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Date:      Wed, 10 Feb 2010 09:25:52 -0800
From:      Randall Stewart <rrs@lakerest.net>
To:        Daniel Eischen <deischen@freebsd.org>
Cc:        threads@freebsd.org
Subject:   Re: Thinking about kqueue's and pthread_cond_wait
Message-ID:  <3CF3033E-FD13-405B-9DC6-DDE9DF4FBF37@lakerest.net>
In-Reply-To: <Pine.GSO.4.64.1002101202060.13656@sea.ntplx.net>
References:  <3581A86D-9C9C-4E08-9AD3-CD550B180CED@lakerest.net> <Pine.GSO.4.64.1002101202060.13656@sea.ntplx.net>

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On Feb 10, 2010, at 9:04 AM, Daniel Eischen wrote:

> On Wed, 10 Feb 2010, Randall Stewart wrote:
>
>> 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?
>
> Please don't mess with the pthread_ API like that :-)  If you
> really want to munge them together, see my email to you a few
> weeks ago last time you brought it up.'

If I remember right your email was basically don't do it... I will
go dig through the archives and re-read it all.

R


>
> -- 
> DE
>

------------------------------
Randall Stewart
803-317-4952 (cell)
803-345-0391(direct)




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