Re: Need a Sanity Check

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

"mark" <ati@san.rr.com> wrote in message
news:1116619695.361267.218380@g49g2000cwa.googlegroups.com...
> "(but an accept statement cannot be called from within a protected
> subprogram or entry)."
>
> Is that a language restriction?  Compiling using GNAT I get -
>
>      warning: potentially blocking operation in protected operation
>
> when calling another tasks entry point from within a protected entry.
> I'm sure its not going to block based on the task it is calling has a
> single accept and is only called from this protected entry.   The task
> called does nothing special besides dump a buffer to disk.  Doing it
> this way just decouples the disk write from the rest of the system.
>
> So, is GNAT not enforcing language standards or is that really not part
> of the standard?

It's a bounded error, meaning that it either raises Program_Error or goes
forward (which might cause deadlock). In any case, it is not checked at
compile-time (because you could call anything from a protected object). And
even if it works on a specific compiler, it's not portable; another compiler
might raise Program_Error. Note that Ada 2006 adds a pragma Detect_Blocking,
which changes this to a requirement to raise Program_Error. (That's part of
Ravenscar, but I generally recommend it to everyone, because it makes the
behavior predictable.)

                           Randy.