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From: Serge Petrenko via Tarantool-patches <tarantool-patches@dev.tarantool.org>
To: Cyrill Gorcunov <gorcunov@gmail.com>,
	tml <tarantool-patches@dev.tarantool.org>
Cc: Vladislav Shpilevoy <v.shpilevoy@tarantool.org>
Subject: Re: [Tarantool-patches] [PATCH v17 3/5] qsync: track confirmed_lsn upon CONFIRM packet
Date: Mon, 27 Sep 2021 10:05:36 +0300	[thread overview]
Message-ID: <e52585b5-4586-d2c6-fb41-96206314a7e5@tarantool.org> (raw)
In-Reply-To: <20210922130535.79479-4-gorcunov@gmail.com>



22.09.2021 16:05, Cyrill Gorcunov пишет:
> While been investigating various cluster split-brain scenarios and
> trying to gather valid incoming synchro request domains and ranges
> we've discovered that limbo::confirmed_lsn updated not dense enough
> to cover our needs.
>
> In particular this variable is always updated by a limbo owner upon
> write of syncro entry (to a journal) while replica just reads such
> record without confirmed_lsn update, so when the replica become a cluster
> leader it sends a promote request back to the former leader where the
> packet carries zero LSN instead of previous confirmed_lsn and validation
> of such packet won't pass.
>
> Note the packet validation is not yet implemented in this patch so it
> is rather a preparatory work for future.
>
> Part-of #6036
>
> Signed-off-by: Cyrill Gorcunov <gorcunov@gmail.com>
> ---
>   src/box/txn_limbo.c | 14 ++++++++++++++
>   1 file changed, 14 insertions(+)
>
> diff --git a/src/box/txn_limbo.c b/src/box/txn_limbo.c
> index eb9aa7780..959811309 100644
> --- a/src/box/txn_limbo.c
> +++ b/src/box/txn_limbo.c
> @@ -774,6 +774,20 @@ txn_limbo_process_run(struct txn_limbo *limbo,
>   	switch (req->type) {
>   	case IPROTO_RAFT_CONFIRM:
>   		txn_limbo_read_confirm(limbo, lsn);
> +		/*
> +		 * We have to adjust confirmed_lsn according
> +		 * to LSN coming from the request. It is because
> +		 * we will need to report it as old's limbo owner
> +		 * LSN inside PROMOTE requests (if administrator
> +		 * or election engine will make us so).
> +		 *
> +		 * We could update confirmed_lsn on every
> +		 * txn_limbo_read_confirm call but this function
> +		 * is usually called in a couple with
> +		 * txn_limbo_write_confirm, thus to eliminate redundant
> +		 * variables update we make so once but explicitly.
> +		 */
> +		limbo->confirmed_lsn = req->lsn;
>   		break;
>   	case IPROTO_RAFT_ROLLBACK:
>   		txn_limbo_read_rollback(limbo, lsn);
LGTM.

-- 
Serge Petrenko


  parent reply	other threads:[~2021-09-27  7:05 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-22 13:05 [Tarantool-patches] [PATCH v17 0/5] qsync: implement packet filtering (part 1) Cyrill Gorcunov via Tarantool-patches
2021-09-22 13:05 ` [Tarantool-patches] [PATCH v17 1/5] latch: add latch_is_locked helper Cyrill Gorcunov via Tarantool-patches
2021-09-22 13:05 ` [Tarantool-patches] [PATCH v17 2/5] qsync: order access to the limbo terms Cyrill Gorcunov via Tarantool-patches
2021-09-26 14:29   ` Vladislav Shpilevoy via Tarantool-patches
2021-09-27  7:42     ` Cyrill Gorcunov via Tarantool-patches
2021-09-22 13:05 ` [Tarantool-patches] [PATCH v17 3/5] qsync: track confirmed_lsn upon CONFIRM packet Cyrill Gorcunov via Tarantool-patches
2021-09-26 14:29   ` Vladislav Shpilevoy via Tarantool-patches
2021-09-27  7:05   ` Serge Petrenko via Tarantool-patches [this message]
2021-09-22 13:05 ` [Tarantool-patches] [PATCH v17 4/5] qsync: export more details on promote tracking Cyrill Gorcunov via Tarantool-patches
2021-09-27  7:00   ` Serge Petrenko via Tarantool-patches
2021-09-27  7:58     ` Cyrill Gorcunov via Tarantool-patches
2021-09-22 13:05 ` [Tarantool-patches] [PATCH v17 5/5] test: add gh-6036-term-order test Cyrill Gorcunov via Tarantool-patches
2021-09-26 14:30   ` Vladislav Shpilevoy via Tarantool-patches
2021-09-27 10:08     ` Cyrill Gorcunov via Tarantool-patches
2021-09-27  7:13   ` Serge Petrenko via Tarantool-patches
2021-09-27  7:33     ` Cyrill Gorcunov via Tarantool-patches

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