Thinking about kqueue's and pthread_cond_wait

Randall Stewart rrs at lakerest.net
Wed Feb 10 14:09:02 UTC 2010


All:

I have once again come around to thinking about joining pthread cond  
waits and
kqueue's.

After thinking about it, I think its doable.. with something like a:

pthread_cond_wait_kqueue_np(kev, cond, mtx, ucontext)

Then you can use kev inside a kqueue i.e.
  ret =  kevent(kq, kev, 1, outkev, 1, NULL);

Now when you saw the event:
    if (kev.filter == EVFILT_UMTX){   /* not sure about the name here */
         pthread_kqueue_cond_wait_ret_np(kev, cond, mtx, ucontext)
         do_user_action(cond,mtx, ucontext);
     }

Which would fill in the cond/mtx and ucontext for the user.

Now does this sound useful to anyone.. i.e. should I spend the time
making it work?

The only down side to this is that it would have to allocate memory so
one would need to do a:

     pthread_kqueue_cond_wait_free_np(kev)

After you were done.. and I think it would be best for this to
be a ONE_SHOT.. i.e. you have to re-arm it if the event happens...
Of course until you free it that can be as simple as passing the kev
back down again (i.e. no pthread_cond_wait_kqueue_np() needed).

Comments? Thoughts?  i.e. especially is it worthwhile doing?


Thanks


R
------------------------------
Randall Stewart
803-317-4952 (cell)



More information about the freebsd-threads mailing list