option) any later version.
--
-- See the GNU Affero General Public License for more details:
-- <https://www.gnu.org/licenses/agpl-3.0.html>.
--
-- Originally licensed under the Apache License, Version 2.0:
-- <http://www.apache.org/licenses/LICENSE-2.0>.
--
-- [This file includes modifications made by New Vector Limited]
--
--
/* Copyright 2021 The Matrix.org Foundation C.I.C
*
* 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.
*/
-- A noddy implementation of a distributed lock across workers. While a worker
-- has taken a lock out they should regularly update the `last_renewed_ts`
-- column, a lock will be considered dropped if `last_renewed_ts` is from ages
-- ago.
CREATE TABLE worker_locks (
lock_name TEXT NOT NULL,
lock_key TEXT NOT NULL,
-- We write the instance name to ease manual debugging, we don't ever read
-- from it.
-- Note: instance names aren't guarenteed to be unique.
instance_name TEXT NOT NULL,
-- A random string generated each time an instance takes out a lock. Used by
-- the instance to tell whether the lock is still held by it (e.g. in the
-- case where the process stalls for a long time the lock may time out and
-- be taken out by another instance, at which point the original instance
-- can tell it no longer holds the lock as the tokens no longer match).
token TEXT NOT NULL,
last_renewed_ts BIGINT NOT NULL
);
CREATE UNIQUE INDEX worker_locks_key ON worker_locks (lock_name, lock_key);