From fae2fc0b5e704d4612fa8ddd6ecb93e4f2e3a5be Mon Sep 17 00:00:00 2001 From: Daniel Waterworth Date: Fri, 5 Mar 2021 13:40:00 -0600 Subject: [PATCH] FIX: Race condition in draft sequence updates (#12299) This was causing RecordNotUnique exceptions --- app/models/draft_sequence.rb | 23 +++++++++++++++-------- 1 file changed, 15 insertions(+), 8 deletions(-) diff --git a/app/models/draft_sequence.rb b/app/models/draft_sequence.rb index b79f3c9256..4afca805e2 100644 --- a/app/models/draft_sequence.rb +++ b/app/models/draft_sequence.rb @@ -9,14 +9,21 @@ class DraftSequence < ActiveRecord::Base return 0 if !User.human_user_id?(user_id) - h = { user_id: user_id, draft_key: key } - c = DraftSequence.find_by(h) - c ||= DraftSequence.new(h) - c.sequence ||= 0 - c.sequence += 1 - c.save! - DB.exec("DELETE FROM drafts WHERE user_id = :user_id AND draft_key = :draft_key AND sequence < :sequence", draft_key: key, user_id: user_id, sequence: c.sequence) - c.sequence + sequence = + DB.query_single(<<~SQL, user_id: user_id, draft_key: key).first + INSERT INTO draft_sequences (user_id, draft_key, sequence) + VALUES (:user_id, :draft_key, 1) + ON CONFLICT (user_id, draft_key) DO + UPDATE + SET sequence = draft_sequences.sequence + 1 + WHERE draft_sequences.user_id = :user_id + AND draft_sequences.draft_key = :draft_key + RETURNING sequence + SQL + + DB.exec("DELETE FROM drafts WHERE user_id = :user_id AND draft_key = :draft_key AND sequence < :sequence", draft_key: key, user_id: user_id, sequence: sequence) + + sequence end def self.current(user, key)