Thinking about kqueue's and pthread_cond_wait

[Daniel Eischen]

On Wed, 10 Feb 2010, Randall Stewart wrote:

>
>
> while (notdone) {
>    nev = kevent(kq, , ev);
>    if (ev.fitler == EVFILTER_READ) {
>         handle_the_read_thingy(ev);
>    } else if (ev.filter == EVFILTER_COND) {
>         lock_mutex(if needed)
>         handle_condition_event();
>    }
> }
>
>
> One of the things I will note about a condition variable is that the downside 
> is
> you ALWAYS have to have a mutex.. and not always do you need one... I have 
> found
> multiple times in user apps where i am creating a mutex only for the benefit 
> of
> the pthread_cond() api... sometimes just being woken up is enough ;-)

[ I didn't see that you were waiting on multiple CVs... ]

I don't understand why you need to wait on multiple
condition variables.  Either way, you have to maintain
a queue of them along with their associated mutexes and
then take some action unique to each one of them.  What
is the difference between that and maintaining a queue of
some other thingies that maintain similar state data?

-- 
DE