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38 lines
1.6 KiB
SQL
38 lines
1.6 KiB
SQL
/* Copyright 2021 The Matrix.org Foundation C.I.C
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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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*/
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-- A noddy implementation of a distributed lock across workers. While a worker
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-- has taken a lock out they should regularly update the `last_renewed_ts`
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-- column, a lock will be considered dropped if `last_renewed_ts` is from ages
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-- ago.
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CREATE TABLE worker_locks (
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lock_name TEXT NOT NULL,
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lock_key TEXT NOT NULL,
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-- We write the instance name to ease manual debugging, we don't ever read
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-- from it.
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-- Note: instance names aren't guarenteed to be unique.
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instance_name TEXT NOT NULL,
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-- A random string generated each time an instance takes out a lock. Used by
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-- the instance to tell whether the lock is still held by it (e.g. in the
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-- case where the process stalls for a long time the lock may time out and
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-- be taken out by another instance, at which point the original instance
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-- can tell it no longer holds the lock as the tokens no longer match).
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token TEXT NOT NULL,
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last_renewed_ts BIGINT NOT NULL
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);
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CREATE UNIQUE INDEX worker_locks_key ON worker_locks (lock_name, lock_key);
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