Re: Termination of periodic tasks

["Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>]

On Tue, 17 Jun 2014 13:14:23 -0700, Charles H. Sampson wrote:

> Natasha Kerensikova <lithiumcat@instinctive.eu> wrote:
> 
>> Hello,
>> 
>> On 2014-06-15, J-P. Rosen <rosen@adalog.fr> wrote:
>>> Le 15/06/2014 12:10, Natasha Kerensikova a écrit :
>>>> And same as before, the task should be able to terminate quickly when
>>>> the program terminates.
>>> Why not have a "stop" entry called by the main program when it
>>> terminates (possibly through an exported subprogram if you don't want to
>>> have the task public)?
>> 
>> Mostly because I believe this to be too heavy for a burden for the
>> client, and somewhat of an abstraction leak.
> 
>      I'm having trouble understanding how this is too heavy. In most
> programs I've written, there's a possibility of stopping. Usually the
> need to stop is detected by or, most commonly, propagated to the main
> program. The main program then signals all of its library packages to do
> whatever is necessary for stopping. An exported Stop subprogram seems a
> quite natural way to do that.

That is true. I am writing a lot of code with tasking and was unaware of
the issue with library level tasks.

>      I've even used implementations that have exported Stop subprograms
> in all library packages, some of them null. That enforces the
> abstractions in that the main program doesn't need to know which library
> packages need to be wrapped up.

I prefer a stateless design of packages with explicit objects maintaining
the state, created by the client. That eliminates the problem of task
termination too.

-- 
Regards,
Dmitry A. Kazakov
http://www.dmitry-kazakov.de