maria-developers team mailing list archive

[Sergei Golubchik <serg@xxxxxxxxxxx>]

Hi, Oleksandr,

On Oct 19, Oleksandr Byelkin wrote:
> On Wed, Oct 19, 2022 at 5:09 PM Sergei Golubchik <serg@xxxxxxxxxxx> wrote:
> > On Oct 19, Oleksandr Byelkin wrote:
> > >
> > >    if (share->view_def->parse((uchar *) &share->tabledef_version, NULL,
> > >                               view_timestamp_parameters, 1,
> > >                               &file_parser_dummy_hook))
> > > +  {
> > > +    // safety if the definition file is brocken
> > > +    share->tabledef_version.length= 0;
> >
> > when can view_def->parse() fail? _Only_ if the definition is invalid?
> > Can it succeed for one TABLE and fail for another, both of the same
> > TABLE_SHARE?
> 
> Also if there is no memory.
> 
> If for the other table there will be more memory or file has changed
> it can succeed.

My point is that if it is possible that two different threads would get
different results from share->view_def->parse(), then you cannot update
the shared share->tabledef_version.length without a lock. And you cannot
read it without a lock.

So if it is possible that two different threads would get different
results from share->view_def->parse(), then it's best not to update
share->tabledef_version.length here and only do it in open_table_def().
 
Regards,
Sergei
VP of MariaDB Server Engineering
and security@xxxxxxxxxxx