maria-developers team mailing list archive

Thread
Date

Re: 0918ae42a83: MDEV-14014 Multi-Slave Replication Fail: bogus data in log event

To: maria-developers@xxxxxxxxxxxxxxxxxxx
From: Sergei Golubchik <serg@xxxxxxxxxxx>
Date: Wed, 13 Jun 2018 16:29:38 +0200
In-reply-to: <201806131327.w5DDRKpK019768@localhost.localdomain>
User-agent: Mutt/1.7.2 (2016-11-26)

Hi, Andrei!

On Jun 13, andrei.elkin@xxxxxxxxxx wrote:
> revision-id: 0918ae42a8394b6faf28f67b70550894851be3bb (mariadb-10.1.33-36-g0918ae42a83)
> parent(s): 26be5072429082e634b8fc102609370975443439
> author: Andrei Elkin
> committer: Andrei Elkin
> timestamp: 2018-06-13 16:27:00 +0300
> message:
> 
> MDEV-14014 Multi-Slave Replication Fail: bogus data in log event
> 
> MDEV-7257 made a dump thread to read from binlog concurrently with
> writers as long as the read bytes are below a water-mark
> (MYSQL_BIN_LOG::binlog_end_pos). However it appeared to be possible a
> dump thread reader reach out for bytes past the water mark through a
> feature of IO_CACHE that fills in the internal buffer and while doing
> so it could read what the reader is not supposed to see (the bytes
> above MYSQL_BIN_LOG::binlog_end_pos).
> 
> The issue is fixed with constraining the IO_CACHE buffer fill to respect
> the watermark.
> An added test simulates potentially unconstrained buffer fill and an
> assert guards this is not the case anymore.

Looks good, thanks!

Regards,
Sergei
Chief Architect MariaDB
and security@xxxxxxxxxxx