Re: Arguments for single-mutex-exclusion on protected types (Was: Does Ada tasking profit from multi-core cpus?)

["Randy Brukardt" <randy@rrsoftware.com>]

"Jeffrey R. Carter" <jrcarter@acm.org> wrote in message
news:B0ULh.28294$PF.23764@attbi_s21...
> Randy Brukardt wrote:
> >
> > Nothing serious, but it's less than ideal:
>
> My concern was that you said it was impossible in Ada 95. It may not be
> ideal, but it doesn't seem to be impossible.

I was thinking about a solution that doesn't clutter the cliient's view of
the library with (usually) irrelevant details (such as whether the library
is implemented with protected objects). After all, information hiding is
good! If you're willing to ignore that (and you are), then it certainly is
possible. But I was thinking about a library that uses as the ceiling
whatever the highest priority it is called with: that can't be implemented
in Ada 95. (Such a library would not make anything having to do with
priorities visible.)

If you really care about priorities, then your solution is probably better
(it allows more analyzability). Which just demonstrates that you can't just
make something "task-safe". You have to answer the question of "task-safe
for what?". And that tends to lead to families of libraries rather than an
all-in-one solution (like Ada.Containers) - or impacts reusability.

                                     Randy.