Re: [boost] [thread] countdown_latch

Subject: Re: [boost] [thread] countdown_latch
From: Vicente J. Botet Escriba (vicente.botet_at_[hidden])
Date: 2013-04-27 03:05:40

Le 22/04/13 10:16, Michael Marcin a écrit :
> On 4/21/2013 11:30 PM, Vicente J. Botet Escriba wrote:
>
Hi,
> Back on topic of latches and barriers.
> I was reading up on Java's CyclicBarrier and found its await return 
> value pretty interesting and probably fairly free to implement.
>
> "...each invocation of await() returns the arrival index of that 
> thread at the barrier."
>
> "the arrival index of the current thread, where index getParties() - 1 
> indicates the first to arrive and zero indicates the last to arrive."
>
> To do this in boost::thread::barrier you would just have to cache 
> m_count right after the decrement and return it instead of the current 
> true/false.
>
>

Yes, boost::barrier return true for the last wait. The change would be 
quite simple, but what would be he utility of such an index?

I have implemented a first prototype of a latch class that could be used 
also as a barrier. I don't know if the name is the good one then.
I have also implemented a completion_latch class that is able to call a 
function when the counter reaches zero. I'm not satisfied with the 
current implementation as it needs a lot of synchronization.

The change set is  https://svn.boost.org/trac/boost/changeset/84055. To 
see the sources, you would need to update the trunk or to take a look at 
https://svn.boost.org/svn/boost/trunk/boost/thread/

Please let me know what do you think.

Best,
Vicente