From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-lj1-f171.google.com (mail-lj1-f171.google.com [209.85.208.171]) (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 94F464696C3 for ; Thu, 2 Apr 2020 19:43:13 +0300 (MSK) Received: by mail-lj1-f171.google.com with SMTP id p14so3920910lji.11 for ; Thu, 02 Apr 2020 09:43:13 -0700 (PDT) Date: Thu, 2 Apr 2020 19:43:11 +0300 From: Konstantin Osipov Message-ID: <20200402164311.GA9239@atlas> References: <20200402132948.12804-1-arkholga@tarantool.org> <20200402134743.GB30577@atlas> <1d29a21b-78bd-d3a8-0210-fb8f9690aea4@tarantool.org> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <1d29a21b-78bd-d3a8-0210-fb8f9690aea4@tarantool.org> Subject: Re: [Tarantool-patches] [PATCH rfc 0/1] replication: stop resetting existing connections List-Id: Tarantool development patches List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Olga Arkhangelskaia Cc: tarantool-patches@dev.tarantool.org * Olga Arkhangelskaia [20/04/02 19:07]: > 02.04.2020 16:47, Konstantin Osipov пишет: > > * Olga Arkhangelskaia [20/04/02 16:30]: > > > > Could you please explain the idea of the patch? > > > > As far I can see, you do some strcmp magic to understand if the > > uri is the same. > Yes. > > > > Why not use instance uuids? > > I did not think of uuids in such a way. But  after reading your description > it > > seems good idea (As I understand  even if we have 3301 and localhost:3301 > they will have the same uuid). > > But I am not sure about appliers that should be removed. > > If there is no UUIDS of existing applier in new appliers pool it should be > removed? > > And we still need to do all this work even if we just changed order in the > config. We could perhaps optimize things based on some heuristics, like old and new uri match 100%, but first we need to settle on the main algorithm. E.g. one variation could be that, given appliers are ref-counted, we do not create a new applier for a 100% match, but simply add it directly to the new uuid -> applier hash. Please suggest an edit to this: > > > 0) Introduce uuid -> applier hash. > > 1) Create new appliers for all entries in replication. > > 2) Establish connections, but do not issue SUBSCRIBE yet. > > 3) Look at connection server uuids. If this uuid is already > > connected to, then (easy) quietly close the new connection, > > and add existing connection to the new instance of uuid hash. > > 4) Add the new connection to the new instance of uuid hash. > > If there is a duplicate in the *new* instance of the uuid hash, > > produce "duplicate connection" error. Otherwise remove/delete all > > appliers that are left in the old uuid hash. > > > > Perhaps we need applier reference counting to make this work > > smoothly -- Konstantin Osipov, Moscow, Russia