Re: [Sablevm-developer] java.lang.Thread.yield()

[Bruno D. <bru...@ma...>]

Hi Chris,

	Etienne is right. You do not need to know where JNI_OK is defined. Unless you 
want to modify the value (and you don't want to that, of course), you should 
not care. But to satisfy your curiosity, look at 
src/libsablevm/include/jni.h. This is the standard place to define it, BTW. 
You should have been able to find that easily using grep.

Cheers,

	Bruno

On Thursday 20 February 2003 02:35 am, Chris Pickett wrote:
> Hi Etienne,
>
> Prof. Etienne M. Gagnon wrote:
> >On Wed, Feb 19, 2003 at 08:36:58PM -0500, Chris Pickett wrote:
> >>I don't know what JNI_OK is defined to be (I couldn't find it with
> >>grep), but if it's zero then that's:
> >>
> >>if (sched_yield() != JNI_OK)
> >>   _svmf_error_InternalError (env);
> >
> >No!!!!  JNI_OK is used by _svmf_* functions to indicate success.  You
> >should never make any relation between the actual integer value JNI_OK
> >is defined as, and the accidental value it matches in another context!
> >
> >
> >If I decided to change JNI_OK to be defined as 36, the code above
> >would start misbehaving (assuming JNI_OK was originally defined as
> >zero).
>
> Okay.  Where is JNI_OK defined?
>
> >Also, you should *ALWAYS* check return values of non-void functions.
> >I had not double-checked if sched_yield returned a value.  I guess I
> >should never trust submitted code and review thoroughly every line of
> >code and the documentation of every called library function...
>
> Well, actually, I realized last night about checking the error status,
> after I emailed you to say that I would send a patch today, but then
> today you had already committed the code.  Then I got caught up in
> making scripts, and didn't get around to telling you yet.
>
> sched_yield() returns 0 if there was no problem, or -1 if there was an
> error.
>
> sched_yield() is not necessarily posix compliant, so perhaps you'd
> better use pthread_yield() ... pthread_yield() doesn't return a value
> ever either, so just replace sched_yield() with pthread_yield() and
> forget about the error check.
>
> sched_yield() is in sched.h which is in the GNU C library, whereas
> pthread_yield() is in pthreads.  The only reason I used sched_yield()
> was because that's what you and Clark and I talked about.
>
> Sorry for not letting you know earlier and not checking the code I sent
> you.  Transgression #1.
>
> Chris