Reduce DB contention on worker locks (#16160)

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Erik Johnston 2023-08-23 13:45:19 +01:00 committed by GitHub
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Reduce DB contention on worker locks.

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/* Copyright 2023 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.
*/
-- Fix up the triggers that were in `78/04_read_write_locks_triggers.sql`
-- Reduce the number of writes we do on this table.
--
-- Note: that we still want to lock the row here (i.e. still do a `DO UPDATE
-- SET`) so that we serialize updates.
CREATE OR REPLACE FUNCTION upsert_read_write_lock_parent() RETURNS trigger AS $$
BEGIN
INSERT INTO worker_read_write_locks_mode (lock_name, lock_key, write_lock, token)
VALUES (NEW.lock_name, NEW.lock_key, NEW.write_lock, NEW.token)
ON CONFLICT (lock_name, lock_key)
DO UPDATE SET write_lock = NEW.write_lock
WHERE OLD.write_lock != NEW.write_lock;
RETURN NEW;
END
$$
LANGUAGE plpgsql;
DROP TRIGGER IF EXISTS upsert_read_write_lock_parent_trigger ON worker_read_write_locks;
CREATE TRIGGER upsert_read_write_lock_parent_trigger BEFORE INSERT ON worker_read_write_locks
FOR EACH ROW
EXECUTE PROCEDURE upsert_read_write_lock_parent();