Code review comment for lp:~akopytov/percona-server/bug1131187-5.6

Hi Laurynas,

On Fri, 24 May 2013 09:25:35 -0000, Laurynas Biveinis wrote:
>
> - Upstream read_view_create_low() allocates the read view and its
> trx_ids in a single allocation. After the fix we are back to
> two allocations. It is possible to have a single allocation
> for us too, but I'm not sure whether it's worth it: on one
> hand, it's a single ut_realloc() anyway when trx_ids grows, on
> the other, reallocating the whole view would improve access
> locality and saves one memcpy() in read_view_clone(). Shall we
> open a bug for this or there is no benefit?
>

Yes I was considering that, but didn't like it. That would reduce
flexibility for some further work (and the fact that upstream code
relies on specific layout of data structures in memory is also
problematic). I don't think one extra mempcy() in read_view_clone() will
have any measurable effect.