[Python-Dev] pthreads question: typedef ??? pthread_t and hacky return statements

[Trent Mick]

I am porting Python to Monterey (64-bit AIX) and have a small (hopefully)
question about POSIX threads. I have Monterey building and passing the
threads test suite using Python/thread_pthread.h with just one issue:


-------------- snipped from current thread_pthread.h ---------------
long
PyThread_get_thread_ident(void)
{
    volatile pthread_t threadid;
    if (!initialized)
        PyThread_init_thread();
    /* Jump through some hoops for Alpha OSF/1 */
    threadid = pthread_self();
    return (long) *(long *) &threadid;
}
-------------------------------------------------------------------

Does the POSIX threads spec specify a C type or minimum size for
pthread_t? Or can someone point me to the appropriate resource to look
this up. On Linux (mine at least):
  /usr/include/bits/pthreadtypes.h:120:typedef unsigned long int pthread_t;

On Monterey:
  typedef unsigned int pthread_t;
 
That is fine, they are both 32-bits, however Monterey is an LP64 platform
(sizeof(long)==8, sizeof(int)=4), which brings up the question:

WHAT IS UP WITH THAT return STATEMENT?
  return (long) *(long *) &threadid;

My *guess* is that this is an attempt to just cast 'threadid' (a pthread_t)
to a long and go through hoops to avoid compiler warnings. I dont' know what
else it could be. Is that what the "Alpha OSF/1" comment is about? Anybody
have an Alpha OSF/1 hanging around. The problem is that when
sizeof(pthread_t) != sizeof(long) this line is just broken.

Could this be changed to
  return threadid;
safely?


Thanks,
Trent

-- 
Trent Mick
TrentM@ActiveState.com