Subj : Re: Can you limit the number of Posts to a POSIX semaphore?
To   : comp.programming.threads
From : the_edge123.nospam
Date : Wed Aug 10 2005 01:55 am


Frank J. Lhota a =E9crit :

> I'm looking into porting a Win32 program to Linux. This program makes
> use of the fact that a Win32 semaphore is created with both an initial
> value and a maximum value. For example,
>
>      hSem =3D CreateSemaphore (NULL, 1, 3, NULL);
>
> creates a semaphore with an initial value of 1 and a maximum value of 3.
> If ReleaseSemaphore (the Win32 version of sem_post) is called for hSem
> when its value is already equal to 3, then ReleaseSemaphore fails with
> an error code of ERROR_TOO_MANY_POSTS, and the value of hSem is not
> incremented.
>
> Is there an easy way to do this with POSIX semaphores? AFAICT there is a
>   fairly large, system-wide upper limit on the value of a POSIX sem_t
> value. What I am looking for is something that works like sem_t, except
> that we can set an upper limit (other than SEM_VALUE_MAX) on the value
> of the semaphore.
>=20
> Any help would be most appreciated.
>=20
You may use sem_getvalue...

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