[tarantool-patches] [PATCH 3/7] Replication: Relay does not rely on xlog boundaries

[Vladimir Davydov]

On Tue, Aug 13, 2019 at 09:27:41AM +0300, Georgy Kirichenko wrote:
> When relay got an ACK then it matches received vclock against xlog file
> boundaries detected using on_close_log trigger and send a consumer
> advance message. However, for each ACK relay send a status update
> message to the tx cord which could be used for gc purposes.
> This patch removes any knowledge about xlog boundaries from relay
> because there would not any xlog files in case of in-memory replication.
> As gc now tracks all xlog files then it is able to handle garbage files
> using relay status updates.
> 
> Note: after parallel applier there is no more one ACK per transaction
> so it should not be too expensive to advance a consumer on each status
> update. However I think it could be improved, for instance with tracking
> the next wal file vclock.

I don't see a way to preserve the old behavior after switching to
replication from memory so I guess this patch is okay.