Re: Structure of the multitasking server

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

On 19 Wrz, 19:02, "Dmitry A. Kazakov" <mail...@dmitry-kazakov.de>
wrote:

> Note that task termination is usually a difficult problem in Ada. You
> should pay an attention to this early.

No problem with that. With separate protected object (instead of
rendezvous) it is enough to do this:

   protected type Channel_State is
      procedure Post (J : in Job_Type);
      procedure Finish;
      entry Get_Job (J : out Job_Type; Finished : out Boolean);
      function Busy return Boolean;
   private
      State : Worker_State := Idle;
      Job_To_Do : Job_Type;
      Should_Finish : Boolean := False;
   end Channel_State;

and later in the worker task:

      loop
         Ch.all.Get_Job (Job, Finished);
         exit when Finished;

         --  do the job ...

      end loop;


There is no need to introduce any special type of job ("poison pill").
Above, the job space is not polluted with task lifetime management
concepts - these should be kept separate.

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

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