Re: task time-out&abort

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

On 23 Jun 2005 03:11:13 -0700, e.coli wrote:

> my goal is kill the task if the calculation is long more than 5 sec,.

I would propose to use a more co-operative way than rather brutal aborting
of a task (which is still possible, of course). What about this:

with Ada.Text_IO;

procedure Semplice2 is --processo genitore
   task Un_Task is
      entry Start;    -- Starts calculation
      entry Drop_It;  -- Aborts calculation
      entry Wait_For; -- Waits for the results
   end Un_Task;

   task body Un_Task is
   begin
      loop
         select
            accept Start;
            Ada.Text_Io.Put_Line ("Start");
            for Iteration in 1..10_000 loop
               select
                  accept Drop_It;
                  goto Cancel;
               else
                  delay 1.0;  -- Doing things
               end select;
            end loop;
            accept Wait_For;
<<Cancel>>  null;            
         or terminate;
         end select;
      end loop;
   end Un_Task;

begin
   Un_Task.Start;
   Ada.Text_Io.Put_Line ("wait for a horribly long calculation");
   select
      delay 5.0;
      un_task.Drop_It;
      Ada.Text_Io.Put_Line ("Horribly long calculation abandoned");
   then abort
      un_task.Wait_For;
      Ada.Text_Io.Put_Line ("Horribly long calculation ready");
   end select;
end Semplice2;

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