Re: [Boost-users] Re: Re: Semaphore and barriers for boost-threads?

From: Victor A. Wagner, Jr. (vawjr_at_[hidden])
Date: 2004-02-18 17:28:52

At Wednesday 2004-02-18 08:15, you wrote:
>Craig Rodrigues wrote:
>
> > OK, well I don't do much Windows programming, so I don't
> > really understand what event variables are.  I'll have to do
> > my homework and read up on them.
> >
> > In terms of explaining what a semaphore is,
> > my frame of reference is the stuff in POSIX:
> >
> > http://www.opengroup.org/onlinepubs/007904975/functions/sem_post.html
> > http://www.opengroup.org/onlinepubs/007904975/functions/sem_wait.html
> > http://www.opengroup.org/onlinepubs/007904975/functions/sem_trywait.html
> > http://www.opengroup.org/onlinepubs/007904975/functions/sem_timedwait.html
> >
> > Basically, a semaphore is initialized with a count.
> > When you call sem_post(), the semaphore count is incremented.
> > When you call sem_wait(), if the semaphore count is 0, then the
> > thread blocks, else the semaphore count is decremented.
>
>The interesting part of "POSIX on semaphores" is in
>
>     http://tinyurl.com/2s89
>
>Look the the phrase "Much experience with semaphores shows" and futher
>paragraphs. In essense, it's says that semaphores are for signal handlers
>and for inter-process synchronization and discourages their use anywhere
>else.

fine....does this mean we can get semaphores now?
or is it still considered "too dangerous" to let people who've been aware 
of the limitations since before boost existed actually USE them?

>- Volodya
>
>
>
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Victor A. Wagner Jr.      http://rudbek.com
The five most dangerous words in the English language:
               "There oughta be a law"