[Info-vax] K-mutex

[Pierre]

On Dec 14, 7:43 pm, koeh... at eisner.nospam.encompasserve.org (Bob
Koehler) wrote:

>    Several months ago, I needed to emulate the POSIX semaphore routines.
>
>    Next time I saw release notes (8.4?), POSIX semaphore routines were
>    supported.
>
>    But I don't have that release of VMS at home, and I assume I never will
>    on my VAX.
>
>    I'll bet I can emaulate them on top of your mutex code, so thanks for
>    posting actual technical content in c.o.v.

as far as I understand POSIX semaphores, there is a major difference
with K-mutex : with semaphores, a process mark a resources slot as
been used but *any other* may free it. with K-mutex, only the process
that marked the resource slot as been used may free it.

the easiest way to emulate semaphores with the DLM is to use a lock
with a value block. this method is not fault-tolerant but neither are
semaphores (if a process crash before freeing the resource slot, this
slot may be totally  lost).

so, depending on what you want to do, one method or the other may fit
your problem.

BTW, what is c.o.v. ?