From 5506b9406db7847ffd0892a0cda1c042b3157a6a Mon Sep 17 00:00:00 2001 From: ThibG Date: Mon, 11 Mar 2019 00:50:31 +0100 Subject: [PATCH] Avoid race conditions when creating backups (#10234) Under load, multiple backups for a single user could be planned, which is very expensive. --- app/controllers/settings/exports_controller.rb | 18 ++++++++++++++++-- 1 file changed, 16 insertions(+), 2 deletions(-) diff --git a/app/controllers/settings/exports_controller.rb b/app/controllers/settings/exports_controller.rb index 0135f21890..3012fbf775 100644 --- a/app/controllers/settings/exports_controller.rb +++ b/app/controllers/settings/exports_controller.rb @@ -13,11 +13,25 @@ class Settings::ExportsController < Settings::BaseController end def create - authorize :backup, :create? + raise Mastodon::NotPermittedError unless user_signed_in? + + backup = nil + + RedisLock.acquire(lock_options) do |lock| + if lock.acquired? + authorize :backup, :create? + backup = current_user.backups.create! + else + raise Mastodon::RaceConditionError + end + end - backup = current_user.backups.create! BackupWorker.perform_async(backup.id) redirect_to settings_export_path end + + def lock_options + { redis: Redis.current, key: "backup:#{current_user.id}" } + end end