From 85d237eba789a667109ced140026d2494b210310 Mon Sep 17 00:00:00 2001 From: Erik Johnston Date: Tue, 29 Jun 2021 19:15:47 +0100 Subject: Add a distributed lock (#10269) This adds a simple best effort locking mechanism that works cross workers. --- synapse/storage/schema/main/delta/59/15locks.sql | 37 ++++++++++++++++++++++++ 1 file changed, 37 insertions(+) create mode 100644 synapse/storage/schema/main/delta/59/15locks.sql (limited to 'synapse/storage/schema/main') diff --git a/synapse/storage/schema/main/delta/59/15locks.sql b/synapse/storage/schema/main/delta/59/15locks.sql new file mode 100644 index 0000000000..8b2999ff3e --- /dev/null +++ b/synapse/storage/schema/main/delta/59/15locks.sql @@ -0,0 +1,37 @@ +/* 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); -- cgit 1.4.1