[Tarantool-patches] [PATCH] relay: yield explicitly every N sent rows

[Vladislav Shpilevoy]

Hi! Thanks for the fixes!

> diff --git a/src/box/relay.cc b/src/box/relay.cc
> index 1d8edf116..6d9269e1d 100644
> --- a/src/box/relay.cc
> +++ b/src/box/relay.cc
> @@ -117,6 +117,11 @@ struct relay {
>          * is passed by the replica on subscribe.
>          */
>         uint32_t id_filter;
> +       /**
> +        * How many rows has this relay sent to the replica. Used to yield once
> +        * in a while when reading a WAL to unblock the event loop.
> +        */
> +       size_t row_cnt;

1. But it is not a size of anything, right? Maybe make it
int64_t then?

> @@ -846,7 +851,7 @@ relay_send(struct relay *relay, struct xrow_header *packet)
>          * It may happen that the socket is always ready for write, so yield
>          * explicitly every now and then to not block the event loop.
>          */
> -       if (++row_cnt % WAL_ROWS_PER_YIELD == 0)
> +       if (++relay->row_cnt % WAL_ROWS_PER_YIELD == 0)

2. I just found WAL_ROWS_PER_YIELD is not a power of 2. This means
'%' may be expensive. If WAL_ROWS_PER_YIELD would be a power of 2,
'%' would be turned by the compiler into '&' to cut the remainder off.

Maybe worth changing in a separate non-related to this bug commit?