Hi Marc,
Thank you very much for your pointer, I believe I'm OK with my data residing in struct
st_my_thread_var with the common key THR_KEY_mysys for now. However if the need changes
in the future I will definitely take a look at what you have done. I appreciate you
taking time to answer my question.
Hiromichi
--- On Wed, 4/27/11, Marc Alff <marc.alff@stripped> wrote:
> From: Marc Alff <marc.alff@stripped>
> Subject: Re: Use of thread specific data with mysqld
> To: internals@stripped, hiromichiwatari@stripped
> Cc: "Sergei Golubchik" <serg@stripped>
> Date: Wednesday, April 27, 2011, 1:14 AM
>
> Hi Hiromichi
>
> The performance schema also uses it's own thread local
> storage, with a dedicated thread key.
>
> Examples of code from storage/perfschema/*.cc:
>
> Init:
>
> if (pthread_key_create(&THR_PFS,
> destroy_pfs_thread))
> return NULL;
>
> THR_PFS_initialized= true;
>
> Anything between init and destroy:
>
> PFS_thread *pfs_thread=
> my_pthread_getspecific_ptr(PFS_thread*, THR_PFS);
> my_pthread_setspecific_ptr(THR_PFS, pfs);
>
> Destroy:
>
> /*
> Be careful to not delete un-initialized
> keys,
> this would affect key 0, which is
> THR_KEY_mysys,
> */
> if (THR_PFS_initialized)
> {
> my_pthread_setspecific_ptr(THR_PFS, NULL);
> pthread_key_delete(THR_PFS);
> THR_PFS_initialized= false;
> }
>
> Note the code around THR_PFS_initialized: this was found
> the hard way, destroying a key that was not properly created
> caused all sort of chaos, so calls to pthread_key_create()
> and pthread_key_delete() have to be *really* well balanced.
>
> I hope this helps.
>
> Regards,
> -- Marc
>
>
> On 4/26/11 1:19 PM, Hiromichi Watari wrote:
> > Hi Sergei,
> > I tried but I just couldn't make my own thread
> specific data to coexist with structure st_my_thread_var so
> I ended up moving my data to the structure and used it
> instead.
> > I suppose there is really no reason to reinvent the
> wheel, is there ?
> > But anyway, thank you for your help and you are the
> best.
> > Hiromichi
> >
> >
> > --- On Sun, 4/24/11, Sergei Golubchik<serg@stripped>
> wrote:
> >
> >> From: Sergei Golubchik<serg@stripped>
> >> Subject: Re: Use of thread specific data with
> mysqld
> >> To: "Hiromichi Watari"<hiromichiwatari@stripped>
> >> Cc: internals@stripped
> >> Date: Sunday, April 24, 2011, 5:04 PM
> >> Hi, Hiromichi!
> >>
> >> On Apr 24, Hiromichi Watari wrote:
> >>> Hi,
> >>> I'm trying to use thread specific data with
> mysqld but
> >> ran into a problem with my_errno generating
> Segmentation
> >> fault at the following line.
> >>> I know that my_errno is also thread specific
> data but
> >> not familiar with its implementation.
> >>> I'm using pthread_key_create(),
> pthread_setspecific()
> >> and pthread_getspecific() for my own thread
> specific data,
> >> is there something I should be aware of ?
> >>> Thanks,
> >>> Hiromichi
> >>>
> >>> p.s. I ran into this problem only if I try to
> use my
> >> own thread specific data, of course.
> >>
> >> probably you forgot to call my_thread_init() in
> the
> >> beginning of your
> >> thread function.
> >>
> >> Anyway, here's the code:
> >>
> >> #define my_errno my_thread_var->thr_errno
> >>
> >> #define my_thread_var (_my_thread_var())
> >>
> >> struct st_my_thread_var *_my_thread_var(void)
> >> {
> >> return
> my_pthread_getspecific(struct
> >> st_my_thread_var*,THR_KEY_mysys);
> >> }
> >>
> >> my_bool my_thread_init(void)
> >> {
> >> ...
> >> if (!(tmp= (struct
> st_my_thread_var *)
> >> calloc(1, sizeof(*tmp))))
> >> {
> >> error= 1;
> >> goto end;
> >> }
> >>
> pthread_setspecific(THR_KEY_mysys,tmp);
> >> ...
> >> }
> >>
> >> Regards,
> >> Sergei
> >>
>
>
