Re: [Boost-users] boost::thread flush()?

From: Graham Reitz (graham.cpp_at_[hidden])
Date: 2007-06-20 17:44:20

Excellent and thanks!   I completely missed boost:condition.

Graham

On 6/18/07, Tobias Schwinger <tschwinger_at_[hidden]> wrote:
>
> Zeljko Vrba wrote:
> > On Mon, Jun 18, 2007 at 10:48:14AM -0500, Graham Reitz wrote:
> >> Is there a method  to release all threads waiting on a mutex?  Or, more
> >> generally, a portable way to release a bunch of threads at the same
> time?
> >> (boost::asio?)
> >>
> >> I didn't see anything in the docs, besides barrier.  Unfortunately, I
> can't
> >> guarantee the N threads will be waiting when a flush is needed.
> >>
> >
> > You want a SYSV-style semaphore (semget/semop/semctl in POSIX; seems not
> to
> > be provided by Boost.Thread).
>
> Not necessarily. It depends on whether we want a thread that reaches the
> synchronization point after the "go" to pass (as when downing a
> semaphore) or to stop (as with a missed condition notification).
>
> Judging from the OP, the Semaphore-approach seems a bit fragile, because
> if a thread misses the "go" twice, another thread won't stop as expected
> (because a down is missing).
>
> Generally, semaphores are very powerful and just as error prone. That's
> why higher-level synchronization primitives should be preferred, if
> available.
>
> Regards,
> Tobias
>
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