Re: Blocking syscalls in Tasks

[Maciej Sobczak <see.my.homepage@gmail.com>]

On 27 Wrz, 19:26, schwer...@gmail.com wrote:

> Are tasks commonly implemented using threads

You should expect that from the quality implementation. This not only
gives some nice properties for potentially blocking I/O calls (exactly
- that only the calling task gets blocked), but also allows to safely
use system-level synchronization primitives (like mutexes) for
interactions between tasks.
Not that this would be recommended over standard Ada mechanisms, but
it might actually happen even behind the scenes when using some
external library. Knowing that Ada tasks are just system threads in
disguise allows to use such libraries safely. Without this guarantee
the interoperability of Ada would be limited.

On the other hand, even this assumption (that tasks are threads in
disguise) is not enough to assert that Ada code can be safely executed
by threads that do not originate from or at least where not prepared
by the Ada runtime, althought in a quality implementation this might
be a very welcome property.
I don't know whether GNAT provides this property.

--
Maciej Sobczak * www.msobczak.com * www.inspirel.com

Database Access Library for Ada: www.inspirel.com/soci-ada