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

[Prof. E. M. G. <eti...@uq...>]

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).

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...

This means I should probably double-check whether sched_yield is
actually a POSIX compliant function?  (No GNU specific code allowed;
SableVM makes portability claims).

Etienne

-- 
Etienne M. Gagnon, Ph.D.             http://www.info.uqam.ca/~egagnon/
SableVM:                                       http://www.sablevm.org/
SableCC:                                       http://www.sablecc.org/