From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-lj1-f195.google.com (mail-lj1-f195.google.com [209.85.208.195]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by dev.tarantool.org (Postfix) with ESMTPS id 3E82F4696C3 for ; Sun, 3 May 2020 13:46:31 +0300 (MSK) Received: by mail-lj1-f195.google.com with SMTP id e25so6803285ljg.5 for ; Sun, 03 May 2020 03:46:31 -0700 (PDT) Date: Sun, 3 May 2020 13:46:29 +0300 From: Konstantin Osipov Message-ID: <20200503104629.GD23133@atlas> References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Subject: Re: [Tarantool-patches] [PATCH 1/1] wal: simplify rollback List-Id: Tarantool development patches List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Vladislav Shpilevoy Cc: tarantool-patches@dev.tarantool.org * Vladislav Shpilevoy [20/05/01 22:16]: This isn't a particularly bad patch. It changes one fairly trivial implementation to another. You claim it simplifies the rollback, I believe it makes it more convoluted with the rest of the code. In any case it's a matter of taste - so perhaps your taste is better than mine. But the reason you had to do this patch *only* because you want to manage rollback in tx - as you claim yourself here: > > Also there is now a single route for commit and rollback cbus > messages, called tx_complete_batch(). This change will come in > hand in scope of synchronous replication, when WAL write won't be > enough for commit. And therefore 'commit' as a concept should be > washed away from WAL's code gradually. Migrate to solely txn > module. The reason it has to be managed in TX is that you don't want to build synchronous replication on top of in-memory relay, which would allow you to manage RAFT rollback in WAL. When I called you out on the fact that you can't simply build your implementation on top of existing code without an in-memory relay, and it will require a bunch of hacks you got mad at me. Now what? You will ask Nikita to review this and Kirill will "LGTM" it and you will proceed with your own design - and even may release it as a "stable" version over some time. This "stable version may be even useful to some people. Will it be worth a dime on a worldwide scale? No. -- Konstantin Osipov, Moscow, Russia